Trends, demographics and disparities in outpatient antibiotic consumption in New Zealand: a national study

Objectives: Knowledge of the patterns of antibiotic consumption within a population provides valuable information on when, where and to whom antibiotics are prescribed. Such knowledge is critical in informing possible public health interventions to reduce inappropriate antibiotic use. The aims of this study were to (i) determine national patterns of antibiotic consumption, including assessment of seasonal variation in prescribing, and (ii) explore potential associations between antibiotic consumption and patient characteristics, such as age, sex and ethnicity. Methods: Data on all subsidized antibiotic dispensing in New Zealand between 1 January 2006 and 31 December 2014 were obtained and stratified according to age, sex and ethnicity. Antibiotic dispensing was expressed as the number of DDDs per 1000 population per day (DID). Results: Total antibiotic consumption in New Zealand increased by 49% from 17.3 DID in 2006 to 25.8 DID in 2014. The increase in antibiotic consumption occurred in all ages and amongst all ethnic groups. The use of extended-spectrum penicillins, which almost doubled in the study period, made a major contribution to the overall increase and was highest in young children and in Pacific peoples. Consumption of quinolones increased early in the study period and then declined from 2011 onwards. Conclusions: Future work should focus on identifying the appropriateness of antibiotic prescribing, particularly for penicillin prescribing in Pacific peoples and children, and on both reducing unwarranted antibiotic use and improving antibiotic selection when therapy is indicated.