Adverse drug reactions in the Veterans Affairs healthcare system: Frequency, severity, and causative medications analyzed by patient age.

Purpose: Adverse drug events (ADEs) in the U.S. Department of Veterans Affairs (VA) were evaluated, and differences in age group report rates and reported medications in different age groups were assessed.

Methods: We utilized the VA Adverse Drug Event Reporting System (ADERS) to assess 10-year age groups regarding ADE reporting rates, event severity, and associated reported medications. Data were derived from 484,351 ADE reports from 395,703 patients included in VA ADERS from 2009 through 2016.

Results: Reported rates of ADEs per 10,000 unique users demonstrated a nonlinear relationship with age, peaking in the group aged 60-69 years (148.6 reports/10,000 unique users) and declining thereafter. However, the percentage of adverse events reported as severe consistently rose with age group (3% in patients age 20-29 years versus 6% in patients older than 90 years). The types of medications reported as causative agents shifted over time from predominantly mental health and pain medications in younger veterans (e.g., age 20-29 years) to medications for chronic diseases in older cohorts (e.g., age 60-69 years).

Conclusion: An analysis of VA ADE reports revealed a nonlinear relationship between age and events, with events peaking at age 60-69 years. Rates of severe ADEs increased in older age groups. Drugs commonly associated with ADEs tended to be those primarily used for mental health and pain treatment in younger patients and those used to address chronic disease states in older patients.