Objectives Leflunomide (LEF) is a disease modifying antirheumatic prodrug with immunomodulating, antiproliferative and antiinflammatory properties. We studied our first daily practice experience with LEF in the Outpatient Department of Rheumatology.

Methods In this prospective study we included all consecutive patients with active rheumatoid arthritis (RA), starting treatment with LEF from February 2000 to January 2001. From patient records data were collected, like patient characteristics, medication data and Disease Activity Scores (DAS28). Analysis was performed on intention to treat basis. Primary endpoints are occurrence of adverse events possibly related to LEF use, incidence and reasons for LEF withdrawal and change in DAS28.

Results 110 patients (n = 38 men and n = 72 women), mean age (SD) 65 (13) years and a median disease duration of 5.5 years were included; mean follow up (SD) was 170 (91) days. Last DMARD prescribed prior to LEF was methotrexate (MTX) 28%, sulfasalazine (SASP) 25%, hydroxychloroquine (HCQ)18% and others 10%; 19% of the patients used LEF as first DMARD. Mean number of DMARDs prescribed before starting LEF was 1.8 ± 1.4. In 9% of the patients LEF was given in combination with another DMARD [MTX (6%), HCQ (2%) or SASP (1%)]. Adverse events (AE) possibly related to LEF use occurred in 56% of patients during follow up, most frequently involving the gastrointestinal tract (62 AE) and skin (21 AE). During follow up 27% discontinued LEF, 16% due to side effects, 5.5% due to inadequate response, 4.5% due to a combination of both. For 1% an undefined cause for withdrawal was recorded. The incidence density for withdrawal of LEF treatment is 56.6 per 100 patient years. Using the change in DAS28 as an efficacy parameter, at the first follow up visit (mean two months) after starting LEF, 22% were categorised good, 48% moderate and 30% non responder. At the second visit (mean six months) 26%, 42% and 31% were categorised good, moderate or non responder.

Conclusion In an outpatient rheumatology practice the incidence density per patient year for withdrawal of LEF treatment is high. Adverse events were the most frequent reasons for withdrawal; gastro-intestinal tract and skin being the organ (systems) most frequently involved. Using the change in DAS28 as efficacy parameter at the sixth month 68% were categorised as good and moderate responders to LEF.