Effectiveness of Pre-Operative Cefazolin in Obese Patients

Background: Cefazolin remains the preferred preoperative antibiotic for the majority of surgical procedures. However, outcome evidence supporting current dosing recommendations for pre-operative prophylaxis is scarce, particularly for obese patients. With more than 33% of adults in the United States classified as obese, it is crucial that we determine the correct dosing regimen in order to maximize the potential to prevent surgical site infections (SSIs). The purpose of this study was to evaluate whether surgical prophylaxis with cefazolin 2 g, as recommended by practice guidelines, is as effective in preventing SSIs in obese as compared to non-obese patients. Methods: In retrospective fashion, data were collected from the electronic medical records of patients who received 2 g of cefazolin preoperatively during a 13-mo period. Patients who met the inclusion criteria were allocated to an obese (n = 99) and non-obese (n = 96) group according to body mass index (BMI). Charts were reviewed for identification of SSIs as defined by the U. S. Centers for Disease Control and Prevention. For the primary outcome, the numbers of SSIs in the two groups were compared using the Pearson chi(2) test. Results: Patient characteristics were similar in the two groups with the expected exception of weight (mean 90 vs. 110 kg; p < 0.001) and BMI (27 vs. 35 kg/m(2); p < 0.001). The highest patient weight was 182 kg with a BMI of 55 kg/m(2). The most common surgical service was orthopedics/hand, accounting for 35% of patients. No significant difference was found in the number of SSIs in the two groups (7 vs. 5; p = 0.56). No differences between weight and BMI were seen in patients with or without a SSI. Conclusions: Obese patients may continue to receive 2 g of cefazolin preoperatively until large-scale controlled trials show differently.