Effect of In-line Clinical Decision Support to Improve Accuracy of American Society of Anesthesiologists Physical Status Documentation: A Two Center Evaluation of a Quality Intervention

Background: American Society of Anesthesiologists Physical Status (ASA PS) classification is a widely used ordinal scale that captures comorbidity burden but has significant inter-rater variability. Previous efforts to enhance ASA PS documentation with Clinical Decision Support (CDS) are limited by inaccurate problem lists, poor user experience, or consideration of select comorbidities. We developed and implemented a CDS which uses the anesthesia clinicians’ documentation to highlight potential under-classification at time of ASA PS assignment. Methods: Building upon examples from ASA Committee on Economics and institutional consensus, we identified 51 conditions warranting an ASA PS of at least 3. This was embedded in CDS and implemented at our large academic medical center (Site 1). We compared the percentage of patients assigned an ASA PS 3 or greater before (May 22, 2023 to May 22, 2024) and after complete implementation (August 14, 2024 to August 14, 2025). A second large midwestern academic medical center served as a contemporaneous external control (Site 2). Using a difference in difference analysis, we constructed odds ratios for assignment of ASA PS 3 in all patients and selected sub-populations. Results: The study included 251,944 anesthetics from Site 1 and 286,172 from Site 2. Baseline characteristics were similar between sites. At Site 1, the proportion of patients classified as ASA PS 3 or higher increased from 52.9% to 61.7% (aOR 1.42, 95% CI 1.38-1.45). Site 2 experienced a small absolute increase from 47.2% to 48.4% (aOR 1.05, 95% CI 1.03-1.07). Among patients at Site 1 with 50 conditions addressed by the latter phase of the CDS, the proportion classified as ASA PS 3 or greater increased from 83.6% to 94.0% (aOR 3.54, 95% CI 3.34-3.76). Conclusions: Implementation of our in-line real-time CDS was associated with a significant increase in the percentage of patients with ASA PS 3 or greater.