Post-Marketing Surveillance Of High-Dose Methotrexate (>8 Mg/Week) In Japanese Patients With Rheumatoid Arthritis: A Post Hoc Sub-Analysis Of Patients According To Duration Of Prior Methotrexate Use

ObjectivesTo explore whether the duration of prior low-dose methotrexate treatment (MTX; <= 8 mg/week) influences the safety and effectiveness of high-dose MTX (>8 mg/week) in Japanese patients with rheumatoid arthritis (RA).MethodsThis post hoc sub-analysis of a Japanese post-marketing surveillance study evaluated patients initiating high-dose MTX with >= 1 year or <1 year prior low-dose MTX use. Over 24 or 52 weeks, adverse drug reactions (ADRs) were monitored, and effectiveness was assessed using the Disease Activity Score in 28 joints, erythrocyte sedimentation rate [DAS28-4 (ESR)].ResultsOne thousand two hundred and ninety-two MTX >= 1 year and 1001 MTX <1 year patients were included. The incidence of ADRs during the 24- and 52-week follow-up period was significantly more frequent in MTX <1 year than >= 1 year patients and serious ADRs were significantly higher in MTX <1 year than >= 1 year patients during the 52-week follow-up period (all p < .05). Over both follow-up periods, the mean DAS28-4 (ESR) significantly decreased from baseline for all groups. Remission and low disease activity rates (DAS28-4 (ESR) <2.6 and <3.2, respectively) increased from baseline for all groups.ConclusionHigh-dose MTX reduced disease activity regardless of prior treatment duration, but ADRs occurred more frequently among MTX <1 year patients compared to MTX >= 1 year patients.