<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Publishing DTD v1.0 20120330//EN" "JATS-journalpublishing1.dtd">
<article article-type="review-article" dtd-version="1.0" xml:lang="en" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">KJIM</journal-id>
<journal-title-group>
<journal-title>The Korean Journal of Internal Medicine</journal-title><abbrev-journal-title>Korean J Intern Med</abbrev-journal-title></journal-title-group>
<issn pub-type="ppub">1226-3303</issn>
<issn pub-type="epub">2005-6648</issn>
<publisher>
<publisher-name>The Korean Association of Internal Medicine</publisher-name></publisher></journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.3904/kjim.2015.30.5.559</article-id>
<article-id pub-id-type="publisher-id">kjim-30-5-559</article-id>
<article-categories>
<subj-group>
<subject>Review</subject></subj-group></article-categories>
<title-group>
<article-title>A systematic approach for the diagnosis and treatment of idiopathic peptic ulcers</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name><surname>Chung</surname><given-names>Chen-Shuan</given-names></name>
<xref ref-type="aff" rid="af1-kjim-30-5-559"><sup>1</sup></xref>
</contrib>
<contrib contrib-type="author">
<name><surname>Chiang</surname><given-names>Tsung-Hsien</given-names></name>
<xref ref-type="aff" rid="af2-kjim-30-5-559"><sup>2</sup></xref>
</contrib>
<contrib contrib-type="author">
<name><surname>Lee</surname><given-names>Yi-Chia</given-names></name>
<xref ref-type="corresp" rid="c1-kjim-30-5-559"/>
<xref ref-type="aff" rid="af2-kjim-30-5-559"><sup>2</sup></xref>
</contrib>
<aff id="af1-kjim-30-5-559">
<label>1</label>Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei City, <country>Taiwan</country></aff>
<aff id="af2-kjim-30-5-559">
<label>2</label>Department of Internal Medicine, National Taiwan University Hospital, Taipei, <country>Taiwan</country></aff>
</contrib-group>
<author-notes>
<corresp id="c1-kjim-30-5-559">Correspondence to Yi-Chia Lee, M.D. Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, No.7, Chung Shan South Road, Zhongzheng Dist., Taipei 10002, Taiwan Tel: +886-2-23123456 ext.63351 Fax: +886-2-23412775 E-mail: <email>yichialee@ntu.edu.tw</email></corresp>
</author-notes>
<pub-date pub-type="ppub">
<month>9</month>
<year>2015</year></pub-date>
<pub-date pub-type="epub">
<day>27</day>
<month>8</month>
<year>2015</year></pub-date>
<volume>30</volume>
<issue>5</issue>
<fpage>559</fpage>
<lpage>570</lpage>
<history>
<date date-type="received">
<day>22</day>
<month>01</month>
<year>2015</year></date>
<date date-type="accepted">
<day>20</day>
<month>06</month>
<year>2015</year></date>
</history>
<permissions>
<copyright-statement>Copyright &#x000A9; 2015 The Korean Association of Internal Medicine</copyright-statement>
<copyright-year>2015</copyright-year>
<license>
<license-p>This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (<ext-link ext-link-type="uri" xlink:href="http://creativecommons.org/licenses/by-nc/3.0/">http://creativecommons.org/licenses/by-nc/3.0/</ext-link>) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.</license-p></license></permissions>
<abstract><p>An idiopathic peptic ulcer is defined as an ulcer with unknown cause or an ulcer that appears to arise spontaneously. The first step in treatment is to exclude common possible causes, including <italic>Helicobacter pylori</italic> infection, infection with other pathogens, ulcerogenic drugs, and uncommon diseases with upper gastrointestinal manifestations. When all known causes are excluded, a diagnosis of idiopathic peptic ulcer can be made. A patient whose peptic ulcer is idiopathic may have a higher risk for complicated ulcer disease, a poorer response to gastric acid suppressants, and a higher recurrence rate after treatment. Risk factors associated with this disease may include genetic predisposition, older age, chronic mesenteric ischemia, smoking, concomitant diseases, a higher American Society of Anesthesiologists score, and higher stress. Therefore, the diagnosis and management of emerging disease should systematically explore all known causes and treat underlying disease, while including regular endoscopic surveillance to confirm ulcer healing and the use of proton-pump inhibitors on a case-by-case basis.</p></abstract>
<kwd-group>
<kwd>Idiopathic peptic ulcer</kwd>
<kwd>Helicobacter pylori infection</kwd>
<kwd>Endoscopy</kwd>
</kwd-group>
</article-meta></front>
<body>
<sec sec-type="intro">
<title>INTRODUCTION</title>
<p><italic>Helicobacter pylori</italic> infection and non-steroidal anti-inflammatory drugs (NSAIDs) are common causes of peptic ulcer disease (PUD). However, in recent years, the global occurrence of non-<italic>H. pylori</italic>, non-NSAID PUD has increased. Management of this emerging disease is increasingly important. Although clinicians tend to describe non-<italic>H. pylori</italic>, non-NSAID PUD as idiopathic, the term &#x0201c;idiopathic&#x0201d; refers to a disease whose cause is not known or appears to arise spontaneously. Therefore, in addition to a missed diagnosis of <italic>H. pylori</italic> and the unrecognized use of NSAIDs/aspirin, a diagnosis of idiopathic peptic ulcer disease (IPUD) should also exclude all other recognized etiologies of PUD, which requires a systematic approach that considers all possible causes.</p>
</sec>
<sec>
<title>IS THE PROPORTION OR ABSOLUTE NUMBER OF IDIOPATHIC PEPTIC ULCERS INCREASING?</title>
<p>The management of PUD changed dramatically after the discovery of <italic>H. pylori</italic> as a major cause of chronic gastritis, peptic ulcer, and gastric cancer. Over half of the world&#x02019;s population is infected with <italic>H. pylori</italic>, especially in developing countries &#x0005b;<xref ref-type="bibr" rid="b1-kjim-30-5-559">1</xref>,<xref ref-type="bibr" rid="b2-kjim-30-5-559">2</xref>&#x0005d;. Historically, <italic>H. pylori</italic> infection was found in 90% to 100% of patients with duodenal ulcer (DU) and 60% to 100% of patients with gastric ulcer (GU) &#x0005b;<xref ref-type="bibr" rid="b3-kjim-30-5-559">3</xref>&#x0005d;. A test-and-treat strategy for <italic>H. pylori</italic> infection has been adopted as first-line management for patients with PUD, while a screen-and-treat strategy for <italic>H. pylori</italic> infection in the asymptomatic population has been considered as an effective approach to decrease future risk of gastric cancer &#x0005b;<xref ref-type="bibr" rid="b4-kjim-30-5-559">4</xref>,<xref ref-type="bibr" rid="b5-kjim-30-5-559">5</xref>&#x0005d;. These strategies have led to a continuous decline in the incidence of <italic>H. pylori</italic>-related peptic ulcers. Studies in Asia have also found that the incidence of <italic>H. pylori</italic> infection in younger patients has decreased &#x0005b;<xref ref-type="bibr" rid="b6-kjim-30-5-559">6</xref>-<xref ref-type="bibr" rid="b10-kjim-30-5-559">10</xref>&#x0005d;, probably due to improved sanitation and hygiene. Conversely, the global use of NSAIDs/aspirin is increasingly prevalent in an aging population and medical comorbidities are frequent. Thus, non-<italic>H. pylori</italic> PUD is relatively more common because of increased use of ulcerogenic drugs &#x0005b;<xref ref-type="bibr" rid="b11-kjim-30-5-559">11</xref>&#x0005d;.</p>
<p>Graham &#x0005b;<xref ref-type="bibr" rid="b12-kjim-30-5-559">12</xref>&#x0005d; proposed a model to illustrate the changing proportion of <italic>H. pylori</italic>-positive and -negative ulcer disease. If the <italic>H. pylori</italic> prevalence were to decline from 80% to 40%, and the risk of PUD from causes other than <italic>H. pylori</italic> were to remain stable at about 250 per 100,000 persons, the total number of ulcers would decrease from 1,050 to 650 per 100,000 persons, but the proportion of <italic>H. pylori</italic>-negative PUD would increase from 24% to 38% &#x0005b;<xref ref-type="bibr" rid="b12-kjim-30-5-559">12</xref>&#x0005d;. Epidemiological studies have consistently reported an increasing proportion of <italic>H. pylori</italic>-negative PUD, especially in Asian countries. Studies in the 1990s in the United States found that only about 6% of DUs were not associated with <italic>H. pylori</italic> infection, particularly in Caucasians &#x0005b;<xref ref-type="bibr" rid="b13-kjim-30-5-559">13</xref>&#x0005d;. However, later studies contradicted these results. A study in Orlando, Florida, found that only 32% of DU patients were <italic>H. pylori</italic>-positive, and only 25% of bleeding ulcers were associated with <italic>H. pylori</italic> &#x0005b;<xref ref-type="bibr" rid="b14-kjim-30-5-559">14</xref>&#x0005d;. A larger scale study including 305 cases showed that &#x0007e;35% of PUD was not associated with <italic>H. pylori</italic> or NSAIDs &#x0005b;<xref ref-type="bibr" rid="b15-kjim-30-5-559">15</xref>&#x0005d;, while a multicenter French study found that about 21.6% of patients with PUD had neither <italic>H. pylori</italic> infection nor a history of using ulcerogenic drugs &#x0005b;<xref ref-type="bibr" rid="b16-kjim-30-5-559">16</xref>&#x0005d;. Thus, it appears that the incidence of idiopathic ulcer remains stable in Western countries, in contrast to the increasing trend in Asian countries in recent years (<xref rid="f1-kjim-30-5-559" ref-type="fig">Fig. 1</xref>) &#x0005b;<xref ref-type="bibr" rid="b15-kjim-30-5-559">15</xref>-<xref ref-type="bibr" rid="b43-kjim-30-5-559">43</xref>&#x0005d;.</p>
<p>In Asian countries, a study published in 1991 revealed that only 6% of DUs were <italic>H. pylori</italic> negative, and when ulcerogenic agents were excluded the incidence was as low as 0.3% &#x0005b;<xref ref-type="bibr" rid="b17-kjim-30-5-559">17</xref>&#x0005d;. In a 2006 Japanese study, DU was idiopathic in one third of cases &#x0005b;<xref ref-type="bibr" rid="b38-kjim-30-5-559">38</xref>&#x0005d;, and the proportion of idiopathic ulcers was found to be as high as 40.6% in a Korean study conducted in 2007 &#x0005b;<xref ref-type="bibr" rid="b31-kjim-30-5-559">31</xref>&#x0005d;. The trend of increasing idiopathic ulcers appears to follow an exponential curve if we focus on large-scale studies with a study population &gt; 300) (<xref rid="f1-kjim-30-5-559" ref-type="fig">Fig. 1A</xref>) and exclude studies that included bleeding PUD (<xref rid="f1-kjim-30-5-559" ref-type="fig">Fig. 1B</xref>). As further evidence for the changing etiology, research conducted in Hong Kong found that only the absolute number of <italic>H. pylori</italic>-related bleeding ulcer was declining, while the number of <italic>H. pylori</italic>-negative bleeding ulcers remained stable &#x0005b;<xref ref-type="bibr" rid="b33-kjim-30-5-559">33</xref>,<xref ref-type="bibr" rid="b44-kjim-30-5-559">44</xref>-<xref ref-type="bibr" rid="b46-kjim-30-5-559">46</xref>&#x0005d;. Thus, the accumulated evidence supports the concept proposed by Graham &#x0005b;<xref ref-type="bibr" rid="b12-kjim-30-5-559">12</xref>&#x0005d;: non-<italic>H. pylori</italic>- and non-NSAIDs-related ulcer diseases are more likely to be found in older, sicker patients, are more resistant to acid suppression therapy, and are associated with a greater risk of bleeding and recurrence and a greater overall mortality rate as compared with traditional <italic>H. pylori</italic>-positive PUD &#x0005b;<xref ref-type="bibr" rid="b44-kjim-30-5-559">44</xref>,<xref ref-type="bibr" rid="b45-kjim-30-5-559">45</xref>&#x0005d;.</p></sec>
