Minimally Clinically Important Difference (MCID) Is a Low Bar

Abstract

Patients don't care about "statistical" significance. Patient-centered outcome measures focus on "clinical" significance and include minimal clinically important difference (MCID), patient acceptable symptomatic state (PASS), substantial clinical benefit (SCB), and maximal outcome improvement (MOI). "Minimal" is a low bar. MCID neither addresses whether patients are satisfied nor whether they have derived a substantial benefit. MCID is commonly reported allowing comparison between studies, and MCID can be calculated retrospectively, so reporting MCID is acceptable. However, we also need to report PASS, SCB, and, in unique patients like high-level athletes, we may also need to report MOI to adjust for high pretreatment scores and a ceiling effect. Finally, threshold scores are patient-level metrics and must be reported as percentage of patients who meet the threshold, not reported as to whether, as a group, the mean score for the cohort meets the threshold or not (which is a common error).