Clinical characteristics and outcome of IgG4-related disease with hypocomplementemia: a prospective cohort study
Abstract Background Immunoglobulin G4 related disease (IgG4-RD) is a newly recognized systemic, immune-mediated and fibro-inflammatory disease. Hypocomplementemia was found in part of IgG4-RD patients especially in the setting of active disease. Objectives This study aimed to clarify the clinical features, treatment efficacy and outcome in IgG4-RD patients with hypocomplementemia. Methods 312 IgG4-RD patients were recruited in our prospective cohort conducted in Peking union medical college hospital. Patient’s demographic data, clinical characteristics, laboratory parameters, treatment and outcome were analyzed. Results Hypocomplementemia was identified in 65(20.8%) cases of untreated IgG4-RD patients at baseline. The average age of hypocomplementemia group was 55.85±10.89 years, with male predominance (72.3%). Compared with normal complement group, patients with hypocomplementemia were likely to have more involved organs,higher IgG4-RD responder index (IgG4-RD RI), higher laboratory parameters such as counts of eosinophils, inflammatory markers༌immunoglobulin G(IgG), IgG1, IgG3, IgG4 and IgE. In addition, lymph nodes, lacrimal gland༌submandibular gland༌parotid gland༌paranasal sinus༌bile ducts and prostate gland were more commonly affected(p < 0.05). Serum C3 and C4 were negatively correlated with the number of involved organs, IgG4-RD RI, hypersensitive C-reactive protein (hsCRP), IgG, IgG1, IgG3 and IgG4. 64(98.5%) patients responded quickly to initial therapy at 3-month follow-up. Fifteen (23.1%) patients relapsed during follow-up with mean recurrence time of 14.2±13.8 months. Compared with normal complement group, there was no significant difference of relapse rate in two groups (P = 0.7559). Conclusions Clinical characteristics of IgG4-related disease with hypocomplementemia differs from normal complement group.Serum C3 and C4 at baseline before treatment could be biological markers for disease activity. IgG4-RD with hypocomplementemia responded well to treatment and had no significant difference of relapse rate in IgG4-RD with normal complement.