The Women's Health Trial as an investment

The Women's Health Trial (WHT), a large, multi-unit randomized controlled trial, would have cost a total of $130 million to test the hypothesis that a 50% reduction in the percentage of calories from dietary fat would yield a detectable reduction in breast cancer incidence. However, the WHT was discontinued because evidence to support the hypothesized relationship between dietary fat and breast cancer was judged insufficient to justify the trial. The analysis presented here was undertaken in order to contribute an economic perspective on this issue. Principles of decision analysis and cost-effectiveness analysis are employed to obtain a preliminary estimate of the expected cost per year of life saved of the WHT, as a function of the prior probability that the hypothesis is true (PRIOR). Under specified basecase assumptions, the estimated expected costs per year of life saved range from $11,900 when PRIOR is assumed to be 0.9 to $25,615 when PRIOR is assumed to be 0.1. Sensitivity analyses suggest that the results are most sensitive to assumptions about the strength of the relationship between dietary fat and breast cancer risk, and that improved when it is assumed that dietary change can be achieved by an inexpensive intervention. The expected cost-effectiveness of the WHT is well within the range of estimates of cost-effectiveness of other disease prevention interventions.