The minimal clinically-important difference of the Prosthesis Evaluation Questionnaire - Mobility Scale in subjects undergoing lower limb prosthetic rehabilitation training

BACKGROUND: There is increasing interest in psychometrically sound outcome measures of mobility for people with lower limb amputation (LLA), in order to accurately monitor the impact of the prosthetic training during and after rehabilitation. AIM: To determine the minimum detectable change (MDC) and minimal clinically important difference (MCID) for the Prosthesis Evaluation Questionnaire-Mobility Scale (PEQ-MS) in people with LLA. DESIGN: Prospective single-group observational study. SETTING: Two free-standing Rehabilitation Hospitals. POPULATION: Eighty-seven adult inpatients with LLA undergoing prosthetic rehabilitation. METHODS: Patients completed the self-report PEQ-MS twice, immediately before and after prosthetic rehabilitation training. We administered a 7-point Global Rating of Change scale at the end of training as external anchor, to quantify the effect (improvement/deterioration) of the intervention. RESULTS: Test-retest reliability of the PEQ-MS (N.=24) was high (ICC2,1=0.90). The MDC at the 95% confidence level was 5.5 points. This value, together with those of the mean-change approach and receiver-operating characteristic-curve analysis (AUC≥0.89), suggested the selection of a MCID for PEQ-MS of eight points of change, i.e. 16.1% of the maximum possible score (95% CI: 6.5-9.5). CONCLUSIONS: The PEQ-MS showed a high ability to detect change over time (responsiveness).The above MCID value - derived from a triangulation of distribution (MDC) and anchor-based methods - represents a minimal level of change (perceived as important by the patient) in mobility of people with LLA undergoing prosthetic rehabilitation training. CLINICAL REHABILITATION IMPACT: The PEQ-MS is a widely used and analyzed outcome measure. The present study calculated - in a sample of people with LLA undergoing prosthetic training - both the MDC and MCID of the PEQ-MS, showing the high responsiveness of this tool. These values increase confidence in interpreting change in PEQ-MS values, and can help in clinical decision making.