The impact of delirium in the intensive care unit on hospital length of stay

Study objective: To determine the relationship between delirium in the intensive care unit (ICU) and outcomes including length of stay in the hospital. Design: A prospective cohort study. Setting: The adult medical ICU of a tertiary care, university-based medical center. Participants: The study population consisted of 48 patients admitted to the ICU, 24 of whom received mechanical ventilation. Measurements: All patients were evaluated for the development and persistence of delirium on a daily basis by a geriatric or psychiatric specialist with expertise in delirium assessment using the Diagnostic Statistical Manual IV (DSM-IV) criteria of the American Psychiatric Association, the reference standard for delirium ratings. Primary outcomes measured were length of stay in the ICU and hospital. Results: The mean onset of delirium was 2.6 days (S.D.±1.7), and the mean duration was 3.4±1.9 days. Of the 48 patients, 39 (81.3%) developed delirium, and of these 29 (60.4%) developed the complication while still in the ICU. The duration of delirium was associated with length of stay in the ICU (r=0.65, P=0.0001) and in the hospital (r=0.68, P<0.0001). Using multivariate analysis, delirium was the strongest predictor of length of stay in the hospital (P=0.006) even after adjusting for severity of illness, age, gender, race, and days of benzodiazepine and narcotic drug administration. Conclusions: In this patient cohort, the majority of patients developed delirium in the ICU, and delirium was the strongest independent determinant of length of stay in the hospital. Further study and monitoring of delirium in the ICU and the risk factors for its development are warranted.