Diagnostic Features of Delirium

Core Diagnostic Features

• The American College of Critical Care Medicine recommends that a disturbed level of consciousness with reduced ability to focus, sustain, or shift attention is a key diagnostic feature of delirium 1
• The Society of Critical Care Medicine states that either a change in cognition or the development of perceptual disturbances is required for a diagnosis of delirium 1
• The British Journal of Anaesthesia reports that the fluctuating nature of symptoms over time distinguishes delirium from other cognitive disorders 1, 3

Clinical Context

• The British Journal of Anaesthesia notes that advanced age is a risk factor for postoperative delirium, occurring in 15-53% of older surgical patients 3
• The American College of Surgeons states that major orthopedic surgery, such as femoral fracture repair, is a risk factor for postoperative delirium 2
• The Society of Critical Care Medicine recommends that systematic screening using validated tools like the Confusion Assessment Method (CAM) should be performed at least once per nursing shift to formally document fluctuations in consciousness 2

Diagnostic Approach

• The American College of Critical Care Medicine suggests that recognizing delirium as characterized by acute onset and fluctuating course, with the level of consciousness being the most reliable distinguishing feature, is key to diagnosis 1, 2
• The Society of Critical Care Medicine notes that neither hallucinations nor delusions are required to make a diagnosis of delirium, and that disturbed and fluctuating level of consciousness with inattention is sufficient when combined with either cognitive changes or perceptual disturbances 1