Pharmacoeconomic Analysis of 3 Treatment Strategies for Cytomegalovirus Retinitis in Patients with AIDS

Summary

A decision-analytical simulation model was constructed to perform a pharmacoeconomic analysis of the following 3 treatment strategies for previously untreated cytomegalovirus (CMV) retinitis in patients with AIDS: (i) intravenous foscarnet (IVF) for induction and maintenance therapy; (ii) intravenous ganciclovir (IVG) for induction and maintenance therapy; and (iii) intravenous ganciclovir for induction therapy, followed by oral ganciclovir for maintenance therapy (IVG-ORG). Patients who experienced significant adverse effects during, or who failed, initial therapy were switched once to one of the other 2 treatments. The model was used to estimate the direct medical cost (from the perspective of a public payer), survival, and survival adjusted for disutility because of lost vision, for each strategy in the first year following treatment initiation.

The expected first-year costs of treatment initiated with IVF, IVG and IVGORG were $US47 918, $US38 817 and $US32 036 (1994 values), respectively, while expected first—year survival was 41 weeks, 35 weeks and 35 weeks, respectively. The incremental cost per incremental year of survival using IVF was $US78 000 versus IVG and $US138 000 versus IVG-ORG before adjustment for lost vision, and $US93 000 versus IVG and $US166 000 versus IVG-ORG after adjustment for lost vision. About 23% of the cost of the IVG treatment strategy was attributable to treatment—related adverse events, compared with 14% of the cost of IVF and 16% of the cost of IVG-ORG. Because of the high failure rate with IVG-ORG, initial treatment with IVG-ORG frequently led to switching to another treatment. Only 27% of the costs associated with the IVG-ORG treatment strategy were in fact attributable to the cost of induction and maintenance therapy prior to a switch to alternative treatment.

In this analysis, initial treatment with IVG-ORG was the least costly approach for treating CMV retinitis in patients with AIDS. Initial treatment with IVF resulted in slightly longer survival adjusted for vision—related quality of life. New treatments for AIDS may reduce the survival benefit of initial treatment with IVF.