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

BackgroundPeople 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. ObjectiveThe aim was to investigate the patterns of medication use for comorbidities in people with and without AD. MethodsAn 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 chi(2) test was used to compare differences in the pattern of medicine use between the two groups. ResultsA 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<0.0001). Medications for depression, pain (treated with opioid analgesics), anxiety, diabetes, hyperthyroidism, epilepsy, Parkinson's disease, and antipsychotics were used significantly more commonly in people with AD than in those without dementia. Medications for cardiac conditions, pain (treated with anti-inflammatory medications), chronic airways disease, gout, glaucoma, renal disease, benign prostatic hyperplasia, cancer, and steroid-responsive conditions were used significantly less commonly among people with AD than the comparison group. ConclusionsThis study highlighted significant variations in medication use for comorbidities between people with and without AD. Future studies should evaluate the reasons for the disparity in medicine utilization for comorbidities in people with AD.