Sufficiently Important Difference: Concepts, Caveats, and Challenges

Key words: attitude to health; clinical significance; cost-benefit analysis; decision making; minimal important difference; outcomes; patient preference; randomized controlled trials; research design; quality of life. (Med Decis Making XXXX; XX: xx–xx) Evidence-based medicine is built on a foundationof randomized trials. Interpretation of trials de-pends on whether a predetermined difference (effect size) between intervention and control groups was observed and the likelihood of this being due to chance (statistical significance). It is now generally agreed that the effect size for which a trial is pow-ered should be just large enough to be clinically sig-nificant. Introduction of the concept of minimal important difference (MID) in the 1980s was fol-lowed by an emerging stream of research aimed a