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Hyperglycemia increases complications after cardiac surgery
Patients without diabetes and those with diabetes not treated with insulin who experienced blood glucose levels of more than 180 mg/dL after cardiac surgery had higher hospital costs, longer hospital stays and increased complications, whereas patients with insulin-treated diabetes who experienced postsurgery hyperglycemia saw more favorable outcomes, according to research in Diabetes Care.
Giampaolo Greco, PhD, an assistant professor of population health science and policy at Mount Sinai Hospital, and colleagues analyzed glucose levels from 4,316 patients without pre-existing infection who underwent cardiac surgery in 2010 at nine U.S. hospitals (66% men; mean age, 66 years; 553 with diabetes not treated with insulin; 419 with insulin-treated diabetes). Glucose was measured at 6-hour intervals for 48 hours postoperatively. Researchers used regression and recycled prediction analyses to measure associations between maximum glucose levels and cost, hospital length of stay, cardiac and respiratory complications, major infections and death. Researchers obtained billing data from the University HealthSystem Consortium; hospitalization costs were calculated using Medicare cost center-specific cost-to-charge ratios.
During the first 48 hours after surgery, 70% of patients with diabetes developed hyperglycemia vs. 36% of patients without diabetes.
Increased glucose levels were associated with a gradual worsening of outcomes in patients without diabetes. For these patients, glucose levels of at least 180 mg/dL were associated after adjustment with an additional cost of $3,192 (95% CI, 1,972-4,456), a 0.8-day increase in hospital stay (95% CI, 0.4-1.3), a 1.6% increase in infections (95% CI, 0.5-2.8), a 2.6% increase in respiratory complications (95% CI, 0-5.3) and a trend toward increased cardiac complications.
Patients with insulin-treated diabetes, however, saw a reduced risk for adverse outcomes when experiencing glucose levels between 180 mg/dL and 240 mg/dL, including a 12.5% reduction in respiratory complications and a 4.1% reduction in major infections. These patients also saw an average cost reduction of $6,225 and a 1.6-day reduction in length of hospital stay. The risk for complications for those with diabetes not treated with insulin did not reach statistical significance.
In an analysis of hypothetical scenarios of different glucose thresholds, outcomes after cardiac surgery would improve for patients without diabetes or with diabetes not treated with insulin with lower postoperative glucose values, according to researchers.
“The expected benefits [of lowering glucose thresholds] comprised an approximate $2,000 cost reduction and a 5% to 15% reduction in complications,” the researchers wrote. “In contrast, in patients with [insulin-treated diabetes], thresholds less than 180 mg/dL would be harmful, although in this range outcomes were uncertain.” – by Regina Schaffer
Disclosure: Greco reports receiving grants from the Institute for Health Technology Studies. Please see the full study for the other authors’ relevant financial disclosures.