<sec>
<title>IDIOPATHIC PEPTIC ULCER DISEASE: A DIAGNOSIS OF EXCLUSION</title>
<p>Because IPUD is defined as PUD that arises without an identifiable cause, it is a diagnosis of exclusion. Possible etiologies to be excluded are shown in the <xref rid="t1-kjim-30-5-559" ref-type="table">Table 1</xref> (upper panel), which may include missed <italic>H. pylori</italic> infection, unidentified use of ulcerogenic medications, rare systemic diseases with upper gastrointestinal tract manifestations, hyperacidity of the stomach, and other rare infections involving the upper gastrointestinal tract.</p>
<sec>
<title>Incorrect diagnosis of <italic>H. pylori</italic></title>
<p>There are several methods available to detect <italic>H. pylori</italic> infection. These methods are characterized according to whether a mucosal specimen is needed for analysis. Biopsy-based tests include histological evaluation, culture, polymerase chain reaction, and the rapid urease test (RUT). Alternatively, non-invasive methods may include the urea breath test (UBT), serology, and the stool antigen test (SAT). A meta-analysis has revealed the following pooled sensitivity and specificity for different methods: RUT 0.67 and 0.93; histology 0.70 and 0.90; culture 0.45 and 0.98; UBT 0.93 and 0.92; SAT 0.87 and 0.70; and serology 0.88 and 0.69 &#x0005b;<xref ref-type="bibr" rid="b46-kjim-30-5-559">46</xref>&#x0005d;, respectively, which clearly demonstrates that each of the different tests has its own limitations, and a single negative test does not exclude <italic>H. pylori</italic> infection.</p>
<p>Current or recent use of antibiotics or proton pump inhibitors (PPIs) is known to influence the accuracy of <italic>H. pylori</italic> tests. Bacterial concentrations are decreased by these medications, leading to false-negative results. A number of studies have demonstrated a lower yield in testing for <italic>H. pylori</italic> infection in patients receiving antibiotic therapy. Borody et al. &#x0005b;<xref ref-type="bibr" rid="b17-kjim-30-5-559">17</xref>&#x0005d; showed that &#x0007e;22% of <italic>H. pylori</italic>-negative DU patients were reported to have used antibiotics recently. Gisbert et al. &#x0005b;<xref ref-type="bibr" rid="b33-kjim-30-5-559">33</xref>&#x0005d; also found a lower prevalence of <italic>H. pylori</italic> in DU patients who had prior antibiotic therapy compared with those who did not (78% vs. 96%). In another study, the prevalence of <italic>H. pylori</italic>-negative DU was shown to be much lower when patients taking antibiotics within 4 weeks of testing were excluded &#x0005b;<xref ref-type="bibr" rid="b47-kjim-30-5-559">47</xref>&#x0005d;. In addition, the use of PPIs and histamine-2 receptor antagonists (H2RAs) can also cause false-negative results by reducing gastric acid secretion and inhibiting the growth of <italic>H. pylori</italic>. Approximately one-third of patients who remained positive for <italic>H. pylori</italic> infection had a negative UBT result while receiving PPIs &#x0005b;<xref ref-type="bibr" rid="b48-kjim-30-5-559">48</xref>&#x0005d;. The study even showed that the proportion of patients whose UBT results turned out to be positive after completion of PPIs therapy were 91% at 3 days, 97% at 7 days, and 100% at 14 days &#x0005b;<xref ref-type="bibr" rid="b48-kjim-30-5-559">48</xref>&#x0005d;. Chey et al. &#x0005b;<xref ref-type="bibr" rid="b49-kjim-30-5-559">49</xref>&#x0005d; also demonstrated that both PPIs and H2RAs could affect the sensitivity of UBT, with an equivocal or false-negative result of 61% and 18%, respectively.</p>
<p>RUT can also yield a false-negative result during an actively bleeding stage of PUD. Lee et al. &#x0005b;<xref ref-type="bibr" rid="b50-kjim-30-5-559">50</xref>&#x0005d; have found that the prevalence of <italic>H. pylori</italic> infection in patients presenting with bleeding DU was 72.7%, which was lower than the prevalence of 92.8% in those with non-bleeding peptic ulcers (<italic>p</italic> &lt; 0.05). The false-negative rate of RUT for bleeding ulcer has been reported to be up to 25% &#x0005b;<xref ref-type="bibr" rid="b50-kjim-30-5-559">50</xref>&#x0005d;. In another study, 55.1% of patients with bleeding ulcers with an initially negative RUT result were discovered to have a positive result at follow-up endoscopy &#x0005b;<xref ref-type="bibr" rid="b23-kjim-30-5-559">23</xref>&#x0005d;. Lee et al. &#x0005b;<xref ref-type="bibr" rid="b51-kjim-30-5-559">51</xref>&#x0005d; have demonstrated that the low sensitivity of RUT (61%) for diagnosis of <italic>H. pylori</italic> infection during bleeding peptic ulcer can be overcome by increasing the number of biopsies from the gastric antrum to 74% or from the gastric body to 73%. Some investigators speculate that these results reflect a buffering effect of serum albumin on the pH indicator of the RUT &#x0005b;<xref ref-type="bibr" rid="b52-kjim-30-5-559">52</xref>&#x0005d;.</p>
<p>The location and number of biopsies taken are also important for the diagnostic accuracy of both RUTs and histological results &#x0005b;<xref ref-type="bibr" rid="b33-kjim-30-5-559">33</xref>,<xref ref-type="bibr" rid="b45-kjim-30-5-559">45</xref>,<xref ref-type="bibr" rid="b53-kjim-30-5-559">53</xref>,<xref ref-type="bibr" rid="b54-kjim-30-5-559">54</xref>&#x0005d;. The distribution of <italic>H. pylori</italic> can be sporadic and variable in the stomach when intestinal metaplasia or atrophic gastritis develops. By histological examination, &lt; 3% of antral biopsy specimens yielded a false-negative interpretation, compared with 6% to 9% of those from the corpus (<italic>p</italic> &#x0003d; 0.02) &#x0005b;<xref ref-type="bibr" rid="b54-kjim-30-5-559">54</xref>&#x0005d;. Another study based on 1,000 biopsy specimens has shown that the area of <italic>H. pylori</italic> colonization was larger than the area of active chronic gastritis, suggesting that <italic>H. pylori</italic> colonization may precede the development of active chronic gastritis &#x0005b;<xref ref-type="bibr" rid="b53-kjim-30-5-559">53</xref>&#x0005d;. In the presence of atrophic gastritis or intestinal metaplasia, <italic>H. pylori</italic> is prone to disappear from the gastric mucosa with such a histological change &#x0005b;<xref ref-type="bibr" rid="b55-kjim-30-5-559">55</xref>&#x0005d;. Therefore, it is postulated that <italic>H. pylori</italic> may migrate proximally from the antrum to the corpus because of lack of acid in the atrophic antrum. A meta-analysis has suggested that the sensitivities of RUT and histology could be improved to 78% and 83%, respectively, if biopsies were taken from both the antrum and the corpus of the stomach &#x0005b;<xref ref-type="bibr" rid="b46-kjim-30-5-559">46</xref>&#x0005d;.</p>
</sec>
<sec>
<title>Unrecognized use of ulcerogenic drugs</title>
<p>Surreptitious use of medications or lack of medication history with regard to ulcerogenic drugs may be of paramount importance when encountering <italic>H. pylori</italic>-negative PUD. By testing the blood for drugs, some studies have shown that a substantial number of users of ulcerogenic drugs cannot provide a correct description of their medication history &#x0005b;<xref ref-type="bibr" rid="b56-kjim-30-5-559">56</xref>,<xref ref-type="bibr" rid="b57-kjim-30-5-559">57</xref>&#x0005d;. Using the platelet cyclo-oxygenase activity test, 12.7% more users of aspirin could be identified than the number obtained by clinical history alone. Sixty-six percent of NSAID users were actually taking aspirin, alone or in combination with other NSAIDS, and 59.3% of patients who claimed no (non-aspirin) NSAID use were actually using NSAIDs &#x0005b;<xref ref-type="bibr" rid="b57-kjim-30-5-559">57</xref>&#x0005d;. Blood salicylic acid concentrations revealed that about half of patients with intractable PUD who denied using aspirin were actually aspirin users &#x0005b;<xref ref-type="bibr" rid="b56-kjim-30-5-559">56</xref>&#x0005d;. Ong et al. &#x0005b;<xref ref-type="bibr" rid="b27-kjim-30-5-559">27</xref>&#x0005d; also found that when serum thromboxane B2 levels were checked, more than 30% of patients who were thought to have IPUD were found to have taken NSAIDs. Other possible non-NSAID, non-aspirin, ulcer-related drugs include steroids, potassium chloride, nitrogen-containing bisphosphonates, and some immunosuppressive medications &#x0005b;<xref ref-type="bibr" rid="b58-kjim-30-5-559">58</xref>,<xref ref-type="bibr" rid="b59-kjim-30-5-559">59</xref>&#x0005d;. Visible gastric mucosal damage was found in 38% of patients who received alendronate as compared to 13% in the placebo group &#x0005b;<xref ref-type="bibr" rid="b59-kjim-30-5-559">59</xref>&#x0005d;. The results demonstrate that a valid review of medication history is mandatory before making the diagnosis of IPUD.</p>
</sec>
<sec>
<title>Excluding malignancies</title>
<p>Follow-up endoscopy is necessary in IPUD, especially in those patients who have alarming symptoms or recurrent ulcers, to determine whether there are secondary causes or undiscovered malignancies (<xref rid="f2-kjim-30-5-559" ref-type="fig">Fig. 2</xref>). In fact, &#x0007e;5% of endoscopically benign-appearing GUs are malignant &#x0005b;<xref ref-type="bibr" rid="b60-kjim-30-5-559">60</xref>,<xref ref-type="bibr" rid="b61-kjim-30-5-559">61</xref>&#x0005d;. Endoscopic surveillance of the gastric pre-malignant condition has been useful in identifying early-stage malignancy at 3- to 6-month follow-up visits scheduled to confirm that the GU is healed &#x0005b;<xref ref-type="bibr" rid="b62-kjim-30-5-559">62</xref>,<xref ref-type="bibr" rid="b63-kjim-30-5-559">63</xref>&#x0005d;. Although the optimal interval for endoscopic surveillance remains to be determined, repeat endoscopic biopsies, obtaining sufficient tissue involving submucosa, or targeted optical biopsy by image-enhanced endoscopy is a reasonable approach for IPUD &#x0005b;<xref ref-type="bibr" rid="b64-kjim-30-5-559">64</xref>&#x0005d;.</p>
</sec>
<sec>
<title>Excluding rare etiologies</title>
<p>Rare etiologies for PUD may include unusual systemic diseases and unusual infectious pathogens. Uncommon systemic diseases, such as Crohn&#x02019;s disease (<xref rid="f3-kjim-30-5-559" ref-type="fig">Fig. 3</xref>), mastocytosis, amyloidosis, sarcoidosis, vasculitis, eosinophilic gastroenteritis, and Zollinger-Ellison syndrome (<xref rid="f4-kjim-30-5-559" ref-type="fig">Fig. 4</xref>), are possible sources of the upper gastrointestinal manifestations of PUD. Screening of the lower gastrointestinal tract for Crohn&#x02019;s disease and specific laboratory and radiological tests (such as repeated measurement of serum fasting gastrin, secretin stimulation test, quantification of gastric acid secretion, measurement of serum chromogranin A, radiological studies, and endoscopic ultrasound for Zollinger-Ellison syndrome) are needed to exclude these uncommon diseases. Rare infectious causes of PUD may include <italic>Helicobacter heilmanii</italic>, tuberculosis, syphilis, cytomegalovirus (<xref rid="f5-kjim-30-5-559" ref-type="fig">Fig. 5</xref>), herpes simplex virus, and fungal infection (<xref rid="f6-kjim-30-5-559" ref-type="fig">Fig. 6</xref>).</p>
