This investigation evaluated the incidence, severity, and harm of adverse drug reactions (ADRs) associated with antipsychotic use for intensive care unit (ICU) delirium.

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."

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.

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.