Abstract
BACKGROUND: Antibiotics are commonly prescribed in older community-dwelling adults, contributing to adverse effects, antimicrobial resistance and increased healthcare costs. Prescribing patterns in dementia are unclear, although healthcare use and goals of care change around diagnosis.
OBJECTIVE: To describe trends in antibiotic dispensing and prevalence amongst Australians aged ≥70 years, compare dispensing between those with and without dementia and identify factors associated with dispensing.
METHODS: We analysed data from 13 659 ASPREE and ASPREE-XT participants (2010-20). Antibiotic dispensing was assessed using Pharmaceutical Benefits Scheme records, with rates stratified by age group. Interrupted time-series analysis compared dispensing rates and the proportion of broad- versus narrow-spectrum antibiotics dementia case and matched controls (matched on time since randomisation, age and sex). Negative binomial regression identified factors associated with dispensing.
RESULTS: Dispensing rates increased to 1651 per 1000 person-years (95% CI: 1604-99) by year 9. Annual prevalence averaged 47%. Broad-spectrum antibiotics were dispensed twice as often as narrow-spectrum. Individuals with dementia had higher dispensing both before and after diagnosis, but dementia was not independently associated with dispensing (IRR 1.06, 95% CI: 0.95-1.18). Female sex, polypharmacy, pre-frailty and higher depressive symptom scores were linked to higher dispensing, whilst hypertension, dyslipidaemia and alcohol use were linked to lower dispensing.
CONCLUSIONS: Antibiotic dispensing in older adults remains high, dominated by broad-spectrum agents. Dementia was not independently associated with increased dispensing. Female sex, polypharmacy, pre-frailty and depressive symptoms identified groups who may benefit most from targeted antimicrobial stewardship interventions.