Minimum Clinically Important Difference in Short Musculoskeletal Function Assessment: What Change Matters in Ankle Fractures

Accurate interpretation of the clinical significance of patient-reported outcome (PRO) research requires determination of the threshold where a difference in PRO score represents a clinical benefit to patients, termed the minimum clinically important difference (MCID). The Short Musculoskeletal Function Assessment (SMFA) is one of the most commonly utilized PRO tools in orthopaedics. However, to date, no MCID has been determined. The purpose of this study was to define the MCID for the SMFA. A prospectively collected ankle fracture outcomes registry was reviewed between 2014 and 2016. Inclusion criteria were isolated ankle fracture, treatment with open reduction and internal fixation, and 6-week follow-up with completed SMFA. Two commonly utilized methods to determine the MCID, the anchor and distribution methods, were performed in this study. Overall, 105 patients met inclusion/exclusion criteria. Utilizing both the overall health anchor and the mental and emotional health anchor, the MCID was 7.3 (n = 17 and n = 19, respectively). The distribution method MCID was 7.0 (n = 105). Our study found the MCID values for the SMFA to converge around a value of 7 for the 3 analyses. This indicates that a threshold of 7 should be applied to studies utilizing the SMFA to determine the clinical significance of the results.