Surgical Risk Calculator

Acute Mesenteric Ischemia Postoperative Morbidity and Mortality Risk Calculator

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Estimates 30-day morbidity and mortality after bowel resection for acute mesenteric ischemia.

Differences from the paper's tables and the original spreadsheet

This page uses the models as they were fitted, taken from the study's analysis output. It differs from two other sources:

  1. The paper's Tables II and III. They leave out two factors that were in the fitted models: coma from the morbidity table and disseminated cancer from the mortality table. Their estimates also come from a coding in which each factor's levels add up to zero, not the reference groups the paper describes. So adding up the printed numbers does not give this model. The odds ratios the paper prints do match this page, for example 0.31 in the mortality model for no DNR order against a DNR order.
  2. The original spreadsheet, which gives different numbers and is no longer offered. It counts the "present" level of each factor as zero, leaves out PTT and disseminated cancer, and has no ASA 5 or other-facility answer. Take a 70-year-old admitted from home, ASA 4, emergent surgery, SIRS, abnormal albumin, SGOT and PTT, a dirty wound and a 180-minute operation, with no other factors. This page gives morbidity 72.55% and mortality 41.75%. The spreadsheet gives 59.75% and 66.19%.

Answers that rest on few patients

  • Coma: answering Yes lowers the morbidity estimate. Only 15 patients had preoperative coma. 9 had a recorded complication and 12 died. The paper's count of 17 comes from a different variable in the data. Do not rely on the morbidity estimate for a comatose patient.
  • Sepsis: in the mortality model, sepsis (47 patients, 48.9% died) carries more weight than septic shock (251 patients, 45.8% died).
  • ASA class 5 rests on 54 patients and admission from another facility on 4 patients.
Acute renal failure Presence of preoperative acute renal failure
Actual age in years, 0 to 110
Albumin (preoperative)
Previous cardiac surgery History of previous cardiac surgery
Coma Preoperative coma
COPD Preoperative GOLD stage 2-4 COPD
Disseminated cancer Preoperative disseminated cancer
DNR order Preoperative DNR order
Functional status prior to surgery
Myocardial infarction within 6 months Recent MI within 6 months
Emergent surgery Declaration of surgery as emergent (has to be within 12 hours of admission)
Open wound Presence of open wound on body at time of surgery
Operative time in minutes, 0 to 900
PTT prior to surgery
SGOT prior to surgery
On ventilator Presence of ventilator preoperatively
Wound classification in the operation

About this model

  • Studied 861 patients who had bowel resection for acute mesenteric ischemia in the American College of Surgeons National Surgical Quality Improvement Program (NSQIP), 2007–2008. The analysis output shows the models were fitted on the 783 (morbidity) and 780 (mortality) with complete data.
  • 30-day morbidity was 56.6% and 30-day mortality was 27.9%.
  • C statistic: 0.794 for morbidity and 0.837 for mortality.
  • The paper states that the calculator awaits validation in subsequent studies.

Citation

Gupta PK, Natarajan B, Gupta H, Fang X, Fitzgibbons RJ. Morbidity and mortality after bowel resection for acute mesenteric ischemia. Surgery. 2011;150(4):779-87. doi:10.1016/j.surg.2011.07.079 · PubMed 22000191

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