More than 5,000,000 patients are admitted to the Intensive Care Unit (ICU) in the United States each year, 80% of whom may develop delirium.1,2,3 Despite controlling for preexisting morbidities, severity of illness, coma, and use of sedatives, patients who develop delirium in the ICU are more than three times as likely to die at 6 months, have a threefold higher re-intubation rate, and require an additional 10 days in the hospital, compared to those patients who do not develop delirium.1,2,4,5 Up to 25% of patients who develop delirium may also develop long-term cognitive impairment that frequently manifests as dementia.6-9 There are currently no drugs with FDA-approval for the treatment of delirium. The Society of Critical Care Medicine and The American Psychiatric Association clinical practice guidelines recommend haloperidol for the treatment of delirium, though this is based on sparse outcome data from nonrandomized case series and anecdotal reports. The most important step in delirium management continues to be early recognition using validated tools such as Confusion Assessment Method for the ICU (CAM-ICU) and the Intensive Care Delirium Screening Checklist (ICDSC).
While the CAM-ICU attempts to capture disturbances in attention and cognition, it fails to capture the fluctuating nature of these disturbances since it's done at one point in time. This could hamper early detection of delirium. Both delirium assessment tools however have high sensitivity and specificity for delirium when administered by research nurses.
In a prospective multicenter study published early this year, the authors report on the performance of CAM-ICU in 10 hospitals in the Netherlands. The main purpose of this study was to measure the diagnostic value of the CAM-ICU when used in daily practice compared with the research setting. Study population included mixed medical and surgical ICU patients. Patients who could not speak Dutch or English and those who could not be examined for logistical reasons were excluded from the study. Daily bedside nurse assessments of patient were compared with the "gold standard" defined as teams of three delirium experts (psychiatrics, neurologists, and geriatricians). Delirium experts and ICU nurses were blinded to each others' conclusions. Fifteen delirium experts assessed 282 patients, of whom 101(36%) were comatose and excluded. In the remaining 181 (64%) patients, the CAM-ICU had a sensitivity and specificity of only 47% (negative predictive value, 72%) and 98% (positive predictive value, 95%), respectively.10 While centers that always used the CAM-ICU performed better than those that did not, none were close to the sensitivities reported in the research setting.
Is it the CAM-ICU as a screening instrument or is it the improper use of the instrument in this study that lead to its poor performance? This is a question that is yet to be answered!
1. Ouimet S, Kavanagh BP, Gottfried SB, et al. Incidence, risk factors and consequences of ICU delirium. Intensive Care Med
2. Pun BT, Ely EW. The importance of diagnosing and managing ICU delirium. Chest 2007;132(2):624-636. ...