Substantial Clinical Benefit Thresholds for Hip Disability and Osteoarthritis Outcome Score Subscales and Associated Risk Factors for Nonattainment After Total Hip Arthroplasty: A Prospective Cohort Study of 9,229 Patients

Background The Centers for Medicare & Medicaid Services (CMS) now requires patient-reported outcome measures (PROMs) collection after total hip arthroplasty (THA), emphasizing substantial clinical benefit (SCB) in the Hip Disability and Osteoarthritis Outcome Score - Joint Replacement (HOOS-JR). This study aimed to establish SCB thresholds for HOOS-Pain, Physical Function Short Form (PS), and JR and to identify factors influencing SCB achievement after THA. Methods A prospective analysis included 13,324 primary THAs performed between 2016 and 2022 at a tertiary health care institution. Of these, baseline PROMs were completed by 11,766 patients (88.3%), and 1-year follow-up data were available for 9,229 patients (78.4%). Demographic characteristics, comorbidities, and PROM data were collected, and patients were stratified into eight phenotypes based on pain, function, and mental health status. The SCB thresholds were calculated using anchor-based methods and anchored by the Veterans RAND-12 physical health question at one year. Multivariable logistic regression was conducted to determine factors linked to not achieving SCB. Results Established SCB thresholds were 40 for HOOS-pain (83.7% sensitivity, 45.3% specificity), 29.3 for HOOS-PS (75.4% sensitivity, 49.5% specificity), and 32.3 for HOOS-JR (79.3% sensitivity, 50.3% specificity). Overall, 72.8% of patients reached SCB. Factors significantly associated with failing to achieve SCB included non-White race, smoking, increased comorbidities, and worse baseline scores in pain, function, and mental health ( P < 0.001). Conclusions This study provides actionable benchmarks for HOOS domains following CMS mandates. Addressing disparities by incorporating preoperative phenotype stratification and risk mitigation strategies could optimize equitable outcomes after THA. Level of Evidence Prognostic Level III.