Increase in surgeons performing outpatient anterior cervical spine surgery leads to a shift in case volumes over time()

BACKGROUND: Prior studies have demonstrated an increase in the performance of outpatient anterior cervical surgery. The degree to which this increase is due to volume increase per individual surgeon versus increase in individual surgeons performing outpatient cervical surgery is unknown. METHODS: Patients undergoing anterior cervical discectomy and fusion (ACDF) or cervical disk arthroplasty (CDA) between 2010 and 2018 in NY state were identified. As a comparison we also evaluated trends for inpatient ACDF and CDA. Annual outpatient case volumes were calculated and defined as being high (> 20/year), intermediate (>5 and ≤ 20/year) or low (>1 and ≤ 5/year). Descriptive statistics were used to report temporal trends and Poisson regression was used to test for statistical significance. We also analyzed trends in various operative metrics by surgeon volume. RESULTS: In 2010, there were 96 surgeons who performed outpatient ACDF or CDA on a total of 1,855 patients. In 2018, this increased to 253 surgeons performing outpatient ACDF or CDA on a total of 3,372 patients. In comparison, there were 350 surgeons performing 6,783 inpatient cases in 2010 and 376 surgeons performing 6,796 inpatient cases in 2018. The average annual outpatient case volume decreased from 18.8 (95% CI, 13.5 – 24.1) to 12.2 (95% CI, 10.0 – 14.3) surgeries per surgeon. The percentage of surgeons with a high case volume also decreased from 30.2% in 2010 to 10.7% in 2018, whereas the percentage with a low case volume increased (32.3% to 49.8%). Differences between high and low volume surgeons in operative time, length of stay and total charges widened over time. CONCLUSION: The increase in outpatient anterior cervical surgery appears to be primarily driven by a greater number of surgeons performing ACDF and CDA on an outpatient basis, as opposed to increased case volumes for each surgeon. In contrast, trends for inpatient anterior cervical surgery were stable.