The effectiveness and retention rates of methotrexate in psoriatic arthritis with methotrexate treated patients with rheumatoid arthritis as a reference population

Elisabeth Lie ^1*, Désirée MFM van der Heijde ², Till Uhlig ¹, Marte S Heiberg ¹, Wenche Koldingsnes ³, Erik Rødevand ⁴, Cecilie Kaufmann ⁵, Knut Mikkelsen ⁶ and Tore K Kvien ¹

¹ Diakonhjemmet Hospital, Norway
² Leiden University Medical Center, Netherlands
³ University Hospital Northern Norway HF, Norway
⁴ St. Olav Hospital, Norway
⁵ Buskerud Central Hospital, Norway
⁶ Lillehammer Hospital for Rheumatic Diseases, Norway

^* To whom correspondence should be addressed. E-mail: elisabeth_lie{at}yahoo.no.

Accepted 26 August 2009

Abstract

Objective: To examine effectiveness and 2-year retention rates of methotrexate (MTX) in MTX naïve patients with psoriatic arthritis (PsA).

Methods: We analyzed data on 430 PsA patients participating in an ongoing longitudinal observational multicenter study in Norway. 1218 MTX naïve rheumatoid arthritis (RA) patients 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 PsA and RA patients improved in most disease activity measures and patient reported outcomes. In the adjusted analysis PsA patients tended to have less improvement, but changes were in the same range as in RA patients. Two-year retention rates of MTX therapy in PsA and RA patients were 65% and 66%, respectively, with only minor differences in reported reasons for discontinuation. Lower age, longer disease duration, and higher MHAQ score and patient global assessment were independent predictors of MTX termination within the first two years of treatment.

Conclusion In this real life study, MTX treatment was associated with improvement of disease activity and health related quality of life in PsA patients after 6 months of therapy. Retention rates of MTX were similar in PsA and RA.