Estimating country-specific cost-effectiveness from multinational clinical trials.

Because costs and outcomes of medical treatments may vary from country to country in important ways, decision makers are increasingly interested in having data based on their own country's health care situations. This paper proposes methods for estimating country-specific cost-effectiveness ratios from data available from multinational clinical trials. It examines how clinical and economic outcomes interact when estimating treatment effects on cost and proposes empirical methods for capturing these interactions and incorporating them when making country-specific estimates. We use data from a multinational phase III trial of tirilazad mesylate for the treatment of subarachnoid haemorrhage to illustrate these methods. Our findings suggest that it is possible for meaningful country-by-country differences to be found in such trial data. These differences can be useful in informing reimbursement, utilization, and other decisions taken at the country level.