Effectiveness and safety profile of leflunomide in rheumatoid arthritis: actual practice compared with clinical trials.

OBJECTIVE Leflunomide, an immunosuppressant agent for treating rheumatoid arthritis, was first marketed in France in 2000. Three years after its launch, we sought to assess its prescription patterns in the real world of prescription and use, and to see if its efficacy and safety profiles observed during clinical trials were confirmed. METHODS All patients treated with leflunomide from May 2000 to April 2003 in the Department of Rheumatology of the Bordeaux University Hospital were identified, and their treatment patterns and outcome ascertained. This was compared to data from clinical trials. RESULTS 116 were included (mean age = 55 years, 70% women). Almost 21.7% stopped treatment for lack of efficacy (after a mean delay of 3.6 months), 16% for secondary loss of efficacy (median = 7 months), and 32% for the occurrence of an adverse event (half within 4 months). Over a similar time frame in clinical trials, in patients of about the same age and sex but with less severe disease, the corresponding figures were 7-17% for lack or loss of efficacy, and 14-22% for adverse effects. At one year of follow-up, the discontinuation rate was 70% in the cohort compared to 28-47% in clinical trials. DISCUSSION The differences between the two populations confirm the need to conduct post-marketing studies in order to obtain better knowledge on the effectiveness and safety of a new drug. In many cases, a simple drug utilization study can provide relevant information on the degree of shift between populations included in clinical trials and those treated in real life.