Prevalence and risk factors of monoclonal gammopathy in patients with autoimmune inflammatory rheumatic disease: A systematic review and meta-analysis

Objective To systemically investigate the prevalence and risk factors of monoclonal gammopathy (MG) in patients with autoimmune inflammatory rheumatic disease (AIIRD). Methods A literature search was conducted using databases of PubMed, EMBASE, and Web of Science for relevant studies from inception to 31 July 2021. The pooled prevalence, odds ratio (OR), weighted mean difference (WMD), and 95% confidence interval (CI) were calculated with Stata 16.0 using a random or fixed effects model. Results In 17 included studies involving 6667 AIIRD patients, the pooled prevalence of MG in AIIRD patients was 7% (95%CI: 0.06-0.09). Compared to general populations, patients with Sjogren's syndrome (SS) possessed the highest risk for MG (OR 4.51; 95%CI: 3.39-5.74), followed by systemic lupus erythematosus (OR 3.99; 95%CI: 2.84-5.14), ankylosing spondylitis (OR 2.04; 95%CI: 1.11-2.97), and rheumatoid arthritis (OR 2.00; 95%CI: 1.79-2.22). Older age (WMD = 5.17 years; 95%CI: 0.68-9.66), higher erythrocyte sedimentation rate (WMD = 14.04 mm/H; 95%CI: 7.77-20.30), higher serum gammaglobulins level (WMD = 1.92 mg/dl, 95%CI: 0.51-3.32) were associated with a greater risk of MG in AIIRD patients. Conclusions MG prevalence was higher in AIIRD patients, especially in SS patients. Older age, higher erythrocyte sedimentation rate, and hypergammaglobulins were risk factors for MG in AIIRD patients.