2028 Propensity Matched Analysis of Hospital Outpatient Department versus Ambulatory Surgical Center Outcomes in Elective Lumbar Spine Surgery: A Michigan Spine Surgery Improvement Collaborative (MSSIC) Study

INTRODUCTION: In an effort to minimize costs, there has been an increased shift in performing elective surgical procedures at ambulatory surgery centers (ASC), and spine surgery is no exception. There is a paucity of literature with direct comparisons between hospital outpatient department (HOPD) and ASC spine procedures within a multi-center study. METHODS: The Michigan Spine Surgery Improvement Collaborative (MSSIC) database was queried for patients who underwent outpatient lumbar decompression surgery from January 2021 to June 2023. Patients in the HOPD and ASC cohorts underwent propensity score matching based on BMI, ASA, and number of levels. Subsequent multivariate analysis was then performed to further control for confounding variables. Outcomes measured included adverse events, timing and disposition of discharge, readmissions, and ED presentations. RESULTS: A total of 3,333 patients were included in the multivariate analysis. Compared to HOPDs, ASCs had a higher risk of any complication (IRR = 1.50; CI: 1.17-1.92, p=0.001) which was driven primarily by an increased risk in return to OR (IRR = 2.30; CI: 1.44-3.68, p < 0.001). Differences in risk of re-operation were driven by an increased rate of recurrent disc herniations in the ASC setting (3.27% versus 1.01% in HOPD). There was no significant difference in the risk of surgical site infection, post-operative ED visit, or 30- and 90-day readmission. CONCLUSIONS: Patients undergoing surgery at ASCs may endure a higher risk of complications and reoperations when compared to an outpatient surgery performed in a hospital setting.