Utility of the American College of Surgeons National Surgical Quality Improvement Program surgical risk calculator in predicting mortality in an Australian acute surgical unit.

BACKGROUND

The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) surgical risk calculator provides an estimate preoperatively of operative risks including mortality; however, its utility is not known in Australian emergency general surgical patients. This study sought to determine accuracy of the calculator in predicting outcome of high-risk patients in an Australian acute surgical unit to establish if this calculator could be a useful tool to identify high-risk patients in an Australian setting.

METHODS

Retrospective analysis of patients admitted to the acute surgical unit at a tertiary referral centre between 2018 and 2019 was conducted. High-risk patients were defined as those who underwent an emergency operation with an ACS-NSQIP surgical mortality score ≥5%. Post-operative outcomes assessed included mortality and return to operating theatre, readmission and discharge to nursing home. External validation of the calculator was performed using discrimination and calibration statistics.

RESULTS

Over a 14-month period, 58 patients were high risk, with an average age of 75 years, 93% were classified as functionally independent/partially dependent and 91.4% underwent a laparotomy. Overall 30-day mortality rate was 20.7%. The ACS-NSQIP calculator was a reliable predictor of mortality, with c-statistic of 0.835 (0.654-0.977), Brier score of 0.125 (0.081-0.176) and Hosmer-Lemeshow statistic of 0.389. The calculator was less accurate in its prediction of other outcomes assessed.

CONCLUSION

The ACS-NSQIP calculator accurately approximated mortality in high-risk Australian patients requiring emergency surgery. This study has demonstrated that in this patient population, the calculator could reliably be applied in the multidisciplinary care of emergency surgical patients.