Screening for dementia in the outpatient setting: the time and change test.

OBJECTIVE

To develop and validate the Time and Change (T&C) test, a simple, standardized method for detecting dementia in a diverse older outpatient population with varying levels of education.

DESIGN

A prospective cohort validation study.

SETTING

Two outpatient clinics at an urban teaching hospital.

PARTICIPANTS

The concurrent validation sample consisted of 100 consecutive outpatients 70 years of age or older who were 58% non-white and had a 16% dementia prevalence rate and educational levels ranging from 0 to 17+ years. Reliability was tested in a sample of 42 consecutive outpatients 75 years of age or older with a 36% dementia prevalence rate.

MEASUREMENTS

T&C ratings were validated against a reference standard based on the Blessed Dementia Rating Scale and the Mini-Mental State Examination. Reliability, contribution to physician recognition of dementia, and ease of use were assessed.

RESULTS

In the outpatient setting, the T&C had a sensitivity of 63%, specificity of 96%, a negative predictive value of 93%, a positive predictive value of 77%, and test-retest and inter-observer reliability agreement rates of 95% and 100%, respectively. When T&C results were added to the physician's documentation of dementia, the number of missed cases decreased from 44% to 19%, and the number of overcalled cases decreased by 100%. When timed cut points were added, the T&C test had a sensitivity of 94 to 100%, specificity of 37 to 46%, negative predictive value of 98 to 100%, positive predictive value of 23 to 25%, and test-retest and inter-observer agreement rates of 82% and 70 to 75%, respectively.

CONCLUSION

The T&C test is a simple, accurate, reliable, performance-based tool that can improve physician ability to recognize dementia in diverse outpatient populations.