Antibiotic utilisation and the impact of antimicrobial resistance action plan on prescribing among older adults in New Zealand between 2005 and 2019

PurposeThe objectives of this study were to examine the overall utilisation of systematic antibiotics and the impact of the launch of the antimicrobial resistance action plan in older adults (65 years or more) living in New Zealand between 2005 and 2019, using data from a national database (Pharmaceutical collections), stratified by antibiotic class, patient age, and sex.MethodsPopulation-level systemic antibiotic dispensing data for older adults in New Zealand was analysed using repeated cross-sectional analysis between 01/01/2005 and 31/12/2019. Data were extracted on the prescribed systemic antibiotics using a unique identifier for each case. Antibiotic utilisation was measured in DDD/TOPD values. In addition, an interrupted time series (ITS) analysis using the autoregressive integrated moving average (ARIMA) models was performed to determine the impact of the antimicrobial resistance action plan.ResultsMost of the antibiotic classes included in this study showed a significant overall decrease in utilisation ranging from 38.64% for sulphonamides to 80.64% for fluoroquinolones compared to 2005. Systemic antibiotic utilisation decreased by 49.6% from the predicted usage between January 2018 and December 2019 following the launch of the antimicrobial resistance action plan. ARIMA model supported the reduction in utilisation with a step change of -0.2206 and slope change of -0.0029.ConclusionsThe ITS analysis has demonstrated that the intervention may have hugely impacted the antibiotic utilisation rate among older adults. Further studies are required to determine whether the reduced consumption rates of antibiotics are associated with reduced rates of antibiotic-associated adverse drug events such as acute kidney injury and haematological abnormalities.