Background/Purpose: The purpose of this study was to characterize clinical and pathological features as well as disease outcome of an Israeli incident cohort of patients with IgG4-related disease (IgG4-RD).

Methods: Retrospective, single-center study of incident patients with IgG4-RD diagnosed between 2010 and 2020. IgG4-RD was classified as ‘definite’, ‘probable’ or ‘possible’ according to international consensus guidelines and comprehensive diagnostic criteria for IgG4-RD or if patients fulfilled organ-specific criteria, as well as the 2019 ACR/EULAR classification criteria. Disease activity was determined by means of the IgG4-RD Responder Index (IgG4-RD RI). Disease features, as well as treatment and disease outcome were retrieved from the patients’ electronic charts. Disease remission was defined as no clinical and imaging evidence of active disease.

Results: Thirty-six incident patients (30.6% female) with median age of 54.9 years were included in the study: 11 patients (30.56 %) – “definite”, 10 patients (27.77%) – “possible”, and 15 (41.67%)- “probable” IgG4RD, and 22 patients (61.1%) fulfilled the 2019 ACR/EULAR classification criteria. Nineteen patients (52.8%) had a single-organ disease, 8 patients (22.2%) had involvement of two organs, and 9 patients (25%) had 3 or more organs involved. The most involved organs were lymph nodes (36%), retroperitoneal fibrosis (25%), and pancreas (16.7%). Median follow-up was 28 months (IQR 13.2-40.7). Thirty-three patients (91.67%) had biopsies available for analysis. Lymphoplasmacytic infiltrate, fibrosis and obliterative phlebitis were found in 88.9%, 61.1%, and 11.1%, respectively. Thirty-four patients (94.4%) were treated with prednisone, 38.9% were treated with methotrexate, 27.8% with azathioprine, 5.6% with mycophenolate mofetil and 47.2% with rituximab. Median IgG4-RD RI at diagnosis and at last encounter was 6.0 (IQR 6.0-9.0) and 1.0 (IQR 0.0-2.0), respectively. Six patients died (16.7%) and malignancy was diagnosed in 8 patients (22.2%). At the time of charts review, 16 patients (44.4%) were in remission after a median time of 16 months (IQR 6.0-30.0). Only two patients (5.6%) relapsed. Disease remission was significantly associated with a shorter time from the first symptom to the time of diagnosis (median 3.5 months vs. 18.5 months, p=0.04), lower ACR/EULAR criteria index at diagnosis (p=0.01), and a trend toward lower number of organs involved and higher initial daily prednisone dose (p=0.06 for each parameter). Neither serum IgG4 level at diagnosis, nor type of organ involvement or type of immunosuppressive/biologic drugs used were associated with disease remission. Significantly higher rates of malignancy (p=0.01) and mortality (p=0.03) were demonstrated amongst patients who did not achieve remission

Conclusion: Our data suggest that remission is an achievable target in the management of IgG4-RD and that delayed diagnosis of IgG4-RD is negatively associated with remission.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/delayed-diagnosis-of-igg4-related-disease-is-associated-with-worse-outcome-a-retrospective-real-life-observational-study/