ANALYSIS OF LIFELONG STRATEGIES TO PREVENT PNEUMOCYSTIS-CARINII PNEUMONIA IN PATIENTS WITH VARIABLE HIV PROGRESSION RATES

Objective: To compare strategies for life-long prophylaxis of Pneumocy stis carinii pneumonia (PCP) in a group of AIDS patients with a wide r ange of disease progression rates. Design: Markov decision models. Met hods: Prophylaxis strategies using high and low doses of trimethoprim- sulfamethoxazole (TS), dapsone, and/or aerosolized pentamidine in sequ ence, were compared. Efficacy and toxicity rates for prophylaxis regim ens were taken from a meta-analysis of pertinent randomized controlled trials. Outcomes measured included lifetime episodes of PCP and drug toxicity per 100 patients treated, average life expectancy, and cost. Results: For patients with an expected survival of 3 years after comme ncement of prophylaxis, the use of standard or low dose TS as the firs t choice agent was comparable, and both were superior to the other str ategies for preventing PCP (between nine and 26 fewer episodes of PCP per 100 patients treated) though they were more toxic (11-44 more epis odes oi toxicity per 100 patients treated). Life expectancy was simila r for all of the treatment strategies. With slower rates of disease pr ogression (expected survival > 3.8 years), as seen with current antire troviral regimens, the use of low dose TS as the first choice agent do minated the use of standard dose TS; when the expected survival time w as 7 years, initial use oi low dose TS led to 2.8 fewer episodes of PC P per 100 patients treated, 32 fewer episodes of toxicity per 100 pati ents treated, and US$1381 per patient lower cost, compared with prophy laxis with standard dose TS. Conclusion: For patients with AIDS and ex pected survival > 3.8 years, low dose TS is better than standard dose TS as the first choice agent for preventing PCP. As patients with AIDS live longer, the routine use of low dose TS will be more than adequat e for patients at risk for PCP. (C) 1998 Lippincott-Raven Publishers.