Effectiveness and retention rates of methotrexate in psoriatic arthritis in comparison with methotrexate-treated patients with rheumatoid arthritis

Objective To examine the effectiveness and 2-year retention rates of methotrexate (MTX) in MTX naive patients with psoriatic arthritis (PsA). Methods Data on 430 patients with PsA participating in an ongoing longitudinal observational multicentre study in Norway were analysed. 1218 MTX naive patients with rheumatoid arthritis (RA) from the same study served as a reference population. Assessments included measures of disease activity (28 joint counts, acute phase reactants), health status and utility scores. Six-month effectiveness data were compared both by crude analyses and with adjustments for age, sex and the respective baseline values. Two-year drug survival was compared by Kaplan-Meier and Cox regression analyses. Results After 6 months of MTX treatment, both patients with PsA and those with RA improved in most disease activity measures and patient reported outcomes. In the adjusted analysis, patients with PsA tended to have less improvement, but changes were in the same range as in patients with RA. Two-year retention rates of MTX therapy in patients with PsA and RA were 65% and 66%, respectively, with only minor differences in reported reasons for discontinuation. Lower age, longer disease duration and higher Modified Health Assessment Questionnaire (MHAQ) score and patient global assessment were independent predictors of MTX termination within the first 2 years of treatment. Conclusion In this real-life study, MTX treatment was associated with improvement in disease activity and health-related quality of life in patients with PsA after 6 months of treatment. Retention rates of MTX were similar in PsA and RA.