(211) Prevalence of Medication-Related Risk Factors for Adverse Drug Reactions

Background: Medication use is high and increasing. While this is usually associated with greater efficacy, it may also increase the risk of adverse drug reactions.

Objectives: We aimed to assess medication use and four risk factors for adverse drug reactions: the use of polypharmacy, Potentially Inappropriate Medications in the elderly, PGX drugs (drugs influenced by CYP2D6, CYP2C19, and SLCO1B1) in individuals with actionable variance for the specific drug, and drugs with a higher risk for adverse drug reactions that lead to emergency room admissions.

Methods: This study is based on cross-sectional data from the Rhineland Study, a large population-based cohort. The population consists of inhabitants aged 30 years or older in geographically defined areas in Bonn, Germany. Participation is only possible upon invitation and regardless of health status. We included all persons who enrolled from 2016 to 2021 (n=8,318) except those with missing medication (n=210) or genetic data (n=987), leaving 7,121 to be included in the analyses (mean age 55.93% women). Medication data was collected by interview. Genotyping of the pharmacogenes was done using the Global Screening Array (GSA). The definition of actionable variants was based on Dutch Pharmacogenetics Working Group recommendations. We used descriptive statistics to assess the risk factors in question.

Results: In our population, 64% used at least one drug regularly, which increased to 84% in participants aged ≥65 years (n=1995). The rates of use of polypharmacy, potentially inappropriate medication in the elderly, PGX drugs in individuals with an actionable variance for the specific drug, and drugs associated with emergency room admissions due to adverse drug reactions were 15.1%, 3.1%, 4.4% and 20.9%, respectively. In participants aged ≥65 years this increased to 34.7%, 5.4%, 8.9% and 41.5%, respectively. In participants aged <65 years 16.9% (95% CI 15.8- 17.9) had at least one risk factor, in participants ≥65 years this increased to 52.9% (95% CI 50.7- 55.1). In participants aged <65 years, 5.3% (95% CI 4.7- 5.9) had at least two risk factors for ADRs. In participants ≥65 years, 29.7% (95% CI 27.7- 31.8) had at least two risk factors for ADRs. Extrapolating these numbers to the German population would imply that around 3.4 million of the 65 million individuals aged <65 years and 5.5 million of the 18.5 million individuals aged 65 years or older are potentially at a highly elevated risk, i.e. having two risk factors or more, for adverse drug reactions.

Conclusions: In this study we show that drug use is complex and that a high proportion of the population is at high risk of adverse drug reactions. In clinical practice deprescribing is complex and challenging, but could potentially improve health, especially in the elderly.