Measurement properties of Patient-Reported Outcome Measures in patients with a tibial shaft fracture; validation...

The aim of this study was to evaluate the measurement properties of the Short Musculoskeletal Function Assessment (SMFA) and Lower Extremity Functional Scale (LEFS) in patients who sustained a tibial shaft fracture, by comparing them with the scores of a general health-related quality of life instrument scale (i.e., EuroQoL-5D). Data of 136 patients participating in a multicenter randomized controlled trial comparing incisions for intramedullary nail entry in adults with a tibial shaft fracture were used. Patients completed the SMFA, LEFS, EQ-5D and an anchor question at 2 and 6 weeks, and at 3, 6 and 12 months. Reliability (internal consistency), construct validity, responsiveness (longitudinal validity), floor and ceiling effects, minimal important change (MIC), and smallest detectable change (SDC) were determined. The SMFA and LEFS (sub)scales showed adequate internal consistency (0.84<α<0.94). Construct and longitudinal validity were also adequate (correctly predicted hypotheses between 83%-100%). Floor effects were not present. Ceiling effects were present at 12 months for the SMFA lower extremity dysfunction and bother subscales (22% and 19%, respectively) and the LEFS (19%). MICs could not be determined with the available data. The SDC was 13.84 points for the SMFA and 38.74 points for the LEFS. This study confirms that the SMFA and LEFS are reliable, valid, and responsive instruments for monitoring functional limitation in patients after sustaining a tibia shaft fracture during at least the first six months post-injury. An anchor-based MIC for the SMFA remains to be determined.