<p>In summary, accurate diagnosis of classic IPUD requires a systematic approach as outlined in <xref rid="t2-kjim-30-5-559" ref-type="table">Table 2</xref>. Confirmation of <italic>H. pylori</italic> infection status of the stomach and duodenum by at least three parallel tests is recommended to decrease the risk of a false-negative result. Thorough review of medication history is important to identify the use of potential ulcerogenic drugs. Moreover, a complete histological study of a benign-appearing ulcerative lesion is crucial to rule out the possibility of malignancy. Repeat endoscopic biopsies, optical targeted biopsy, or obtaining tissues deeper than the mucosal layer may improve diagnostic accuracy. Zollinger-Ellison syndrome should always be kept in mind when encountering poorly-healed peptic ulcers. Finally, rare infectious agents should be considered in the differential diagnosis, especially in immunocompromised subjects.</p>
</sec></sec>
<sec>
<title>RISK FACTORS AND THE CLINICAL COURSE OF CLASSICAL IPUD</title>
<p>Risk factors for classical IPUD may include demographic risk factors, use of psychoactive substances, genetic risk factors, comorbid diseases, chronic mesenteric ischemia, and higher psychological stress (<xref rid="t1-kjim-30-5-559" ref-type="table">Table 1</xref>, lower panel).</p>
<p>Demographic factors, such as being Caucasian and older age, are associated with IPUD. A greater prevalence of <italic>H. pylori</italic>-negative ulcers was found in whites than in non-whites in previous studies &#x0005b;<xref ref-type="bibr" rid="b13-kjim-30-5-559">13</xref>,<xref ref-type="bibr" rid="b15-kjim-30-5-559">15</xref>&#x0005d;. In multi-racial studies, a greater prevalence of <italic>H. pylori</italic>-negative DUs was found in Malays and Chinese than in Indians &#x0005b;<xref ref-type="bibr" rid="b7-kjim-30-5-559">7</xref>,<xref ref-type="bibr" rid="b65-kjim-30-5-559">65</xref>&#x0005d;. Molecular changes in gastric protective factors, such as mucin, are also hypothesized to be associated with risk of ulcers. The gastric protective layer, which prevents enzymatic attachment by gastric acid, pepsin, and other aggressive factors, is created by secreted mucin. Structural changes of membrane-bound mucin and glycan side-chain sialic acids are associated with protective efficiency against offending factors. Based on an immunochemical study of ulcer tissues, cytoplasmic MUC17 staining intensity was significantly lower in patients with IPUD than in those with <italic>H. pylori</italic>-related peptic ulcer &#x0005b;<xref ref-type="bibr" rid="b66-kjim-30-5-559">66</xref>&#x0005d;. In addition to genetic or epigenetic changes in the gastric mucin molecule, the <italic>HLA-DQA1&#x0002a;</italic>0102 allele was associated with increased risk of IPUD &#x0005b;<xref ref-type="bibr" rid="b67-kjim-30-5-559">67</xref>,<xref ref-type="bibr" rid="b68-kjim-30-5-559">68</xref>&#x0005d;. Ethnic differences in the prevalence of <italic>H. pylori</italic>-negative PUD may correlate with different lifestyles or unknown genetic factors. Several studies in different areas have demonstrated that patients with IPUD are significantly older than those with PUD associated with <italic>H. pylori</italic> or NSAID use &#x0005b;<xref ref-type="bibr" rid="b23-kjim-30-5-559">23</xref>,<xref ref-type="bibr" rid="b26-kjim-30-5-559">26</xref>,<xref ref-type="bibr" rid="b27-kjim-30-5-559">27</xref>,<xref ref-type="bibr" rid="b34-kjim-30-5-559">34</xref>,<xref ref-type="bibr" rid="b69-kjim-30-5-559">69</xref>&#x0005d;.</p>
<p>Older age was associated with a significantly lower level of prostaglandin concentration in the fundus, antrum, and post-bulbar duodenum &#x0005b;<xref ref-type="bibr" rid="b70-kjim-30-5-559">70</xref>&#x0005d;. Because prostaglandins protect the gastric mucosa from damage, diminished synthesis in elderly subjects makes their mucosa more susceptible to aggressive factors, followed by the ulcerogenic process. Moreover, older patients have higher risk for vascular disease, especially chronic mesenteric ischemia &#x0005b;<xref ref-type="bibr" rid="b71-kjim-30-5-559">71</xref>&#x0005d;. A combination of risk factors, including reduced blood flow, decreased production of prostaglandins by the stomach, a higher prevalence of concomitant diseases, and a higher American Society of Anesthesiologists score in the elderly render the mucosa more fragile and, thus, PUD is more likely to develop &#x0005b;<xref ref-type="bibr" rid="b16-kjim-30-5-559">16</xref>,<xref ref-type="bibr" rid="b72-kjim-30-5-559">72</xref>,<xref ref-type="bibr" rid="b73-kjim-30-5-559">73</xref>&#x0005d;. Cigarette smoking also increases xanthine oxidase activity, production of leukotrienes and nitric oxide, and neutrophil infiltration into the gastric mucosa &#x0005b;<xref ref-type="bibr" rid="b72-kjim-30-5-559">72</xref>&#x0005d;. An association between psychological stress and PUD has long been suggested. Two recent studies of Japanese victims of the Great East Japan Earthquake and Tsunami that occurred in 2011 have found that the incidence of PUD increased significantly after the psychological trauma &#x0005b;<xref ref-type="bibr" rid="b74-kjim-30-5-559">74</xref>,<xref ref-type="bibr" rid="b75-kjim-30-5-559">75</xref>&#x0005d;. In the first 3 months after the earthquake, the incidence of PUD was increased 1.5 fold, and the incidence of bleeding PUD was increased 2.2 fold &#x0005b;<xref ref-type="bibr" rid="b74-kjim-30-5-559">74</xref>,<xref ref-type="bibr" rid="b75-kjim-30-5-559">75</xref>&#x0005d;. Furthermore, after the earthquake, the proportion of IPUD doubled from 13% in 2010 to 24% in 2011 (<italic>p</italic> &lt; 0.05) &#x0005b;<xref ref-type="bibr" rid="b75-kjim-30-5-559">75</xref>&#x0005d;. A population-based study of 3,379 Danish adults in 1982 to 1983 revealed a greater incidence of ulcers among subjects in the highest tertile of stress scores (3.5%) than in those in the lowest tertile (1.6%; <italic>p</italic> &lt; 0.01) and high psychological stress has been identified as an independent risk factor for PUD on multivariate analysis (odds ratio, 1.12 per point increment of stress index; 95% confidence interval &#x0005b;CI&#x0005d;, 1.01 to 1.23; <italic>p</italic> &#x0003d; 0.03) &#x0005b;<xref ref-type="bibr" rid="b76-kjim-30-5-559">76</xref>&#x0005d;.</p>
<p>The clinical course of IPUD remains poorly understood because of the heterogeneity of diagnostic methods and populations recruited for studies. Nevertheless, idiopathic ulcer disease tends to cause longer-lasting ulceration, a greater recurrence rate and mortality rate, and greater symptoms of dyspepsia. In addition, it is more refractory to treatment than <italic>H. pylori</italic>-positive ulcer disease &#x0005b;<xref ref-type="bibr" rid="b26-kjim-30-5-559">26</xref>,<xref ref-type="bibr" rid="b77-kjim-30-5-559">77</xref>-<xref ref-type="bibr" rid="b84-kjim-30-5-559">84</xref>&#x0005d;. Furthermore, IPUD is also more likely to present with hemorrhage, and multiple and larger ulcers &#x0005b;<xref ref-type="bibr" rid="b84-kjim-30-5-559">84</xref>&#x0005d;. After a bleeding episode, the risk of recurrent ulcer complications within 12 months was higher in patients with <italic>H. pylori</italic>-negative PUD than in those with <italic>H. pylori</italic>-related PUD after eradication therapy (13.4% vs. 2.5%, <italic>p</italic> &lt; 0.001) &#x0005b;<xref ref-type="bibr" rid="b26-kjim-30-5-559">26</xref>&#x0005d;. In Hong Kong, a 7-year cohort study has shown that the cumulative incidence of recurrent bleeding from ulcers was higher in the <italic>H. pylori</italic>-negative ulcer cohort than in the positive cohort (42.3% vs. 11.2%, <italic>p</italic> &lt; 0.0001), and more patients died in the <italic>H. pylori</italic>-negative ulcer cohort than in the <italic>H. pylori</italic>-positive ulcer cohort (87.6% vs. 37.3%, <italic>p</italic> &lt; 0.0001) &#x0005b;<xref ref-type="bibr" rid="b84-kjim-30-5-559">84</xref>&#x0005d;. A randomized trial with a 2-year follow-up period consistently showed that the prognosis of <italic>H. pylori</italic>-negative ulcers was poorer &#x0005b;<xref ref-type="bibr" rid="b81-kjim-30-5-559">81</xref>&#x0005d;. The rates of recurrent ulcer or ulcer that has not healed (35% vs. 26%), and relapse of dyspepsia symptoms (16% vs. 7%) were higher in those with <italic>H. pylori</italic>-negative ulcers than in those with <italic>H. pylori</italic>-positive ulcers &#x0005b;<xref ref-type="bibr" rid="b81-kjim-30-5-559">81</xref>&#x0005d;.</p>
</sec>
<sec>
<title>MANAGEMENT OF IDIOPATHIC PEPTIC ULCER DISEASE</title>
<p>As IPUD is increasingly encountered, whether we should modify the standard treatment of PUD, including short-term PPI therapy and once-off <italic>H. pylori</italic> eradication, is of clinical significance. Based on present knowledge regarding a poorer response to acid-suppressing therapy in IPUD than in <italic>H. pylori</italic>-positive ulcers, anti-secretory medication remains the mainstay of treatment &#x0005b;<xref ref-type="bibr" rid="b77-kjim-30-5-559">77</xref>&#x0005d;. In a Danish study, outcomes in PPI-treated patients with DU did not differ according to <italic>H. pylori</italic> status, which suggested that PPI therapy was effective in the prevention of recurrence of IPUD &#x0005b;<xref ref-type="bibr" rid="b81-kjim-30-5-559">81</xref>&#x0005d;. In contrast, another study from Hong Kong demonstrated that the risk of re-bleeding (2.9 per 100 person-years vs. 1.1 per 100 person-years, <italic>p</italic> &lt; 0.001) and mortality (hazard ratio, 1.1; 95% CI, 0.6 to 1.7) were not reduced by gastro-protective agents in patients with bleeding IPUD &#x0005b;<xref ref-type="bibr" rid="b30-kjim-30-5-559">30</xref>&#x0005d;. Gillen et al. &#x0005b;<xref ref-type="bibr" rid="b85-kjim-30-5-559">85</xref>&#x0005d; found that <italic>H. pylori</italic> infection may potentiate the anti-secretory effect of PPIs. During PPI administration, median basal intragastric pH was higher in the <italic>H. pylori</italic>-positive (7.95) versus -negative (3.75) subjects (<italic>p</italic> &lt; 0.002) &#x0005b;<xref ref-type="bibr" rid="b85-kjim-30-5-559">85</xref>&#x0005d;. The poorer response to the anti-secretory therapy and altered gastric physiology of IPUD could indicate the necessity of longer duration and higher dose of acid-suppressing agents. Quan and Talley &#x0005b;<xref ref-type="bibr" rid="b45-kjim-30-5-559">45</xref>&#x0005d; have proposed a flow chart for the management of IPUD (<xref rid="f7-kjim-30-5-559" ref-type="fig">Fig. 7</xref>). After excluding gastric <italic>H. pylori</italic> infection (by multiple testing with a parallel interpretation of results) and the use of common ulcerogenic medications, the diagnosis of clinical IPUD is made. PPIs administration for 4 to 8 weeks is recommended, and a longer duration of therapy may be needed for complicated ulcer (e.g., bleeding or perforated). Otherwise, patients with uncomplicated ulcer disease may wean off therapy with a wait-and-see strategy, or receive on-demand/maintenance PPI therapy if symptoms recur. Re-evaluation of IPUD by endoscopy should be considered. If healing is slow or absent, items listed in <xref rid="t2-kjim-30-5-559" ref-type="table">Table 2</xref> should be re-evaluated to confirm whether classic IPUD is the correct diagnosis.</p>
</sec>
<sec sec-type="Conclusions">
<title>CONCLUSIONS</title>
