The Short Musculoskeletal Function Assessment: a study of the reliability, construct validity and responsiveness in patients sustaining trauma

Objective: To assess test-retest reliability, construct validity and responsiveness of the Dutch Short Musculoskeletal Function Assessment (SMFA-NL) in patients who sustained acute physical trauma. Design: A longitudinal cohort study. Setting: A level 1 trauma center in The Netherlands. Subjects: Patients who required hospital admission after sustaining an acute physical trauma. Intervention: Patients completed the SMFA-NL at six weeks, eight weeks and six months post-injury. Main measure: The measures used were The Dutch Short Musculoskeletal Function Assessment. Test-retest reliability (between six and eight weeks post-injury) using intraclass correlation coefficients, the smallest detectable change and Bland and Altman plots. Construct validity (six weeks post-injury) and responsiveness (between six weeks and six months post-injury) were evaluated using the hypothesis testing method. Results: A total of 248 patients (mean age: 46.5, SD: 13.4) participated, 145 patients completed the retest questionnaires (eight weeks) and 160 patients completed the responsiveness questionnaires (six months). The intraclass correlation coefficients indicated good to excellent reliability on all subscales (0.80 to 0.98). The smallest detectable change was 17.4 for the Upper Extremity Dysfunction subscale, 11.0 for the Lower Extremity Dysfunction subscales, 13.9 for the Problems with Daily Activities subscale and 16.5 for the Mental and Emotional Problems subscale. At group level, the smallest detectable change ranged from 1.48 to 1.96. A total of 86% of the construct validity hypotheses and 79% of the responsiveness hypotheses were confirmed. Conclusion: This study showed that the SMFA-NL has good to excellent reliability, sufficient construct validity and is able to detect change in physical function over time.