Clinical and immunologic features of adult primary antibody deficiency according to IVIGRT exposure

Han, Jung-Eun; Lee, Hyun young; Kim, Haeng Jun; Shin, Yoo Seob; Ye, Yeong-Min; Park, Hae-Sim

doi:2026.41.5.940

Korean J Intern Med > Volume 41(5); 2026 > Article

ORIGINAL ARTICLE

Korean J Intern Med. 2026;41(5):940-951. doi: https://doi.org/10.3904/kjim.2026.072

Clinical and immunologic features of adult primary antibody deficiency according to IVIGRT exposure

Jung-Eun Han¹, Hyun young Lee², Haeng Jun Kim¹, Yoo Seob Shin¹, Yeong-Min Ye¹, and Hae-Sim Park¹

¹Department of Allergy and Clinical Immunology, Ajou University School of Medicine, Suwon, Korea
²Clinical Trial Center, Ajou University Medical Center, Suwon, Korea

Corresponding Author: Hae-Sim Park , Tel: +82-31-219-5196, Email: hspark@ajou.ac.kr

Received: February 10, 2026; Revised: April 6, 2026; Accepted: May 28, 2026.

Abstract

Background/Aims: Primary antibody deficiency (PAD) in adults is increasingly recognized, but remains underdiagnosed and undertreated. We described the clinical and immunologic features of adult patients with PAD according to real-world exposure to intravenous immunoglobulin replacement therapy (IVIGRT) and explored whether the Ajou-PAD score reflects treatment decisions in routine clinical practice.
Methods: We conducted a retrospective cohort study at Ajou University Hospital (January 1, 2020–November 18, 2024), screening adults (age ≥ 18 yr) diagnosed with PAD, and excluding those with IVIGRT exposure before diagnosis. After 1:1 propensity score matching by age and sex, clinical and laboratory findings between the IVIGRT-exposed and -unexposed groups were compared. The discriminatory performance of the Ajou-PAD score, a composite index integrating clinical and immunologic parameters, was evaluated for IVIGRT exposure using receiver operating characteristic analysis.
Results: The final matched cohort included 602 patients (301 per group). Immunoglobulin G subclass 3 deficiency (IgG3SCD) was the most prevalent phenotype and more frequent in the IVIGRT-exposed group than in the IVIGRT-unexposed group. The Ajou-PAD score showed modest discriminatory performance for IVIGRT exposure (AUC = 0.61; 95% CI, 0.56–0.65).
Conclusions: In Korean adults with PAD, IgG3SCD was the most prevalent phenotype and was more common among patients receiving IVIGRT in routine clinical practice. The Ajou-PAD score showed modest discriminatory performance for IVIGRT exposure and should be considered an exploratory adjunct rather than a standalone tool for treatment decision-making.

Keywords: Primary immunodeficiency diseases ; Antibodies ; Immunoglobulins ; Immunoglobulins, intravenous ; Propensity score