<p>An increase in the proportion of idiopathic ulcers has been confirmed worldwide, and peptic ulcer, once considered to be an infectious disease after the discovery of <italic>H. pylori</italic>, has gradually reverted to the original &#x0201c;no acid, no ulcer&#x0201d; theory. Given that the prognosis of IPUD is poorer than that of PUD associated with <italic>H. pylori</italic> or NSAIDs, careful evaluation of <italic>H. pylori</italic> infection by multiple parallel tests, detailed review of medication history, and thorough exclusion of other possible causes are of paramount importance before making the diagnosis of IPUD. Further well-designed clinical trials are needed to elucidate the natural history of IPUD, and to optimize the treatment strategy for this emerging disease.</p>
</sec>
</body>
<back>
<fn-group><fn fn-type="conflict"><p>No potential conflict of interest relevant to this article was reported.</p></fn></fn-group>
<ref-list>
<title>REFERENCES</title>
<ref id="b1-kjim-30-5-559">
<label>1</label>
<element-citation publication-type="journal">
<article-title>Infection with Helicobacter pylori</article-title>
<source>IARC Monogr Eval Carcinog Risks Hum</source>
<year>1994</year>
<volume>61</volume>
<fpage>177</fpage>
<lpage>240</lpage>
</element-citation></ref>
<ref id="b2-kjim-30-5-559">
<label>2</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Torres</surname><given-names>J</given-names></name>
<name><surname>Lopez</surname><given-names>L</given-names></name>
<name><surname>Lazcano</surname><given-names>E</given-names></name>
<name><surname>Camorlinga</surname><given-names>M</given-names></name>
<name><surname>Flores</surname><given-names>L</given-names></name>
<name><surname>Munoz</surname><given-names>O</given-names></name>
</person-group>
<article-title>Trends in Helicobacter pylori infection and gastric cancer in Mexico</article-title>
<source>Cancer Epidemiol Biomarkers Prev</source>
<year>2005</year>
<volume>14</volume>
<fpage>1874</fpage>
<lpage>1877</lpage>
</element-citation></ref>
<ref id="b3-kjim-30-5-559">
<label>3</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Kuipers</surname><given-names>EJ</given-names></name>
<name><surname>Thijs</surname><given-names>JC</given-names></name>
<name><surname>Festen</surname><given-names>HP</given-names></name>
</person-group>
<article-title>The prevalence of Helicobacter pylori in peptic ulcer disease</article-title>
<source>Aliment Pharmacol Ther</source>
<year>1995</year>
<volume>9 Suppl 2</volume>
<fpage>59</fpage>
<lpage>69</lpage>
</element-citation></ref>
<ref id="b4-kjim-30-5-559">
<label>4</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Lee</surname><given-names>YC</given-names></name>
<name><surname>Chen</surname><given-names>TH</given-names></name>
<name><surname>Chiu</surname><given-names>HM</given-names></name>
<etal/>
</person-group>
<article-title>The benefit of mass eradication of Helicobacter pylori infection: a community-based study of gastric cancer prevention</article-title>
<source>Gut</source>
<year>2013</year>
<volume>62</volume>
<fpage>676</fpage>
<lpage>682</lpage>
</element-citation></ref>
<ref id="b5-kjim-30-5-559">
<label>5</label>
<element-citation publication-type="web">
<person-group person-group-type="author">
<collab>IARC Helicobacter pylori Working Group</collab>
</person-group>
<article-title>Helicobacter pylori eradication as a strategy for gastric cancer prevention (IARC Working Group Reports, No. 8) [Internet]</article-title>
<publisher-loc>Lyon (FR)</publisher-loc>
<publisher-name>International Agency for Research on Cancer</publisher-name>
<year>c2015</year>
<comment>[cited 2015 Jun 22]. Available from: <ext-link ext-link-type="uri" xlink:href="http://www.iarc.fr/en/publications/pdfs-online/wrk/wrk8/index.php">http://www.iarc.fr/en/publications/pdfs-online/wrk/wrk8/index.php</ext-link></comment>
</element-citation></ref>
<ref id="b6-kjim-30-5-559">
<label>6</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Xia</surname><given-names>B</given-names></name>
<name><surname>Xia</surname><given-names>HH</given-names></name>
<name><surname>Ma</surname><given-names>CW</given-names></name>
<etal/>
</person-group>
<article-title>Trends in the prevalence of peptic ulcer disease and Helicobacter pylori infection in family physician-referred uninvestigated dyspeptic patients in Hong Kong</article-title>
<source>Aliment Pharmacol Ther</source>
<year>2005</year>
<volume>22</volume>
<fpage>243</fpage>
<lpage>249</lpage>
</element-citation></ref>
<ref id="b7-kjim-30-5-559">
<label>7</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Uyub</surname><given-names>AM</given-names></name>
<name><surname>Raj</surname><given-names>SM</given-names></name>
<name><surname>Visvanathan</surname><given-names>R</given-names></name>
<etal/>
</person-group>
<article-title>Helicobacter pylori infection in north-eastern peninsular Malaysia: evidence for an unusually low prevalence</article-title>
<source>Scand J Gastroenterol</source>
<year>1994</year>
<volume>29</volume>
<fpage>209</fpage>
<lpage>213</lpage>
</element-citation></ref>
<ref id="b8-kjim-30-5-559">
<label>8</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Sugiyama</surname><given-names>T</given-names></name>
<name><surname>Nishikawa</surname><given-names>K</given-names></name>
<name><surname>Komatsu</surname><given-names>Y</given-names></name>
<etal/>
</person-group>
<article-title>Attributable risk of H. pylori in peptic ulcer disease: does declining prevalence of infection in general population explain increasing frequency of non-H. pylori ulcers?</article-title>
<source>Dig Dis Sci</source>
<year>2001</year>
<volume>46</volume>
<fpage>307</fpage>
<lpage>310</lpage>
</element-citation></ref>
<ref id="b9-kjim-30-5-559">
<label>9</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Singh</surname><given-names>V</given-names></name>
<name><surname>Trikha</surname><given-names>B</given-names></name>
<name><surname>Nain</surname><given-names>CK</given-names></name>
<name><surname>Singh</surname><given-names>K</given-names></name>
<name><surname>Vaiphei</surname><given-names>K</given-names></name>
</person-group>
<article-title>Epidemiology of Helicobacter pylori and peptic ulcer in India</article-title>
<source>J Gastroenterol Hepatol</source>
<year>2002</year>
<volume>17</volume>
<fpage>659</fpage>
<lpage>665</lpage>
</element-citation></ref>
<ref id="b10-kjim-30-5-559">
<label>10</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Asaka</surname><given-names>M</given-names></name>
<name><surname>Kimura</surname><given-names>T</given-names></name>
<name><surname>Kudo</surname><given-names>M</given-names></name>
<etal/>
</person-group>
<article-title>Relationship of Helicobacter pylori to serum pepsinogens in an asymptomatic Japanese population</article-title>
<source>Gastroenterology</source>
<year>1992</year>
<volume>102</volume>
<fpage>760</fpage>
<lpage>766</lpage>
</element-citation></ref>
<ref id="b11-kjim-30-5-559">
<label>11</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Musumba</surname><given-names>C</given-names></name>
<name><surname>Jorgensen</surname><given-names>A</given-names></name>
<name><surname>Sutton</surname><given-names>L</given-names></name>
<etal/>
</person-group>
<article-title>The relative contribution of NSAIDs and Helicobacter pylori to the aetiology of endoscopically-diagnosed peptic ulcer disease: observations from a tertiary referral hospital in the UK between 2005 and 2010</article-title>
<source>Aliment Pharmacol Ther</source>
<year>2012</year>
<volume>36</volume>
<fpage>48</fpage>
<lpage>56</lpage>
</element-citation></ref>
<ref id="b12-kjim-30-5-559">
<label>12</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Graham</surname><given-names>DY</given-names></name>
<name><surname>Large</surname><given-names>U.S</given-names></name>
</person-group>
<article-title>clinical trials report a high proportion of H. pylori negative duodenal ulcers at study entry as well as a high recurrence rate after cure of the infection: have we all been wrong?</article-title>
<source>Gastroenterology</source>
<year>1998</year>
<volume>114</volume>
<issue>Suppl 1</issue>
<fpage>A17</fpage>
</element-citation></ref>
<ref id="b13-kjim-30-5-559">
<label>13</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Nensey</surname><given-names>YM</given-names></name>
<name><surname>Schubert</surname><given-names>TT</given-names></name>
<name><surname>Bologna</surname><given-names>SD</given-names></name>
<name><surname>Ma</surname><given-names>CK</given-names></name>
</person-group>
<article-title>Helicobacter pylori-negative duodenal ulcer</article-title>
<source>Am J Med</source>
<year>1991</year>
<volume>91</volume>
<fpage>15</fpage>
<lpage>18</lpage>
</element-citation></ref>
<ref id="b14-kjim-30-5-559">
<label>14</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Sprung</surname><given-names>DJ</given-names></name>
<name><surname>Apter</surname><given-names>MN</given-names></name>
</person-group>
<article-title>What is the role of Helicobacter pylori in peptic ulcer and gastric cancer outside the big cities?</article-title>
<source>J Clin Gastroenterol</source>
<year>1998</year>
<volume>26</volume>
<fpage>60</fpage>
<lpage>63</lpage>
</element-citation></ref>
<ref id="b15-kjim-30-5-559">
<label>15</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Jyotheeswaran</surname><given-names>S</given-names></name>
<name><surname>Shah</surname><given-names>AN</given-names></name>
<name><surname>Jin</surname><given-names>HO</given-names></name>
<name><surname>Potter</surname><given-names>GD</given-names></name>
<name><surname>Ona</surname><given-names>FV</given-names></name>
<name><surname>Chey</surname><given-names>WY</given-names></name>
</person-group>
<article-title>Prevalence of Helicobacter pylori in peptic ulcer patients in greater Rochester, NY: is empirical triple therapy justified?</article-title>
<source>Am J Gastroenterol</source>
<year>1998</year>
<volume>93</volume>
<fpage>574</fpage>
<lpage>578</lpage>
</element-citation></ref>
<ref id="b16-kjim-30-5-559">
<label>16</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Charpignon</surname><given-names>C</given-names></name>
<name><surname>Lesgourgues</surname><given-names>B</given-names></name>
<name><surname>Pariente</surname><given-names>A</given-names></name>
<etal/>
</person-group>
<article-title>Peptic ulcer disease: one in five is related to neither Helicobacter pylori nor aspirin/NSAID intake</article-title>
<source>Aliment Pharmacol Ther</source>
<year>2013</year>
<volume>38</volume>
<fpage>946</fpage>
<lpage>954</lpage>
</element-citation></ref>
<ref id="b17-kjim-30-5-559">
<label>17</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Borody</surname><given-names>TJ</given-names></name>
<name><surname>George</surname><given-names>LL</given-names></name>
<name><surname>Brandl</surname><given-names>S</given-names></name>
<etal/>
</person-group>
<article-title>Helicobacter pylori-negative duodenal ulcer</article-title>
<source>Am J Gastroenterol</source>
<year>1991</year>
<volume>86</volume>
<fpage>1154</fpage>
<lpage>1157</lpage>
</element-citation></ref>
<ref id="b18-kjim-30-5-559">
<label>18</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Higuchi</surname><given-names>K</given-names></name>
<name><surname>Arakawa</surname><given-names>T</given-names></name>
<name><surname>Fujiwara</surname><given-names>Y</given-names></name>
<etal/>
</person-group>
<article-title>Is Helicobacter pylori-negative duodenal ulcer masked by the high prevalence of H. pylori infection in the general population?</article-title>
<source>Am J Gastroenterol</source>
<year>1999</year>
<volume>94</volume>
<fpage>3083</fpage>
<lpage>3084</lpage>
</element-citation></ref>
