Pharmacoeconomic analysis of 3 treatment strategies for cytomegalovirus retinitis in patients with AIDS
Griffiths RI., Bleecker GC., Jabs DA., Dieterich DT., Coleson L., Winters D., Wolitz R., Steinberg EP.
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 IVG-ORG were $US47,918, $US38,817 and SUS32,036 (1994 values), respectively, while expected first-yea r 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.