A NEW DECISION-MODEL FOR COST-UTILITY COMPARISONS OF CHEMOTHERAPY IN RECURRENT METASTATIC BREAST-CANCER

In the absence of comparative clinical and pharmacoeconomic trial data for docetaxel versus paclitaxel as second-line therapy for patients w ith anthracycline-resistant metastatic breast cancer. a computer-based decision-analysis model was designed to evaluate the comparative util ity to patients of these two taxoids. The model used the Markov proces s to analyse disease states (response, stable disease, progressive dis ease) and toxicities (acute, cumulative) for each treatment during the period from commencement of up to six 3-weekly cycles of chemotherapy , to death. A cost-utility analysis was carried out using the model wi th a probability, a cost and a utility determined for each health stat e. Response rates were obtained from clinical trial data supplemented by expert clinical opinion. Costs were taken from UK national database s and published sources and the published UK prices of docetaxel and p aclitaxel. Utilities for the various health states were established by use of standard gamble and visual analogue methods assessed by 30 onc ology nurses in the UK who were acting as proxy patients. The results of the model showed that response rate is the key parameter determinin g the utility and cost utility of treatments for metastatic breast can cer. Although the total per-patient cost associated with docetaxel was marginally higher than that for paclitaxel (pound 8233 vs pound 8013, the higher response rate associated with docetaxel produced an improv ement in utility to the patient at an incremental healthcare cost that is acceptable according to available defined limits. Sensitivity anal yses revealed that. although the model was sensitive to changes in res ponse rate and drug costs, the cost-utility ratio for docetaxel versus paclitaxel varied within acceptable limits in response to all likely changes in key parameters. In summary, in the base case used in this m odel, docetaxel produces a substantially larger utility benefit than p aclitaxel, at a small additional cost per QALY gained (equivalent to p ound 7 per additional day of perfect health).