<ref id="b19-kjim-30-5-559">
<label>19</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Tsuji</surname><given-names>H</given-names></name>
<name><surname>Kohli</surname><given-names>Y</given-names></name>
<name><surname>Fukumitsu</surname><given-names>S</given-names></name>
<etal/>
</person-group>
<article-title>Helicobacter pylori-negative gastric and duodenal ulcers</article-title>
<source>J Gastroenterol</source>
<year>1999</year>
<volume>34</volume>
<fpage>455</fpage>
<lpage>460</lpage>
</element-citation></ref>
<ref id="b20-kjim-30-5-559">
<label>20</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Arakawa</surname><given-names>T1</given-names></name>
<name><surname>Higuchi</surname><given-names>K</given-names></name>
<name><surname>Fujiwara</surname><given-names>Y</given-names></name>
<etal/>
</person-group>
<article-title>Helicobacter pylori: criminal or innocent bystander?</article-title>
<source>J Gastroenterol</source>
<year>2000</year>
<volume>35 Suppl 12</volume>
<fpage>42</fpage>
<lpage>46</lpage>
</element-citation></ref>
<ref id="b21-kjim-30-5-559">
<label>21</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Aoyama</surname><given-names>N</given-names></name>
<name><surname>Shinoda</surname><given-names>Y</given-names></name>
<name><surname>Matsushima</surname><given-names>Y</given-names></name>
<etal/>
</person-group>
<article-title>Helicobacter pylori-negative peptic ulcer in Japan: which contributes most to peptic ulcer development, Helicobacter pylori, NSAIDS or stress?</article-title>
<source>J Gastroenterol</source>
<year>2000</year>
<volume>35 Suppl 12</volume>
<fpage>33</fpage>
<lpage>37</lpage>
</element-citation></ref>
<ref id="b22-kjim-30-5-559">
<label>22</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Nishikawa</surname><given-names>K</given-names></name>
<name><surname>Sugiyama</surname><given-names>T</given-names></name>
<name><surname>Kato</surname><given-names>M</given-names></name>
<etal/>
</person-group>
<article-title>Non-Helicobacter pylori and non-NSAID peptic ulcer disease in the Japanese population</article-title>
<source>Eur J Gastroenterol Hepatol</source>
<year>2000</year>
<volume>12</volume>
<fpage>635</fpage>
<lpage>640</lpage>
</element-citation></ref>
<ref id="b23-kjim-30-5-559">
<label>23</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Chan</surname><given-names>HL</given-names></name>
<name><surname>Wu</surname><given-names>JC</given-names></name>
<name><surname>Chan</surname><given-names>FK</given-names></name>
<etal/>
</person-group>
<article-title>Is non-Helicobacter pylori, non-NSAID peptic ulcer a common cause of upper GI bleeding? A prospective study of 977 patients</article-title>
<source>Gastrointest Endosc</source>
<year>2001</year>
<volume>53</volume>
<fpage>438</fpage>
<lpage>442</lpage>
</element-citation></ref>
<ref id="b24-kjim-30-5-559">
<label>24</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Kamada</surname><given-names>T</given-names></name>
<name><surname>Haruma</surname><given-names>K</given-names></name>
<name><surname>Kusunoki</surname><given-names>H</given-names></name>
<etal/>
</person-group>
<article-title>Significance of an exaggerated meal-stimulated gastrin response in pathogenesis of Helicobacter pylori-negative duodenal ulcer</article-title>
<source>Dig Dis Sci</source>
<year>2003</year>
<volume>48</volume>
<fpage>644</fpage>
<lpage>651</lpage>
</element-citation></ref>
<ref id="b25-kjim-30-5-559">
<label>25</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Chu</surname><given-names>KM</given-names></name>
<name><surname>Kwok</surname><given-names>KF</given-names></name>
<name><surname>Law</surname><given-names>S</given-names></name>
<name><surname>Wong</surname><given-names>KH</given-names></name>
</person-group>
<article-title>Patients with Helicobacter pylori positive and negative duodenal ulcers have distinct clinical characteristics</article-title>
<source>World J Gastroenterol</source>
<year>2005</year>
<volume>11</volume>
<fpage>3518</fpage>
<lpage>3522</lpage>
</element-citation></ref>
<ref id="b26-kjim-30-5-559">
<label>26</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Hung</surname><given-names>LC</given-names></name>
<name><surname>Ching</surname><given-names>JY</given-names></name>
<name><surname>Sung</surname><given-names>JJ</given-names></name>
<etal/>
</person-group>
<article-title>Long-term outcome of Helicobacter pylori-negative idiopathic bleeding ulcers: a prospective cohort study</article-title>
<source>Gastroenterology</source>
<year>2005</year>
<volume>128</volume>
<fpage>1845</fpage>
<lpage>1850</lpage>
</element-citation></ref>
<ref id="b27-kjim-30-5-559">
<label>27</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Ong</surname><given-names>TZ</given-names></name>
<name><surname>Hawkey</surname><given-names>CJ</given-names></name>
<name><surname>Ho</surname><given-names>KY</given-names></name>
</person-group>
<article-title>Nonsteroidal anti-inflammatory drug use is a significant cause of peptic ulcer disease in a tertiary hospital in Singapore: a prospective study</article-title>
<source>J Clin Gastroenterol</source>
<year>2006</year>
<volume>40</volume>
<fpage>795</fpage>
<lpage>800</lpage>
</element-citation></ref>
<ref id="b28-kjim-30-5-559">
<label>28</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Jang</surname><given-names>HJ</given-names></name>
<name><surname>Choi</surname><given-names>MH</given-names></name>
<name><surname>Shin</surname><given-names>WG</given-names></name>
<etal/>
</person-group>
<article-title>Has peptic ulcer disease changed during the past ten years in Korea? A prospective multi-center study</article-title>
<source>Dig Dis Sci</source>
<year>2008</year>
<volume>53</volume>
<fpage>1527</fpage>
<lpage>1531</lpage>
</element-citation></ref>
<ref id="b29-kjim-30-5-559">
<label>29</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Chen</surname><given-names>TS</given-names></name>
<name><surname>Luo</surname><given-names>JC</given-names></name>
<name><surname>Chang</surname><given-names>FY</given-names></name>
</person-group>
<article-title>Prevalence of Helicobacter pylori infection in duodenal ulcer and gastro-duodenal ulcer diseases in Taiwan</article-title>
<source>J Gastroenterol Hepatol</source>
<year>2010</year>
<volume>25</volume>
<fpage>919</fpage>
<lpage>922</lpage>
</element-citation></ref>
<ref id="b30-kjim-30-5-559">
<label>30</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Wong</surname><given-names>GL</given-names></name>
<name><surname>Au</surname><given-names>KW</given-names></name>
<name><surname>Lo</surname><given-names>AO</given-names></name>
<etal/>
</person-group>
<article-title>Gastroprotective therapy does not improve outcomes of patients with Helicobacter pylori-negative idiopathic bleeding ulcers</article-title>
<source>Clin Gastroenterol Hepatol</source>
<year>2012</year>
<volume>10</volume>
<fpage>1124</fpage>
<lpage>1129</lpage>
</element-citation></ref>
<ref id="b31-kjim-30-5-559">
<label>31</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Kim</surname><given-names>JJ</given-names></name>
<name><surname>Kim</surname><given-names>N</given-names></name>
<name><surname>Park</surname><given-names>HK</given-names></name>
<etal/>
</person-group>
<article-title>Clinical characteristics of patients diagnosed as peptic ulcer disease in the third referral center in 2007</article-title>
<source>Korean J Gastroenterol</source>
<year>2012</year>
<volume>59</volume>
<fpage>338</fpage>
<lpage>346</lpage>
</element-citation></ref>
<ref id="b32-kjim-30-5-559">
<label>32</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Ciociola</surname><given-names>AA</given-names></name>
<name><surname>McSorley</surname><given-names>DJ</given-names></name>
<name><surname>Turner</surname><given-names>K</given-names></name>
<name><surname>Sykes</surname><given-names>D</given-names></name>
<name><surname>Palmer</surname><given-names>JB</given-names></name>
</person-group>
<article-title>Helicobacter pylori infection rates in duodenal ulcer patients in the United States may be lower than previously estimated</article-title>
<source>Am J Gastroenterol</source>
<year>1999</year>
<volume>94</volume>
<fpage>1834</fpage>
<lpage>1840</lpage>
</element-citation></ref>
<ref id="b33-kjim-30-5-559">
<label>33</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Gisbert</surname><given-names>JP</given-names></name>
<name><surname>Blanco</surname><given-names>M</given-names></name>
<name><surname>Mateos</surname><given-names>JM</given-names></name>
<etal/>
</person-group>
<article-title>H. pylori-negative duodenal ulcer prevalence and causes in 774 patients</article-title>
<source>Dig Dis Sci</source>
<year>1999</year>
<volume>44</volume>
<fpage>2295</fpage>
<lpage>2302</lpage>
</element-citation></ref>
<ref id="b34-kjim-30-5-559">
<label>34</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Meucci</surname><given-names>G</given-names></name>
<name><surname>Di Battista</surname><given-names>R</given-names></name>
<name><surname>Abbiati</surname><given-names>C</given-names></name>
<etal/>
</person-group>
<article-title>Prevalence and risk factors of Helicobacter pylori-negative peptic ulcer: a multicenter study</article-title>
<source>J Clin Gastroenterol</source>
<year>2000</year>
<volume>31</volume>
<fpage>42</fpage>
<lpage>47</lpage>
</element-citation></ref>
<ref id="b35-kjim-30-5-559">
<label>35</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Arents</surname><given-names>NL</given-names></name>
<name><surname>Thijs</surname><given-names>JC</given-names></name>
<name><surname>van Zwet</surname><given-names>AA</given-names></name>
<name><surname>Kleibeuker</surname><given-names>JH</given-names></name>
</person-group>
<article-title>Does the declining prevalence of Helicobacter pylori unmask patients with idiopathic peptic ulcer disease? Trends over an 8 year period</article-title>
<source>Eur J Gastroenterol Hepatol</source>
<year>2004</year>
<volume>16</volume>
<fpage>779</fpage>
<lpage>783</lpage>
</element-citation></ref>
<ref id="b36-kjim-30-5-559">
<label>36</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Sbrozzi-Vanni</surname><given-names>A</given-names></name>
<name><surname>Zullo</surname><given-names>A</given-names></name>
<name><surname>Di Giulio</surname><given-names>E</given-names></name>
<etal/>
</person-group>
<article-title>Low prevalence of idiopathic peptic ulcer disease: an Italian endoscopic survey</article-title>
<source>Dig Liver Dis</source>
<year>2010</year>
<volume>42</volume>
<fpage>773</fpage>
<lpage>776</lpage>
</element-citation></ref>
<ref id="b37-kjim-30-5-559">
<label>37</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Vu</surname><given-names>C</given-names></name>
<name><surname>Ng</surname><given-names>YY</given-names></name>
</person-group>
<article-title>Prevalence of Helicobacter pylori in peptic ulcer disease in a Singapore hospital</article-title>
<source>Singapore Med J</source>
<year>2000</year>
<volume>41</volume>
<fpage>478</fpage>
<lpage>481</lpage>
</element-citation></ref>
<ref id="b38-kjim-30-5-559">
<label>38</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Yakoob</surname><given-names>J</given-names></name>
<name><surname>Jafri</surname><given-names>W</given-names></name>
<name><surname>Jafri</surname><given-names>N</given-names></name>
<etal/>
</person-group>
<article-title>Prevalence of non-Helicobacter pylori duodenal ulcer in Karachi, Pakistan</article-title>
