Medication Use for Comorbidities in People with Alzheimer's Disease: An Australian Population-Based Study

Background: People with Alzheimer's disease (AD) often have multimorbidity and take multiple medicines. Yet few studies have examined medicine utilization for comorbidities comparing people with and without AD. Objective: The aim was to investigate the patterns of medication use for comorbidities in people with and without AD. Methods: An Australian population-based study was conducted using the Pharmaceutical Benefits Scheme 10% sample of pharmacy claims data.People with AD were defined as those dispensed medicines for dementia (cholinesterase inhibitors, memantine, or risperidone for behavioral and psychological symptoms of dementia) between January 1, 2005 and December 31, 2015, who were aged 65 years or older and alive at the end of 2016. An age- and gender-matched comparison cohort (5:1) of people without AD were identified.Medication use for comorbidities was identified using the validated comorbidity index, Rx-Risk-V. A χ2 test was used to compare differences in the pattern of medicine use between the two groups. Results: A total of 8280 people with AD and 41,400 comparisons without AD were included;63.4% were female and the median age was 82 years. The median number of comorbidities was greater in people with AD (median (interquartile range (IQR)): 5(3-7)) than the comparison group (median (IQR): 4(3 –6)), p