Trends in antibacterial use in US academic health centers: 2002 to 2006.

BACKGROUND Antibacterial drug use is a major risk factor for bacterial resistance, but little is known about antibacterial use in US hospitals. The objectives of this study were to characterize trends in antibacterial use in a sample of US hospitals and to identify predictors of use. METHODS We measured systemic antibacterial use from validated claims data at 22 university teaching hospitals from January 1, 2002, through December 31, 2006, and we examined potential predictors of use in 2006, including hospital and patient demographics and antibacterial stewardship policies. RESULTS A total of 775,731 adult patients were discharged in 35 hospitals during 2006, and 492,721 (63.5%) received an antibacterial drug. The mean (SD) total antibacterial use increased from 798 (113) days of therapy per 1000 patient days in 2002 to 855 (153) in 2006 (P < .001). Fluoroquinolones were the most commonly used antibacterial class from 2002 through 2006, and use remained stable. Piperacillin sodium-tazobactam sodium and carbapenem use increased significantly, and aminoglycoside use declined. Cefazolin sodium was the most commonly used antibacterial drug in 2002 and 2003 but was eclipsed by vancomycin hydrochloride in 2004. The strongest predictor of broad-spectrum antibacterial use was explained by differences across hospitals in the mean durations of therapy. CONCLUSIONS Total antibacterial use in adults increased significantly from 2002 through 2006 in this sample of academic health centers, driven by increases in the use of broad-spectrum agents and vancomycin. These developments have important implications for acquired resistance among nosocomial pathogens, particularly for methicillin-resistant Staphylococcus aureus (MRSA).