Predictors of failed outpatient total hip arthroplasty: a retrospective cohort study

Background: Outpatient total hip arthroplasty (THA) offers potential cost savings and efficiency benefits in publicly funded health systems; however, the procedure fails for a subset of patients. This study aimed to identify the primary reasons for failed outpatient THA and perioperative factors associated with failure. Methods: We conducted a retrospective cohort study of patients booked for outpatient primary THA based on institutional eligibility criteria at a single tertiary care centre between January 2015 and December 2021. We obtained demographic, clinical, and operative data from institutional databases. We classified patients as having successful or failed outpatient discharge. Between-group comparisons used t tests and χ2 analyses, and multivariable logistic regression identified independent predictors of failed discharge. Results: Of 768 patients booked for outpatient THA, 87 (11.3%) required inpatient admission. The most common reasons for failure were inability to meet ambulation goals (24.1%) and hypoxemia (24.1%). Patients with failed discharges had higher rates of diabetes (p < 0.001), cardiac disease (p = 0.001), and obstructive sleep apnea (p = 0.01). Failure rates increased with later operative start times (p = 0.01). Surgical approach and anesthetic type did not differ between patients with successful or failed discharges. In multivariable analysis, diabetes (odds ratio [OR] 3.34, 95% confidence interval [CI] 1.56 to 7.13), cardiac disease (OR 2.39, 95% CI 1.27 to 4.51), midday (OR 3.39, 95% CI 1.60 to 7.16), and afternoon start times (OR 4.49, 95% CI 1.65 to 12.21) independently predicted failed discharge. Conclusion: Operative start time, diabetes, and cardiac disease are significant independent risk factors for failed outpatient discharge following primary THA. These findings underscore the importance of comprehensive preoperative risk assessment and optimized perioperative management for high-risk patients to improve the safety and efficiency of outpatient THA programs.