Table 3.

Diagnostic algorithm for DSM-5 delirium

DSM-5 criteria	Tests to be performed or information needed		Criterion fulfilled?
			Yes	No
A. Disturbance in attention (ie, reduced ability to direct, focus, sustain and shift attention) and awareness (reduced orientation to the environment)	Test	Cut-off (definition of inattention)
	Digit span forward	<5 forward
	SAVEAHAART	>2 errors
	Days of the week backwards	Any error
	Months of the year backwards	Unable to pass June
	Count backwards from 20 to 1	Any error
	Digit span backwards	<5 digits
	Observation (by the examiner during the interview): Distractibility. Comprehension. Tendency to lose the tread of conversation Level of arousal measured using RASS and OSLA
B. The disturbance develops over a short period of time (usually hours to a few days), represents a change from baseline attention and awareness, and tends to fluctuate in severity during the course of a day	Acute onset and/or fluctuation obtained from informant history from nursing staff and clinical notes. Questions to carer/nursing staff or derived from clinical notes: Has there been a sudden change in the patient’s mental state? Does the patient seem to be better at any period in the day compared with other times? Has the level of consciousness been altered (drowsy/not interacting or agitated)? Sleep-wake cycle disturbances?
C. An additional disturbance in cognition (eg, memory deficit, disorientation, language, visuospatial ability or perception)	Questions to the patient: Orientation to time, place and person 3-item recall at 3 min Questions from CAM-ICU: Why are you in hospital? Will a stone float in water? Are there fish in the sea? Questions to carer/nursing staff or derived from clinical notes: Any evidence of perceptual disturbances as illusions or hallucinations? Memory disturbances? Psychotic symptoms? Psychomotor abnormalities?
D. The disturbances in criteria A and C are not explained by another pre-existing, established or evolving neurocognitive disorder and do not occur in the context of a severely reduced level of arousal, such as coma	Information from history/chart/clinical assessment
E. There is evidence from the history, physical examination or laboratory findings that the disturbance is a direct physiological consequence of another medical condition, substance intoxication or withdrawal (ie, because of a drug of abuse or to a medication), or exposure to a toxin or is because of multiple aetiologies	By virtue of the surgery, all participants are considered to fulfil this criterion
Delirium based on the tests and information above?	All DSM-5 criteria fulfilled
Subsyndromal delirium based on the tests and information above?	Defined as evidence of change, in addition to any one of these: (a) altered arousal, (b) attentional deficits, (c) other cognitive change, (d) delusions or hallucinations. Criteria D and E must be met

CAM-ICU, confusion assessment method for intensive care units; DSM-5, Diagnostic and Statistical Manual of Mental Disorders, 5th edition; OSLA, Observational Scale of Level of Arousal; RASS, Richmond Agitation Sedation Scale.