Editorial Commentary: Research on Clinically Important Differences Has Value but Over-reliance on Thresholds May Obscure the Complexity of Patient-Perceived Improvement.

Abstract

Efforts to determine the relationship between patient-reported outcome measures (PROMs) and patient-reported improvement have largely been focused on determining threshold values to classify patients as having experienced a certain amount of improvement or satisfaction. Although these metrics aid in understanding the extent to which specific PROM scores associated with improvement vary across studies, they are imperfect thresholds sensitive to the practice and setting in which they are estimated. Even when applied to the patients who contributed to their estimation, thresholds misclassify patients. The misclassification is often exacerbated when threshold values are used outside the setting in which they were derived owing to differences in patient expectations, settings, and practice patterns, among others. The growing amount of research reporting thresholds for various measures and patient populations in the orthopaedic and sports medicine literature provides the opportunity to evaluate the consistency between PROM scores and patient-reported improvement and satisfaction across different settings. Although this is valuable, over-reliance on thresholds to determine substantial improvement or satisfaction will obscure the complexity and nuance of patient-perceived improvement.