Because hypoactive delirium is especially under-recognized, we analyzed which Mini-Mental State Examination (MMSE) items predicted incident delirium and its hypoactive motor presentation. Over a 1-year period, older medical inpatients (n=291) were consecutively screened on admission with the Confusion Assessment Method-Spanish (CAM-S) to exclude prevalent delirium. Nondelirious patients were evaluated the same day with the MMSE, followed by daily ratings with the CAM-S. Those who became CAM-S positive were rated using the Delirium Rating Scale-Revised-98 to assess severity and motor subtype. Disorientation to time (OR 4.4, 95% CI 1.7-11.1) and place (OR 3.8, 95% CI 1.7-8.2) at admission were risk factors for delirium at follow-up and together correctly classified 88.3% of subjects as to delirium status. Disorientation to time and place, and visuoconstructional impairment were each associated with either hypoactive or mixed subtype (p<0.05 χ2 test). Simple bedside evaluation of cognitive function in nondelirious patients revealed deficits that detected patients at risk for developing incident delirium at follow-up (especially hypoactive or mixed). We recommend patients with orientation deficits be monitored closely for emergence of delirium. A separate evaluation for possible dementia or other causes of cognitive impairment at admission should be considered too.
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