<source>World J Gastroenterol</source>
<year>2005</year>
<volume>11</volume>
<fpage>3562</fpage>
<lpage>3565</lpage>
</element-citation></ref>
<ref id="b39-kjim-30-5-559">
<label>39</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Ootani</surname><given-names>H</given-names></name>
<name><surname>Iwakiri</surname><given-names>R</given-names></name>
<name><surname>Shimoda</surname><given-names>R</given-names></name>
<etal/>
</person-group>
<article-title>Role of Helicobacter pylori infection and nonsteroidal anti-inflammatory drug use in bleeding peptic ulcers in Japan</article-title>
<source>J Gastroenterol</source>
<year>2006</year>
<volume>41</volume>
<fpage>41</fpage>
<lpage>46</lpage>
</element-citation></ref>
<ref id="b40-kjim-30-5-559">
<label>40</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Goenka</surname><given-names>MK</given-names></name>
<name><surname>Majumder</surname><given-names>S</given-names></name>
<name><surname>Sethy</surname><given-names>PK</given-names></name>
<name><surname>Chakraborty</surname><given-names>M</given-names></name>
</person-group>
<article-title>Helicobacter pylori negative, non-steroidal anti-inflammatory drug-negative peptic ulcers in India</article-title>
<source>Indian J Gastroenterol</source>
<year>2011</year>
<volume>30</volume>
<fpage>33</fpage>
<lpage>37</lpage>
</element-citation></ref>
<ref id="b41-kjim-30-5-559">
<label>41</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Kang</surname><given-names>JM</given-names></name>
<name><surname>Seo</surname><given-names>PJ</given-names></name>
<name><surname>Kim</surname><given-names>N</given-names></name>
<etal/>
</person-group>
<article-title>Analysis of direct medical care costs of peptic ulcer disease in a Korean tertiary medical center</article-title>
<source>Scand J Gastroenterol</source>
<year>2012</year>
<volume>47</volume>
<fpage>36</fpage>
<lpage>42</lpage>
</element-citation></ref>
<ref id="b42-kjim-30-5-559">
<label>42</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Uyanikoglu</surname><given-names>A</given-names></name>
<name><surname>Danalioglu</surname><given-names>A</given-names></name>
<name><surname>Akyuz</surname><given-names>F</given-names></name>
<etal/>
</person-group>
<article-title>Etiological factors of duodenal and gastric ulcers</article-title>
<source>Turk J Gastroenterol</source>
<year>2012</year>
<volume>23</volume>
<fpage>99</fpage>
<lpage>103</lpage>
</element-citation></ref>
<ref id="b43-kjim-30-5-559">
<label>43</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Yoon</surname><given-names>H</given-names></name>
<name><surname>Kim</surname><given-names>SG</given-names></name>
<name><surname>Jung</surname><given-names>HC</given-names></name>
<name><surname>Song</surname><given-names>IS</given-names></name>
</person-group>
<article-title>High recurrence rate of idiopathic peptic ulcers in long-term follow-up</article-title>
<source>Gut Liver</source>
<year>2013</year>
<volume>7</volume>
<fpage>175</fpage>
<lpage>181</lpage>
</element-citation></ref>
<ref id="b44-kjim-30-5-559">
<label>44</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Chow</surname><given-names>DK</given-names></name>
<name><surname>Sung</surname><given-names>JJ</given-names></name>
</person-group>
<article-title>Non-NSAID non-H. pylori ulcer disease</article-title>
<source>Best Pract Res Clin Gastroenterol</source>
<year>2009</year>
<volume>23</volume>
<fpage>3</fpage>
<lpage>9</lpage>
</element-citation></ref>
<ref id="b45-kjim-30-5-559">
<label>45</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Quan</surname><given-names>C</given-names></name>
<name><surname>Talley</surname><given-names>NJ</given-names></name>
</person-group>
<article-title>Management of peptic ulcer disease not related to Helicobacter pylori or NSAIDs</article-title>
<source>Am J Gastroenterol</source>
<year>2002</year>
<volume>97</volume>
<fpage>2950</fpage>
<lpage>2961</lpage>
</element-citation></ref>
<ref id="b46-kjim-30-5-559">
<label>46</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Gisbert</surname><given-names>JP</given-names></name>
<name><surname>Abraira</surname><given-names>V</given-names></name>
</person-group>
<article-title>Accuracy of Helicobacter pylori diagnostic tests in patients with bleeding peptic ulcer: a systematic review and meta-analysis</article-title>
<source>Am J Gastroenterol</source>
<year>2006</year>
<volume>101</volume>
<fpage>848</fpage>
<lpage>863</lpage>
</element-citation></ref>
<ref id="b47-kjim-30-5-559">
<label>47</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Raj</surname><given-names>SM</given-names></name>
<name><surname>Yap</surname><given-names>K</given-names></name>
<name><surname>Haq</surname><given-names>JA</given-names></name>
<name><surname>Singh</surname><given-names>S</given-names></name>
<name><surname>Hamid</surname><given-names>A</given-names></name>
</person-group>
<article-title>Further evidence for an exceptionally low prevalence of Helicobacter pylori infection among peptic ulcer patients in north-eastern peninsular Malaysia</article-title>
<source>Trans R Soc Trop Med Hyg</source>
<year>2001</year>
<volume>95</volume>
<fpage>24</fpage>
<lpage>27</lpage>
</element-citation></ref>
<ref id="b48-kjim-30-5-559">
<label>48</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Laine</surname><given-names>L</given-names></name>
<name><surname>Estrada</surname><given-names>R</given-names></name>
<name><surname>Trujillo</surname><given-names>M</given-names></name>
<name><surname>Knigge</surname><given-names>K</given-names></name>
<name><surname>Fennerty</surname><given-names>MB</given-names></name>
</person-group>
<article-title>Effect of proton-pump inhibitor therapy on diagnostic testing for Helicobacter pylori</article-title>
<source>Ann Intern Med</source>
<year>1998</year>
<volume>129</volume>
<fpage>547</fpage>
<lpage>550</lpage>
</element-citation></ref>
<ref id="b49-kjim-30-5-559">
<label>49</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Chey</surname><given-names>WD</given-names></name>
<name><surname>Woods</surname><given-names>M</given-names></name>
<name><surname>Scheiman</surname><given-names>JM</given-names></name>
<name><surname>Nostrant</surname><given-names>TT</given-names></name>
<name><surname>DelValle</surname><given-names>J</given-names></name>
</person-group>
<article-title>Lansoprazole and ranitidine affect the accuracy of the 14C-urea breath test by a pH-dependent mechanism</article-title>
<source>Am J Gastroenterol</source>
<year>1997</year>
<volume>92</volume>
<fpage>446</fpage>
<lpage>450</lpage>
</element-citation></ref>
<ref id="b50-kjim-30-5-559">
<label>50</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Lee</surname><given-names>JM</given-names></name>
<name><surname>Breslin</surname><given-names>NP</given-names></name>
<name><surname>Fallon</surname><given-names>C</given-names></name>
<name><surname>O&#x02019;Morain</surname><given-names>CA</given-names></name>
</person-group>
<article-title>Rapid urease tests lack sensitivity in Helicobacter pylori diagnosis when peptic ulcer disease presents with bleeding</article-title>
<source>Am J Gastroenterol</source>
<year>2000</year>
<volume>95</volume>
<fpage>1166</fpage>
<lpage>1170</lpage>
</element-citation></ref>
<ref id="b51-kjim-30-5-559">
<label>51</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Lee</surname><given-names>TH</given-names></name>
<name><surname>Lin</surname><given-names>CC</given-names></name>
<name><surname>Chung</surname><given-names>CS</given-names></name>
<name><surname>Lin</surname><given-names>CK</given-names></name>
<name><surname>Liang</surname><given-names>CC</given-names></name>
<name><surname>Tsai</surname><given-names>KC</given-names></name>
</person-group>
<article-title>Increasing biopsy number and sampling from gastric body improve the sensitivity of rapid urease test in patients with peptic ulcer bleeding</article-title>
<source>Dig Dis Sci</source>
<year>2015</year>
<volume>60</volume>
<fpage>454</fpage>
<lpage>457</lpage>
</element-citation></ref>
<ref id="b52-kjim-30-5-559">
<label>52</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Leung</surname><given-names>WK</given-names></name>
<name><surname>Sung</surname><given-names>JJ</given-names></name>
<name><surname>Siu</surname><given-names>KL</given-names></name>
<name><surname>Chan</surname><given-names>FK</given-names></name>
<name><surname>Ling</surname><given-names>TK</given-names></name>
<name><surname>Cheng</surname><given-names>AF</given-names></name>
</person-group>
<article-title>False-negative biopsy urease test in bleeding ulcers caused by the buffering effects of blood</article-title>
<source>Am J Gastroenterol</source>
<year>1998</year>
<volume>93</volume>
<fpage>1914</fpage>
<lpage>1918</lpage>
</element-citation></ref>
<ref id="b53-kjim-30-5-559">
<label>53</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Bayerdorffer</surname><given-names>E</given-names></name>
<name><surname>Oertel</surname><given-names>H</given-names></name>
<name><surname>Lehn</surname><given-names>N</given-names></name>
<etal/>
</person-group>
<article-title>Topographic association between active gastritis and Campylobacter pylori colonisation</article-title>
<source>J Clin Pathol</source>
<year>1989</year>
<volume>42</volume>
<fpage>834</fpage>
<lpage>839</lpage>
</element-citation></ref>
<ref id="b54-kjim-30-5-559">
<label>54</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Genta</surname><given-names>RM</given-names></name>
<name><surname>Graham</surname><given-names>DY</given-names></name>
</person-group>
<article-title>Comparison of biopsy sites for the histopathologic diagnosis of Helicobacter pylori: a topographic study of H. pylori density and distribution</article-title>
<source>Gastrointest Endosc</source>
<year>1994</year>
<volume>40</volume>
<fpage>342</fpage>
<lpage>345</lpage>
</element-citation></ref>
<ref id="b55-kjim-30-5-559">
<label>55</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Craanen</surname><given-names>ME</given-names></name>
<name><surname>Dekker</surname><given-names>W</given-names></name>
<name><surname>Blok</surname><given-names>P</given-names></name>
<name><surname>Ferwerda</surname><given-names>J</given-names></name>
<name><surname>Tytgat</surname><given-names>GN</given-names></name>
</person-group>
<article-title>Intestinal metaplasia and Helicobacter pylori: an endoscopic bioptic study of the gastric antrum</article-title>
<source>Gut</source>
<year>1992</year>
<volume>33</volume>
<fpage>16</fpage>
<lpage>20</lpage>
</element-citation></ref>
<ref id="b56-kjim-30-5-559">
<label>56</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Hirschowitz</surname><given-names>BI</given-names></name>
<name><surname>Lanas</surname><given-names>A</given-names></name>
</person-group>
<article-title>Intractable upper gastrointestinal ulceration due to aspirin in patients who have undergone surgery for peptic ulcer</article-title>
<source>Gastroenterology</source>
<year>1998</year>
<volume>114</volume>
<fpage>883</fpage>
<lpage>892</lpage>
</element-citation></ref>
<ref id="b57-kjim-30-5-559">
<label>57</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Lanas</surname><given-names>A</given-names></name>
<name><surname>Serrano</surname><given-names>P</given-names></name>
<name><surname>Bajador</surname><given-names>E</given-names></name>
<name><surname>Esteva</surname><given-names>F</given-names></name>
