Adverse drug events in patients admitted to an emergency department: an analysis of direct costs.

Purpose: Several economic evaluations of adverse drug events (ADEs) exist, but the underlying methodology has not been standardized so far. The aim of the study was to combine prospective, intensive pharmacovigilance methods, and standardized accounting data to calculate direct costs of community-acquired ADEs (caADEs) contributing to emergency department (ED) admission and subsequent hospitalization.

Methods: A prospective observational study with three phases extending over 2 years was implemented in a 749 bed tertiary care hospital with an annual ED census of approximately 45 000 patients. The patient records of all adult non-trauma ED admissions were systematically analyzed by a team of emergency physicians, clinical pharmacologists, and pharmacists for potential ADE. Associated diagnosis related group costs were extracted from standardized accounting data.

Results: Of 2262 patients attending the ED during the study periods, the hospitalization of 366 patients (16.2%) was related to one or more caADEs of which 97.5% were considered predictable and 62.0% were classified as preventable. The mean caADE-related diagnosis related group costs were €2743 (95% bias-corrected and accelerated CI: €2498 to €3018). Extrapolated to a national scale, this corresponds to caADE-related costs of €2.245bn for the German health insurance funds, annually. Costs of €1.310bn could be attributed to events classified as predictable and preventable.

Conclusions: In an ED, caADEs are frequent, and a significant proportion of these events and their related costs appear to be predictable and preventable. The ED as a first-line provider for ADE cases appears to be an appropriate environment to implement strategic and operative improvements for enhanced patient safety.