Changes in the Prevalence of Polypharmacy in People with and without Dementia from 2000 to 2014: A Nationwide Study

Abstract

Background: Polypharmacy, the use of multiple medications, has become increasingly widespread. Information on time trends in polypharmacy in people with dementia is limited, although they may be more susceptible to risks associated with polypharmacy.

Objective: To examine changes in the prevalence of polypharmacy and excessive polypharmacy in people with dementia compared to changes in people without dementia.

Methods: Repeated cross-sectional study of the entire Danish population aged≥65 from 2000 (n = 790,717) to 2014 (n = 1,028,377) using linked register data on diagnoses, filled prescriptions, and demographic data. Multivariate analyses were performed to explore changes in the prevalence of polypharmacy and excessive polypharmacy (≥5 and≥10 different prescription drugs). This was done before and after 2011 to examine whether increasing awareness of potential problems associated with polypharmacy has altered the trend. Estimates for people with and without dementia were compared.

Results: In people with dementia, the prevalence of polypharmacy increased from 47.3% to 69.4% from 2000 to 2011 and excessive polypharmacy from 7.4% to 20.9%. In people without dementia, polypharmacy increased from 22.7% to 36.1% and excessive polypharmacy from 3.5% to 7.7%. The increase was significantly more marked in people with dementia across all age groups. From 2011 to 2014, the prevalence of polypharmacy and excessive polypharmacy remained relatively stable: Polypharmacy decreased negligibly from 69.4% to 68.1% in people with dementia and from 36.1% to 35.2% in people without dementia.

Conclusion: Although the increasing trend has halted, polypharmacy remains widespread in people with dementia. Further research is needed to explore possible implications.

Keywords: Dementia; inappropriate prescribing; pharmacoepidemiology; polypharmacy.