3D-CAM (3 minutes)

The 3D-CAM uses the CAM algorithm

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.

1Marcantonio ER, et al. Ann Intern Med. 2014;161(8):554–561.
2Kuczmarska A, et al. J Gen Intern Med. 2016;31(3):297–303.
3D-CAM, 3-Minute Diagnostic Interview for Confusion Assessment Method
APN, advance practice nurse
ED, emergency department
LR, likelihood ratio
RA, research assistant

Using the 3D-CAM

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.

Advantages and disadvantages of 3D-CAM


  • Inattention and disorganized thinking determined objectively
  • Combines objective testing and clinical observations
    • ↑ diagnostic accuracy
  • Less operator dependent than the CAM


  • More complex than bCAM and CAM-ICU
  • Subjective components
    • more operator dependent
    • ↑ training requirements
  • No validation studies in ED patients


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.