Antibiotic use in 26 departments of internal medicine in 6 general hospitals in Israel: variability and contributing factors

Received 6 January 2008; returned 28 January 2008; revised 3 March 2008; accepted 9 March 2008Objectives: Increased antibiotic consumption is associated with increased bacterial resistanceworldwide. We aimed to analyse antibiotic consumption and potential contributory factors in internalmedicine departments in Israel.Methods: Data (2003–04) from 26 departments in 6 hospitals were retrieved. Defined daily doses(DDD)/100 bed-days were calculated for total antibiotic use and by antibiotic class. Patterns identifiedwere correlated with 15 patients’ and departmental variables by univariate and multivariate analyses.Results: Total antibiotic consumption differed by a factor of 2.3 (115 DDD/100 bed-days to 49.1 DDD/100 bed-days) between the highest and lowest consuming departments. Antibiotic classes differed bya factor of 22.8 for macrolides, a factor of 20 for piperacillin/tazobactam, a factor of 17 for carbape-nems, a factor of 13.3 for quinolones, a factor of 9 for vancomycin, a factor of 6.8 for amoxicillin/clavu-lanate, a factor of 6.6 for aminoglycosides, a factor of 5.3 for penicillins and a factor of 2.8 forcephalosporins. Even among departments within hospitals, there was a difference of up to 1.5-foldfor total use and antibiotic class differences ranged between 2.5- and 7.2-fold for third- and fourth-generation cephalosporins, despite similar Charlson scores and other patient variables. In the multi-variate analysis, hospital affiliation and rate of 1 day hospitalization were the only significant variablespredicting total antibiotic use, contributing 43% and 7.3%, respectively, to the variance. By antibioticclass, controlling for hospital affiliation, patients with neutropenia, lower respiratory tract infectionsand assisted ventilation were the most common significant contributors, ranging from 3.5% for quino-lones to 7.7% for piperacillin/tazobactam.Conclusions: Patterns of antibiotic use vary widely among internal medicine departments in Israel,which cannot be explained by objective parameters related either to patients or wards. Ongoing moni-toring and guideline formulation are needed to regulate antibiotic prescription.Keywords: antibiotic consumption, internal medicine departments, drug utilization