Association of persistent postoperative hyperglycemia with mortality after elective craniotomy

Objective: The influence of persistent postoperative hyperglycemia after craniotomy has not yet been explored. This study aimed to investigate the hypothesis that persistent postoperative hyperglycemia is associated with mortality in patients undergoing an elective craniotomy. Methods: This study included adult patients (age >= 18 years) undergoing an elective craniotomy between January 2011 and March 2021 at the West China Hospital, Sichuan University. Peak daily blood glucose values measured within the first 7 days after craniotomy were collected. Persistent hyperglycemia was defined by two or more consecutive serum glucose levels of mild, moderate, or severe hyperglycemia. Normoglycemia, mild hyperglycemia, moderate hyperglycemia, and severe hyperglycemia were defined as glucose values of <= 6.1 mmol/L, > 6.1 and <= 7.8 mmol/L, > 7.8 and <= 10.0 mmol/L, and > 10.0 mmol/L, respectively. Results: This study included 14,907 patients undergoing an elective craniotomy. In the multivariable analysis, both moderate (adjusted OR 3.76, 95% CI 2.68-5.27) and severe (adjusted OR 3.82, 95% CI 2.54-5.76) persistent hyperglycemia in patients were associated with higher 30-day mortality compared with normoglycemia. However, this association was not observed in patients with mild hyperglycemia (adjusted OR 1.32, 95% CI 0.93-1.88). Interestingly, this association was observed regardless of whether patients had preoperative hyperglycemia. There was no interaction between moderate or severe hyperglycemia and preexisting diabetes (p for interaction = 0.65). When postoperative peak blood glucose values within the first 7 days after craniotomy were evaluated as a continuous variable, for each 1-mmol/L increase in blood glucose, the adjusted OR of 30-day mortality was 1.17 (95% CI 1.14-1.21). Postoperative blood glucose (area under the curve [AUC] = 0.78) was superior to preoperative blood glucose (AUC = 0.65; p < 0.001) for predicting mortality. Moderate and severe persistent hyperglycemia in patients were associated with an increased risk of deep venous thrombosis (adjusted OR 3.20, 95% CI 2.31-4.42), pneumonia (adjusted OR 2.77, 95% CI 2.40-3.21), myocardial infarction (adjusted OR 4.38, 95% CI 3.41-5.61), and prolonged hospital stays (adjusted OR 1.43, 95% CI 1.29-1.59). Conclusions: In patients undergoing an elective craniotomy, moderate and severe persistent postoperative hyperglycemia were associated with an increased risk of mortality compared with normoglycemia, regardless of preoperative hyperglycemia.