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%, speci
ficity of 96%, a negative predictive value of 93%, a positive predictive va
lue 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 c
ut points were added, the T&C test had a sensitivity of 94 to 100%, specifi
city of 37 to 46%, negative predictive value of 98 to 100%, positive predic
tive 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 o
utpatient populations.