The LIMB-Q: Reliability and Validity of a Novel Patient-Reported Outcome Measure for Lower Extremity Trauma Patients.

ABSTRACT

BACKGROUND: The LIMB-Q is a novel patient-reported outcome measure for lower extremity trauma patients. The aim of this study was to perform a psychometric validation of the LIMB-Q based on the Rasch Measurement Theory. METHODS: An international, multi-site convenience sample of patients with lower extremity traumatic injuries distal to the mid-femur were recruited via clinical sites (United States, Netherlands) and online platforms (English; Trauma Survivors Network, Prolific). A cross-sectional survey of the LIMB-Q was conducted with test-rest (TRT) measured 1-2 weeks after initial completion in a sub-group of patients. RESULTS: The LIMB-Q was field-tested in 713 patients. The mean age was 41 years (standard deviation (SD) 17, range 18-85), mean time from injury was 7 years (SD 9, range 0-58), and there were variable injury and treatment characteristics (39% fracture surgery only, 38% flap or graft, 13% amputation, 10% amputation and flap/graft). Out of 382 items tested, 164 were retained across 16 scales. Reliability was demonstrated with person separation index values 0.80 and greater in 14 scales (0.78-0.79 in remaining 2 scales), Cronbach alpha values 0.83 and greater, and intraclass correlation coefficient values 0.70 and greater. Each scale was unidimensional, measurement invariance was confirmed across clinical and demographic factors, TRT showed adequate reliability, and construct validity was demonstrated. CONCLUSIONS: The LIMB-Q is a patient reported outcome measure with 16 independently functioning scales (6-15 items per scale) developed and validated specifically for lower extremity trauma patients with fractures, reconstruction, and/or amputation.