Defining Clinically Meaningful Improvement Thresholds for Inpatient Vs Outpatient Medicare Total Hip Arthroplasty Patients: A Reassessment of Centers for Medicare and Medicaid Services Patient-Reported Outcome Performance Measure Policy Benchmarks.

BACKGROUND: The Centers for Medicare and Medicaid Services Patient-Reported Outcomes Performance Measure defines substantial clinical benefit (SCB) on the Hip Disability and Osteoarthritis Outcome Score for Joint Replacement (HOOS-JR) as a 22-point improvement for all Medicare patients undergoing total hip arthroplasty (THA). Because inpatient and outpatient THA patients differ at baseline, a single threshold may not fully reflect substantial improvement across care settings.

PURPOSE: We sought to determine separate HOOS-JR SCB thresholds for inpatient and outpatient Medicare THA patients.

METHODS: We retrospectively analyzed prospectively gathered data from 5480 Medicare patients ages 65 years and older who underwent primary, elective THA between 2016 and 2022 at a single institution. Patients were stratified by inpatient and outpatient status. An anchor-based approach was used with the Veterans RAND 12-Item Health Survey transition item, "Compared to 1 year ago, how would you rate your physical health now?" Patients were categorized as substantially improved, improved, or unimproved. SCB for HOOS-JR absolute change was derived separately for inpatient and outpatient cohorts using receiver operating characteristic analysis, with the optimal cutoff selected by maximizing Youden's J statistic.

RESULTS: Baseline HOOS subdomain scores were worse in the inpatient cohort. The HOOS-JR SCB was 31.9 points for inpatients and 32.3 points for outpatients. Using these thresholds, 61% of inpatients and 66% of outpatients achieved SCB.

CONCLUSIONS: This retrospective analysis of prospectively collected data from a single, high-volume institution found that Medicare THA inpatients and outpatients demonstrated similar HOOS-JR SCB of approximately 32 points. These findings suggest that a unified SCB across care settings may be reasonable, although the current 22-point benchmark may overestimate SCB achievement. Further studies are needed to clarify how baseline status and patient expectations influence SCB attainment.

LEVEL OF EVIDENCE: Level III: prognostic study.