Beyond the "two-midnight rule": social factors drive prolonged stay after outpatient total shoulder arthroplasty

Total shoulder arthroplasty (TSA) has been removed from the Center for Medicare and Medicaid Services "in-patient only" list. Thus, the onus of TSA outpatient versus inpatient classification has become more complex, leading to failed outpatient TSA and unintended extended hospital stays. While most patients can be safely treated with outpatient TSA, a select vulnerable population may benefit from inpatient designation. This study aims to identify the rate of failure to discharge after 2 midnights, perioperative reasons for failure to discharge, and independent risk factors associated with failure to discharge. This study retrospectively identified elective, outpatient designated, unilateral primary anatomic, and reverse TSA procedures performed at a single institution between 2017 and 2023. Operative indications included osteoarthritis, rheumatoid arthritis, dislocation, and fracture. Demographics, medical comorbidities, surgical characteristics, and social factors were compared using univariate analysis. A multivariable regression model was built to determine independent risk factors associated with conversion to inpatient stay. A total of 648 patients met inclusion criteria, with a total of 122 patients (19%) staying over 2 midnights. The most common reason for late discharge was inpatient medical management (63%), followed by physical therapy recommendation/rehab placement (30%) and patient/family readiness (7%). Multivariable regression found living alone to be the strongest predictor of conversion to inpatient stay (odds ratio [OR] 4.2, 95% confidence interval [CI] 2.6-7.1), followed by female sex (OR 2.6, 95% CI 1.5-4.6) and Charlson Comorbidity Index (OR 1.6, 95% CI 1.3-1.9). Nearly 1 in 5 patients failed to discharge before 2 midnights, most commonly due to postoperative medical needs or rehabilitation barriers. Above patient comorbidities, living alone was the strongest predictor of prolonged stay. These findings support the need for more nuanced, patient-centered, risk stratification models for predicting feasibility of outpatient discharge in patients undergoing TSA.