Leflunomide use in New Zealand. A national prospective post-marketing study.
BACKGROUND
This post-marketing study aimed to record rates of retention, adverse effects and efficacy of leflunomide in the treatment of rheumatoid arthritis (RA). The secondary objectives were to make a semi-quantitative assessment of response to treatment and to examine the effect of a loading dose on adverse events and treatment duration.


METHODS
Rheumatologists in New Zealand contributed to a prospective leflunomide treatment registry. Baseline data were collected on leflunomide initiation and information about treatment experience was sought every 6 months. Each patient was followed for 2 years. Kaplan-Meier analysis was used to evaluate differences in stopping rates between lack of efficacy and adverse effects. Hazard analysis was used to evaluate the effect of using a loading dose on retention rate.


RESULTS
Three hundred and eight patients were enrolled in the study; complete follow-up data were available for 244 patients. Retention of patients on leflunomide was 64% at 12 months and 49.4% at 2 years. Reasons for stopping were adverse events (54 patients), loss of effect (25 patients) and miscellaneous reasons (14 patients). Use of a loading dose had no effect on retention; there was no difference in treatment duration between those who stopped from adverse effects or loss of efficacy.


CONCLUSIONS
Leflunomide was effective in treating RA in a group that had longer duration of disease and greater prior use of disease-modifying agents than the groups studied in clinical trials. Rates of withdrawal were lower than those reported in other post-marketing studies, but were higher than those from phase III clinical trials.
White
D H N
DH
Rheumatology and Rehabilitation, QE Health, Auckland University, Auckland, New Zealand.
Lynskey
N V
NV
Jones
P B B
PB
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000188:drug therapy / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D005767:Gastrointestinal Diseases / Q000139:chemically induced / Q000453:epidemiology; D006801:Humans; D007555:Isoxazoles / Q000009:adverse effects / Q000191:economics / Q000627:therapeutic use*; D000077339:Leflunomide; D008297:Male; D008875:Middle Aged; D009520:New Zealand / Q000453:epidemiology; D011358:Product Surveillance, Postmarketing / Q000191:economics / Q000639:trends*; D011446:Prospective Studies; D012042:Registries; D055815:Young Adult
D007555:Isoxazoles; D000077339:Leflunomide