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Brief, Practical Screening for Dementia in Outpatients
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Am Fam Physician. 1999 Apr 1;59(7):1952-1956.
Routine screening for dementia in elderly patients in the outpatient setting is increasingly recommended as the population ages and the corresponding incidence of dementia increases. Unfortunately, existing screening tests are relatively lengthy or simply too complex to use in a typical outpatient setting. The Time and Change (T&C) test is a simple, yet rapid screening device that assesses a patient's ability to tell time and make change. This test has been previously validated to detect dementia in inpatient populations. Froehlich and colleagues evaluated the validity of the T&C test in an outpatient population.
Briefly, the T&C test includes two tasks: telling time and making change. In the telling time task, patients are shown an analog clock face set at 11:10. Those who are able to tell the time receive a correct rating. In the making change task, patients must make one dollar in change when shown three quarters, seven dimes and seven nickels. Those who can complete the task within two minutes receive a correct rating. Patients are allowed two tries for each task. Incorrect responses on both tasks suggest dementia. A timed cut point test is also performed, with a negative (or “no dementia”) rating achieved if the patient can tell the time correctly in one try within three seconds and can make change in one try within 10 seconds.
Patients eligible for the study were at least 75 years old and were selected from a primary care center and a geriatric assessment center. Medical records were also reviewed to identify any documentation of cognitive loss, memory loss or dementia within the past two years. The procedure for validation of the test was as follows: after a patient interview in which demographic information was obtained, patients were given the T&C test, followed by the Mini-Mental State Examination (MMSE) and digit span. Caregivers were given the modified Blessed Dementia Rating Scale (mBDRS). Dementia was defined for this study as either an mBDRS score of greater than four or an mBDRS score of greater than two and an MMSE score of less than 20 with symptoms of cognitive loss for at least six months.
Out of 100 patients who were included in the validation portion of this study, 16 had dementia according to the study definition. Of these 16 patients, 10 scored positive for dementia on the T&C test. Of the 84 patients who did not meet the study definition, 81 scored negative for dementia on the T&C test. Thus, the sensitivity of the test was 63 percent, the specificity 96 percent and the negative predictive value 93 percent. Unlike the MMSE, the T&C test did not appear to be affected by education level. When the timed cut points were used for the telling time task, all 16 patients with dementia were identified as having dementia. In the concurrent validation sample, review of patients' medical records revealed that physicians had identified only nine of the 16 patients with dementia. Four of the remaining seven patients were correctly identified as having dementia on the basis of the T&C test, reducing the percentage of unrecognized patients from 44 to 19 percent. All patients with chart documentation of dementia were also correctly identified with the T&C test.
Detection of dementia is important, since treatment of reversible causes is occasionally possible, new treatments are emerging, and family and patient support may delay certain end points, such as nursing home placement. The authors conclude that the T&C test can be reliably used in an outpatient setting to screen for dementia, particularly in settings where no testing is currently done. However, with a sensitivity of only 63 percent, mild cases may still be missed. Therefore, the performance of the T&C test in patients with mild dementia requires further study. Additional dementia measures should be used in these patients if dementia is suspected.
Froehlich TE, et al. Screening for dementia in the outpatient setting: the time and change test. J Am Geriatr Soc. December 1998;46:1506–11.
editor's note: One striking aspect of this study is that not one patient refused to complete even a portion of the T&C test. Anyone who has ever administered an MMSE knows that patients often claim that they are “bad at math” or unable to draw or feel that the questions are inappropriate, leaving the physician with incomplete results. A simple screening test such as the T&C test could be useful in determining cognitive loss. However, it must be emphasized that this test should not be used to establish the diagnosis because it has a fairly high rate of false-positive results, especially on the timed portion, which could have devastating consequences to the patient. Therefore, suspected cases of dementia require other diagnostic measures.—g.b.h.
Copyright © 1999 by the American Academy of Family Physicians.
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