Problems in interpreting cost effectiveness in clinical trials. Experimental versus implementation costs.

OBJECTIVE

To demonstrate the difficulty of estimating cost effectiveness of alternative implementation strategies using clinical trial data.

DESIGN

Two examples drawn from a hearing-aid intervention trial and a physical-therapy trial for frail elderly are used to demonstrate how alternative implementation strategies may affect cost effectiveness. Sensitivity analysis is used to document a range of possible economic outcomes for each example and show how assumptions based on trials may bias implementation decisions.

MAIN OUTCOME MEASURES

Costs and cost-effectiveness ratios are estimated for alternative implementation strategies and compared with trial results.

MAIN RESULTS

Staffing and equipment substitutions, reconfigurations, and economies of scale can reduce the cost of trial interventions substantially. Such resource alterations as well as protocol and target group modifications may also have an impact on effectiveness. In both examples effectiveness can be reduced by as much as 50% and under certain conditions alternative implementation strategies will still be cost effective.

CONCLUSIONS

Cost effectiveness of implementations can differ substantially from a trial when different resources or target populations are incorporated. Institutions must conduct preimplementation studies which consider alternative resource configurations before adopting an intervention based on trial results.