Cost-effectiveness of the addition of early hormonal therapy in locally advanced prostate cancer: results decisively determined by the cut-off time-point chosen for the analysis

We present a retrospective cost-effectiveness analysis using data from a ra ndomised controlled trial (EORTC 22863) of the addition of early hormonal t herapy with a luteinising hormone-releasing horn-tone (LHRH) analogue to ra diotherapy in the treatment of patients with locally advanced prostate canc er. Data on the use of medical resources were extracted from the hospital c harts of 90 patients recruited into the trial by one French hospital. Costs are assessed from the viewpoint of the French healthcare financing system and adjusted for censoring. Expected costs per patient of each treatment is related to the expected outcome, mean survival time, estimated by a restri cted means analysis. The time point of restriction is determined by statist ical criteria. In the base case analysis with a cut-off time point at 8.58 years, the combined therapy group (COMB) had a gain in mean survival time o f 1.06 years (7.05 versus 5.99 years) and a reduction of average total cost s of 12 700 French francs (FF) (58 300 FF versus 71 000 FF). The analysis o f uncertainty uses bootstrap techniques with 5000 replicates to examine the joint distribution of cost and survival outcomes. In 76% of the cases, COM B results in longer mean survival time and lower costs than the radiotherap y group (RT). In cases where COMB therapy raises costs (13% of the cases), it is rarely by more than 20 000 FF per patient, no matter the size of the associated survival gain. It is thus highly likely that COMB should be cons idered a cost-effective option compared with RT for these patients. The exa ct result of the economic evaluation is decisively determined by the restri ction time point selected for the determination of mean survival time, part ly also because the average total costs of the two treatments develop entir ely differently as a function of the survival time. (C) 2001 Elsevier Scien ce Ltd. All rights reserved.