A modified method for measuring antibiotic use in healthcare settings: implications for antibiotic stewardship and benchmarking

M.A. Aldeyab, J.C. McElnay, M.G. Scott, W.J. Lattyak, F.W. Darwish Elhajji, M.A. Aldiab, F.A. Magee, G. Conlon, M.P. Kearney

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Objectives: To determine whether adjusting the denominator of the common hospital antibiotic use measurement unit (defined daily doses/100 bed-days) by including age-adjusted comorbidity score (100 bed-days/age-adjusted comorbidity score) would result in more accurate and meaningful assessment of hospital antibiotic use. Methods: The association between the monthly sum of age-adjusted comorbidity and monthly antibiotic use was measured using time-series analysis (January 2008 to June 2012). For the purposes of conducting internal benchmarking, two antibiotic usage datasets were constructed, i.e. 2004-07 (first study period) and 2008-11 (second study period). Monthly antibiotic use was normalized per 100 bed-days and per 100 bed-days/age-adjusted comorbidity score. Results: Results showed that antibiotic use had significant positive relationships with the sum of age-adjusted comorbidity score (P = 0.0004). The results also showed that there was a negative relationship between antibiotic use and (i) alcohol-based hand rub use (P = 0.0370) and (ii) clinical pharmacist activity (P = 0.0031). Normalizing antibiotic use per 100 bed-days contributed to a comparative usage rate of 1.31, i.e. the average antibiotic use during the second period was 31% higher than during the first period. However, normalizing antibiotic use per 100 bed-days per age-adjusted comorbidity score resulted in a comparative usage rate of 0.98, i.e. the average antibiotic use was 2% lower in the second study period. Importantly, the latter comparative usage rate is independent of differences in patient density and case mix characteristics between the two studied populations. Conclusions: The proposed modified antibiotic measure provides an innovative approach to compare variations in antibiotic prescribing while taking account of patient case mix effects. © The Author 2013. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.
Original languageEnglish
Pages (from-to)1132-1141
Number of pages9
JournalJournal of Antimicrobial Chemotherapy
Issue number4
Early online date11 Nov 2013
Publication statusPublished (in print/issue) - 1 Apr 2014

Bibliographical note

First published 11 November 2013. Had to remove this date to ensure the item became eligible for proposal for REF


  • Age-adjusted comorbidity index
  • Antibiotic measure
  • Pharmacoepidemiology
  • Time-series analysis
  • aminoglycoside derivative
  • amoxicillin plus clavulanic acid
  • antibiotic agent
  • antiinfective agent
  • carbapenem derivative
  • cephalosporin derivative
  • chloramphenicol
  • glycopeptide
  • imidazole derivative
  • lincosamide
  • macrolide
  • monobactam derivative
  • nitrofuran derivative
  • penicillin derivative
  • quinolone derivative
  • steroid
  • streptomycin derivative
  • sulfonamide
  • tetracycline derivative
  • trimethoprim derivative
  • antibiotic therapy
  • article
  • Clostridium difficile infection
  • comorbidity
  • drug utilization
  • hospital care
  • human
  • observational study
  • pharmacist
  • quality control
  • time series analysis
  • age-adjusted comorbidity index
  • antibiotic measure
  • pharmacoepidemiology
  • time-series analysis
  • Adult
  • Anti-Bacterial Agents
  • Benchmarking
  • Drug Prescriptions
  • Drug Utilization
  • Health Facilities
  • Humans


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