Leflunomide in clinical practice. A retrospective observational study on use of leflunomide in New Zealand

Aim: The aim was to study the side-effect profile and the survival characteristics of leflunomide used in a regional patient population in New Zealand (NZ). Method: Patients were identified using special authority forms (SAFs) that had been prospectively filed from January 2001 to June 2007. Statistical analysis of survival data was done using the Kaplan-Meier (KM) method. Results: Of 110 patients identified on SAFs, only 90 were suitable for analysis. The percentage of women and men were 74% and 26%, respectively. Their mean age was 55.58 years +/- 13.44. Their diagnoses were rheumatoid arthritis 75%, psoriatic arthritis 15%, others 10%. Their mean disease duration was 11.31 years +/- 8.93. The mean number of concomitant disease-modifying antirheumatic drugs used was 1.95. These were methotrexate (MTX) in 48, hydroxychloroquine in 29, prednisone in 30 and sulfasalazine in 27. Thirty-two of 90 (35.5%) discontinued treatment, 12 (13.3%) of these were in the first 6 months. The mean time to discontinuation was 14.2 months. Twenty-three of 32 discontinuations were for side-effects. The incidence of side-effects were similar to those of an earlier 2-year NZ study, and better than other earlier studies. Leflunomide survival using the KM method at 5 years was 57%, higher than suggested by previous leflunomide studies and this compares well with MTX studies. Conclusions: Our study suggests a better side-effect profile and a better drug survival for leflunomide than suggested by previous studies with survival comparable to that of MTX.