NELA 1 - Actual and predicted 30-day mortality following emergency laparotomy using National Emergency Laparotomy Audit (NELA) and American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) risk prediction tools

Abstract Background Emergency laparotomy (EL) is common, with >30,000 performed annually in the UK. EL has a high 30-day mortality of 9.2%, especially in the elderly. Reliable preoperative risk assessment is essential to aid decision-making and perioperative care arrangements. NELA and ACS-NSQIP risk calculators can both be used to assess risk, and both can under or over-predict mortality. Methods This is a multi-center, retrospective, observational, cohort study investigating the correlation between actual 30-dm (a-30-dm) and predicted 30-dm (p-30-dm) following EL using NELA and ACS-NSQIP in adults over and under 70, over 2-years, in two UK centres. Sample size was calculated at 385 cases. Statistical analysis was carried out using GraphPad Prism 10.1.1. Results 626 cases were analyzed. A-30-dm, NELA, and ACS-NSQIP p-30-dm in the under 70s subgroup were 5.78%, 5.53%, and 3.41% respectively, with NELA and ACS-NSQIP correlating positively with a-30-dm: R²=0.12, p<0.0001 and R²=0.09, p<0.0001. In over 70s, a-30-dm was 13.96%, NELA p-30-dm 14.02% and ACS-NSQIP 9.76%, with a positive correlation between the latter two (R²=0.56, p<0.0001), but a weak one between a-30-dm and NELA (R²=0.04, p<0.0001) or ACS-NSQIP (R²=0.02, p<0.0001). For the entire cohort a-30-dm, NELA and ACS-NSQIP p-30-dm were 9.74%, 9.8%, and 6.59% respectively. NELA and ACS-NSQIP p-30-dm showed a strong positive correlation (R²=0.89; p<0.0001) with only NELA showing a strong positive correlation with a-30-dm (R²=0.31, p<0.0001); and not ACS-NSQIP (R²=0.05, p<0.0001). Conclusion NELA can accurately predict 30-day mortality in patients aged <70 undergoing EL but not >70. ACS-NSQIP and a-30-dm correlated in a very weak manner.