A randomized trial of daily and thrice-weekly trimethoprim-sulfamethoxazole for the prevention of Pneumocystic carinii pneumonia in human immunodeficiency virus-infected persons

We enrolled 2,625 human immunodeficiency virus-infected patients into a randomized trial to assess the efficacy and tolerability of daily vs. thrice-weekly trimethoprim-sulfamethoxazole (160 mg/800 mg) for prophylaxis of Pneumocystis carinii pneumonia (PCP), The rate of PCP was 3.5 and 4.1 per 100 person-years in the daily and thrice-weekly groups, respectively, with a relative risk (RR) of 0.82 (95% confidence interval [CI], 0.61-1.09; P =.16) (RR of < 1.0 favors daily trimethoprimsulfamethoxazole), The RR for PCP determined by on-treatment analysis was 0.59 (P =.03). The RR for death was 0.91 (P =.12); for bacterial pneumonia, 0.82 (P =.06); and for combined PCP and bacterial pneumonia, 0.84 (P =.04), Discontinuation due to adverse events occurred more commonly in the daily trimethoprim-sulfamethoxazole group (RR, 2.14; 95% CI, 1.73-2.66; P <,001), Overall estimates for efficacy end points favored daily trimethoprim-sulfamethoxazole, although rates of intolerance were higher among patients receiving that dose. Daily trimethoprim-sulfamethoxazole may offer advantages as a first choice for PCP prophylaxis; thrice-weekly dosing is an appropriate option for patients intolerant of the daily dose.