Background/Purpose: This study aimed to explore the clinical characteristics, treatment, and prognosis of IgG4-related disease (IgG4-RD) patients with comorbid autoimmune diseases (AIDs).

Methods: A total of 879 treatment naïve IgG4-RD patients from Peking Union Medical College Hospital were retrospectively included in this study. IgG4-RD Patients with comorbid autoimmune diseases were classified into the AID-positive (AID-Pos) subgroup, while those without autoimmune diseases were classified into the AID-negative (AID-Neg) subgroup. Additionally, AIDs were classified as systemic or organ-specific. The clinical features, laboratory findings, treatment regimens, and long-term prognosis were compared among the AID-Pos and AID-Neg groups, and the characteristics of AIDs were also explored.

Results: The prevalence rate of AIDs in IgG4-RD patients was 9.67% (85/879), including 47 cases of systemic AIDs and 38 cases of organ-specific AIDs. The types of comorbid AIDs were diverse, such as vitiligo (15 patients), systemic vasculitis (12 patients), psoriasis (12 patients), Hashimoto’s thyroiditis (11 patients), and rheumatoid arthritis (10 patients). Most AIDs occurred before or simultaneously with IgG4-RD. Among AID-Pos subgroup patients, 75 (88.2%) had only one type of AID. AID-Pos subgroup patients had lower serum IgG4 levels than AID-Neg subgroup patients (6017 [2729;13900] vs 9176 [3956;18100], p=0.004). Compared with AID-Neg subgroup patients, those with systemic AIDs had higher level of erythrocyte sedimentation rate (40 [22.5; 74.] vs 18.0 [10.0;52.0] mm/hr, adjusted p < 0.001) and higher serum IgG1 level (11500 [8355;13575] vs 8700 [7215;11000] mg/L, adjusted p=0.002). There was no significant difference in treatment regimens and long-term prognosis between AID-Pos and AID-Neg subgroup patients.

Conclusion: IgG4-RD patients can complicate with other AIDs. Compared with AID-neg subgroup patients, IgG4-RD patients with comorbid AIDs have lower serum IgG4 levels, while the clinical characteristics, treatment, and prognosis were similar between two subgroups.

Table 1 Comparisons of baseline demographics and clinical features in IgG4-RD patients with or without AIDs.

a Prostate involved was compared only among males, which also applied to subsequent comparisons.

RI scores: Responder Index. PGA scores: Physician Global Assessment.

Figure 2 Types of AIDs and disease sequence. (a) The statistics of AIDs comorbid with IgG4-RD; (b) The temporal sequence of diseases between IgG4-RD and AIDs; (c) The number of AIDs each patient had. PSO: Psoriasis; HT, Hashimoto’s thyroiditis; RA, Rheumatoid arthritis; PBC, Primary biliary cirrhosis; T1DM, Type 1 Diabetes Mellitus; UCTD, Undifferentiated connective tissue disease; SpA, Spondyloarthritis; pSS, Primary Sjögren′s syndrome; ARF, Acute rheumatic fever; AIHA, Autoimmune hemolytic anemia; APS, Antiphospholipid syndrome; GBS, Guillain-Barré syndrome; GD, Graves’ disease; NMOSD, Neuromyelitis optica spectrum disorders; PP, Palmoplantar pustulosis; PMR, Polymyalgia rheumatica; UC, Ulcerative colitis.

Figure 3 The prognoses of IgG4-RD patients with or without AIDs during follow-up. (a) IgG4-RD patients in AID-Pos group or AID-Neg group; (b) IgG4-RD patients in systemic AID group, Organ-Specific AID group or AID-Neg group.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/igg4-related-disease-with-comorbid-autoimmune-diseases-a-retrospective-study-from-a-large-cohort/