The clinical utility of preoperative surgical risk indices and ICU bed allocation on outcomes of noncardiac surgical patients: A cohort study

Summary statement: In non-cardiac surgical patients, respiratory failure index and intensivists’ (expert) opinion predicted postoperative mortality and respiratory failure. Intermediate risk patients allocated to postoperative ICU care vs. surgical high intensity care demonstrated increasing lengths of hospital stay. Background: No guidance exists for allocating postoperative ICU resources for patients undergoing noncardiac surgery. We determined the predictive value of preoperative risk sores and “expert opinion” in predicting postoperative mortality and complications. Methods: A cohort study involving 403 adults undergoing elective noncardiac surgery and being assessed in a preoperative clinic within a university affiliated tertiary care hospital. Postoperative outcomes included 30-day mortality, respiratory failure at 48hour, unplanned intubation, cardiac composite score, hospital length of stay, hypotension, hypertension, and delirium. Results: Preoperative respiratory failure index (PRFI) predicted 30-day mortality (OR 1.11, 95% CI 1.04 to 1.19). An intensivist’s opinion predicted respiratory failure 48-hour postoperatively (OR 28.70, 95% CI 7.44 to 110.70). Patients with an equivalent PRFI risk had a longer hospital stay (17.2 v. 8.9 days, P = 0.01), increased respiratory failure risk (P = 0.009), hypertension (P = 0.009), hypotension (P = 0.005) and delirium (P = 0.05) if allocated to an ICU bed versus a high-intensity bed. Conclusions: PRFI predicts 30-day postoperative mortality and cardiac events. A decision to allocate an ICU bed predicted the development of postoperative respiratory failure. Patients with an intermediate PRFI risk and allocated to an ICU demonstrated increasing lengths of hospital stay and morbidity.