Investigators have designed a variety of instruments to make
a formal diagnosis of delirium. These instruments consist of operationalized
delirium criteria from a variety of diagnostic systems, often in
the form of a checklist incorporating information from patient observation
and the medical record (e.g., DSM-III-R, DSM-IV, ICD-9, and ICD-10).
The rate of delirium diagnosis obtained by using these diagnostic
instruments varies according to both the diagnostic system that
was used and the particular way in which the authors chose to operationalize
the criteria. One structured diagnostic interview schedule, the
Delirium Symptom Interview (DSI), can be administered by lay interviewers and
used in epidemiological studies (36). Other delirium diagnostic
instruments include the Confusion Assessment Method (CAM) (37),
Delirium Scale (Dscale) (38), Global Accessibility Rating Scale
(GARS) (39), Organic Brain Syndrome Scale (OBS) (40), and Saskatoon
Delirium Checklist (SDC) (41).