Presentation (CTI)

OBJECTIVES: IgG4-related disease (IgG4-RD) is a rare, progressive fibro-inflammatory condition affecting multiple organs. This targeted literature review (TLR) aimed to develop a disease conceptual model (DCM) of IgG4-RD by systematically identifying patient-reported signs, symptoms, and impacts to inform Clinical Outcome Assessment (COA) strategy development.
METHODS: A protocol-driven TLR was conducted across MEDLINE, Embase, and Ichushi (Japanese publications), covering studies from database inception to October 2025. The scarce resources and the higher prevalence of the disease in Japan were the reasons for expanding the search to the Japanese database. A PICOS-T framework targeted qualitative, mixed-methods, and quantitative patient experience studies. Inclusion criteria encompassed studies reporting signs, symptoms, and impacts, excluding clinical guidelines, case reports, pathology-focused studies, and pre-1985 publications. Two-stage screening and systematic data extraction were performed following PRISMA guidelines.
RESULTS: Six (6) studies met inclusion criteria (all English; no Japanese studies qualified). The dataset comprised 3 quantitative surveys, 1 qualitative phenomenological study, 1 mixed-methods study, and 1 prospective observational study.The signs and symptoms identified across multiple organ systems included gastrointestinal (steatorrhea, frequent bowel movements), systemic (weight loss, fatigue), pain-related (abdominal pain), nasal, ocular, oral, renal, urinary, dermatologic, and respiratory symptoms.The impacts identified were psychological (fear, anxiety, distress, uncertainty, feeling helpless and hopeless, frustration), functional (reduced physical function, inability to work), and financial.
CONCLUSIONS: This TLR identified a multidimensional symptom and impact burden in IgG4-RD. Limited qualitative evidence precluded the development of a DCM with defined causal pathways, but it was a pioneering effort in building a model that represents patients' experiences. Critical gaps were identified in symptom-impact associations and patient voice representation. Further qualitative research is essential to support fit-for-purpose COA strategy development for IgG4-RD clinical trials. Only 6 qualifying studies, absence of Japanese evidence, and limited qualitative data constrained our conclusions. Inconsistent prevalence reporting limited quantitative synthesis.