Introduction: The Centers for Medicare & Medicaid Services removed total knee arthroplasty (TKA) from the inpatient-only list effective January 2018. Our institution interpretation led to scheduling all TKAs as outpatient (23-hour observation) without workflow modifications. The purpose of this study was to examine the preoperative factors associated with delayed discharge following this policy change among a non-selected cohort, as published data in this area are lacking.

Methods: TKA patients admitted between January 01, 2018 and August 01, 2018 were retrospectively analyzed. Patients were stratified into two groups based on hospital night stay: ≤1 night (non-delayed discharge) or >1 night (delayed discharge). Preoperative factors associated with delayed discharge were examined using 2-tailed t -tests for continuous data, and Pearson’s chi-square or Fischer exact tests for categorical data. All analyses were conducted on SPSS (IBM, version 23.0).

Results:We identified 447 TKA patients: 279 (62.4%) had non-delayed discharge and 168 (37.6%) had delayed discharge. Delayed discharge patients were more likely to be older (mean =71.5 (8.0) vs. 69.9 (8.6) years, p =0.033), female (76.8% vs. 55.6%, p

Conclusion: Among a non-selected sample of outpatient TKAs, factors associated with delayed discharge included age, female sex, hypertension, and COPD. The influence of social support warrants further investigation.