An Evaluation of Adverse Drug Reactions Associated with Antipsychotic Use for the Treatment of Delirium in the Intensive Care Unit

Purpose: This investigation evaluated the incidence, severity, and harm of adverse drug reactions (ADRs) associated with antipsychotic use for intensive care unit (ICU) delirium. Methods: In this prospective, observational study patients were screened for development of delirium with the Intensive Care Delirium Screening Checklist (ICDSC). An ICDSC score of ≥4 was considered delirious. Patients with delirium were screened daily for ADRs. Suspected ADRs were evaluated for drug causality using 3 published, objective assessment tools. Suspected ADRs were considered positive when 2 of 3 instruments had an agreement rating of "possible" or greater. ADR severity was defined as "mild/moderate" or "severe" using the National Cancer Institute's Common Terminology Criteria for Adverse Events scale. A modified National Coordinating Council Medication Error Reporting Index for Categorizing Errors categorized ADRs into "no harm" or "harmful." Results: Of 90 patients with delirium, 56 received antipsychotics. Ten suspected ADRs occurred attributed to antipsychotic use. QTc prolongation was the most observed ADR (50%). Patients with ADRs had higher mean Acute Physiology and Chronic Health Evaluation II (APACHE II) scores (P =.038). Patients who received haloperidol experienced more severe (P =.048) ADRs. Conclusions: ADRs were observed in 18% of patients having delirium treated with antipsychotics with about half considered severe or harmful. A risk versus benefit assessment is needed before initiating antipsychotic therapy in ICU patients.