Postoperative Hyperglycemia and Surgical Site Infection in General Surgery Patients

Hypothesis: Postoperative hyperglycemia is an independent risk factor for postoperative surgical site infection (SSI). Design: Retrospective medical record review. Setting: Academic tertiary referral center. Patients: A total of 2090 general and vascular surgery patients in an institutional quality improvement database between November 1, 2006, and April 30, 2009. Main Outcome Measure: Postoperative SSI. Results: Postoperative glucose levels were available for 1561 patients (74.7.0%), of which 803 (51.4%) were obtained within 12 hours of surgery. The significant univariate predictors of SSI in general surgery patients were increasing age, emergency status, American Society of Anesthesiologists physical status classes P3 to P5, operative time, more than 2 U of red blood cells transfused, preoperative glucose level higher than 180 mg/dL (to convert to millimoles per liter, multiply by 0.0555), diabetes mellitus, and postoperative hyperglycemia. On multivariate adjustment, increasing age, emergency status, American Society of Anesthesiologists classes P3 to P5, operative time, and diabetes remained significant predictors of SSI for general surgery patients. After adjustment for postoperative glucose level, all these variables ceased to be significant predictors of SSI; only incremental postoperative glucose level remained significant. Sub-analysis revealed that a serum glucose level higher than 140 mg/dL was the only significant predictor of SSI (odds ratio, 3.2; 95% confidence interval [CI], 1.4-7.2) for colorectal surgery patients. Vascular surgery patients were 1.8 times (95% Cl, 1.3-2.5 times) more likely to develop SSI than were general surgery patients. Operative time and diabetes mellitus were the only significant univariate predictors of SSI among vascular surgery patients, and postoperative hyperglycemia was not associated with SSI. Conclusions: Postoperative hyperglycemia may be the most important risk factor for SSI. Aggressive early postoperative glycemic control should reduce the incidence of SSI.