The Confusion Assessment Method: a systematic review of current usage.

OBJECTIVES: To examine the psychometric properties, adaptations, translations, and applications of the Confusion Assessment Method (CAM), a widely used instrument and diagnostic algorithm for identification of delirium.

DESIGN: Systematic literature review.

SETTING: Not applicable.

MEASUREMENTS: Electronic searches of PubMED, EMBASE, PsychINFO, CINAHL, Ageline, and Google Scholar, augmented by reviews of reference listings, were conducted to identify original English-language articles using the CAM from January 1, 1991, to December 31, 2006. Two reviewers independently abstracted key information from each article.

PARTICIPANTS: Not applicable.

RESULTS: Of 239 original articles, 10 (4%) were categorized as validation studies, 16 (7%) as adaptations, 12 (5%) as translations, and 222 (93%) as applications. Validation studies evaluated performance of the CAM against a reference standard. Results were combined across seven high-quality studies (N=1,071), demonstrating an overall sensitivity of 94% (95% confidence interval (CI)=91-97%) and specificity of 89% (95% CI=85-94%). The CAM has been adapted for use in the intensive care unit, emergency, and institutional settings and for scoring severity and subsyndromal delirium. The CAM has been translated into 10 languages where published articles are available. In application studies, CAM-rated delirium is most commonly used as a risk factor or outcome but also as an intervention or reference standard.

CONCLUSION: The CAM has helped to improve identification of delirium in clinical and research settings. To optimize performance, the CAM should be scored based on observations made during formal cognitive testing, and training is recommended. Future action is needed to optimize use of the CAM and to improve the recognition and management of delirium.