Does stress-induced hyperglycemia increase the risk of perioperative infectious complications in orthopaedic trauma patients?

OBJECTIVE: To determine if hyperglycemia in postoperative orthopaedic trauma patients with no known history of diabetes mellitus is associated with an increased rate of infectious complications.
DESIGN: Retrospective review.
SETTING: University Level I trauma center. PATIENTS: One hundred ten consecutive orthopaedic trauma patients, MAIN OUTCOME MEASUREMENTS: Perioperative pneumonia, urinary tract infection, sepsis, or wound infection.
METHODS: Patients were divided into two subgroups based on mean serum glucose greater than 220 mg/dL (hyperglycemic index [HGI] 3.0 or greater). The incidence of infections was calculated for the following factors: age, medical comorbidities, Injury Severity Score, body mass index, HGI, sex, transfusions, tobacco use, and presence of open fracture. Means were compared using two-sample t tests (with or without adjustment for unequal variances as necessary), and percentages were compared using either chi square or Fisher exact tests. If the data were not normally distributed or measured on the ordinal scale, then the Wilcoxon rank sum test was used. A multivariate analysis using logistic regression was performed with the presence or absence of an infection as the dependent variable. A two-tailed P value < 0.05 was considered significant. SAS, Version 9.1 (SAS Institute Inc, Cary, NC), was used for all analyses.
RESULTS: Forty-six infections occurred in 28 patients, including 11 wound infections, 17 pneumonia, 11 urinary tract infections, and seven sepsis or bacteremia. The overall infection rate for the study cohort was 28 of 110 (25%). No significant associations were identified among age, comorbidities, transfusions, tobacco use, open fracture, sex, body mass index, Injury Severity Score, and the presence of any infection. Ninety nine patients had an HGI less than 3.0 and 21 (21%) of these had a perioperative infection. Eleven patients had an HGI 3.0 or greater and seven (64%) of these had a perioperative infection. This difference was significant (P = 0.0056).
CONCLUSIONS: Mean perioperative glucose levels greater than 220 mg/dL (HGI greater than 3.0) were associated with a seven times higher risk of infection in orthopaedic trauma patients with no known history of diabetes mellitus. Further prospective studies are needed to study the effects of stress-induced hyperglycemia and to determine whether this physiological response is protective or detrimental to the postoperative trauma patient.