# Impact of Transitioning Elective Orthopedic Surgeries to the Ambulatory Setting on Acute-Care Hospital Operations and Quality

## TL;DR

Moving elective orthopedic surgeries to outpatient centers changed the types of patients in hospitals, leading to more complex cases and longer stays.

## Contribution

This study is the first to analyze how shifting surgeries to ambulatory centers affects hospital patient characteristics and outcomes in a specialized orthopedic unit.

## Key findings

- Patients in the hospital post-ASC transition were older, had higher BMIs, and more comorbidities.
- The proportion of non-joint/spine surgery patients increased, leading to longer hospital stays and more readmissions.
- Hospital operations changed, with increased census and turnover but reduced nursing hours per patient.

## Abstract

Introduction

Total joint arthroplasty (TJA) and spine surgeries are increasingly being performed in the ambulatory surgery center (ASC) setting. As high-volume elective surgeries shift out of the acute-care setting, the acuity and complexity of patients requiring hospital care have increased. The current study evaluates how the transition of TJA and spine procedures from the hospital to the ASC affected patient acuity and outcomes in a historically specialized hospital joint and spine unit (JSU).

Methods

A retrospective review of 12,067 patients receiving care at the JSU during calendar years 2018-2019 and 2022-2023 was performed. In 2021, our institution began performing TJA and spine procedures in a hospital-affiliated ASC. Calendar years 2020 and 2021 were excluded, as this period coincided with both the COVID-19 pandemic and the ASC ramp-up period. Bivariate analyses were performed using a pre-post intervention (i.e., ASC opening) design. Comparisons of patient characteristics and outcomes between the two periods were performed for all patients, patients undergoing total joint or spine surgery, and patients not undergoing total joint or spine surgery (i.e., other surgical or medical admissions to the unit). Operational measures, quality indicators, and staffing measures were compared between time periods for the entire unit.

Results

Compared to pre-ASC patients, those receiving care in the JSU post-ASC were older and had higher BMIs on average (both p<0.001). Furthermore, the post-ASC population was more diverse, with a greater percentage of Black (17.7% vs. 14.0%, p<0.001) and Medicaid patients (1.7% vs. 0.6%, p<0.001). Post-ASC, patients presented with a higher comorbidity burden as demonstrated by a higher Charlson Comorbidity Index (CCI) score, severity of illness, and risk of mortality scores (all p<0.001). Post-ASC, joint/spine surgery patients accounted for 71.0% of patients, compared to 90.7% pre-ASC (p<0.001). In contrast, ED arrivals increased from 5.3% to 24.2% of JSU patients post-ASC (p<0.001).

The average hospital length of stay (LOS) increased (pre-ASC 1.6 vs. post-ASC 2.6 days, p<0.001), and rates of 0/1 day LOS decreased while rates of 2+ day LOS increased (all p<0.001) post-ASC. In addition, rates of skilled nursing facility discharge and 30-day readmissions increased (both p<0.001), but 30-day ED return rates remained stable post-ASC. These trends were largely driven by the outcomes of non-total joint/spine surgery patients.

Post-ASC, the average daily census increased from 13.10 to 16.75 patients (p<0.001). CCI-adjusted nursing hours per patient day decreased significantly (pre-ASC 12.4 vs. post-ASC 11.0, p<0.001). Finally, overall unit turnover increased from 27% to 59% post-ASC.

Conclusion

This study highlights the changing patient landscape of a specialized orthopedic unit that has seen a growth in medically complex cases amidst the opening of a hospital-affiliated ASC. While these changes cannot be considered directly caused by the ASC opening, further evaluation of the impact of the migration of orthopedic surgeries to ASCs is warranted to confirm or refute the findings from this retrospective single-center study. These findings highlight the challenges of caring for a more racially and socioeconomically diverse population; hospitals should continue to refine strategies for delivering high-quality, equitable care as the demographics of patients treated in the acute-care setting evolve.