Predictors of response to methotrexate in early DMARD naive rheumatoid arthritis: results from the initial open-label phase of the SWEFOT trial

Objective To identify predictors of response to methotrexate (MTX) in early rheumatoid arthritis (RA). Methods In the SWEFOT trial, patients with RA with symptom duration <1 year started MTX monotherapy (20 mg/weekly) and 405/487 continued until the 3-4-month visit. The primary outcome measure was the DAS28-based European League against Rheumatism (EULAR) response criteria. Multivariate logistic regression was used to study the association between response and the following baseline characteristics: gender, age, symptom duration, cigarette smoking habits, autoantibody status, Health Assessment Questionnaire (HAQ) score, concurrent prednisolone and treatment with non-steroidal anti-inflammatory drugs. Secondary response and remission measures were the American College of Rheumatology and the Simple Disease Activity Index and Clinical Disease Activity Index (SDAI/CDAI)-derived criteria. Results After 3-4 months of MTX treatment, the frequency of EULAR good/moderate/no response was 34%/41%/25%, respectively. Parameters associated with a decreased likelihood of EULAR response were female gender (adjusted OR (adj OR) 0.50, 95% CI 0.31 to 0.81), symptom duration (adj OR per month increase 0.93, 95% CI 0.88 to 0.99), current smoking (adj OR 0.35, 95% CI 0.20 to 0.63) and higher HAQ (adj OR 0.56, 95% CI 0.40 to 0.80). Parameters associated with an increased likelihood of EULAR response were higher age (adj OR per 10-year increase 1.30, 95% CI 1.11 to 1.51) and prednisolone treatment (adj OR 2.84, 95% CI 1.43 to 5.63). The findings were similar when patients on prednisolone were excluded and other response criteria tested, although current smoking was the only significant predictor using all response criteria, while HAQ was the only significant predictor of all the remission criteria used. A matrix showed up to ninefold differences between subgroups stratified by the main predictors. Conclusion Current smoking, female sex, longer symptom duration and younger age predict a worse response to MTX in patients with new-onset RA. TrialRegNo NCT00764725