Geographic variation in top-10 prescribed medication and potentially inappropriate prescription in Portugal: An ecological study of 2.2 million older adults

Background: The use of multiple medications by older adults is considered a Public Health concern since it is associated to a higher risk of adverse drug reactions and potentially inappropriate medication (PIM). This study aimed to describe the top-10 prescribed active substances in older adults considering geographical distribution and PIM prescription. Methods: : A retrospective ecological study was conducted using data on the prescribed active substances during 2020 to people with 65 years or older. Information on active substances and defined daily doses (DDD) by age group, sex and region were retrieved from a Portuguese health administrative database. The average number of prescribed packages and DDD per 1000 inhabitants per day of top-10 active substances were calculated. Results: : A total of 2228090 older adults (58% females) were included. The active substances with higher prescription rates (mean DDD/1000 inhabitants/day) in all ARS were furosemide and atorvastatin in both males and females, compared to the other active substances of the top-10. Geographic differences in prescription were observed (higher prescription in ARS North and Centre and lower in ARS Algarve). In females, 2/10 most prescribed active substances were PIM (benzodiazepines and opioids) with geographic disparities across regions. Conclusions: : Most prescribed active substances to older adults belong to the cardiovascular system. The prescription of benzodiazepines and opioids in females, classified as PIM, alert for the need of public health policies to reduce inappropriate prescribing. Geographic differences in the top-10 most prescribed active substances and in PIM highlighted the importance of medication optimisation across regions.