Treatment Completion and Costs of a Randomized Trial of Rifampin for 4 Months versus Isoniazid for 9 Months

There is little published information regarding treatment completion, safety, and efficacy of rifampin administered daily for 4 months-a recommended alternative to 9 months of isoniazid for therapy of latent tuberculosis infection. In an open-label randomized trial at a university-affiliated respiratory hospital, consenting patients whose treating physician had recommended therapy for latent tuberculosis infection were randomized to daily self-administered rifampin for 4 months or daily self-administered isoniazid for 9 months. Of 58 patients randomized to rifampin, 53 (91%) took 80% of doses, and 50 (86%) took more than 90% of doses within 20 weeks compared with 44 (76%) and 36 (62%) who took 80 and 90%, respectively, of doses of isoniazid within 43 weeks (relative risks: 80% of doses, 1.2 95% confidence interval: 1.02, 1.4; 90% of doses, 1.4 1.1, 1.7). Adverse events resulted in permanent discontinuation of therapy for two (3%) patients taking rifampin, and for eight (14%) patients taking isoniazid. Three patients developed drug-induced hepatitis--all were taking isoniazid. Total costs of therapy were significantly higher for isoniazid. In conclusion, completion of therapy was significantly better with 4 months of rifampin and major side effects were somewhat lower. Further studies are needed to assess the safety and efficacy of the 4-month rifampin regimen.