Adverse drug events (ADEs) are an important cause of hospitalizations in older adults. Based on data from the OPERAM trial, this study explored the accuracy of triggers for identifying medication-related hospital admissions in older adults. Triggers were related to diagnoses (e.g., falls, bleeding, thromboembolic events), laboratory values (e.g., hypo- or hyperglycemia) and other factors (e.g., mention of an ADE in the patient record, abrupt medication discontinuation). Among 1,235 included hospitalizations, 58% cases had at least one trigger; medication-related admissions were adjudicated in 72% of these cases.