The ICDSC is an eight-item checklist of delirium symptoms evaluated over an 8- to 24-hour period. Patients are given one point for each symptom that manifests during the specified time frame (zero points if symptom did not manifest). The eight symptoms are: level of consciousness, inattention, disorientation, hallucinations/delusions/psychosis, psychomotor agitation or retardation, inappropriate speech or mood, sleep/wake cycle disturbances, and symptom fluctuation. A score greater than or equal to 4 indicates a positive ICDSC and the presence of delirium. Key symptoms of delirium can be part of a focused evaluation from the bedside clinician. For example, as the nurse introduces himself/herself to the patient and performs the clinical assessment, he/she also assesses for signs that may indicate the patient is inattentive, has disorganized thinking, psychomotor agitation/retardation, etc. Presence of any symptoms noted during an initial focused evaluation can immediately be scored on the ICDSC. The patient can subsequently be observed and scored for additional symptoms that manifest or fluctuate during the remainder of the specified time period. Without objective criteria, there could be variation in how symptoms are identified in intubated patients. Suggestions on how to assess delirium symptoms in this special population using the ICDSC are shown in Table 2.
Suggestions for Assessing Delirium With the Intensive Care Delirium Screening Checklist
Efficacy of Delirium Screening Tools in Adults
Two recent systematic reviews and meta-analyses reviewed the psychometric properties of both the CAM-ICU and ICDSC and the reader is referred to these for a broader discussion of these properties of these tools.[44,45] Briefly, the CAM-ICU's pooled sensitivity was 76% and 80%, respectively, and pooled specificity was 96% in both studies. The pooled sensitivity for the ICDSC was 74% and 80% and the pooled specificity was 75% and 82%. Furthermore, the CAM-ICU's reliability and validity have been evaluated against DSM reference raters in 12 studies totaling 1,179 ventilated and nonventilated adult patients[1,9,23,33,38,42,46–51] (Table 3). Three studies were performed in medical ICUs, two in surgical ICUs, six in mixed (medical and surgical) ICUs, and one in a neurologic ICU. Five studies (Table 3) have evaluated the ICDSC against DSM reference raters (7, 33, 46, 52, 53). All studies enrolled in mixed ICUs and included 465 patients, both ventilated and nonventilated.
Clinical Differences between the CAM-ICU and ICDSC
The CAM-ICU and the ICDSC demonstrate two major clinical differences: the duration over which symptoms are assessed and methods for identifying delirium symptoms.
Most CAM-ICU assessments can be completed in less than 1 minute. The ICDSC gathers information over 8–24 hours (depending on how the teams decide to implement and collect data). Since delirium is characterized by a fluctuating course, the "spot" nature of the CAM-ICU may miss an episode of delirium if specific delirium symptoms are not found at the time of the assessment, and this is more likely to be an issue in populations with a low severity of illness. This limitation can be addressed by increasing assessment frequency (e.g., every 4–12 hr) and with changes in the patient's mental status. Conversely, the longer assessment period of the ICDSC may lead to increased false-positive screens for delirium if a patient exhibited signs of delirium in the last 24 hours, but currently exhibits no signs.
The second clinical difference is how each tool identifies delirium symptoms. The CAM-ICU uses specifically defined and validated measures requiring interaction with the patient to determine the presence or absence of each delirium feature, providing a reproducible measure. A potential disadvantage is that the diagnostic performance may be dependent on patient characteristics such as age, premorbid cognition, and severity of illness. Nevertheless, Ely et al found the CAM-ICU's diagnostic performance was consistent across these subgroups. The ICDSC relies on observational methods to detect inattention, disorientation, hallucinations, presence of sleep, and inappropriate speech or mood. Detection of these symptoms may be particularly difficult in nonverbal mechanically ventilated patients, yet the ICDSC allows subjective interpretation with those more difficult circumstances. For this reason, the ICDSC relies more on clinical experience. Although researchers have sought to operationalize specific definitions of the symptom descriptions in the ICDSC, they surmised that these definitions warrant further validation.[54–56]
Crit Care Med. 2013;41(9):2196-2208. © 2013 Lippincott Williams & Wilkins