Minimal Clinically Important Difference (MCID) for the Short Musculoskeletal Function Assessment (SMFA) in Severe Lower Extremity Trauma: Pooled Data from 7 Multicenter, Prospective Clinical Trials

• Published in: Journal of bone and joint surgery. American volume 2024-07, Vol.106 (19), p.1767-1775
• Main Authors: Carlini, Anthony R, Agel, Julie, Bosse, Michael J, Frey, Katherine P, Staguhn, Elena D, Vallier, Heather A, Obremskey, William, Swiontkowski, Marc F, Cannada, Lisa K, Tornetta, 3rd, Paul, MacKenzie, Ellen J, O'Toole, Robert V, Reider, Lisa, Allen, Lauren E, Collins, Susan C, Castillo, Renan C
• Format: Article
• Language: English
• ISSN: 0021-9355; 1535-1386; 1535-1386
• DOI: 10.2106/JBJS.23.01201

The Short Musculoskeletal Function Assessment (SMFA) is a well validated, widely used patient-reported outcome (PRO) measure for orthopaedic patients. Despite its widespread use and acceptance, this measure does not have an agreed upon minimal clinically important difference (MCID). The purpose of the present study was to create distributional MCIDs with use of a large cohort of research participants with severe lower extremity fractures. Three distributional approaches were used to calculate MCIDs for the Dysfunction and Bother Indices of the SMFA as well as all its domains: (1) half of the standard deviation (one-half SD), (2) twice the standard error of measurement (2SEM), and (3) minimal detectable change (MDC). In addition to evaluating by patient characteristics and the timing of assessment, we reviewed these calculations across several injury groups likely to affect functional outcomes. A total of 4,298 SMFA assessments were collected from 3,185 patients who had undergone surgical treatment of traumatic injuries of the lower extremity at 60 Level-I trauma centers across 7 multicenter, prospective clinical studies. Depending on the statistical approach used, the MCID associated with the overall sample ranged from 7.7 to 10.7 for the SMFA Dysfunction Index and from 11.0 to 16.8 for the SMFA Bother Index. For the Dysfunction Index, the variability across the scores was small (