Factors Associated with Increased Lengths of Stay After Total Hip Arthroplasty: A Single Institution Retrospective Review.

BACKGROUND: Enabling same-day discharge after total hip arthroplasty (THA) has become a priority to optimize hospital resources while maintaining high-quality care. Discharge timing is influenced by clinical, social, and operational factors, including the Risk Assessment and Prediction Tool (RAPT) score. This study aimed to identify variables associated with increased lengths of stay and later-day discharges following THA. METHODS: This retrospective cohort study evaluated patient- and hospital-level factors to identify variables associated with later-day discharges among 463 patients who underwent THA at an orthopaedic specialty hospital between 2022 and 2025. Patients were categorized by discharge timing (same-versus later-day). Baseline demographic and clinical characteristics were compared using univariate analyses; multivariable logistic and regression models were constructed to identify variables associated with later-day discharge. A qualitative review of electronic medical records was performed to identify barriers to discharge not captured in quantitative analyses. RESULTS: Of 463 patients, 433 (93.5%) were discharged on postoperative day zero. Multivariable logistic regressions identified three variables associated with later-day discharge: modified RAPT score (adjusted odds ratio [aOR], 0.71; 95% confidence interval [CI], 0.52 to 0.98; P = 0.04), time out of the operating room (aOR, 1.35; 95% CI, 1.16 to 1.56; P < 0.01 per hour after eight A.M.), and operative duration (aOR, 1.03; 95% CI, 1.03 to 1.07; P = 0.01). These findings were further validated using a regression model with 10-fold cross-validation, confirming the modified RAPT score, operative duration, and time out of the operating room as the most strongly associated variables. A qualitative review identified unanticipated social delays in seven patients. CONCLUSIONS: Discharge following THA is influenced by clinical, social, and operational factors, with the modified RAPT score and time out of the OR emerging as statistically significant variables. Incorporating these findings, specifically the modified RAPT score, into preoperative planning may improve operating room efficiency, optimize resources, and support safe and efficient discharge pathways.