PARIS — Methotrexate is an effective therapy for psoriatic arthritis, albeit somewhat less so than for rheumatoid arthritis, according to findings from a large Norwegian registry.
The same data that confirm methotrexate's usefulness in RA offer promise that the agent may be of use in some patients with PsA, Dr. Elisabeth Lie said at the annual congress of the European League Against Rheumatism.
Although methotrexate is widely prescribed for psoriatic arthritis, the supporting evidence for this practice is quite sparse. So Dr. Lie and her coinvestigators examined how methotrexate performed over 6 months in the real-world, nonclinical trial setting of the NOR-DMARD (Norwegian Disease-Modifying Antirheumatic Drug) registry.
NOR-DMARD is a collaboration between five Norwegian rheumatology departments. It features longitudinal patient follow-up with periodic comprehensive collection of data on disease activity and patient outcome measures, explained Dr. Lie of Diakonhjemmet Hospital, Oslo.
The 430 participants with PsA and 1,218 with RA were methotrexate naive at the start. Two-thirds had a disease duration less than 3 years. After 6 months of methotrexate, the mean weekly dose was 13.7 mg in the PsA group and 13.9 mg in the RA patients.
Among the outcomes assessed were 6-month changes in C-reactive protein, erythrocyte sedimentation rate, number of involved joints, the bodily pain and physical functioning scales of the Short Form-36, and patient-assessed fatigue and joint pain. Both groups showed significant overall improvements after 6 months of methotrexate. In the unadjusted analysis, however, the RA patients showed significantly greater mean improvements over baseline than did the PsA patients on virtually all measures.
Yet the RA patients also tended to have worse baseline disease activity. After adjustment for this, as well as age, gender, and dose, the outcome differences between the PsA and RA groups shrank below the level of statistical significance with just two exceptions: The drug remained significantly more effective at improving fatigue and pain scores in the RA group than in patients with PsA.
At baseline, 3, and 6 months, patients in both groups were asked if they were satisfied with their level of function and pain. At baseline, 44% of RA patients and 34% of PsA patients answered affirmatively. At 3 months, the RA patients remained significantly more likely to answer “yes,” by a margin of 64% to 57%. By 6 months, the difference between the two groups was not significant.
Patients also were asked at 3 and 6 months if they'd experienced significant improvement since initiation of methotrexate. Both times, the RA patients were significantly more likely to reply affirmatively, Dr. Lie noted.