What Are the Reasons and Risk Factors for 30-Day Readmission After Outpatient Total Hip Arthroplasty?

Background: A higher volume of primary total hip arthroplasty (THA) is starting to be performed as an outpatient procedure. However, data on appropriate patient selection for this surgical protocol is scarce.

Methods: Patients who underwent primary THA were identified in the 2012-2018 National Surgical Quality Improvement Program database. Outpatient procedure was defined as having a hospital length of stay of 0 days. The primary outcome was a readmission within the 30-day postoperative period. Risk factors for and effect of overnight hospital stay on 30-day readmission after outpatient THA were identified through multivariable models. Reasons for and timing of readmission were also identified.

Results: A total of 5245 outpatient THA patients and 44,171 patients who stayed 1 night were identified. The incidence of 30-day readmission after outpatient THA was 1.60% (95% confidence interval [CI] 1.26-1.94). Risk factors for 30-day readmission after outpatient THA include the following: older age relative to 18-60 years old (most notably 71-75 years old, relative risk [RR] = 2.3, 95% CI = 1.15-4.62; 76-80 years old, RR = 6.6, 95% CI = 3.55-12.43; and >80 years old, RR = 5.6, 95% CI = 2.43-12.89, P < .001) and bleeding disorders (RR = 4.5, 95% CI = 1.45-14.31, P = .010). For patients who had some of these risk factors, their risk of medically related 30-day readmission was reduced if they had stayed 1 night at the hospital (P < .05). The majority of readmissions were surgically related (62%), including wound complications (27%) and periprosthetic fractures (25%).

Conclusion: The rate of 30-day readmission after outpatient THA was low. Patients who are at high risk for 30-day readmission after outpatient THA include those with older age and bleeding disorders. Some of these patients may benefit from an inpatient hospital stay.