Background: Surgical risk stratification tools have existed since Goldman created the cardiac risk index in 1977. Since then, there has been a proliferation of risk calculators: the three most notable being the Revised Cardiac Risk Index (RCRI), the American College of Surgeons-Surgical Risk Calculator (ACS-SRC), and the Gupta Myocardial Infarction and Cardiac Arrest calculator (MICA). The American College of Cardiology/American Heart Association (ACC/AHA) recommends a step-wise preoperative risk stratification process, classifying patients as either low risk (<1% risk of major adverse cardiac events) or at elevated risk, using either the RCRI, ACS-SRC, or MICA tools, without privileging one above the others. Patients at elevated risk should be further stratified according to their functional capacity, specifically metabolic equivalents (METS). Although they cannot be directly compared to one another because of differences in end points and outcomes, retrospective studies have shown differences in how risk is stratified by these tools. Due to uncertainly regarding the optimal tool for risk stratification, significant heterogeneity likely exists in perioperative assessment practices.

Methods: To better understand the degree of heterogeneity surrounding the choice of surgical risk stratification tools, investigators conducted a retrospective chart review of 200 unique encounters staffed by the hospital medicine consult service at the University of Chicago from June 2019 to July 2020. This entailed approximately 40% of all consults from that year. This was done to characterize patterns of risk stratification in hopes of developing more uniform practices. By characterizing these patterns, investigators hope to elucidate strengths and weakness within the hospital medicine consult service and make recommendations about how perioperative consults might be standardized to improve communication. Standardization and simplicity in consult notes have been shown to increase compliance with recommendations.

Results: Among the 200 encounters reviewed, there were 71 perioperative risk assessments (36%). There was significant variation in how surgical risk was evaluated. 13 distinct approaches were used, employing some combination of RCRI, ACS-SRC, MICA, METS, or no tool at all. 19 (27%) used multiple risk stratification tools (excluding METS as it is intended to be adjunctive). The most commonly used approach was the use of RCRI in conjunction with METS: 21 (30%). Among the 71 assessments, there were 11 (15%) that were not consistent with ACC/AHA guidelines in that either there was no formal tool recorded (7 patients) or only METS (4 patients). All the patients evaluated by a single tool were found to be low risk, not requiring further characterization of functional capacity/METS.

Conclusions: There was significant variation in the approaches to surgical risk stratification, though the vast majority were in accord with ACC/AHA guidelines. Although RCRI, ACS-SRC, and MICA are all approved by the ACC/AHA, we are concerned that this degree of heterogeneity in consult notes unnecessarily complicates the electronic health record (EHR), inhibiting effective communication. The results of this research are spurring our evolving effort to standardize perioperative assessments. Further work remains to be done to achieve group consensus on best practices, reformat note templates, and perhaps embed one or more of these tools into the EHR.

IMAGE 1: Approaches to Surgical Risk Assessment