Potentially Inappropriate Medication Among Older Adults: Prevalence, regional variation and risk of initiation

Pharmacokinetic and pharmacodynamic alterations, chronic diseases and concomitant use of several medications predispose older adults to higher sensitivity of adverse drug events (ADEs) and interactions. Potentially inappropriate medications (PIMs) are defined as medications in which the risk of harm (for example ADEs, drug-drug or drug-disease interaction) usually outweighs the clinical benefits in older adults.

The aim of this thesis is to compare distribution and rating of PIMs between nine published criteria and determine which social and health care service related factors and population characteristics are associated with regional variation of PIM use among Finnish older adults. Further, the aim is to identify patient-related characteristics associated with PIM initiation among older home care clients.

The present study examines Finnish Social Insurance Institution’s (SII) nationwide outpatient prescription PIM purchase data of older adults aged ≥75 years in years 2017‒2019 (n=497,663). To assess regional variation of PIM use, the information on older adults residency (i.e., hospital district) was obtained from the benefit register of SII and regional characteristics were drawn from Finnish Institute for Health and Welfare, Finnish Medical Association, Finnish Medicines Agency Fimea and Official Statistics of Finland. Data to determine characteristics associated with PIM initiation was based on Resident Assessment Instrument (RAI) data of home care clients aged ≥65 years (n=2,015) in the city of Tampere in years 2014‒ 2015.

The annual PIM prevalence varied markedly (11‒57%) between the nine criteria and was due to differences in identifying medicine classes (for example proton pump inhibitors, loop-diuretics, non-steroidal anti-inflammatory drugs and hypnotics) with varying level as PIMs. Similarly, annual PIM use varied markedly (16‒25%) across the hospital districts and in linear mixed-effect model home care personnel and physician shortages, higher coverage of RAI assessment, and higher proportions of older adults with excessive polypharmacy and living alone were associated with higher PIM prevalence. Also, rate of initiation of PIMs was high (11%) among older home care clients. In generalized estimating equations the higher odds to initiate PIMs was associated with client’s higher education, independent activity outdoors, cognitive impairment, reduced social interaction, Parkinson’s disease and diabetes. Longer interval between RAI assessments was also associated with higher risk to initiate PIMs.

The results of this thesis show that PIM prevalence among Finnish older adults is high, but professionals must be aware of the great variation between the criteria in identifying medicine classes as PIMs. Findings of the regional variation in PIM use show that personnel shortage, polypharmacy and living alone challenge medication safety. Therefore, both continuity of care and older adults self-care ability need to be supported to promote medication safety. RAI assessments have potential to detect older adults in higher risk to initiate PIMs, such as client’s with cognitive impairment. The care needs associated with PIM initiation reflect the importance to reduce PIM use and decrease the risks of harmful outcomes to maintain functional performance and independence of home care clients.