Expansion of the Surgical Apgar Score across All Surgical Subspecialties as a Means to Predict Postoperative Mortality

Abstract

Background A surgical scoring system, akin to the obstetrician's Apgar score, has been developed to assess postoperative risk. To date, evaluation of this scoring system has been limited to general and vascular services. The authors attempt to externally validate and expand the Surgical Apgar Score across a wide breadth of surgical subspecialties. Methods Intraoperative data for 123,864 procedures including all surgical subspecialties were collected and associated with Surgical Apgar Scores (created by the summation of point values associated with the lowest mean arterial pressure, lowest heart rate, and estimated blood loss). Patients' death records were matched to the corresponding score, and logistic regression models were created in which mortality within 7, 30, and 90 days was regressed on the Apgar score. Results Lower Surgical Apgar Scores were associated with an increased risk of death. The magnitude of this association varied by subspecialty. Some subspecialties exhibited higher odds ratios, suggesting that the score is not as useful for them. For most of the subspecialties the association between the Apgar score and mortality decreased as the time since surgery increased, suggesting that predictive ability ceases to be helpful over time. After adjusting for the patient's American Society of Anesthesiologists classification, Apgar scores remained associated with death among most of the subspecialties. Conclusion A previously published methodology for calculating risk among general and vascular surgical patients can be applied across many surgical services to provide an objective means of predicting and communicating patient outcomes in surgery as well as planning potential interventions.