ADVANCED HIV-INFECTION TREATED WITH ZIDOVUDINE MONOTHERAPY - LIFETIMEVALUES OF ABSOLUTE COST-EFFECTIVENESS AS A PHARMACOECONOMIC REFERENCEFOR FUTURE STUDIES EVALUATING ANTIRETROVIRAL COMBINATION TREATMENTS

OBJECTIVE: This study was undertaken to evaluate the cost and the effe ctiveness of zidovudine monotherapy in patients with advanced HIV infe ction and to derive preliminary data on the cost-effectiveness of the triple treatment with saquinavir plus zalcitabine plus zidovudine comp ared with zidovudine alone. DESIGN: We used a combined method of survi val analysis utilizing both the quality-adjusted time without symptoms or toxicity (Q-TWIST) method and the Gompertz approach. This combined method was applied to assess the absolute cost-effectiveness and cost -utility ratios of zidovudine monotherapy and to perform a preliminary incremental cost-effectiveness comparison of saquinavir plus zalcitab ine plus zidovudine versus zidovudine alone. The clinical material use d in our study was derived from two reports on the treatment of advanc ed HIV infection. Data of lifetime costs of HIV infection were obtaine d from published information. RESULTS: In patients with advanced HIV i nfection treated with zidovudine monotherapy, lifetime survival was 25 2.1 discounted person-years per 100 patients. Using an average lifetim e cost of $93 000 (discounted) per individual the absolute ratio of co st-effectiveness for zidovudine monotherapy was $36 980 per life-year, while the absolute cost-utility ratio was $47 112 per quality-adjuste d life-year. In the comparative analysis of saquinavir plus zalcitabin e plus zidovudine versus zidovudine alone, our calculations showed tha t the administration of the triple treatment can have an ''average'' c ost-effectiveness, provided that mean lifetime survival per patient (d iscounted) is improved to at least 3.68 years (with an average surviva l gain of at least 14 mo per patient). CONCLUSIONS: The values of abso lute cost-effectiveness and cost-utility ratios for zidovudine monothe rapy are a useful reference point for further pharmacoeconomic studies in the area of antiretroviral drugs.