Longitudinal surveillance of outpatient β-lactam antimicrobial use in Canada, 1995 to 2010.

Introduction: 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%.

Discussion: 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.