Measurement properties of the HOOS-PS in revision total hip arthroplasty: a validation study on validity, interpretability, and responsiveness in 136 revision hip arthroplasty patients

BACKGROUND AND PURPOSE: To determine whether the Hip disability and Osteoarthritis Outcome Score-Physical function Short-form (HOOS-PS) is able to appropriately evaluate physical function in revision hip arthroplasty patients, this study assesses psychometric properties of the Dutch HOOS-PS in this patient population. PATIENTS AND METHODS: We assessed psychometric properties of the HOOS-PS following the Consensus-based Standards for the selection of health Measurement Instruments (COSMIN) criteria. Content validity, including comprehensibility, comprehensiveness, and relevance of the items, was assessed using cognitive debriefing interviews in hip revision patients (n = 8) and orthopedic surgeons specialized in revision surgery (n = 7). Construct validity, responsiveness, and interpretability (floor/ceiling effects) were assessed in revision hip arthroplasty patients (baseline n = 136, follow-up n = 67). We formulated hypotheses a priori to assess construct validity and responsiveness using the EuroQol 5-Dimensions Health Questionnaire, Numeric Rating scale for pain, and Oxford Hip Score as comparators. All questionnaires were measured at baseline and 1 year postoperatively. RESULTS: We found insufficient content validity of the HOOS-PS, as relevance and comprehensibility of the items scored < 85% on the COSMIN criteria for revision hip arthroplasty patients. Construct validity was sufficient as all hypotheses were confirmed (≥ 75% COSMIN criteria). Interpretability was sufficient (< 15% COSMIN criteria) and responsiveness was insufficient (< 75% COSMIN criteria). INTERPRETATION: The Dutch HOOS-PS is not able to sufficiently evaluate physical function in revision hip arthroplasty patients. Minor changes in the items are needed for the HOOS-PS to become sufficiently content valid, because the HOOS-PS lacks relevant items and comprehensiveness.