title: Longitudinal surveillance of outpatient β-lactam antimicrobial use in Canada, 1995 to 2010.
abstract: BACKGROUND
  β-lactam antimicrobials are the most commonly prescribed group of antimicrobials in Canada, and are categorized by the WHO as critically and highly important antimicrobials for human medicine. Because antimicrobial use is commonly associated with the development of antimicrobial resistance, monitoring the volume and patterns of use of these agents is highly important.
  
  
  OBJECTIVE
  To assess the use of penicillin and cephalosporin antimicrobials within Canadian provinces over the 1995 to 2010 time frame according to two metrics: prescriptions per 1000 inhabitant-days and the average defined daily doses dispensed per prescription.
  
  
  METHODS
  Antimicrobial prescribing data were acquired from the Canadian Integrated Program for Antimicrobial Resistance Surveillance and the Canadian Committee for Antimicrobial Resistance, and population data were obtained from Statistics Canada. The two measures developed were used to produce linear mixed models to assess differences among provinces and over time for the broad-spectrum penicillin and cephalosporin groups, while accounting for repeated measurements at the provincial level.
  
  
  RESULTS
  Significant differences among provinces were found, as well as significant changes in use over time. A >28% reduction in broad-spectrum penicillin prescribing occurred in each province from 1995 to 2010, and a >18% reduction in cephalosporin prescribing occurred in all provinces from 1995 to 2010, with the exception of Manitoba, where cephalosporin prescribing increased by 18%.
  
  
  CONCLUSIONS
  Significant reductions in the use of these important drugs were observed across Canada from 1995 to 2010. Newfoundland and Labrador and Quebec emerged as divergent from the remaining provinces, with high and low use, respectively.
authors.affiliation: Public Health Agency of Canada, Centre for Food-borne, Environmental and Zoonotic Infectious Diseases, Guelph, Ontario;
authors.forename: Shiona K
authors.initials: SK
authors.lastname: Glass-Kaastra
authors.affiliation: Public Health Agency of Canada, Centre for Food-borne, Environmental and Zoonotic Infectious Diseases, Guelph, Ontario;
authors.forename: Rita
authors.initials: R
authors.lastname: Finley
authors.affiliation: Division of Medical Microbiology, Island Medical Program, University of British Columbia, Vancouver, British Columbia;
authors.forename: Jim
authors.initials: J
authors.lastname: Hutchinson
authors.affiliation: British Columbia Centre for Disease Control, University of British Columbia, Vancouver, British Columbia; ; School of Population and Public Health, University of British Columbia, Vancouver, British Columbia;
authors.forename: David M
authors.initials: DM
authors.lastname: Patrick
authors.affiliation: Department of Infectious Diseases and Microbiology, University of Montreal, Hôpital Maisonneuve-Rosemont, Montreal;
authors.forename: Karl
authors.initials: K
authors.lastname: Weiss
authors.affiliation: Department of Medicine, University of Calgary, Calgary, Alberta.
authors.forename: John
authors.initials: J
authors.lastname: Conly
keywords: Antimicrobial use; Broad-spectrum penicillin; Cephalosporin; Penicillin; Provincial variation; Surveillance; β-lactam