The positive influence of methotrexate on the mortality of patients with rheumatoid arthritis is partly independent of its effect on disease activity: results of a re-evaluation 18 years after baseline.

OBJECTIVES: Methotrexate (MTX) is the anchor drug in the treatment of patients with rheumatoid arthritis (RA). MTX shows effects on disease activity and mortality. However, it is unclear whether the effect of MTX on mortality depends on its effect on disease activity.
METHODS: In a post-hoc analysis we analysed the data of our cohort established in Ratingen, Germany, and included all patients starting treatment with MTX (n=271) between 1980 and 1987. One year after baseline (BL), response to MTX treatment was assessed using a modified ACR 20 response. Follow-up data of 250 patients were available after 10 and 18 years.
RESULTS: After 1 year, there were 66% responders and 20% non-responders; only 14% had discontinued MTX treatment due to side effects or lack of efficacy. Most patients continued MTX treatment irrespective of efficacy. Ten years after BL, 61% of the patients were still treated with MTX. After 18 years, the responder-group showed a standardised mortality ratio of 1.6 compared to 3.2 for the group of non-responders. However, when adjusting for age, gender, response to MTX treatment one year after BL, number of swollen joints and comorbidities after 10 years an independent association of continued MTX treatment with lower mortality was found for the period 10 to 18 years after BL (hazard ratio (HR): 0.63, 95% confidence interval: 0.43-0.92, p=0.015).
CONCLUSIONS: In this cohort, the mortality lowering effect of continued MTX use was partly independent of its effect on disease activity. This finding may affect treatment decisions concerning RA patients with insufficient response to MTX.