The impact of polypharmacy on the health of Canadian seniors.

Background: Prescription medication use increases with age. Seniors face an increased risk of adverse drug reactions from medications, partly because the kidneys and liver can lose functional ability with increasing age, resulting in the need for changes in dosage.

Objective: To use population survey data to understand the extent and impact of multiple medication use and adverse drug events among Canadian seniors.

Methods: This study consists of analysis of data from the Canadian Survey of Experiences with Primary Health Care, which was conducted through telephone by Statistics Canada in 2008. These analyses focussed on the 3132 respondents who were ≥ 65 years of age.

Results: Twenty-seven per cent of seniors reported taking five or more medications on a regular basis. Within the past year, 12% of seniors taking five or more medications experienced a side effect that required medical attention compared with 5% of seniors taking only one or two medications. Even when controlling for age and number of chronic conditions, the number of prescription medications was associated with the rate of emergency department use. Less than half of all seniors reported having received medication reviews and having the possible side effects of their prescription medications explained to them by their physician.

Conclusions: Many Canadian seniors have an elevated risk of adverse events due to taking a high number of prescription medications and not having the potential side effects and drug interactions explained to them. There are interventions that can potentially reduce polypharmacy and adverse events, including routine medication reviews.