The Differential Effect of COVID on Total Joint Arthroplasty Between Hospital and Ambulatory Surgery Centers/Hospital Outpatient Departments: A Michigan Arthroplasty Registry Collaborative Quality Initiative Analysis.

Background: Coronavirus disease (COVID) created unprecedented challenges, especially for high-volume elective subspecialties like total joint arthroplasty. Limited inpatient capacity and resource conservation led to new outpatient selection criteria and site of service changes. As a Michigan Arthroplasty Registry Quality Collaborative Initiative quality project, demographic changes, complications, and differential effects on inpatient vs outpatient centers pre- and post-COVID were analyzed.

Methods: The registry identified all total joint arthroplasty at hospitals and ASCs/HOPDs between 07/2019-12/2019 and 07/2020-12/2020. These intervals represented pre-COVID and post-COVID elective surgery shutdowns. Case volumes, demographics, and 90-day complications were compared.

Results: Comparing 2020 to 2019, hospital volumes decreased (-9% total hip arthroplasty [THA], -17% total knee arthroplasty [TKA]), and ambulatory surgery center (ASC)/hospital outpatient department (HOPD) increased (+84% THA, +125% TKA). Entering 2020, ASC/HOPD patients were older ( = .0031, < .0001: THA, TKA), had more American Society of Anesthesiologists score 3-4 ( = .0105,  = .0021), fewer attended joint class ( < .0001, < .0001), and more hips were women ( = .023). Hospital patients had higher preoperative pain scores ( = .0117, < .0001; THA, TKA), less joint education attendance ( < .0001, < .0001), younger TKAs ( = .0169), and more American Society of Anesthesiologists score 3-4 (0.0009). After propensity matching, there were no significant differences between site of service for 90-day fractures, deep vein thromboses or pulmonary embolisms, infection, or hip dislocations. Hospital THAs had higher readmissions ( = .0003) and TKAs had higher 30-day emergency department visits ( = .005). ASC/HOPD patients were prescribed higher oral morphine equivalents ( < .0001, < .0001; THA, TKA).

Conclusions: COVID's elective surgery shutdown caused a dramatic site of service shift. Traditional preoperative education was negatively impacted, and older and sicker patients became outpatients. But short-term complications were not increased in ASCs/HOPDs. These site of service and associated patient demographic changes may be safely sustained.