medwireNews: Cigarette smoking among people with early rheumatoid arthritis (RA) significantly reduces the clinical benefit of methotrexate – in a dose-dependent manner – regardless of whether concomitant prednisone is used, researchers report.
The findings are based on an analysis of data from the CAMERA-II trial, in which 236 patients with early RA were randomly assigned to receive methotrexate on a tight control and treat-to-target strategy (starting dose 10 mg/week) in combination with prednisone 10 mg/day or placebo for 24 months. Of these, 213 had data on smoking status available.
Mary Safy-Khan (Utrecht University, the Netherlands) and co-investigators found that, overall, current smokers had significantly smaller improvements in DAS28 over time than non-smokers, and the effect was not modified by prednisone use.
At baseline, mean DAS28 was 5.8 among people in the prednisone group and 5.7 among those in the placebo group, with 37% and 28% of each group, respectively, reporting that they were current smokers.
After 24 months, mean DAS28 in the prednisone group was approximately 2.0 for non-smokers and approximately 2.7 for smokers. In the placebo group, the DAS28 values were approximately 2.3 and 2.9 for non-smokers and smokers, respectively.
The team also observed that the impact of current smoking on DAS28 was dose-dependent, increasing with the number of cigarettes smoked per day. Specifically, people who smoked 1–9 cigarettes per day had comparable DAS28 improvements over 24 months to non-smokers, whereas people who smoked 10–19 or 20 or more cigarettes per day had significantly smaller improvements in disease activity than non-smokers.
In line with the main findings, the researchers note that the dose-dependent association between cigarettes smoked and DAS28 was not significantly different according to whether or not prednisone was used.
Writing in The Journal of Rheumatology, Safy-Kahn and co-authors say their findings “corroborate previously found negative associations between current smoking and response to [methotrexate] treatment in patients with early RA.”
They add: “As [methotrexate] is often used in daily clinical practice, our results emphasize the importance of nonsmoking in patients with early RA.”
medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2021 Springer Healthcare Ltd, part of the Springer Nature Group