Frequency and Timing of Postoperative Complications After Outpatient Total Hip Arthroplasty.

Background: Although there have been several studies describing risk factors for complications after outpatient total hip arthroplasty (THA), data describing the timing of such complications is lacking. Methods: Patients who underwent outpatient or inpatient primary THA were identified in the 2012-2019 National Surgical Quality Improvement Program database. For 9 different 30-day complications, the median postoperative day of diagnosis was determined. Multivariable regressions were used to compare the risk of each complication between outpatient vs inpatient groups. Multivariable Cox proportional hazards modeling was used to evaluate the differences in the timing of each adverse event between the groups. Results: After outpatient THA, the median day of diagnosis for readmission was 12.5 (interquartile range 5-22), surgical site infection 15 (2-21), urinary tract infection 13.5 (6-19.5), deep vein thrombosis 13 (8-21), myocardial infarction 4.5 (1-7), pulmonary embolism 15 (8-25), sepsis 16 (9-26), stroke 2 (0-7), and pneumonia 6.5 (3-10). On multivariable regressions, outpatients had a lower relative risk (RR) of readmission (RR = 0.73), surgical site infection (RR = 0.72), and pneumonia (RR = 0.1), all Conclusions: The timing of complications after outpatient THA was similar to inpatient procedures. Consideration should be given to lowering thresholds for diagnostic testing after outpatient THA for each complication during the at-risk time periods identified here. Although extremely rare, this is especially important for catastrophic adverse events, which tend to occur early after discharge.