Objectives: To assess the prevalence of, and the variation in, avoidable use of metronidazole in the Veterans Affairs (VA) healthcare system
Methods: Barcode Medication Administration (BCMA) data were retrospectively assessed for all patients hospitalized between January 2006 and December 2010 in acute-care wards of all VA medical centres (VAMCs) with complete BCMA data and at least 10 acute-care non-intensive care unit (ICU) beds. Potentially avoidable metronidazole days of therapy (DOT) were defined as the administration of metronidazole with another anti-anaerobic antibiotic on the same day for at least two consecutive days during the same hospitalization. Metronidazole was not considered redundant in combination with another anti-anaerobic agent within 28 days after a positive test for Clostridium difficile and during hospitalizations associated with discharge diagnosis codes for cholecystitis or cholangitis.
Results: A total of 128 VAMCs satisfied the inclusion criteria. Over the study period there were a total of 782,821 DOT of metronidazole (57.4 DOT per 1000 patient-days), of which 183,267 (23.4%) fulfilled the criteria for avoidable metronidazole DOT. The percentage of avoidable metronidazole DOT remained stable over the study period (22.8% in 2006 and 22.9% in 2010) despite a decrease in overall metronidazole use. There was wide variation in the percentage of avoidable metronidazole DOT among facilities (2010: median 20.3%, IQR 15.3%-29.4%). Piperacillin/tazobactam was the most commonly administered drug on avoidable metronidazole DOT (56.8%).
Conclusions: Potentially avoidable use of metronidazole affected about a quarter of all days when metronidazole was given. The combination of metronidazole with piperacillin/tazobactam was particularly common and represents a possible target for antibiotic stewardship interventions.