Severity of delirium in the ICU is associated with short term cognitive impairment. A prospective cohort study.

Objectives: To examine the hypothesis that severity of delirium in the intensive care unit (ICU) is positively associated with cognitive impairment at the time of hospital discharge.

Design: A prospective cohort study.

Setting: Adult medical and surgical ICU of a tertiary-care teaching hospital in Japan in ICU patients who were enrolled and admitted for more than 48hours.

Methods: Severity of delirium was represented as a score of the Intensive Care Delirium Screening Checklist (ICDSC) during the patients' stay in the ICU under the assumption that higher ICDSC score indicated severe delirium. After discharge from the ICU, the patients were followed up for cognitive impairment using the Mini-Mental State Examination (MMSE).

Results: Of the 79 patients enrolled, 50 (63.3%) developed delirium during their stay in the ICU. Patients who developed delirium had higher rates of cognitive impairment (28.0% vs. 3.4%, p=0.03). After adjusting for covariates, the averaged ICDSC score during the ICU stay indicated a positive association between severity of delirium and cognitive impairment at the time of hospital discharge (adjusted odds ratio (OR) 1.6; 95% confidential interval (CI), 1.02-2.54; p=0.041).

Conclusions: Our findings indicate that severity of delirium during ICU stay may be associated with cognitive impairment at the time of discharge from the hospital in ICU survivors.