A national study on prescribed medicine use in Australia on a typical day

To describe Australians' prescribed medicine use on a typical day (September 25, 2018).

We conducted a cross-sectional study using nationally representative dispensing claims data using the Australian Government Department of Human Services random 10% sample of all Australians eligible for prescription medicines subsidised through the Australian Pharmaceutical Benefits Scheme (PBS). Our main outcome measures were the number and proportion of people using at least one prescribed medicine and the specific medicine groups and classes on the day. We estimated the proportion of Australians using these medicines using the mid-year Australian population as the denominator. We quantified multiple medicine use by calculating the number and proportion of people experiencing polypharmacy (the use of 5 or more unique medicines) and hyper-polypharmacy (the use of 10 or more unique medicines).

We found that 9.0 million Australians used at least one PBS medicine on September 25, 2018; equating to 27.5 million medicines in use across Australia. "Cardiovascular system", "nervous system" and "alimentary tract and metabolism" medicines comprised the top three medicine groups. Over 1.8 million people experienced polypharmacy on the day, accounting for 13.6 million dispensed medicines. 1 022 590 (45%) people aged ≥70 years old experienced polypharmacy and 188 930 (8%) experienced hyper-polypharmacy.

Rates of polypharmacy were high, particularly in the people most susceptible to polypharmacy-related harm. Strategies to optimise the risk-benefit ratio of medicines and to reduce polypharmacy through "choosing wisely" and "de-prescribing" in this age group are needed. Australia's national data provides a benchmark to inform global medicine utilisation practices.