The aim of this study was to determine the risk of infection in adults with inflammatory rheumatic diseases (IRDs) treated with methotrexate. We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) assessing methotrexate versus placebo in adults using MEDLINE, EMBASE, and CENTRAL databases from 1980 to August 2017. The primary outcome was the risk of infection associated with methotrexate therapy. We chose a random effect model to summarize adverse event outcomes as risk ratios (RRs) and related 95% confidence intervals (95% CI). Twelve RCTs (total patients 1146) met the inclusion criteria for our main analysis, and ten for risk of serious infection (total patients 906). Overall, methotrexate was associated with increased risk of infection in rheumatoid arthritis (RA) (RR: 1.25; 95% CI, 1.01⁻1.56; p = 0.04; I² = 0%), but not in other non-RA IRD populations. There was no increased risk of total infections (RR: 1.14; 95% CI, 0.98⁻1.34; p = 0.10; I² = 0%) or serious infections (RR: 0.76; 95% CI, 0.11⁻5.15; p = 0.78; I² = 0%) in all included IRDs. Conclusively, methotrexate use in IRDs is associated with a higher risk of all infections in RA, but not in other non-RA (IRD) populations. There is no increased risk of serious infections.
Keywords: DMARDs; infections and arthritis; inflammation; methotrexate.