Mandatory Biological/Targeted Synthetic Disease-Modifying Antirheumatic Drugs Dose Reduction on Risk of Serious Infections in Patients with Rheumatoid Arthritis: A Nationwide Nested Case–Control Study

<b>Background</b>: We aimed to investigate the risk for a serious infection in rheumatoid arthritis (RA) patients after tapering the dose of biological/targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs). <b>Methods</b>: This nested case-control study investigated the risk for a serious infection in RA patients who underwent mandatory b/tsDMARDs dose reduction 2.5 years after starting therapy with a single b/tsDMARD in the National Health Insurance Research Database (NHIRD). Cases were those patients who developed a serious infection afterwards. Matched controls were selected from those patients who did not develop a serious infection. We used unconditional logistic regression to analyze the odds ratios (ORs) of b/tsDMARDs dose reduction and discontinuation between cases and controls. <b>Results</b>: RA patients underwent an average dose reduction of 60%. Among a total of 268 cases and 1072 controls, we did not observe a lower risk for a serious infection in those patients who tapered or discontinued b/tsDMARDs. However, those patients who had discontinued b/tsDMARDs had a higher risk for a serious infection when compared with those who had not and had reduced their b/stDMARDs dose reduction below the average (i.e., ≤60%), with an adjusted OR of 1.48 (95%CI: 1.05, 2.09). <b>Conclusions</b>: Dose reduction in b/tsDMARDs in RA patients might not be associated with a lower risk for serious infection. Discontinuation of b/tsDMARDs, however, was likely associated with a higher risk for serious infection.