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.