Risk of Inflammatory Central Nervous System Diseases After Tumor Necrosis Factor–Inhibitor Treatment for Autoimmune Diseases

Importance Tumor necrosis factor (TNF) inhibitors have been used extensively to treat various autoimmune diseases. However, there are ongoing debates about the risk of inflammatory central nervous system (CNS) disease events following TNF inhibitor therapy, as well as uncertainty about how this risk varies across different autoimmune diseases or TNF-blocking agents. Objective To evaluate the risk of inflammatory CNS diseases after anti-TNF initiation and assess the difference in risk among different types of underlying autoimmune diseases or TNF inhibitors. Data Sources Separate searches were conducted across PubMed, Embase, and the Cochrane Library from inception until March 1, 2024. Study Selection Observational studies assessing the association between anti-TNF therapy and inflammatory CNS diseases relative to a comparator group. Data Extraction and Synthesis Study eligibility assessment and data extraction were independently conducted by 2 investigators following PRISMA guidelines. The risk ratio (RR) was used as the effect measure of the pooled analysis. Main Outcomes and Measures The primary outcome was the risk of incident inflammatory CNS events after anti-TNF therapy for autoimmune diseases. Secondary analyses were performed based on different types of underlying autoimmune diseases and TNF inhibitors. Results Eighteen studies involving 1 118 428 patients with autoimmune diseases contributing more than 5 698 532 person-years of follow-up were analyzed. The incidence rates of new-onset inflammatory CNS events after initiating TNF inhibitors ranged from 2.0 to 13.4 per 10 000 person-years. Overall, exposure to TNF inhibitors was associated with a 36% increased risk of any inflammatory CNS disease compared to conventional therapies (RR, 1.36; 95% CI, 1.01-1.84; I 2 , 49%), mainly attributed to demyelinating diseases (RR, 1.38; 95% CI, 1.04-1.81; I 2 , 31%). Secondary analyses revealed a similar risk of inflammatory CNS diseases across different types of underlying autoimmune diseases (rheumatic diseases: RR, 1.36; 95% CI, 0.84-2.21; inflammatory bowel disease 1.49; 95% CI, 0.93-2.40; P for subgroup = .74) and TNF inhibitors (anti-TNF monoclonal antibodies vs etanercept: RR, 1.04; 95% CI, 0.93-1.15; I 2 , 0%). Conclusions and Relevance Compared to conventional therapies, exposure to TNF inhibitors was associated with a 36% increased risk of inflammatory CNS diseases, irrespective of background autoimmune disease or TNF inhibitor type.