When measuring quality of life, patient preferences, health status, or other types of patient reported outcomes (PROs), the term minimal clinically significant difference (MCSD) indicates the smallest amount of meaningful change or difference that can be assessed by a PRO measure. The term meaningful change, in this context, refers to the smallest difference that is perceived by patients (or other stakeholders) as beneficial or harmful and that would lead to a change in treatment.

From this perspective, the MCSD is a numerical value, and PRO score differences that exceed this value are considered indicative of important or meaningful change. MCSDs vary across different PRO measures (i.e., a difference of 10 points may be indicative of meaningful change for one measure but not another) and different populations ...