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Margaret A. Pisani, MD, MPH; Terrence E. Murphy, PhD; Peter H. Van Ness, PhD, MPH; Katy L. B. Araujo, MPH; Sharon K. Inouye, MD, MPH

Arch Intern Med. 2007;167(15):1629-1634.

Background  Delirium is a highly prevalent disorder among older patients in the intensive care unit.

Methods  We performed a prospective cohort study of 304 patients 60 years or older admitted from September 5, 2002, through September 30, 2004, to a 14-bed ICU in an urban university teaching hospital. The main outcome measure was ICU delirium that developed within 48 hours of ICU admission. Patients were assessed for delirium with the Confusion Assessment Method for the ICU and medical record review. Risk factors for delirium were assessed on ICU admission by interview with proxies and medical record review. A model was developed using multivariate logistic regression and internally validated with bootstrapping methods.

Results  Delirium occurred in 214 study participants (70.4%) within the first 48 hours of ICU admission. In a multivariate regression model, 4 admission risk factors for delirium were identified. These risk factors included dementia (odds ratio [OR], 6.3; 95% confidence interval [CI], 2.9-13.8), receipt of benzodiazepines before ICU admission (OR, 3.4; 95% CI, 1.6-7.0), elevated creatinine level (OR, 2.1; 95% CI, 1.1-4.0), and low arterial pH (OR, 2.1; 95% CI, 1.1-3.9). The C statistic was 0.78.

Conclusions  Delirium is frequent among older ICU patients. Admission characteristics can be important markers for delirium in these patients. Knowledge of these admission risk factors can prompt early correction of metabolic abnormalities and may subsequently reduce delirium duration.

Author Affiliations: Pulmonary & Critical Care Section (Dr Pisani) and Geriatrics Section (Drs Murphy and Van Ness and Ms Araujo), Department of Internal Medicine, and the Program on Aging, Yale University School of Medicine, New Haven, Connecticut; and Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, and Aging Brain Center, Hebrew SeniorLife Institute (Dr Inouye), Boston, Massachusetts.