Risk Factors for Acute Delirium in Critically Ill Adult Patients: A Systematic Review

Abstract

Background. Delirium is characterized by disturbances of consciousness, attention, cognition, and perception. Delirium is a serious but reversible condition associated with poor clinical outcomes. This has implications for the critically ill patient; the effects of delirium cause long term sequelae, principally cognitive deficits, and functional decline. Objectives. The objective of the paper was to describe risk factors associated with delirium in critically ill adult patients. Methods. Published and unpublished literature from 1990 to 2012, limited to English, was searched using ten databases. Results. Twenty-two studies were included in this paper. A large number of risk factors were presented in the literature; some of these were common across all settings whilst others were exclusive to the type of setting. Benzodiazepines and opioids were shown to be risk factors for delirium independent of setting. Conclusion. With regard to patients admitted to medical and surgical intensive care units, risk factors of older age and comorbidity were common. In the cardiac ICU, older age and lower Mini-Mental Status Examination scores were cited most often as risk factors for delirium, but other risk factors exclusive to the setting were also significant. Benzodiazepines were identified as the most significant pharmacological risk factor for delirium.