Integrating Patient-Reported Functional Outcome Measures in Determining Eligibility for Outpatient Total Hip Arthroplasty

Background Since the removal of total hip arthroplasty (THA) from the Medicare Inpatient‑Only (IPO) list in 2020, there has been a growing trend towards outpatient procedures. Recent studies have demonstrated equivalent complications and patient-reported outcome measures (PROMs) among inpatient and outpatient THA patients, but existing selection tools primarily emphasize medical comorbidities. This study assessed the value of incorporating preoperative PROMs into clinical-decision making tools to adequately identify patients most suitable for outpatient THA. Methods Adult patients who underwent unilateral THA between 2018-2024 and used a web-based home therapy program were included in this retrospective cohort study. Patients were stratified by length of stay into outpatient (same-day discharge, LOS <24 hours from surgery to discharge) and inpatient (LOS ≥24 hours). Patient demographics, clinical characteristics, and preoperative PROMs were compared. Backward logistic regression and receiver operating characteristic (ROC) curve analyses were performed to identify preoperative parameters predictive of outpatient THA. Results Among 1,090 patients (mean age 68.6 years, 51% female), Outpatient THA patients had lower mean age (64.8 vs 69.3 years), Medicare insurance rates (31% vs 44%), preoperative assistive device use (21% vs 30%), and frailty (0.1 vs 0.2) (all p<0.05). In addition, they had higher PROMIS Overall (34.1 vs 31.6), Physical (41.6 vs 39.1), and Mental (50.9 vs 48.2), and HOOS JR (52.5 vs 49.1) scores (all p<0.01). Regression analyses identified age <75 years (OR=3.6, p<0.001), PROMIS Overall >40 (OR=2.0, p=0.002), and HOOS JR >40 (OR=1.6, p=0.042) to be predictive of outpatient THA candidacy. ROC curve analyses incorporating these parameters showed good model discrimination (area under the curve=0.7, p<0.001). Conclusion Patient age, PROMIS Overall and HOOS JR scores were independent predictors of outpatient THA. Functional outcomes should be integrated in traditional comorbidity-based tools when selecting patients for outpatient THA.