Underestimating the risk for postsurgical complications in patients is associated with increased morbidity and mortality, according to a recent study.

In the research published in JAMA Network Open (2021;4[11]:e2131669), investigators at UF (University of Florida) Health, in Gainesville, reported that patients at high risk for postoperative complications who are undertriaged after surgery experienced higher morbidity and mortality than a risk-matched control group of ICU admissions.

Postoperative triage provides an opportunity to evaluate patients for the risk for complications and to ensure those with high risk are moved to the ICU. However, in some cases, high-risk patients are moved to hospital wards instead, which could result in worse surgical outcomes.

“Although it seems intuitive that postoperative undertriage would be associated with worse outcomes, this association had not been previously reported in peer-reviewed literature,” said Tyler Loftus, MD, an assistant professor in the UF’s Department of Surgery and lead author of the study.

Dr. Loftus and his team evaluated 12,348 hospital ward admissions for inpatient surgical procedures. Using a random forest machine learning algorithm, the researchers identified patients’ risk for hospital mortality or prolonged ICU stay (=48 hours) and compared patients admitted to hospital wards with risk-matched patients admitted to the ICU.

“The algorithm considered a large set of electronic health record variables (laboratory values, medications, comorbidities, social determinants of health, surgery type, etc.) that were collected during the one-year period before surgery, as well as vital signs and ventilator settings during surgery,” Dr. Loftus said.

The algorithm found 10.6% of postoperative ward admissions were undertriaged.

“That does seem high, though I imagine it is because postoperative destination is largely determined preoperatively,” commented study co-author Jeremy Balch, MD, a general surgery resident at UF. “There may be subtle shifts in vital signs during the case or unaccounted-for preoperative variables (such as Area Deprivation Index) that did not enter the decision-making process.”

Compared with the control group, the undertriaged patients had a higher median age (64 years; interquartile range [IQR], 54-74 vs. 62 years; IQR, 50-73 years; P=0.001), a larger proportion of women (49.7% vs. 44.0%; P<0.001), and more patients with a “do not resuscitate” order before first surgical procedure (4.1% vs. 1.1%; P<0.001).

The researchers found the undertriaged group had worse outcomes than the control group—most notably, an increased incidence of hospital mortality (1.5% vs. 0.7%; P=0.04) and elevated risk for morbidity, including a larger proportion of patients with discharge to hospice (1.8% vs. 0.6%; P<0.001), unplanned intubation (3.4% vs. 2.0%; P=0.01), acute kidney injury (26.1% vs. 19.5%; P<0.001), and median hospital length of stay (8.1 days; IQR, 5.1-13.6 days vs. 6.0 days; IQR, 3.3-9.3 days; P<0.001).

Compared with controls, the undertriaged group also had a smaller proportion of admitted patients with prolonged ICU admission (12.6% vs. 57.4%; P<0.001), a similar proportion of admitted patients with prolonged mechanical ventilation (2.5% vs. 2.2%; P=0.60), and an increased proportion of admitted patients receiving postoperative red blood cell transfusion (21.1% vs. 13.7%; P<0.001). In addition, undertriaged inpatients had decreased median total costs per admission ($26,900; IQR, $18,400-$42,300 vs. $32,700; IQR, $22,700-$48,500; P<0.001) compared with the control group.

The study authors were not surprised by these findings.

“The observed associations between postoperative undertriage and morbidity and mortality were not unexpected from a clinical intuition perspective,” Dr. Loftus noted.

“Undertriage, by definition, implies these patients are sicker and at higher risk for complications than what was assumed preoperatively. Unfortunately but expectedly, these patients suffered higher rates of complications,” Dr. Balch said. “The vast majority (about 90%) of preoperative decision making was appropriate, implying that surgeons are generally good at predicting where their patients should end up.”

From these data, the researchers concluded that while surgeons generally perform accurate postsurgical triage, there remains an opportunity to improve patient evaluation. The authors also noted the importance of the opposite phenomenon: postoperative overtriage of low-risk patients.

“The flip side is overtriage, which we have also analyzed and found to be around 5%. I had assumed this would be higher than the undertriage rate, but it appears, at least at our institution, that postoperative triage decisions err on the optimistic side,” Dr. Balch said.

Ultimately, postoperative triage presents an important opportunity to improve surgical decision making.

“Right now, surgeons can be mindful of the importance of postoperative triage decision making, and critically evaluate their practice patterns and associated outcomes to determine whether there is an opportunity to minimize postoperative undertriage and associated mortality and morbidity,” Dr. Loftus said.

Dr. Loftus reported research support from the National Institute of General Medical Sciences of the National Institutes of Health, under Award No. K23 GM140268.