NEW YORK (Reuters Health) – Patients with psoriatic arthritis showed a greater disease response to treatment with antitumor necrosis factor (TNF) therapy than with conventional methotrexate treatment, Norwegian investigators report in the August issue of the Annals of the Rheumatic Diseases.

Dr. Marte Schrumpf Heiberg and colleagues at Diakonhjemmet Hospital in Oslo are conducting a longitudinal study of 526 patients with psoriatic arthritis, comparing the effects of TNF inhibitors, including infliximab, etanercept and adalimumab, with or without concomitant methotrexate with methotrexate alone.

The investigators measured disease activity and health-related quality of life at baseline and again at 3 and 6 months. Analyses of covariance (ANCOVA) were compared.

Patients reported on in this phase of study had been treated for at least 6 months.

The adjusted changes at 6 months were "significantly larger" in the anti-TNF group than in the methotrexate-treated patients for erythrocyte sedimentation rate and the disease activity score at 28 joints.

Improvements were also significant on the four-point medical health assessment questionnaire potassium depletion and in patients’ assessments of pain, fatigue and global disease activity on a visual analogue scale and on the three-question short form.

"The introduction of biological drugs represents a major progress in the treatment of psoriatic arthritis, and has led to an increased interest in the disease," Dr. Heiberg and colleagues note.

"The efficacy of traditional disease-modifying anti-rheumatic drugs (DMARDs), by contrast, is poorly documented through systematic trials. Nevertheless, they are widely used, mainly based on the clinical impression that these drugs are effective," the researchers comment.

"Although no head-to-head comparisons have been performed between the different TNF-blocking agents, similar magnitude of clinical response has been observed across trials with the different agents with respect to joint symptoms, whereas improvements in skin manifestations seem to be somewhat greater with the monoclonal antibodies," the authors write.

"Our conclusion is that psoriatic arthritis patients seem to benefit more from TNF-blocking agents than methotrexate when treated in daily clinical practice. This result is consistent with findings in randomized clinical trials and contributes to improve external validity of results from randomized clinical trials examining anti-TNF drugs in psoriatic arthritis."

"However, more studies are needed to further establish the role of traditional DMARDs in the treatment of psoriatic arthritis," Dr. Heiberg and colleagues conclude.

Ann Rheum Dis 2007;66:1038-1042.

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