Smoking reduces effect of methotrexate-based treatment in RA patients

Current smoking reduces the response of patients with early rheumatoid arthritis (RA) to methotrexate (MTX) in a dose-responsive manner, regardless of concomitant prednisone use, a recent study has found.

In this study, the investigators sought to determine whether current smoking affected the clinical response to concomitant prednisone in an MTX-based strategy. Patients with early RA in the CAMERA-II trial initiated an MTX-based treatment and were then randomly assigned to receive either concomitant prednisone (MTX + pred) or placebo (MTX + PBO) for 24 months.

The investigators performed a linear mixed modeling, with Disease Activity Score assessing 28 joints (DAS28) as the dependent variable and strategy group and current smoking status as independent variable, correcting for relevant covariates. They also tested for the interaction between current smoking and strategy to determine whether the effect of current smoking on clinical response was different between the two MTX-based strategy groups.

Current smoking was found to be significantly correlated with higher DAS28 over time (mean difference with nonsmokers, 0.57, 95 percent confidence interval, 0.22–0.92; p<0.01). Such association did not differ between the strategy groups with prednisone or PBO (p=0.73). Of note, the negative effect of current smoking on DAS28 was dose dependent.

“Current smoking reduces clinical response to several disease-modifying antirheumatic drugs,” the investigators said.