The Clock Drawing Test: A Reasonable Instrument to Assess Probable Dementia in Primary Care?

E-ISSN： 1875-5828|15|1|38-43

ISSN： 1567-2050

Source： Current Alzheimer Research, Vol.15, Iss.1, 2018-01, pp. : 38-43

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Abstract

Objective: The primary aim of the study was to determine accuracy, sensitivity and specificityof the Clock Drawing Test (CDT) in detecting probable dementia as compared to the multi-domaindementia screening test DemTect.Methods: The sample was derived from the general practitioner (GP)-based, cluster-randomized controlledintervention trial DelpHi-MV (Dementia: life- and person-centered help in Mecklenburg-WesternPomerania). Selected from 6.440 patients systematically screened for dementia in primary care, we examinedthree groups (a,b,c) where the CDT (as index test) as well as the DemTect (as reference standard)were available. After excluding cases with missing values, we included a sample of n=462 with“probable dementia”, n=586 with “mild cognitive impairment” and n=553 with “no cognitive impairment”matched for age and gender. We analyzed the accuracy of the CDT in identifying people withprobable dementia by the DemTect and report sensitivity, and specificity for the CDT. We further analyzedage and gender differences associated with the groups.Results: In comparison to the DemTect the CDT identified more than twice as many of the screenedpatients as cognitively impaired (63.1% in the CDT vs. 28.9% in the DemTect). The sensitivity andspecificity for the CDT were 84.4% and 45.6% respectively. We found considerable age and gender differencesfor the performance of the CDT. Higher age (p < 0.001) and female sex (p < 0.001) were associatedwith incorrect clock drawings.Conclusion: The CDT shows a considerably high rate of false positive screening outcomes compared tothe DemTect and disadvantages older people and women. Thus, in contrary to previous findings our resultsindicate that the CDT should not be used as exclusive instrument to screen for probable dementiain primary care.