Incidence and spectrum of typical complications associated with immunosuppressant use in rheumatic disease: A nationwide retrospective study

Aim: To estimate the incidence and characteristics of typical complications associated with immunosuppressant therapy across various types of rheumatic disease (RD). Methods: We conducted a retrospective analysis using Korean claims data, including patients who were first diagnosed with rheumatic disease (rheumatoid arthritis, spondyloarthrosis, lupus erythematosus, vasculitis, sclerosis, Sjögren's syndrome, and polymyalgia rheumatica) and initiated immunosuppressant therapy between 2015 and 2018. We focused on several typical complications, including infections, cancer, cardiovascular complications, bone marrow suppression, gastrointestinal complications, diabetes, interstitial lung disease, demyelinating disease, acute kidney injury, and hepatotoxicity. Results: Among 464 753 patients prescribed immunosuppressants, 59 548 initiated treatment following their RD diagnosis. The most prevalent complications included opportunistic infections (60.6 events per 1000 person-years), serious infections (41.1), hypertension (31.5), diabetes (18.3), and cancer (14.1). Most complications peaked in the first month after treatment initiation. While the risk of serious infections and cancer increased with age, the incidence of opportunistic infections did not significantly vary. Furthermore, risk of serious infection or cancer did not significantly differ among RD types. Conclusions: This investigation elucidated the incidence and spectrum of typical complications associated with immunosuppressants among patients with RD, using a vast real-world dataset to highlight key safety concerns.