Meta-Regression of a Dose-Response Relationship of Methotrexate in Mono- and Combination Therapy in Disease-Modifying Antirheumatic Drug-Naive Early Rheumatoid Arthritis Patients

To investigate a possible short-term dose-response relationship of initial treatment with methotrexate (MTX) in monotherapy and combination therapy in recent-onset rheumatoid arthritis (RA) patients. A systematic literature search was performed on trials and cohorts, including early, disease-modifying antirheumatic drug (DMARD)-naive RA patients treated with MTX, with data on clinical results within 6 months from treatment start. Cohen's effect sizes were calculated for the Health Assessment Questionnaire (HAQ), erythrocyte sedimentation rate (ESR)/C-reactive protein (CRP) level, and/or Disease Activity Score (DAS)/in 28 joints (DAS28) in 4 treatment groups: MTX monotherapy, or MTX in combination with synthetic (cs) DMARDs, biologic (b) DMARDs, or glucocorticoids. Random-effects meta-regression analyses were performed for each outcome, with treatment group as the predictor corrected for baseline HAQ or disease activity and assessment point. Thirty-one studies including 5,589 patients were included. The meta-regression did not support higher effectiveness of increasing MTX dose in monotherapy. The number of treatment groups using combination therapy with csDMARDs was too small to perform meta-regression analyses. In combination therapy with glucocorticoids, a higher MTX dose was associated with higher (worse) outcome HAQ, but not with DAS/DAS28 or ESR/CRP level. In combination therapy with bDMARDs, a higher MTX dose was associated with higher outcome HAQ and DAS/DAS28, but not with ESR/CRP level. All effect sizes were small. In DMARD-naive, early RA patients who start MTX, either as monotherapy or in combination with bDMARDs or glucocorticoids, a higher initial dose of MTX was not associated with better clinical outcomes. This finding suggests that there is little short-term gain from starting with high compared to low MTX doses