Background: Appropriate patient-reported outcome measures are paramount to determine the clinical relevance of change experienced by patients after a surgical procedure. The purpose of this study was to evaluate the psychometric properties of 3 patient-reported outcome measures (Hip disability and Osteoarthritis Outcome Score [HOOS], modified Harris hip score, and Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC]) in a large population of patients treated with periacetabular osteotomy for symptomatic developmental dysplasia of the hip.
Methods: Patients who underwent a periacetabular osteotomy for acetabular dysplasia between October 2011 and October 2016 completed multiple questionnaires preoperatively and at the 1-year follow-up. Internal consistency for subscores was evaluated with the Cronbach alpha. Validity was assessed against the Short Form-12. Interpretability included the calculation of the distribution of scores, floor and ceiling effects, and the minimal clinically important difference. Responsiveness was assessed by correlating the score changes with the Global Perceived Effect score.
Results: Of 294 patients, 246 (84%) were female. The median age was 21 years (interquartile range, 17 to 29 years). All WOMAC and HOOS subscores demonstrated adequate internal consistency, and none of the modified Harris hip score components did. All scores except the WOMAC stiffness score exhibited adequate validity and interpretability, with no floor and ceiling effects over 15%. For the HOOS subscores, the minimal clinically important difference was 10.3 for pain, 10.2 for symptoms, 12.6 for sports and recreation, 11.2 for quality of life, and 10.8 for activities of daily living. The minimal clinically important difference for the modified Harris hip score was 7.4. For the WOMAC subscores, the minimal clinically important difference was 10.8 for pain, 12.9 for stiffness, 10.8 for physical, and 10.4 for total. All scores demonstrated adequate responsiveness.
Conclusions: The HOOS, WOMAC, and modified Harris hip score have adequate psychometric properties for use in patients undergoing periacetabular osteotomy, with minor shortcomings. Among the scores analyzed, the HOOS appears to be the most appropriate measure of patient-reported outcome in patients undergoing periacetabular osteotomy.
Clinical relevance: By establishing the psychometric properties of patient-reported outcome measures for periacetabular osteotomy, this study enables a more informed choice of measures for clinical practice and research. The estimated minimal clinically important difference values will facilitate understanding the importance of change in patient-reported outcomes after a surgical procedure in a clinical setting and sample size calculation for further studies.