Patient-reported adverse drug-related events from emergency department discharge prescriptions.

Objective: The tolerability of drugs prescribed on emergency department (ED) discharge is unknown. Our objectives were to quantify and describe adverse drug-related events (ADREs) as reported by patients triaged as Canadian Emergency Department Triage and Acuity Scale scores 3, 4 or 5, discharged from the ED with prescriptions.

Methods: This prospective observational study was a planned substudy of a larger study on adherence to discharge prescriptions. This study was conducted in a tertiary care centre with an annual ED census of 69 000 visits. The primary outcome was the frequency of ADREs reported during a structured telephone questionnaire 2 weeks after ED discharge. An ADRE was deemed to have occurred if the patient reported a symptom consistent with a known ADRE that began and resolved within a plausible time frame after starting and stopping the drug, and if no alternative diagnosis was probable.

Results: Research assistants contacted 258/301 (85.7%) patients discharged from the ED with a prescription. An ADRE was reported by 54/258 patients (20.9%, 95% confidence interval [CI] 16.4%-26.3%). The most commonly reported ADREs were nausea, constipation and drowsiness. None required hospital admission or caused death. Participants reporting ADREs were not more likely to make an unplanned ED or clinic revisit (crude odds ratio [OR] 1.1, 95% CI 0.6-2.2; adjusted OR 1.2, 95% CI 0.6-2.4).

Conclusion: Approximately one-fifth of low-acuity patients prescribed medication on discharge from the ED report ADREs, but most of these are neither severe nor associated with an increase in use of health services. Attention to common preventable ADREs, such as opioid-associated constipation, could reduce the rate of ADREs in this population.