Clock Drawing Test and the diagnosis of amnestic mild cognitive impairment: Can more detailed scoring systems do the work?

Abstract

Introduction: The Clock Drawing Test is a frequently used cognitive screening test with several scoring systems in elderly populations. We compare simple and complex scoring systems and evaluate the usefulness of the combination of the Clock Drawing Test with the Mini-Mental State Examination to detect patients with mild cognitive impairment. Method: Patients with amnestic mild cognitive impairment (n = 48) and age- and education-matched controls (n = 48) underwent neuropsychological examinations, including the Clock Drawing Test and the Mini-Mental State Examination. Clock drawings were scored by three blinded raters using one simple (6-point scale) and two complex (17- and 18-point scales) systems. The sensitivity and specificity of these scoring systems used alone and in combination with the Mini-Mental State Examination were determined. Results: Complex scoring systems, but not the simple scoring system, were significant predictors of the amnestic mild cognitive impairment diagnosis in logistic regression analysis. At equal levels of sensitivity (87.5%), the Mini-Mental State Examination showed higher specificity (31.3%, compared with 12.5% for the 17-point Clock Drawing Test scoring scale). The combination of Clock Drawing Test and Mini-Mental State Examination scores increased the area under the curve (0.72; p < .001) and increased specificity (43.8%), but did not increase sensitivity, which remained high (85.4%). Conclusions: A simple 6-point scoring system for the Clock Drawing Test did not differentiate between healthy elderly and patients with amnestic mild cognitive impairment in our sample. Complex scoring systems were slightly more efficient, yet still were characterized by high rates of false-positive results. We found psychometric improvement using combined scores from the Mini-Mental State Examination and the Clock Drawing Test when complex scoring systems were used. The results of this study support the benefit of using combined scores from simple methods.

Keywords:

• Clock Drawing Test
• Amnestic mild cognitive impairment
• Mini-Mental State Examination
• Combination of scores
• Neuropsychology

We would like to thank Julie A. Suhr and three anonymous reviewers for their valuable comments on the first draft of the manuscript. The information in this manuscript and the manuscript itself have never been published either electronically or in print.

The research was supported by the European Regional Development Fund project FNUSA-ICRC [grant number CZ.1.05/1.1.00/02.0123]; Charles University in Prague, Faculty of Arts, internal grants 2012 [grant number VG137]; and Ministry of Health, Czech Republic—Conceptual Development of Research Organization, University Hospital Motol, Prague, Czech Republic [grant number 00064203]. All authors reported no financial interests or potential conflicts of interest.