Delirium is a common and potentially preventable source of morbidity and mortality for older hospitalized patients, affecting 25-60% of older hospitalized patients and resulting in mortality rates of 25-33%. In 1994, delirium accounted for over 2.3 million hospitalizations and 17.5 million inpatient days, with Medicare expenditures totaling 8 billion dollars. The Confusion Assessment Method (CAM) was developed in 1988-1990 to improve the identification and recognition of delirium.

The CAM was designed to provide a standardized method to enable non-psychiatrically trained clinicians to identify delirium quickly and accurately in both clinical and research settings. Since its development, it has become the most widely used instrument for detecting delirium worldwide due to its strong validation results and ease of use. The CAM has been used in over 4000 original articles as either a process or outcome measure and has been translated into over 14 languages.

When validated against the reference standard ratings of geriatric psychiatrists based on comprehensive psychiatric assessment, the CAM had a sensitivity of 94-100% and a specificity of 90-95%, with high inter-observer reliability. In recent studies, the CAM had a sensitivity of 94% and a specificity of 89%.

The CAM is typically rated by a clinical or trained lay interviewer based on an interview with the patient that includes at least a brief cognitive assessment. The Mini-Mental State Examination was used in the original validation, but its use is now restricted by copyright law. A more brief assessment, such as the Short Portable Mental Status Questionnaire or Modified Mini-Cog Test, is recommended for quick screening. The entire CAM rating typically takes 5-10 minutes to complete.

To assist with the administration and coding of the CAM and provide supplementary information for interested clinical investigators, a CAM training manual has been designed. The recommended training procedure involves one-on-one sessions where pairs of interviewers practice the interviews with each other. Pilot interviews on floors with delirious and non-delirious patients are also recommended, as well as inter-rater reliability assessments where pairs of interviewers observe the same patient. Special coding sessions are recommended once a month for all interviewers with the principal investigator and project director to answer questions about scoring the CAM, and inter-rater reliability assessments should be conducted every six months for the duration of the study.

In conclusion, delirium is a significant concern for older hospitalized patients, and the CAM is a widely used instrument for detecting delirium in both clinical and research settings due to its strong validation results and ease of use. A CAM training manual has been designed to assist with its administration and coding.