Factors associated with conversion of outpatient total shoulder arthroplasty to inpatient

Outpatient total shoulder arthroplasty (TSA) is increasingly performed as perioperative pathways and value-based care models expand. However, a subset of patients scheduled for outpatient TSA require unexpected inpatient admission, which may indicate higher perioperative risk and increased resource use. We hypothesized that older age, greater comorbidity burden, and longer operative time would be associated with conversion from planned outpatient TSA to inpatient admission, and that conversion would be associated with worse short-term outcomes. Planned outpatient TSA cases were identified in the American College of Surgeons National Surgical Quality Improvement Program database from 2011 to 2021. Revision arthroplasty, hemiarthroplasty, procedures for infection or malignancy, fracture-related cases, emergency or other nonelective cases, records with missing length of stay (LOS), and extreme LOS outliers were excluded. All included cases were planned outpatient procedures; patients with LOS 0-1 day comprised the outpatient cohort, and those with LOS &#x2265;2 days comprised the conversion-to-inpatient cohort. Demographics, comorbidities, operative time, and 30-day outcomes were compared between groups, and multivariable logistic regression identified independent predictors of conversion and associations with adverse events. A total of 6,755 planned outpatient TSA cases met inclusion criteria, including 6,302 (93.3%) outpatient and 453 (7.2%) conversion-to-inpatient cases. Compared with outpatient patients, the conversion-to-inpatient cohort was older (70.3 &#xb1; 9.6 vs. 68.0 &#xb1; 9.5 years), more often female, and more frequently Hispanic, with higher body mass index and a greater proportion of American Society of Anesthesiologists class &#x2265;3 and comorbidities (all P < .05). Mean operative time was longer among converted patients (127.9 &#xb1; 59.3 vs. 104.7 &#xb1; 40.8 minutes, P < .001). On multivariable analysis, older age, female sex, Hispanic ethnicity, American Society of Anesthesiologists &#x2265;3, diabetes, chronic obstructive pulmonary disease, and longer operative time were independent predictors of conversion. Conversion-to-inpatient status was associated with higher odds of 30-day reoperation, overall morbidity, bleeding transfusion, and non-home discharge, while adjusted 30-day readmission did not differ significantly between cohorts. Unplanned conversion from outpatient to inpatient status occurs in approximately 7% of planned outpatient TSAs and is associated with identifiable demographic, comorbidity, and operative risk factors, as well as higher morbidity, transfusion requirements, and non-home discharge. These findings may help inform patient counseling and perioperative planning for outpatient TSA pathways.