Study objective: Among the various types of outpatient surgery centers, there are differences in higher American Society of Anesthesiologists Physical Status (ASA PS) scores and surgical complexity among patients who are undergoing surgery. The primary objective of this study was to describe the differences performed at various types of outpatient surgery facilities.
Design: We performed a retrospective analysis of the National Anesthesia Clinical Outcomes Registry (NACOR) data.
Setting: NACOR from 2012 to 2017.
Patients: From 2012 to 2017, there were a total of 13,053,115 outpatient surgeries in the database. After removing cases with unknown facility type, the final study sample was 9,217,336.
Measurements: To calculate the probability of either American Society of Anesthesiologists Physical Status (ASA PS) score ≥ 3 or physiologically complex cases (defined as Common Procedural Terminology start-up units ≥8), we performed mixed effects logistic regression for each institution per facility type, controlling for year and using facility identification as the random effect. We present the mean rate of these two classifications as case per 10,000 cases and report the 99.9% confidence interval (CI), to control for multiple comparisons.
Main results: Among all cases, 5,919,844 (64.2%) were classified as ASA PS 1 or 2 and 254,110 (2.8%) of surgical procedures were considered physiologically complex. The mean rate of cases with ASA PS ≥ 3in the university setting was 2982 per 10,000 cases [99.9% CI 2701-3278 per 10,000 cases]. Large community hospitals had a higher proportion of ASA PS ≥3 patients, medium-sized hospitals had no difference, and all other facility types had a decreased proportion. The mean rate of cases that were physiologically complex in the university setting was 133 per 10,000 cases [99.9% CI 117-151 per 10,000 cases]. Large community hospitals had a higher proportion of physiologically complex cases, medium-sized and small-sized hospitals had no difference, and all other facility types had a decreased proportion.
Conclusions: Freestanding and attached surgery centers exhibited smaller rates of patients that were ASA PS ≥ 3, as well as a decrease in surgically complex cases, when compared to university settings. This suggests that the level of conservativeness for patient and surgery appropriateness for outpatient surgery differs across various facility types.
Keywords: ASA class; Ambulatory; Comorbidities; NACOR; Outpatient surgery.
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