Abstract
Accurately interpreting scores on patient-reported outcome (PRO) measures is essential to understanding and communicating treatment benefit. Over the years, terminology and methods for developing recommendations for PRO score interpretation in clinical trials have evolved, leading to some confusion in the field. The phrase "minimal clinically important difference (MCID)" has been simplified to "minimal important difference (MID)" and use of responder thresholds to interpret statistically significant treatment effects has increased. Anchor-based derivation methods continue to be the standard, with specific variations preferred by regulatory authorities for drug development programs. In the midst of these changes, the Evaluating Respiratory Symptoms™ in COPD (E-RS:COPD) was developed and qualified for use as an endpoint in chronic obstructive pulmonary disease (COPD) drug development programs. This paper summarizes the evolution of terminology and method preferences for the development of recommendations for interpreting scores from PRO measures used in clinical trials, and how these changes are reflected in the E-RS:COPD recommendations. The intent is to add clarity to discussions around PRO endpoints and facilitate use of the E-RS:COPD as a key efficacy endpoint in clinical trials of COPD.