DELIRIUM SEVERITY AND COGNITIVE OUTCOMES

Delirium is heterogeneous and can vary by severity. The impact of its severity is unclear. This prospective cohort study enrolled emergency department (ED) patients who were > 65 years old and admitted to the hospital. Delirium severity was determined by the Confusion Assessment Method for the Intensive Care Unit Severity (CAM-ICU-S) Scale measured at enrollment. This scale ranges from 0 (no symptoms) to 7 (most severe). Premorbid and 6-month cognition were determined using the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) which ranges from 1 to 5 (severe cognitive impairment). Multiple linear regression was performed to determine if delirium severity was associated with 6-month function and cognition adjusted for pre-illness IQCODE, baseline functional status, comorbidity burden, severity of illness, and central nervous system diagnosis. Two-factor interactions were incorporated to determine if pre-illness cognition modified the relationship between delirium severity as measured by the CAM-ICU-S and 6-month cognition. A total of 228 older patients were enrolled in the ED and of these, 105 were delirious. Median (interquartile range) CAM-ICU-S scores was 2 (0, 5). In patients with intact pre-illness cognition, a point increase in the CAM-ICU-S significantly increased the 6-month IQCODE by 0.06 (95%CI: 0.01 to 0.12) points. In patients with impaired pre-illness cognition, there was no significant association between the CAM-ICU-S and 6-month IQCODE. Thus delirium severity is associated with poorer 6-month cognition, but this association is more prominent in those with intact pre-illness cognition.