The effect of smoking on response to methotrexate in rheumatoid arthritis patients: A systematic review and meta-analysis.

This article systematically reviews and meta-analyzes the association between smoking and inadequate response to methotrexate (MTX-IR) in patients with rheumatoid arthritis (RA). Based on 23 studies included in the review and 13 in the meta-analysis, smokers with RA were found to have a significantly higher likelihood—ranging from 58% to 169% increased odds depending on the analysis—of inadequate response to MTX compared to nonsmokers, particularly among disease-modifying antirheumatic drug (DMARD)-naïve early RA patients. The study accounted for various confounders such as age, sex, baseline disease activity, and body mass index, and identified two outlier studies with longer disease duration or prior DMARD use that influenced heterogeneity. The findings suggest smoking is a significant predictor of MTX-IR, highlighting the importance of considering smoking status in personalized treatment strategies for RA.