Incremental Cost-Effectiveness Analysis of Intravenous Ganciclovir Versus Oral Ganciclovir in the Maintenance Treatment of Newly Diagnosed Cytomegalovirus Retinitis in Patients with AIDS

Abstract

Objective: To evaluate the cost effectiveness of a new product, oral ganciclovir, in comparison to a current therapy, intravenous (IV) ganciclovir, in the maintenance treatment of newly diagnosed cytomegalovirus (CMV) retinitis in patients with AIDS.

Design: This was a retrospective economic study of a prospective non-blinded randomised clinical trial. The model included IV ganciclovir induction, IV or oral ganciclovir maintenance and IV ganciclovir reinduction for patients whose CMV retinitis progressed. Safety and efficacy data were derived from the trial. A panel of Canadian infectious disease physicians and family physicians estimated the following in relation to IV ganciclovir treatment for CMV retinitis and related adverse events: healthcare resource utilisation, clinical practice patterns, patient out-of-pocket expenses and time loss from work. The incremental cost-effectiveness analysis is reported from a societal and a Ministry of Health perspective.

Setting: The trial was conducted in Canada (2 centres) and the US (13 centres) between March 1991 and November 1992. The model assumed that patients received either inpatient or outpatient care, or both. The model provided an analysis in a Canadian setting.

Patients and participants: Participants were patients with AIDS and newly diagnosed CMV retinitis.

Interventions: All patients received induction therapy with IV ganciclovir 5 mg/kg, twice daily for 14 days then once daily for 7 days. Patients whose CMV retinitis stabilised were randomised to maintenance therapy with either IV ganciclovir (5 mg/kg/day; n = 57) or oral ganciclovir (3000 mg/day; n = 60) and were followed for up to 140 days after the start of maintenance therapy.

Main outcome measures and results: The trial demonstrated that the mean time to progression of CMV retinitis was 57 days for oral ganciclovir compared with 62 days for IV ganciclovir maintenance therapy, as measured by masked fundus photography, and 96 days with IV ganciclovir compared with 68 days with oral ganciclovir according to the funduscopy results. There were more adverse events in the IV ganciclovir group compared with the oral ganciclovir group. The cost-effectiveness results provide the dollar amount expended in order to continue to provide additional benefit using IV ganciclovir compared with oral ganciclovir. The incremental cost-effectiveness (C/E) ratio was 482 Canadian dollars ($Can; 1993 to 1995 values) per progression-free day gained with IV ganciclovir. Sensitivity analysis using funduscopy, rather than fundus photography, to document progression of CMV retinitis resulted in a C/E ratio of $Can42.

Conclusions: This analysis found that IV ganciclovir provided additional days free of progression of CMV retinitis when compared with oral ganciclovir, but the costs were higher