Hyperglobulinemia predicts increased risk of mortality in primary Sjögren's syndrome: Based on a Chinese multicentre registry.

Objective: To investigate whether primary Sjögren's syndrome (pSS) patients with hyperglobulinemia have an increased risk of all-cause mortality.

Methods: Patients who registered in the Chinese Rheumatism Data Centre from May 2016 to July 2021 and met the 2002 American European Consensus Group criteria or 2016 American College of Rheumatology /European League Against Rheumatism classification criteria for Sjögren's syndrome were included. Hyperglobulinemia was defined as any elevated serum levels of immunoglobulin G (IgG), immunoglobulin A (IgA), or immunoglobulin M (IgM). The primary outcome was all-cause death. Data for demographic and clinical characteristics, laboratory results, disease activity, damage scores, and treatments were evaluated.

Results: A total of 9527 pSS patients were included in the analysis, of whom 4236 (44.5%) had at least one kind of elevated immunoglobulin level among IgG, IgA, and IgM. Patients with hyperglobulinemia had a significantly increased risk of death (crude hazard ratio 2.60; 95% confidence interval 1.91-3.55; adjusted hazard ratio 1.90; 95% confidence interval 1.20-3.01). The risk of death was positively correlated with IgG level (P trend <.001). The 5-, 10-, and 15-year survival rates of patients with hyperglobulinemia were 96.9%, 92.3%, and 87.9%, respectively, and significantly lower than the corresponding rates of 98.8%, 97.9%, and 96.4% in patients without hyperglobulinemia.

Conclusions: Hyperglobulinemia is an independent risk factor for increased all-cause mortality in pSS patients. The risk of death is positively correlated with IgG level.