PROPHYLAXIS FOR DISSEMINATED MYCOBACTERIUM-AVIUM COMPLEX (MAC) INFECTION IN PATIENTS WITH AIDS - A COST-EFFECTIVENESS ANALYSIS

Objective: To determine the effectiveness and costs of prophylaxis for disseminated Mycobacterium avium complex (MAC) infection in patients with AIDS. Design: A decision analysis model was constructed to compar e rifabutin (300 mg/day), azithromycin (1200 mg/week), and clarithromy cin (500 mg twice per day) with no prophylaxis. Sensitivity analysis w as done on all model parameters, including initial CD4 count for begin ning prophylaxis. Setting: The setting was hypothetical for the cost-e ffectiveness model. Clinical data were taken from published prospectiv e randomized controlled trials. Main Outcome Measures: Outcomes were m easured in terms of projected life expectancy, quality-adjusted life e xpectancy, direct medical costs, and cost-effectiveness in U.S. dollar s per quality-adjusted life-year saved ($/QALY). Results: For patients with AIDS and those having CD4 counts <75 cells/mm(3), azithromycin, clarithromycin, and rifabutin prophylaxis increased lifetime per perso n MAC-related costs by $994, $2,117, and $2,185 U.S., respectively. Qu ality-adjusted life expectancy increased from 1.6068 QALYs to between 1.6186 and 1.6255 QALYs. The cost-effectiveness ratios were $58,200, $ 116,000, and $179,100/QALY saved for azithromycin, clarithromycin, and rifabutin prophylaxis, respectively, each compared with no prophylaxi s. Results were most dependent on the annual cost of prophylaxis, the initial CD4 count when starting prophylaxis, and any survival benefit with prophylaxis. For each type of prophylaxis, strategies beginning w ith CD4 counts <25 or 50 cells/mm(3) were substantially more cost-effe ctive than those beginning in patients with higher CD4 counts. Conclus ions: MAC prophylaxis is likely to cost society an additional $99 to $ 219 million U.S. per 100,000 patients treated. In the context of Cente rs for Disease Control and Prevention (CDC) recommendations to use pro phylaxis in patients with CD4 counts <75 cells/mm(3), azithromycin rep resents the best value and is most cost-effective when used in patient s with CD4 counts <25 cells/mm(3).