Summary

Interpreting results from patient-reported outcome measures (PROMs) and judging the magnitude of effect (for instance, as large, moderate, small but still important, or negligible) is critical for optimal healthcare decision-making.

The most common reference point for PROMs’ interpretation is the minimal important difference (MID), which provides a measure of the smallest change in a PROM that patients experience as important. Relating PROM results to an anchor measuring a similar construct that is itself interpretable represents the optimal method for the development of a MID. Guidance on determining the credibility of MID estimates generated in this way has until now been unavailable.

McMaster researchers have developed a novel instrument that will allow evaluation of the extent to which the design and conduct of studies measuring MIDs are likely to have protected against misleading estimates. This instrument has proved reliable and will facilitate the identification of trustworthy MIDs for application in clinical trials, systematic reviews and clinical practice guidelines to inform evidence-based clinical and health policy decision-making.