The 3-Minute Diagnostic Interview for CAM-defined delirium (3D-CAM) also uses the CAM algorithm, and a patient must be positive for both Features 1 and 2, and either Feature 3 or 4 to be 3D-CAM–positive. The 3D-CAM incorporates both objective testing and subjective observations to determine the presence of each feature.
Like the CAM, altered mental status or fluctuating course (Feature 1) is determined by proxy interview or observation. Unlike the CAM, bCAM, and CAM-ICU, it also incorporates patient self-report data. A patient is also considered to be Feature 1–positive if they self-report confusion, disorientation, and hallucinations.
The 3D-CAM tests for inattention (Feature 2) by asking the patient to repeat 3 digits in backward order (digit span backward), repeat 4 digits in forward order (digit span forward), recite the days of the week backwards, and recite the months backwards from December to January.
Disorganized thinking (Feature 3) is assessed by asking the patient to state the year, day of the week, or type of place. A patient can also be considered to be Feature 2– or Feature 3–positive if there is clinical evidence of inattention and disorganized thinking, respectively, based upon the rater’s interaction with the patient.
Thus far, no studies have validated the 3D-CAM in older ED patients. In hospitalized patients, the 3D-CAM has been shown to have excellent sensitivity and specificity for delirium. A positive 3D-CAM strongly increases the likelihood of delirium, and a negative 3D-CAM strongly decreases the likelihood of delirium. However, additional validation studies conducted in older ED patients are needed.
Additional details of the 3D-CAM, including the instruction manual and videos, can be seen at www.hospitalelderlifeprogram.org.
Marcantonio ER, et al. Ann Intern Med. 2014;161(8):554–561
Kuczmarska A, et al. J Gen Intern Med. 2016;31(3):297–303
3D-CAM, 3-Minute Diagnostic Interview for CAM
bCAM, brief CAM
CAM, Confusion Assessment Method
CAM-ICU, CAM for the Intensive Care Unit
ED, emergency department.