Background: Spontaneous cases of hepatic adverse events have been reported in patients with rheumatoid arthritis who were being treated with leflunomide, one of the newer disease-modifying antirheumatic drugs (DMARDs). We assessed the risk of hepatic events associated with the use of leflunomide and other DMARDs.
Methods: Two cohorts comprising 41,885 patients with rheumatoid arthritis who had been dispensed a DMARD between September 1, 1998, and December 31, 2001, were formed using claims databases. Follow-up was from the first dispensing date to the occurrence of a serious or nonserious hepatic event. A nested case-control approach was used to estimate adjusted rate ratios of hepatic events associated with DMARDs dispensed during the prior year, as compared with methotrexate monotherapy.
Results: There were 25 cases of serious hepatic events (rate, 4.9 per 10,000 per year) and 411 nonserious hepatic events (rate, 80.0 per 10,000 per year). There was no increase in the rate of serious hepatic events with either leflunomide (rate ratio [RR] = 0.9; 95% confidence interval [CI]: 0.2 to 4.9) or traditional DMARDs (RR = 2.3; 95% CI: 0.8 to 6.5). However, the rate was increased with biologic DMARDs (RR = 5.5; 95% CI: 1.2 to 24.6). The rate of nonserious hepatic events was also increased with biologic DMARDs (RR = 1.5; 95% CI: 1.0 to 2.3), but not with leflunomide (RR = 0.9; 95% CI: 0.7 to 1.3) and traditional DMARDs (RR = 1.1; 95% CI: 0.8 to 1.4).
Conclusions: We found no evidence of an excess risk of serious or nonserious hepatic events with the use of leflunomide as compared with methotrexate. Still, the increased risk observed with the new biologic DMARDs should be investigated further.