Dramatic Shift Towards Outpatient Total Hip Arthroplasty in 2020 with No Change in Patient Comorbidities

Background Centers for Medicare & Medicaid Services removed total hip arthroplasty (THA) from the inpatient-only list on January 1, 2020. The purpose of this study is to assess the changes in arthroplasty coding site-of-care (inpatient versus outpatient), length of stay, and evaluate the comorbidities of patients undergoing outpatient THA following this change. Methods Patients who received THA in the first quarter (Q1) of 2018, 2019, and 2020 were analyzed from the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database. Q1 data were selected to minimize the effects of the COVID-19 pandemic. Patient demographics, length of stay (LOS), comorbidities, and inpatient/outpatient coding were compared among 2018, 2019, and 2020 cohorts. Results 9,534, 11,120 and 9,822 THAs were included in Q1 of 2018, 2019, and 2020, respectively. There were small increases in patients age (p < 0.01), bleeding disorder (p = 0.01), and congestive heart failure (p = 0.02) in 2020 compared to 2018 and 2019. The overall rates of chronic obstructive pulmonary disease, hypertension, and diabetes did not change significantly; p > 0.05. Patients admitted as outpatient THA increased from 2.8% in 2018 to 22.5% in 2020; p < 0.01. The mean LOS in 2018, 2019, and 2020 decreased from 2.2, 2.0, to 1.8 days, respectively; p < 0.01. Conclusion There was a significant increase in the volume of outpatient admission in THA as well as the ratio of outpatient to inpatient THAs performed with no significant change in the demographics or comorbidities.