<name><surname>Benito</surname><given-names>R</given-names></name>
<name><surname>Sainz</surname><given-names>R</given-names></name>
</person-group>
<article-title>Evidence of aspirin use in both upper and lower gastrointestinal perforation</article-title>
<source>Gastroenterology</source>
<year>1997</year>
<volume>112</volume>
<fpage>683</fpage>
<lpage>689</lpage>
</element-citation></ref>
<ref id="b58-kjim-30-5-559">
<label>58</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Blank</surname><given-names>MA</given-names></name>
<name><surname>Ems</surname><given-names>BL</given-names></name>
<name><surname>Gibson</surname><given-names>GW</given-names></name>
<etal/>
</person-group>
<article-title>Nonclinical model for assessing gastric effects of bisphosphonates</article-title>
<source>Dig Dis Sci</source>
<year>1997</year>
<volume>42</volume>
<fpage>281</fpage>
<lpage>288</lpage>
</element-citation></ref>
<ref id="b59-kjim-30-5-559">
<label>59</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Graham</surname><given-names>DY</given-names></name>
<name><surname>Malaty</surname><given-names>HM</given-names></name>
</person-group>
<article-title>Alendronate gastric ulcers</article-title>
<source>Aliment Pharmacol Ther</source>
<year>1999</year>
<volume>13</volume>
<fpage>515</fpage>
<lpage>519</lpage>
</element-citation></ref>
<ref id="b60-kjim-30-5-559">
<label>60</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Pruitt</surname><given-names>RE</given-names></name>
<name><surname>Truss</surname><given-names>CD</given-names></name>
</person-group>
<article-title>Endoscopy, gastric ulcer, and gastric cancer: follow-up endoscopy for all gastric ulcers?</article-title>
<source>Dig Dis Sci</source>
<year>1993</year>
<volume>38</volume>
<fpage>284</fpage>
<lpage>288</lpage>
</element-citation></ref>
<ref id="b61-kjim-30-5-559">
<label>61</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Podolsky</surname><given-names>I</given-names></name>
<name><surname>Storms</surname><given-names>PR</given-names></name>
<name><surname>Richardson</surname><given-names>CT</given-names></name>
<name><surname>Peterson</surname><given-names>WL</given-names></name>
<name><surname>Fordtran</surname><given-names>JS</given-names></name>
</person-group>
<article-title>Gastric adenocarcinoma masquerading endoscopically as benign gastric ulcer: a five-year experience</article-title>
<source>Dig Dis Sci</source>
<year>1988</year>
<volume>33</volume>
<fpage>1057</fpage>
<lpage>1063</lpage>
</element-citation></ref>
<ref id="b62-kjim-30-5-559">
<label>62</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Saini</surname><given-names>SD</given-names></name>
<name><surname>Eisen</surname><given-names>G</given-names></name>
<name><surname>Mattek</surname><given-names>N</given-names></name>
<name><surname>Schoenfeld</surname><given-names>P</given-names></name>
</person-group>
<article-title>Utilization of upper endoscopy for surveillance of gastric ulcers in the United States</article-title>
<source>Am J Gastroenterol</source>
<year>2008</year>
<volume>103</volume>
<fpage>1920</fpage>
<lpage>1925</lpage>
</element-citation></ref>
<ref id="b63-kjim-30-5-559">
<label>63</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Breslin</surname><given-names>NP</given-names></name>
<name><surname>Sutherland</surname><given-names>LR</given-names></name>
</person-group>
<article-title>Survey of current practices among members of CAG in the follow-up of patients diagnosed with gastric ulcer</article-title>
<source>Can J Gastroenterol</source>
<year>1999</year>
<volume>13</volume>
<fpage>489</fpage>
<lpage>493</lpage>
</element-citation></ref>
<ref id="b64-kjim-30-5-559">
<label>64</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Kaltenbach</surname><given-names>T</given-names></name>
<name><surname>Sano</surname><given-names>Y</given-names></name>
<name><surname>Friedland</surname><given-names>S</given-names></name>
<name><surname>Soetikno</surname><given-names>R</given-names></name>
<collab>American Gastroenterological Association</collab>
</person-group>
<article-title>American Gastroenterological Association (AGA) Institute technology assessment on image-enhanced endoscopy</article-title>
<source>Gastroenterology</source>
<year>2008</year>
<volume>134</volume>
<fpage>327</fpage>
<lpage>340</lpage>
</element-citation></ref>
<ref id="b65-kjim-30-5-559">
<label>65</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Goh</surname><given-names>KL</given-names></name>
</person-group>
<article-title>Prevalence of and risk factors for Helicobacter pylori infection in a multi-racial dyspeptic Malaysian population undergoing endoscopy</article-title>
<source>J Gastroenterol Hepatol</source>
<year>1997</year>
<volume>12</volume>
<fpage>S29</fpage>
<lpage>S35</lpage>
</element-citation></ref>
<ref id="b66-kjim-30-5-559">
<label>66</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Niv</surname><given-names>Y</given-names></name>
<name><surname>Boltin</surname><given-names>D</given-names></name>
<name><surname>Halpern</surname><given-names>M</given-names></name>
<etal/>
</person-group>
<article-title>Membrane-bound mucins and mucin terminal glycans expression in idiopathic or Helicobacter pylori, NSAID associated peptic ulcers</article-title>
<source>World J Gastroenterol</source>
<year>2014</year>
<volume>20</volume>
<fpage>14913</fpage>
<lpage>14920</lpage>
</element-citation></ref>
<ref id="b67-kjim-30-5-559">
<label>67</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Niv</surname><given-names>Y</given-names></name>
<name><surname>Boltin</surname><given-names>D</given-names></name>
</person-group>
<article-title>Secreted and membrane-bound mucins and idiopathic peptic ulcer disease</article-title>
<source>Digestion</source>
<year>2012</year>
<volume>86</volume>
<fpage>258</fpage>
<lpage>263</lpage>
</element-citation></ref>
<ref id="b68-kjim-30-5-559">
<label>68</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Azuma</surname><given-names>T</given-names></name>
<name><surname>Konishi</surname><given-names>J</given-names></name>
<name><surname>Ito</surname><given-names>Y</given-names></name>
<etal/>
</person-group>
<article-title>Genetic differences between duodenal ulcer patients who were positive or negative for Helicobacter pylori</article-title>
<source>J Clin Gastroenterol</source>
<year>1995</year>
<volume>21 Suppl 1</volume>
<fpage>S151</fpage>
<lpage>S154</lpage>
</element-citation></ref>
<ref id="b69-kjim-30-5-559">
<label>69</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Xia</surname><given-names>HH</given-names></name>
<name><surname>Wong</surname><given-names>BC</given-names></name>
<name><surname>Wong</surname><given-names>KW</given-names></name>
<etal/>
</person-group>
<article-title>Clinical and endoscopic characteristics of non-Helicobacter pylori, nonNSAID duodenal ulcers: a long-term prospective study</article-title>
<source>Aliment Pharmacol Ther</source>
<year>2001</year>
<volume>15</volume>
<fpage>1875</fpage>
<lpage>1882</lpage>
</element-citation></ref>
<ref id="b70-kjim-30-5-559">
<label>70</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Cryer</surname><given-names>B</given-names></name>
<name><surname>Redfern</surname><given-names>JS</given-names></name>
<name><surname>Goldschmiedt</surname><given-names>M</given-names></name>
<name><surname>Lee</surname><given-names>E</given-names></name>
<name><surname>Feldman</surname><given-names>M</given-names></name>
</person-group>
<article-title>Effect of aging on gastric and duodenal mucosal prostaglandin concentrations in humans</article-title>
<source>Gastroenterology</source>
<year>1992</year>
<volume>102</volume>
<issue>4 Pt 1</issue>
<fpage>1118</fpage>
<lpage>1123</lpage>
</element-citation></ref>
<ref id="b71-kjim-30-5-559">
<label>71</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Lee</surname><given-names>YC</given-names></name>
<name><surname>Yen</surname><given-names>AM</given-names></name>
<name><surname>Tai</surname><given-names>JJ</given-names></name>
<etal/>
</person-group>
<article-title>The effect of metabolic risk factors on the natural course of gastro-oesophageal reflux disease</article-title>
<source>Gut</source>
<year>2009</year>
<volume>58</volume>
<fpage>174</fpage>
<lpage>181</lpage>
</element-citation></ref>
<ref id="b72-kjim-30-5-559">
<label>72</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Ma</surname><given-names>L</given-names></name>
<name><surname>Chow</surname><given-names>JY</given-names></name>
<name><surname>Cho</surname><given-names>CH</given-names></name>
</person-group>
<article-title>Effects of cigarette smoking on gastric ulcer formation and healing: possible mechanisms of action</article-title>
<source>J Clin Gastroenterol</source>
<year>1998</year>
<volume>27 Suppl 1</volume>
<fpage>S80</fpage>
<lpage>S86</lpage>
</element-citation></ref>
<ref id="b73-kjim-30-5-559">
<label>73</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Luo</surname><given-names>JC</given-names></name>
<name><surname>Leu</surname><given-names>HB</given-names></name>
<name><surname>Hou</surname><given-names>MC</given-names></name>
<etal/>
</person-group>
<article-title>Cirrhotic patients at increased risk of peptic ulcer bleeding: a nationwide population-based cohort study</article-title>
<source>Aliment Pharmacol Ther</source>
<year>2012</year>
<volume>36</volume>
<fpage>542</fpage>
<lpage>550</lpage>
</element-citation></ref>
<ref id="b74-kjim-30-5-559">
<label>74</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Kanno</surname><given-names>T</given-names></name>
<name><surname>Iijima</surname><given-names>K</given-names></name>
<name><surname>Abe</surname><given-names>Y</given-names></name>
<etal/>
</person-group>
<article-title>Hemorrhagic ulcers after Great East Japan Earthquake and Tsunami: features of post-disaster hemorrhagic ulcers</article-title>
<source>Digestion</source>
<year>2013</year>
<volume>87</volume>
<fpage>40</fpage>
<lpage>46</lpage>
</element-citation></ref>
<ref id="b75-kjim-30-5-559">
<label>75</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Kanno</surname><given-names>T</given-names></name>
<name><surname>Iijima</surname><given-names>K</given-names></name>
<name><surname>Abe</surname><given-names>Y</given-names></name>
<etal/>
</person-group>
<article-title>Peptic ulcers after the Great East Japan earthquake and tsunami: possible existence of psychosocial stress ulcers in humans</article-title>
<source>J Gastroenterol</source>
<year>2013</year>
<volume>48</volume>
<fpage>483</fpage>
<lpage>490</lpage>
</element-citation></ref>
<ref id="b76-kjim-30-5-559">
<label>76</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Levenstein</surname><given-names>S</given-names></name>
<name><surname>Rosenstock</surname><given-names>S</given-names></name>
<name><surname>Jacobsen</surname><given-names>RK</given-names></name>
<name><surname>Jorgensen</surname><given-names>T</given-names></name>
</person-group>
<article-title>Psychological stress increases risk for peptic ulcer, regardless of Helicobacter pylori infection or use of nonsteroidal anti-inflammatory drugs</article-title>
<source>Clin Gastroenterol Hepatol</source>
<year>2015</year>
<volume>13</volume>
<fpage>498.e1</fpage>
<lpage>506.e1</lpage>
</element-citation></ref>
<ref id="b77-kjim-30-5-559">
<label>77</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Freston</surname><given-names>JW</given-names></name>
