Background and aims: The objective was to study occurrence and risk factors of delirium in a new model of care, the Sub-Intensive Care Unit for the elderly (SICU), which is a level of care between that offered by ordinary wards and intensive care.
Methods: A prospective observational study of 401 consecutively admitted patients, 60+ years, in a four-bed SICU in the geriatric ward of a general hospital. Delirium was detected by the Confusion Assessment Method (CAM) at admission (prevalent) and during SICU stay (incident). Impaired function (Barthel Index) and/or IADL two weeks prior to admission identified disability, and additional Mini-Mental State Examination (MMSE) <18 at discharge identified probable dementia.
Results: Delirium was detected in 117 patients (29.2%). Of these 62 (15.5%) had delirium at admission and a further 55 developed delirium during their time in the SICU. Delirium occurred in 19 (11.4%) of the "robust" (no dementia or disability), 28 (24.1%) of the disabled and 70 (58.4%) of the demented patients (p<0.001). Prevalent delirium was found in 8 (4.8%), 11 (9.5%) and 43 (36.1%) (p<0.001) and incident in 11 (6.6%), 17 (14.7%) and 27 (22.7%) (p<0.001) of the robust, disabled, and demented patients respectively. Heavy alcohol use, maximum intake of 7 or more drugs, and the use of a bladder catheter were independently associated with delirium.
Conclusions: Delirium was common in the SICU, and patients with probable dementia had the highest risk. They tended to have delirium at admission, whereas patients without dementia, although less at risk, were more prone to developing delirium during their stay in the SICU.