Concurrent use of medicines with similar adverse drug reaction profiles in older adults: identifying potential deprescribing opportunities using population-level dispensing data

INTRODUCTION: Older adults are more vulnerable to medicine-related harm. Identifying concurrent use of medicines with similar adverse drug reaction (ADR) profiles may support opportunities for safer prescribing and deprescribing. AIM: To examine the frequency of concurrent use of medicines with overlapping ADR profiles in older adults. A secondary aim was to examine the contribution of potentially inappropriate medicine (PIMs) to overlapping ADR profiles. METHOD: We used data from the 10% sample of dispensing claims from the Australian Pharmaceutical Benefits Scheme between April and June 2022. Medicines were classified by ADR risk using an adapted version of the 2018 Scottish cumulative toxicity tool, which identifies 13 ADR types based on product information. PIMs were identified using the 2024 Australian PIMs list. Individuals aged 65 years or older who were dispensed at least one medicine associated with a listed ADR were included. The outcome of interest was the percentage of persons with an overlapping ADR (dispensed at least two medicines associated with the same ADR). A secondary analysis examined changes in overlapping ADR profiles under a hypothetical scenario excluding PIMs. RESULTS: Our analysis included 323,599 older adults, of which 75.5% (n = 244,331) had at least one overlapping ADR risk, while 64% (n = 206,815) had two or more overlapping ADR risks. Falls/fractures 70.1% (n = 226,873), constipation 53.5% (n = 173,287), and renal injury 38.5% (n = 124,471) were the most common overlapping ADR risks. Under a hypothetical scenario excluding PIMs, an additional 13,803 people would have no falls/fracture overlapping ADR risk, and 19,396 would have no overlapping ADR risk. CONCLUSION: Concurrent use of medicines with similar ADR profiles is common among older adults. Structured tools to identify the use of medicines with similar ADR risks may support deprescribing and safer medicine use in this population.