Abstract
OBJECTIVE: To investigate the age, period, and cohort effects of polypharmacy in older adults using Swedish register data covering the period 2006 to 2020. DESIGN: Repeated cross-sectional study using routinely-collected health care data. SETTING: Nationwide, Sweden. PARTICIPANTS: A 10% random sample was drawn each year from the source population of all adults aged ≥ 65 in Sweden, 2006-2020 (cumulative n > 3,000,000). MEASUREMENT: Polypharmacy was defined as the use of ≥ 5 medicines. Drug data were extracted from the National Prescribed Drug Register (NPDR) Medication use was assessed on 1st January (1-day point prevalence) each year based on the drug duration episodes. Age-Period-Cohort analysis was conducted to explore these effects. RESULTS: Overall, 32.8% of older adults was exposed to polypharmacy in 2020 compared to 28.6% in 2006. This increase was more pronounced among individuals aged 85 to 89, from while the prevalence remained relatively steady among those aged 65 to 84. In the formal Age-Period-Cohort analysis, the cohort differences were weak for polypharmacy, but more prevalent for specific medication classes. CONCLUSION: Polypharmacy is mainly influenced by age and period effects, but not by cohort. The rise in polypharmacy is primarily propelled by an increased pace in medication use among individuals aged 75 to 89 years. These findings can provide valuable insights for making effective strategies aimed at reducing polypharmacy.