The effectiveness of leflunomide in psoriatic arthritis

This study aimed to evaluate the effectiveness and safety of leflunomide alone and in combination with methotrexate in the treatment of psoriatic arthritis (PsA).

Patients were followed at the University of Toronto PsA Clinic. PsA patients who received leflunomide alone or in combination with methotrexate were identified from the PsA clinic database. Effectiveness was defined by drug persistence, a ≥40% reduction in actively inflamed joints, a ≥40% reduction in swollen joint count, and PASI50 and PASI75 response following treatment with leflunomide. Descriptive statistics and logistic regression analyses with stepwise selection were used for data analysis.

85 patients were identified. 43 patients (50.6%) were on leflunomide alone and 42 (49.4%) patients were on combined leflunomide and methotrexate therapy. 30 patients discontinued leflunomide mainly due to toxicity. Of the 55 patients who continued the drug, 38%, 48% and 56% achieved a ≥40% reduction of actively inflamed joint count at 3, 6 and 12 months, respectively. PASI50 was achieved by 27%, 28% and 38% at 3, 6 and 12 months, whereas PASI75 was achieved by 19% at 3 and 6 months and 32% at 12 months. Longer duration of PsA and higher swollen joint count at baseline were predictive for improvement of the swollen joint count at 3 months. The use of concomitant MTX was predictive of achieving PASI50 at 12 months.

Leflunomide led to improvement in almost 50% of the patients by 1 year. Those also taking methotrexate were more likely to achieve a PASI50 response.