No abstract

CDT should not be used for MCI-screening.

None of the present CDT scoring systems has sufficient utility to screen reliably for MCI. The clinical value of the CDT could be improved by using semi-quantitative scoring, having a wider score range and focusing on specific details of the clock (e.g. the hands and numbers).

Background: Individuals with mild cognitive impairment (MCI) are at high risk of developing dementia and are a target group for preventive interventions. Therefore, research aims at diagnosing MCI at an early stage with short, simple and easily administrable screening tests. Due to the fact that the Clock Drawing Test (CDT) is widely used to screen for dementia, it is questionable whether it is suited to screen for MCI. Methods: 3,198 primary care patients aged 75+ were divided into two groups according to their cognitive status, assessed by comprehensive neuropsychological testing: individuals without MCI and individuals with MCI. The CDT scores, evaluated by the scoring system of Sunderland et al. [J Am Geriatr Soc 1989;37:725–729], of both groups were compared. Multivariate analyses were calculated and the sensitivity and specificity of the CDT to screen for MCI were reported. Results: Significant differences were found for CDT results: MCI patients obtained worse results than cognitively unimpaired subjects. CDT has a significant impact on the diagnosis of MCI. However, sensitivity and specificity as well as receiver operating characteristic analyses are not adequate, meaning that the CDT could not be named as an exact screening tool. Limitations: Applying different CDT versions of administration and scoring could yield different results. Conclusions: CDT does not achieve the quality to screen individuals for MCI.

Background/Aims: Conversion rates to dementia are known to be high for patients with mild cognitive impairment (MCI), but the diagnosis of MCI is very time-consuming. Since the Clock Drawing Test (CDT) is quick to administer, it will be of interest to compare the predictive validity of the CDT and of an MCI diagnosis for the diagnosis of dementia. Methods: In a sample of 384 individuals, CDT scores and the presence of MCI were assessed at baseline and then compared between individuals with an incident dementia diagnosis at follow-up and those without. Multivariate analyses, receiver operating characteristic analyses and values of sensitivity and specificity of the CDT were performed. Results: Individuals with incident dementia had significantly higher CDT scores at baseline than those without dementia. CDT was a significant predictor of incident dementia after adjusting for other factors. CDT reached a sensitivity of 68% and specificity of 65%. The area under the receiver operating characteristic curve of CDT was 0.70 and therefore slightly lower than for MCI diagnosis (0.78). Conclusions: Because of the only slightly lower predictive value of the CDT, its quick application and scoring compared to the MCI concept applied, it will be worthwhile to improve the CDT scoring system in order to increase the predictive validity in dementia.