Regional variation in potentially inappropriate medicine use in older adults. - A national register-based cross-sectional study on economic, health system-related and patient-related characteristics.

Background: Potentially inappropriate medicines (PIM), i.e. medicines in which the potential harms may outweigh the benefits, use may be associated with e.g. hospitalization, outpatient visits and health care costs. As regional institutions are often responsible for financing pharmaceuticals, understanding the regional variation of PIM use could help to tackle the associated problems and costs.

Objective: To explore regional variation in PIM use among older adults and the association with regional health-system related, patient-related and economic characteristics and the frequency of PIM use.

Methods: This is a nation-wide study based on the Finnish Prescription Register. PIM use was defined according to the Finnish Meds75+ database and regional characteristics derived from national statistics.

Results: Variation at the hospital district level was large, with the largest difference between the most and least PIM prescribing being 45.2%. The factors associated with high PIM prescribing were a higher share of women and a higher number of private doctor visits per inhabitant in a municipality. The factor associated to lower PIM prescribing was a higher share of Swedish-speaking population. The studied factors explained 23% of the municipal-level variation in PIM.

Conclusions: Large regional differences may lead to regional inequality in prescribing and in the distribution of pharmaceutical costs. As only a small share of the variation was explained by economic, health system-related and patient-related factors, the key reasons may lie in unobserved prescribing practices.