Background IgG4-related disease (IgG4-RD) is a recently recognized systemic inflammatory disease [1-3]. In parallel with its increasing recognition, the number of new patients (pts) diagnosed with IgG4-RD is also increasing. However, owing to its extremely diverse clinical picture, each clinician encounters a clinically distinct pt group depending on his/her specialty, and it is difficult to avoid institutional bias when evaluating the clinical features of IgG4-RD in a single center. This prompted us to conduct a relatively large-scale multicenter study with well-experienced physicians of IgG4-RD including rheumatologists, gastroenterologists, and nephrologists.
Objectives To clarify the clinical and laboratory features of IgG4-RD using a relatively large-scale cohort of 328 IgG4-RD pts.
Methods Between 2001 and 2014, we retrospectively evaluated 328 pts with IgG4-RD in four institutions. The diagnosis of IgG4-RD was made based on the comprehensive diagnostic criteria or criteria of each organ, which include elevated serum levels of IgG4 and pathological findings with supporting clinical course and imaging findings, with the final judgment made by the experts of IgG4-RD at each hospital. We analyzed the serum levels of IgG, IgG4, C3, C4, CH50 and CRP, the affected organs, the target organs for biopsy and treatment. Then we analyzed the organ specific features.
Results Two hundred and one pts were male, and 127 pts were female (male 61.3%). The mean age was 63.8 years (range 25-91). At diagnosis, mean serum IgG and IgG4 were 2389 mg/dL and 747 mg/dL respectively. Serum IgG4 was not elevated in 15 of 327 (4.6%). Hypocomplementemia was seen in 133 of 322 (41.3%). Serum level of CRP was less than 1.0 mg/dL in 90.1%. Mean number of organs involved was 3.2 (range 1-11); salivary gland (SG) was the most frequently involved organ (72.3%), followed by lacrimal glands (LG) (57.3%), pancreas (25.6%), retroperitoneal fibrosis/periaortitis (25.0%), kidney (24.1%), and lung (22.3%). Single organ involvement was seen in 63 of 322 (19.2%), with the most frequently affected organs being SG (26 pts) followed by LG (20 pts). Biopsy was performed in 265 of 328 (80.8%), with SG 39.2%, minor SG 16.5%, pancreas 15.5%, kidney 15.2%, lung 11.0%. Corticosteroid therapy was performed in 240 of 308 (79.5%), and the mean initial dose of prednisolone (PSL) was 30.4 mg/day. Hypocomplementemia was seen in pts with kidney lesions more often than in those without it (59.5% vs. 35.4%, p<0.001).
Conclusions The present study clarified the organs most frequently affected by IgG4-RD by a retrospective multicenter study. In addition, we reconfirmed the high frequency of hypocomplementemia in pts with kidney involvement. Moreover, in more than 95% of pts, serum elevated IgG4 levels were useful for the diagnosis of IgG4-RD.
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Disclosure of Interest None declared