Validity, Reliability, and Framing Effects in Equity-Efficiency Trade-Off Studies: A Systematic Review

Health system resources are limited, and decision makers often need to make trade-offs between equity and efficiency. Such trade-offs are guided by public values that are elicited using choice experiments. There is no standard approach to elicit equity-efficiency trade-offs. Previous studies have found significant variability in public values, raising concerns about the robustness of trade-off experiments. The objective of this systematic review was to determine whether and how equity-efficiency trade-off studies consider validity, reliability, and framing effects.

We searched Medline, EMBASE, and Web of Science in May 2025 for health-related equity-efficiency trade-off studies. Two reviewers independently screened titles and abstracts, followed by full-text review, data extraction, and quality assessment.

122 equity-efficiency trade-off studies were identified, of which 33 studies (27%) investigated validity, reliability, and/or framing effects. Seventeen (13.9%) studies assessed validity, 10 (8.2%) studies assessed reliability, and 11 (9.0%) assessed framing or cognitive effects. Validity was most frequently assessed by comparing results with hypothesized expectations, whereas reliability was commonly assessed by providing a repeated test or questionnaire. Framing and cognitive effects were assessed by varying question order or changing the wording or framing of the scenario. Twenty-three of 27 studies reported high or acceptable validity or reliability, and 6 of 11 studies found no significant framing or cognitive effects.

This article identifies key methodological challenges and considerations that can inform the design of future choice experiments estimating inequity aversion.