Risk assessment tools validated for patients undergoing emergency laparotomy: a systematic review

Emergency laparotomies are performed commonly throughout the world, but one in six patients die within a month of surgery. Current international initiatives to reduce the considerable associated morbidity and mortality are founded upon delivering individualised perioperative care. However, while the identification of high-risk patients requires the routine assessment of individual risk, no method of doing so has been demonstrated to be practical and reliable across the commonly encountered spectrum of presentations, co-morbidities and operative procedures. A systematic review of Embase and Medline identified 20 validation studies assessing 25 risk assessment tools in patients undergoing emergency laparotomy. The most frequently studied general tools were APACHE II, ASA-PS and P-POSSUM. Comparative, quantitative analysis of tool performance was not feasible due to the heterogeneity of study design, poor reporting and infrequent within-study statistical comparison of tool performance. Reporting of calibration was notably absent in many prognostic tool validation studies. APACHE II demonstrated the most consistent discrimination of individual outcome across a variety of patient groups undergoing emergency laparotomy when used either preoperatively or postoperatively (area under the curve 0.76-0.98). While APACHE systems were designed for use in critical care, the ability of APACHE II to generate individual risk estimates from objective, exclusively preoperative data items may lead to better-informed shared decisions, triage and perioperative management of patients undergoing emergency laparotomy. Future endeavours should include the recalibration of APACHE II and P-POSSUM in contemporary cohorts, modifications to enable prediction of morbidity and assessment of the impact of adoption of these tools on clinical practice and patient outcomes.