NELA Risk Calculator Significantly Underestimates Mortality Risk of Laparotomy for Mesenteric and Colonic Ischaemia in Older Adult Surgical Patients

Aim: To establish if the NELA risk calculator underestimates mortality risk in older adults undergoing laparotomy for mesenteric or colonic ischaemia. Methods: A retrospective search of the operative database was performed for all patients over age 65 years who underwent laparotomy across two tertiary centres over a 3-year period. Cases of mesenteric or colonic ischaemia were identified from the operative records. Cases where ischaemia occurred secondarily to a primary obstructive or other pathology were excluded. Cases where a NELA score was not documented preoperatively were excluded. We then compared the NELA scores to the observed 30-day mortality rate. Secondary outcomes were hospital length of stay and intensive care unit length of stay. Results: Sixty cases were included in our analysis. There were 27 cases of colonic ischaemia and 33 cases of mesenteric ischaemia (mesenteric ischaemia group included five cases of distal small-bowel and colonic ischaemia). The overall mean NELA score was 21.9%, while the actual 30-day mortality was 43.3% ( p =0.0094). Mean NELA score for mesenteric ischaemia cases only was 20.6% with an actual mortality rate of 45.5%. Mean NELA score for the colonic ischaemia cases was 23.5% with an actual mortality rate of 40.7%. The median time from operation to mortality was 8 days. Mean age was 77 years. Length of stay for survivors was a mean 27 days with intensive care unit length of stay of 9.3 days. Conclusion: The NELA risk score for mortality post–emergency laparotomy underestimates mortality risk by a factor of two in older adults where the primary pathology is mesenteric or colonic ischaemia.