Increased patient comorbidities among inpatient total joint arthroplasty following increase of outpatient surgery.

Abstract

Outpatient total joint arthroplasty (TJA) has undergone a rapid expansion since COVID-19 and removal of TJA from the inpatient only (IPO) list. The rapid shift has been driven by decreased costs, patient preference, and profitability of surgical centers. During this time, we have also seen a shift to most TJA procedures in the hospital setting being listed as outpatient and decreasing reimbursements for the hospital system. As healthier patients transition to outpatient settings, inpatient TJA populations may increasingly consist of sicker, more complex cases. Our hypothesis is the shift to outpatient TJA may lead to a sicker and more complex TJA population in the hospital setting. We included all TJA Medicare patients at a large, high volume academic hospital from June 2018 to 2024 to evaluate change in inpatient status. We compared volume, ASA scores, infection rate, and inpatient status from June 2018-2024 to assess for changes in our baseline admission status and patient demographics. Statistical analysis was performed using chi-square and ANOVA tests and significance was set at p < 0.05. In June-December 2018, 5.91% of our Medicare TJA patients were outpatient compared to 85.57% in 2024 (p < 0.0001). During the same period, we saw a significant increase in the average ASA score from 2.437 to 2.698 (p < 0.01). We also saw a significant increase in our Charleston Comorbidity Index score (CCI) for both inpatient and outpatient populations, going from 3.109 to 3.692 (p < 0.01) in the outpatient population and 3.853 to 4.86 (p < 0.01) in the inpatient population. The overall volume of Medicare patients during this time period increased from 2401 to 2793. We have seen a significant increase in ASA scores, CCI scores, and a decrease in inpatient admission status in the hospital TJA population following removal of TJA from the IPO list. With the increase in outpatient surgical center TJA, we are seeing a significant increase in disease severity in the hospital based TJA population.