Delirium is associated with increased morbidity and mortality but is often undetected by physicians and nurses. This is especially the case in intensive care units (ICU), where equipment may impair the communication needed for psychiatric evaluation. An abbreviated version of the recently developed cognitive test for delirium (CTD) was studied to test for validity of screening delirium in an ICU setting (J of Psychosomatic Research 43:4 417-423, 1997). Subjects were of four clinical groups: 26 outpatients with dementia, 25 inpatients with schizophrenia, 30 inpatients with depression, and 19 ICU patients with delirium.

The abbreviated CTD takes only a few minutes to administer. It consists of five subtests: Orientation, Attention 1 and 2, Memory 1 and 2, Comprehension 1 and 2, and Vigilance 1 and 2. Responses to all test items are nonverbal (pointing, nodding head, raising hand).

All five subtest scores and all nine content scores differentiated (1) the four clinical groups, (2) delirium and dementia patients, and (3) delirium patients and the most impaired dementia patients. Analyses also suggested that attention span backward (Attention 2) might differentiate delirium and the most impaired dementia patients. The abbreviated CTD correctly classified 80 of 81 nondelirium patients for an estimated specificity of 98.8% and correctly classified 18 of 19 delirium patients for an estimated sensitivity of 94.7%. Only one delirium patient was misclassified using the abbreviated form. Measures of attention span forward and immediate memory for five objects contributed uniquely to differentiating delirium from all other groups, including patients with severe dementia.

Earlier intervention and reduced treatment complications may, in turn, reduce mortality, the level of required nursing care, duration of hospitalization, and likelihood of persistent symptoms following discharge. For this reason, the development and validation of the abbreviated CTD is exciting.