Diabetes Ups Mortality, and More, After Noncardiac Surgery

Kate Johnson

September 13, 2013

Preexisting diabetes increases the likelihood of dying within 30 days of a noncardiac operation and raises the risk for other acute complications, such as myocardial infarction and renal failure after the surgery, according to Taiwanese researchers.

And uncontrolled diabetes, diabetes-related comorbidities, and other coexisting medical conditions increase this risk further, say Ta-Liang Chen, MD, PhD, from Taipei Medical University, Taiwan, and colleagues in their report, published online August 29 in Diabetes Care.

"Integrated care perioperatively for the surgical patients with diabetes should be considered [especially] when [there are] coexisting…diabetic-related or other medical comorbidities," Dr. Chen told Medscape Medical News. "Prediction, assessment, and prevention for these specific postoperative complications" should be a priority in this patient population, he added.

To this end, "Medical resources should be appropriately allocated to patients with diabetes and coexisting medical conditions when they undergo noncardiac surgeries," he and his colleagues write. "Whether intensive glycemic control in the noncardiac-surgery postoperative period could reduce the risk of short-term mortality still needs to be elucidated,” they say.

Asked by Medscape Medical News to comment on the research, Basem Abdelmalak, MD, associate professor of anesthesiology at the Cleveland Clinic, Ohio, said that Dr. Chen and colleagues "have done a great job utilizing their administrative database in a large number of patients to shed more light on the association between diabetes and postoperative outcome. The study provides more evidence linking diabetes, especially 'uncontrolled diabetes,' to postoperative poor outcomes and short-term mortality."

However, he added, "I doubt that intensive glucose control postoperatively would improve outcomes," as the investigators suggested. He noted that his group has recently published the results of a randomized trial studying intraoperative tight vs conventional glucose control in elective major noncardiac surgery patients ( Br J Anaesth 2013 Aug;111:209-21), but that the intervention did not improve surgical complications. Nor did it worsen them, however.

"Thus, more work is still needed to identify optimal perioperative glycemic targets," not just postoperative ones as Dr. Chen and team have proposed, said Dr. Abdelmalak.

Uncontrolled Diabetes, Comorbidities, All Up Death Risk

Dr. Chen and colleagues used Taiwan National Health Insurance Program reimbursement claims to identify 4855 diabetic patients aged 20 years or older who underwent major inpatient noncardiac surgery between 2008 and 2010 in Taiwan.

The patients were matched to randomly selected nondiabetic control individuals according to characteristics such as sex, age, and type of noncardiac surgery.

The primary outcome of the study was 30-day postsurgical in-hospital mortality; there were 6 secondary postoperative outcomes: septicemia, pneumonia, stroke, acute renal failure, deep wound infection, and acute myocardial infarction. Length of hospital stay and medical expenditures were also assessed.

After adjustment, diabetes significantly increased 30-day postoperative mortality (odds ratio [OR], 1.84 compared with nondiabetic patients), particularly among those with uncontrolled diabetes, type 1 diabetes, and those who also had preoperative diabetic complications, such as eye involvement, peripheral circulatory disorders, ketoacidosis, renal manifestations, and coma.

The higher risk for death associated with type 1 vs type 2 diabetes (OR, 1.99 vs 1.83) was an "unprecedented" observation that requires further investigation, say the researchers.

And compared with patients without diabetes, those with diabetes and various coexisting medical conditions also had increased mortality risk at 30 days: for example, the odds ratio of death for those who had prior liver cirrhosis was 3.59; for prior stroke, it was 2.87; for mental disorders, 2.35; and for ischemic heart disease, 2.08.

Patients with diabetes also faced a higher risk for the 6 secondary postoperative outcomes compared with control individuals, including septicemia (OR, 2.76), pneumonia (OR, 1.88), stroke (OR, 1.70), acute renal failure (OR, 3.59), deep wound infection (OR, 1.33), and acute myocardial infarction (OR, 3.65).

"To our knowledge this is the first nationwide, population-based...study to demonstrate that diabetes increases postoperative complications, particularly for acute myocardial infarction and renal failure, [for those] undergoing noncardiac surgeries," say Dr. Chen and colleagues.

In addition, diabetes was associated with prolonged length of stay both in the hospital as well as in the intensive care unit, and it increased medical expenditures (OR, 2.30, 1.67, and 1.32, respectively).

The Devil Is in the Detail; Difficult to Compare Studies

Dr. Abdelmalak notes that he has recently published a retrospective study ( Br J Anaesth 2013) of 61,536 diabetic and nondiabetic patients undergoing noncardiac surgery showing that hyperglycemic patients with diabetes had significantly lower 1-year postsurgical mortality than hyperglycemic patients without diabetes (OR, 0.58; P < .001); among euglycemic patients, mortality was higher among those diagnosed with diabetes vs those who were not (OR, 1.27; P = .003).

And in contrast to the Taiwanese finding of higher mortality and complications with uncontrolled diabetes, his study found no significant relationship between preoperative blood glucose levels and short-term in-hospital complications in both diabetic and nondiabetic patients.

"The differences in the results between our study and theirs can be partially explained by the differences between the studied populations," he told Medscape Medical News. "We studied patients who underwent elective nonemergent, noncardiac surgery…where they only studied patients undergoing major noncardiac surgery. They must have included a multitude of emergency surgeries, as out of the near 15,000 patients studied, almost 1000 had diabetic ketoacidosis and more than 1000 had preoperative coma."

Also, the definition of diabetes used by Dr. Chen and colleagues "is unique and different from other similar studies," said Dr. Abdelmalak. And finally, "no mention of what really constituted 'uncontrolled diabetes' was rightfully discussed by the authors," he said. He added that it would also have been helpful "if the Taiwanese study had included glucose concentrations to help identify potential targets for future glucose control trials in noncardiac surgery."

The authors and Dr. Abdelmalak have disclosed no relevant financial relationships.

Diabetes Care. Published online August 29, 2013. Abstract

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