Is there any difference between the findings of Clock Drawing Tests if the clocks show different times?

The Clock Drawing Test (CDT) is a widely-used, rapid assessment tool for the screening of cognitive decline though its evaluation and interpretation are still not uniform. The aim of present study was to investigate the difference in sensitivity and specificity of two types of CDTs and to compare the clinical benefits of quantitative and semiquantitative scoring systems.

To investigate the difference in sensitivity and specificity of two types of CDTs and to compare the clinical benefits of quantitative and semiquantitative scoring systems.

Six hundred and ninety-two participants with or without dementia completed 10-item CDTs in nursing homes in two counties in southern Hungary. The dementia was not further subclassified. The results of the two tests, CDT1 (representing five minutes to a quarter to four) and CDT2 (representing ten past five), were evaluated quantitatively and semiquantitatively.

In the quantitative evaluation, the sensitivity and the specificity for the diagnosis of dementia at cut-off scores of 7 points were determined: 87.1% and 51.9%, respectively, for CDT1, and 81.7% and 57% for CDT2, respectively. The semiquantitative analysis revealed a sensitivity of 67.3% and a specificity of 65.3% for CDT1, and of 64.6% and 66.6% for CDT2, respectively.

The results of CDT tests do not appear to depend on the positions of the clock hands and additionally suggest that the quantitative evaluation method is more sensitive than the semiquantitative method.