Regional variation of potentially inappropriate medication use and associated factors among older adults: A nationwide register study.

Background: Certain medications should be used with caution in older persons, which challenges rational prescribing. Potentially inappropriate medications (PIMs) are defined as medicines whose potential risk of harm typically outweighs the clinical benefits in geriatric population. Earlier studies have found regional differences in PIM use, but the factors underlying this phenomenon are unclear.

Objective: To compare prescription PIM prevalence among Finnish hospital districts and determine which population characteristics and factors related to social and health care are associated with regional variation.

Methods: This nationwide register study was based on the Prescription Centre data on all people aged ≥75 years in 2017-2019. Hospital district (n = 20) characteristics were drawn from the Finnish Institute for Health and Welfare's, Finnish Medical Association's, and Finnish Medicines Agency's publicly open data. PIMs were defined according to the Finnish Meds75+ database. A linear mixed-effect model was used to analyze potential associations of regional characteristics with PIM prevalence.

Results: Prevalence of PIMs varied between 16.4% and 24.8% across regions. The highest prevalence was observed in the southern regions, while the lowest prevalence was on the west coast. Hospital district characteristics associated with higher PIM prevalence were higher share of population living alone, with excessive polypharmacy, or assessed using the Resident Assessment Instrument, shortage of general practitioners in municipal health centers, and low share of home care personnel. Waiting time in health care or share of population with morbidities were not associated with PIM use. Of the total variance in PIM prevalence, 86% was explained by group-level factors related to hospital districts. The regional variables explained 75% of this hospital-district-level variation.

Conclusions: PIM prevalence varied significantly across hospital districts. Findings suggest that higher PIM prevalence may be related to challenges in the continuity of care rather than differences in health care accessibility or share of the population with morbidities.