Validation of the telephone interview for cognitive status-modified in subjects with normal cognition, mild cognitive impairment, or dementia

Abstract

Background: The telephone assessment of cognitive functions may reduce the cost and burden of epidemiological studies.

Methods: We validated the Telephone Interview for Cognitive Status-modified (TICS-m) using an extensive in-person assessment as the standard for comparison. Clinical diagnoses of normal cognition, mild cognitive impairment (MCI), or dementia were established by consensus of physician, nurse, and neuropsychological assessments.

Results: The extensive in-person assessment classified 83 persons with normal cognition, 42 persons with MCI, and 42 persons with dementia. There was considerable overlap in TICS-m scores among the three groups. Receiver operating characteristic curves identified < or = 31 as the optimal cutoff score to separate subjects with MCI from subjects with normal cognition (sensitivity = 71.4%; subjects with dementia excluded), and < or = 27 to separate subjects with dementia from subjects with MCI (sensitivity = 69.0%; subjects with normal cognition excluded). The TICS-m performed well when subjects with MCI were pooled either with subjects with dementia (sensitivity = 83.3%) or with subjects with normal cognition (sensitivity = 83.3%).

Conclusions: Although the TICS-m performed well when using a dichotomous classification of cognitive status, it performed only fairly in separating MCI from either normal cognition or dementia. The TICS-m should not be used as a free-standing tool to identify subjects with MCI, and it should be used with caution as a tool to detect dementia.

2009 S. Karger AG, Basel.

Figures

Fig. 1

Scatterplot of TICS-m scores for subjects with normal cognition, with MCI, and with dementia. The horizontal line at ≤31 shows the optimal cutoff score to separate subjects with normal cognition from subjects with MCI. The horizontal line at ≤27 shows the optimal cutoff score to separate subjects with MCI from subjects with dementia. The asterisks indicate the median value for each distribution.

Fig. 2

a ROC curve of the TICS-m for comparison of subjects with MCI versus subjects with normal cognition (subjects with dementia are excluded). The area under the ROC curve was 0.83 (95% CI = 0.74–0.91). b ROC curve of the TICS-m for subjects with dementia versus subjects with MCI (subjects with normal cognition are excluded). The area under the ROC curve was 0.79 (95% CI = 0.70–0.89).

Fig. 3

a ROC curve of the TICS-m for comparison of subjects with cognitive impairment (MCI + dementia) versus subjects with normal cognition in the complete sample. The area under the ROC curve was 0.89 (95% CI = 0.83–0.94). b ROC curve of the TICS-m for comparison of subjects with dementia versus subjects without dementia (normal cognition + MCI) in the complete sample. The area under the ROC curve was 0.89 (95% CI = 0.83–0.96).

Fig. 4

Score distributions on the immediate (a) and delayed (b) 10-word recall item of the TICS-m. Note the substantial overlap among groups. White bars = Subjects with normal cognition; gray bars = subjects with MCI; and black bars = subjects with dementia.