The direct costs of adverse drug events in emergency department admissions

Background: Adverse drug events (ADE) are a health thread for patients and result in rising healthcare costs. Adverse events causing follow-up treatments claim the health insurance funds for prolonged diagnostics and treatment. Several German and international studies confirmed the economic impact, but an internationally accepted and standardized methodical approach to assess the effects has not been established so far. The aim of our study was to derive a portable measurement technique and to analyze the direct costs of community acquired adverse drug events (ADE) in patients with an emergency department (ED) admission and a subsequent hospital stay.

Materials and Methods: We conducted a prospective observational study in a 749 bed tertiary care hospital with an annual ED census of more than 40,000 patients. The patient records of all emergencies were systematically analyzed by a team of emergency physicians, clinical pharmacologists and pharmacists for potential ADE. For hospitalized patients with an ADE we calculated the direct costs according to paragraph 21 of the Hospital Remuneration Act (KHEntgG) taking data from the hospital information system (HIS).

Results: Among 752 patients we identified 106 patients (mean age: 70.8 years) with an inpatient stay (mean length of stay: 7.5 days) having a total of 153 ADE. This subgroup caused mean costs of 2,968.49 €. Extrapolating these costs for Germany we estimate an amount of € 1.46 bn to be spent for hospitalized patients with ADE annually. Among the patients with ADE cases with cardiovascular disorders and gastrointestinal diseases were dominating. Compared with typical prescription quantities antipsychotic drugs cause frequently ADE and dopaminerge substances lead to extensive hospitalization. The most common drugs associated with ADE were antipsychotics (11.9%), platelet inhibiting factors (10.8%) and ACE blockers (8.7%). Most events were predictable (96.7%), almost 65.4% of the observed ADE were judged to be preventable.

Conclusion: Since there is no gold standard for the evaluation of ADE-costs, we recommend the intensive pharmacovigilance method described here in combination with standardized cost data of hospital reimbursement as an appropriate approach for inpatients. ADE were common, often preventable and associated with significant costs. Thus, many stakeholders could benefit from effective and cost efficient prevention strategies for ADE.