Medication-related emergency department visits and hospitalizations among older adults.

OBJECTIVE To identify medications that have a high risk of adverse drug effects (ADEs) among seniors, using data from publicly available administrative databases. DESIGN Cross-sectional study using the Discharge Abstracts Database (DAD) (which contains data on acute care institutions in all provinces and territories except Quebec), the National Ambulatory Care Reporting System (NACRS) (which contains data on emergency department [ED] visits in Ontario), and the IMS Brogan database Canadian CompuScript. SETTING Canada. PARTICIPANTS Adults 65 years of age and older with diagnostic codes for drugs, medicaments, and biologic substances causing adverse effects in therapeutic use. MAIN OUTCOME MEASURES Adverse drug events from 2006 to 2008 associated with hospitalizations and ED visits among adults 65 years of age and older were identified by the DAD and the NACRS. The medications most frequently prescribed by primary care providers in 2008 were identified using data from Canadian CompuScript. RESULTS From 2006 to 2008, the DAD identified 92 141 ADEs among older adults, and the NACRS identified 23 845 ADEs among older adults in Ontario EDs, which represented 2.9% of inpatients and 0.8% of ED patients (21.5% of whom were admitted to hospital). Drugs implicated in the DAD ADEs included anticoagulants (15.4%), antineoplastic agents (10.6%), opioids (9.2%), and nonsteroidal anti-inflammatory drugs (6.5%); drugs included in the ADEs of ED visits were anti-infective agents (15.9%), anticoagulants (14.2%), antineoplastic agents (9.6%), and opioids (7.3%). CONCLUSION Among older adults, the drug classes most often associated with causing harm in the hospital setting and occurring out of proportion to the frequency prescribed were anticoagulants, opioids, antibiotics, and cardiovascular drugs. Thus, these drug classes should be the focus of quality improvement efforts in primary care.