Addition of metronidazole to cefazolin for antibiotic prophylaxis at hysterectomy: a weighted analysis.

Abstract

Background: The relationship between perioperative antibiotic choice and surgical site infection (SSI) associated with hysterectomy warrants more investigation on a national scale.

Methods: This was a retrospective cohort study utilizing data from the Premier Healthcare Database. Overall, 242,349 patients were identified using CPT codes who underwent hysterectomy for benign indications between January 2000 and March 2020. Patients were grouped by antibiotic regimen and characteristics and surgical information and postoperative complications were collected. Multivariable logistic regression and inverse probability of treatment weighted analysis (IPTW) were performed.

Results: The most utilized prophylaxis was cefazolin alone (67.3%). About 3.9% of patients received cefazolin with metronidazole and 28.8% received other antibiotics. There were significantly more episodes of SSI at 1 month in those receiving other antibiotics when compared to those receiving either cefazolin or cefazolin with metronidazole (P<0.001). Multivariable logistic regression revealed a significant relationship between SSI and tobacco use, obesity, Charlson Comorbidity Index, and diabetes. Cefazolin with metronidazole was associated with a similar probability of developing SSI as cefazolin alone (OR 0.98, P=0.90). After IPTW, the probability of SSI at 1 month was not significantly different between cefazolin and cefazolin with metronidazole (OR 1.003, 95% CI: [0.81, 1.24]).

Conclusions: After weighting based on preoperative characteristics, the addition of metronidazole to cefazolin for prophylaxis at the time of hysterectomy did not significantly decrease the probability of developing SSI compared to cefazolin alone. Any regimen of antibiotics other than cefazolin or cefazolin with metronidazole was associated with increased probability of SSI.