</person-group>
<article-title>Review article: role of proton pump inhibitors in non-H. pylori-related ulcers</article-title>
<source>Aliment Pharmacol Ther</source>
<year>2001</year>
<volume>15 Suppl 2</volume>
<fpage>2</fpage>
<lpage>5</lpage>
</element-citation></ref>
<ref id="b78-kjim-30-5-559">
<label>78</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Freston</surname><given-names>JW</given-names></name>
</person-group>
<article-title>Helicobacter pylori-negative peptic ulcers: frequency and implications for management</article-title>
<source>J Gastroenterol</source>
<year>2000</year>
<volume>35 Suppl 12</volume>
<fpage>29</fpage>
<lpage>32</lpage>
</element-citation></ref>
<ref id="b79-kjim-30-5-559">
<label>79</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Howden</surname><given-names>CW</given-names></name>
<name><surname>Leontiadis</surname><given-names>GI</given-names></name>
</person-group>
<article-title>Current indications for acid suppressants in Helicobacter pylori-negative ulcer disease</article-title>
<source>Best Pract Res Clin Gastroenterol</source>
<year>2001</year>
<volume>15</volume>
<fpage>401</fpage>
<lpage>412</lpage>
</element-citation></ref>
<ref id="b80-kjim-30-5-559">
<label>80</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>McColl</surname><given-names>KE</given-names></name>
</person-group>
<article-title>Helicobacter pylori-negative ulcer disease</article-title>
<source>J Gastroenterol</source>
<year>2000</year>
<volume>35 Suppl 12</volume>
<fpage>47</fpage>
<lpage>50</lpage>
</element-citation></ref>
<ref id="b81-kjim-30-5-559">
<label>81</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Bytzer</surname><given-names>P</given-names></name>
<name><surname>Teglbjaerg PS</surname><given-names>PS</given-names></name>
<collab>Danish Ulcer Study Group</collab>
</person-group>
<article-title>Helicobacter pylori-negative duodenal ulcers: prevalence, clinical characteristics, and prognosis: results from a randomized trial with 2-year follow-up</article-title>
<source>Am J Gastroenterol</source>
<year>2001</year>
<volume>96</volume>
<fpage>1409</fpage>
<lpage>1416</lpage>
</element-citation></ref>
<ref id="b82-kjim-30-5-559">
<label>82</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Hyvarinen</surname><given-names>H</given-names></name>
<name><surname>Salmenkyla</surname><given-names>S</given-names></name>
<name><surname>Sipponen</surname><given-names>P</given-names></name>
</person-group>
<article-title>Helicobacter pylori-negative duodenal and pyloric ulcer: role of NSAIDs</article-title>
<source>Digestion</source>
<year>1996</year>
<volume>57</volume>
<fpage>305</fpage>
<lpage>309</lpage>
</element-citation></ref>
<ref id="b83-kjim-30-5-559">
<label>83</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>McColl</surname><given-names>KE</given-names></name>
<name><surname>el-Nujumi</surname><given-names>AM</given-names></name>
<name><surname>Chittajallu</surname><given-names>RS</given-names></name>
<etal/>
</person-group>
<article-title>A study of the pathogenesis of Helicobacter pylori negative chronic duodenal ulceration</article-title>
<source>Gut</source>
<year>1993</year>
<volume>34</volume>
<fpage>762</fpage>
<lpage>768</lpage>
</element-citation></ref>
<ref id="b84-kjim-30-5-559">
<label>84</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Wong</surname><given-names>GL</given-names></name>
<name><surname>Wong</surname><given-names>VW</given-names></name>
<name><surname>Chan</surname><given-names>Y</given-names></name>
<etal/>
</person-group>
<article-title>High incidence of mortality and recurrent bleeding in patients with Helicobacter pylori-negative idiopathic bleeding ulcers</article-title>
<source>Gastroenterology</source>
<year>2009</year>
<volume>137</volume>
<fpage>525</fpage>
<lpage>531</lpage>
</element-citation></ref>
<ref id="b85-kjim-30-5-559">
<label>85</label>
<element-citation publication-type="journal">
<person-group person-group-type="author">
<name><surname>Gillen</surname><given-names>D</given-names></name>
<name><surname>Wirz</surname><given-names>AA</given-names></name>
<name><surname>Neithercut</surname><given-names>WD</given-names></name>
<name><surname>Ardill</surname><given-names>JE</given-names></name>
<name><surname>McColl</surname><given-names>KE</given-names></name>
</person-group>
<article-title>Helicobacter pylori infection potentiates the inhibition of gastric acid secretion by omeprazole</article-title>
<source>Gut</source>
<year>1999</year>
<volume>44</volume>
<fpage>468</fpage>
<lpage>475</lpage>
</element-citation></ref>
</ref-list>
<sec sec-type="display-objects">
<title>Figures and Tables</title>
<fig id="f1-kjim-30-5-559" position="float">
<label>Figure 1.</label><caption><p>(A) Global incidence of clinical idiopathic peptic ulcer disease from 1991 to 2013 reported in large-scale studies with a sample size &gt; 300 patients. (B) Reports of idiopathic peptic ulcer disease in Asian countries, excluding studies on bleeding peptic ulcers.</p></caption>
<graphic xlink:href="kjim-30-5-559f1.tif"/>
</fig>
<fig id="f2-kjim-30-5-559" position="float">
<label>Figure 2.</label><caption><p>A case of gastric ulcer with a missed diagnosis of gastric cancer. (A) One healing gastric ulcer was seen at the lesser curvature of the lower body. A biopsy showed only chronic inf lammation. (B) The ulcer remained present on follow-up endoscopy at 3 months despite continuous proton-pump inhibitor treatment. A repeated biopsy showed a well-differentiated adenocarcinoma. (C) An image of the tumor margin delineated by arrows under chromoendoscopy with indigo carmine spraying before endoscopic resection. (D) An image of the <italic>en bloc</italic> resected specimen.</p></caption>
<graphic xlink:href="kjim-30-5-559f2.tif"/>
</fig>
<fig id="f3-kjim-30-5-559" position="float">
<label>Figure 3.</label><caption><p>A case of Crohn’s disease with upper gastrointestinal manifestations. (A) One oral ulcer was found on the soft palate. (B) One gastric ulcer was noted on the posterior wall of the antrum. (C) Upon colonoscopic examination, multiple colonic ulcers were seen with a cobblestone appearance over the ascending colon and (D) descending colon.</p></caption>
<graphic xlink:href="kjim-30-5-559f3.tif"/>
</fig>
<fig id="f4-kjim-30-5-559" position="float">
<label>Figure 4.</label><caption><p>A case of hyperacidity of the stomach due to Zollinger-Ellison syndrome. (A) Repeat upper endoscopy showed poorly healed duodenal ulcers and (B) reflux erosive esophagitis, suggestive of gastric acid over-production. (C) Upon abdominal sonography, a pancreatic tumor originating from the uncinate process of the pancreas was noted. (D) The pancreatic tumor specimen was confirmed as a neuroendocrine tumor (circle).</p></caption>
<graphic xlink:href="kjim-30-5-559f4.tif"/>
</fig>
<fig id="f5-kjim-30-5-559" position="float">
<label>Figure 5.</label><caption><p>A case of gastric and duodenal ulcers due to cytomegalovirus infection. Multiple areas of erythema were found over the lower body (A) and antrum of the stomach (B) with a negative <italic>Helicobacter pylori</italic> test. (C) A bleeding ulcer was noted on the posterior wall of the gastric antrum. (D) Diffuse ulcerations in the jejunum found by the balloon-assisted enteroscopy. A biopsy was positive for cytomegalovirus inclusion bodies.</p></caption>
<graphic xlink:href="kjim-30-5-559f5.tif"/>
</fig>
<fig id="f6-kjim-30-5-559" position="float">
<label>Figure 6.</label><caption><p>A case of a mucormycosis-related gastric ulcer. (A) Upon upper endoscopy, a gastric ulcer with greenish coating was noted in the greater curvature of the middle body. (B) Pathology showed numerous right-angled, pauci-septated, and ribbon-like hyphae (arrows), indicating a fungal infection (H&amp;E, &#x000d7;100).</p></caption>
<graphic xlink:href="kjim-30-5-559f6.tif"/>
</fig>
<fig id="f7-kjim-30-5-559" position="float">
<label>Figure 7.</label><caption><p>A f low chart for the diagnosis and management of an idiopathic peptic ulcer disease. <italic>H. pylori</italic>, <italic>Helicobacter pylori</italic>; NSAID, nonsteroidal anti-inflammatory drug; ASA, acetylsalicylic acid (aspirin); H2RA, histamine-2 receptor antagonists; PPI, proton pump inhibitor. Adapted from Quan et al. &#x0005b;<xref ref-type="bibr" rid="b45-kjim-30-5-559">45</xref>&#x0005d;, with permission from Nature Publishing Group.</p></caption>
<graphic xlink:href="kjim-30-5-559f7.tif"/>
</fig>
<table-wrap id="t1-kjim-30-5-559" position="float">
<label>Table 1.</label>
<caption><p>Etiologies to be excluded for the diagnosis of idiopathic peptic ulcer and associated risk factors</p></caption>
<table rules="groups" frame="hsides">
<tbody><tr>
<td align="left" valign="top">Etiologies to be excluded</td>
</tr>
<tr>
<td align="left" valign="top">&#x02003;Missed diagnosis of <italic>Helicobacter pylori</italic> infection</td>
</tr>
<tr>
<td align="left" valign="top">&#x02003;Surreptitious usage of ulcerogenic medications (e.g., unrecognized nonsteroidal anti-inflammatory drugs, aspirin, and other ulcerogenic drugs)</td>
</tr>
<tr>
<td align="left" valign="top">&#x02003;Rare systemic diseases with upper gastrointestinal tract manifestations (e.g., Crohn&#x02019;s disease, mastocytosis, sarcoidosis, amyloidosis, eosinophilic gastroenteritis, and vasculitis)</td>
</tr>
<tr>
<td align="left" valign="top">&#x02003;Hyperacidity of the stomach (i.e., Zollinger-Ellison syndrome).</td>
</tr>
<tr>
<td align="left" valign="top">&#x02003;Other infections (e.g., <italic>Helicobacter heilmanii</italic>, cytomegalovirus, herpes simplex virus, tuberculosis, syphilis, and fungal infection)</td>
</tr>
<tr>
<td align="left" valign="top">Risk factors of idiopathic ulcer disease</td>
</tr>
<tr>
<td align="left" valign="top">&#x02003;Demographic risk factors (e.g., white race and older age)</td>
</tr>
<tr>
<td align="left" valign="top">&#x02003;Psychoactive substance use (e.g., tobacco use and alcohol)</td>
</tr>
<tr>
<td align="left" valign="top">&#x02003;Genetic risk factors (e.g., mucin genes and HLA-DQA1)</td>
</tr>
<tr>
<td align="left" valign="top">&#x02003;Comorbid diseases (e.g., liver cirrhosis, end-stage renal disease, diabetes mellitus, cerebrovascular accident, and malignancy)</td>
</tr>
<tr>
<td align="left" valign="top">&#x02003;Chronic mesenteric ischemia</td>
</tr>
<tr>
<td align="left" valign="top">&#x02003;Higher psychological stress</td>
</tr>
</tbody></table>
</table-wrap>

<table-wrap id="t2-kjim-30-5-559" position="float">
<label>Table 2.</label>
<caption><p>Considerations to review prior to making a diagnosis of idiopathic peptic ulcer</p></caption>
<table rules="groups" frame="hsides">
<tbody><tr>
<td align="left" valign="top">Exclusion of <italic>Helicobacter pylori</italic> infection</td>
</tr>
<tr>
<td align="left" valign="top">History of use of ulcerogenic medication</td>
</tr>
<tr>
<td align="left" valign="top">Completeness of histopathology to rule out occult malignancy, inflammatory bowel disease or vasculitis</td>
</tr>
<tr>
<td align="left" valign="top">Exclusion of Zollinger-Ellison syndrome, including the measurement of serum levels of fasting gastrin and chromogranin A, basal and maximal gastric acid secretion, secretin test, and radiological studies</td>
</tr>
<tr>
<td align="left" valign="top">Exclusion of other infectious pathogens</td>
</tr>
</tbody></table>
</table-wrap>
</sec>
</back></article>