Adverse drug reactions as the cause of visits to the Observational Emergency Department: a prospective analysis

Study objectives: To determine the prevalence, preventability, characteristics of the population, and medications involved, in adverse drug reaction visits (ADRVs). Methods: This was a prospective, transversal and descriptive study conducted at an 845 bed adult tertiary care hospital during an eight week period. Among all the patients who attended the Observational Emergency Department, we selected those whose reason for attendance corresponded to an alert diagnosis list. The clinical and medical histories of these patients were investigated and, if there was a temporal relationship with the start of drug therapy, other causes were unclear, and adverse drug reaction (ADR) could not be ruled out, each patient was interviewed to assess whether the Observational Emergency Department visit was caused by an ADR. Results: Of the 290 patients included, 40 (13.4%, 95% CI: 9.52%-17.37%) visits were identified as having an ADR cause. Forty-two different ADRs were identified in 39 patients. Thirty (71.43%, 95% CI: 57.77%-85.09%) cases were deemed to be preventable and 12 (28.57%) non-preventable. Approximately 35.6% of female and 33.9% of male Observational Emergency Department admissions involved an ADR. The average age of the population was 75 years (SD: 12.3 years). The average number of medications taken by patients involved in an ADRV was 8.8. The most common drug classes implicated were cardiovascular agents (29.6%), nervous system therapy (18.5%), digestive and metabolism therapy (17.2%). Conclusion: The Observational Emergency Department concentrates a high number of ADRVs (more than one in eight visits), a potentially preventable problem in our healthcare system. Therefore, this is a highly appropriate place to introduce pharmacovigilance programmes and pharmacist specialist teaching.