The clock drawing test in primary care: sensitivity in dementia detection and specificity against normal and depressed elderly

Abstract

Objectives: The aim of this study was to examine the sensitivities and specificities of the clock drawing test (CDT) in the detection of dementia among older people in primary care, with particular emphasis on the effect of depression on CDT specificity. Most previous studies have been sited in specialist settings and few have addressed the issue of specificity against depression.

Methods: Comparison of cohorts identified from community-based screening with GMS-AGECAT. The CDT and the Mini-Mental State Examination (MMSE) were administered to 41 elderly subjects with organic disorder (dementia), 84 elderly subjects with case level depression and 523 normal elderly subjects. Sensitivities and specificities of the CDT were calculated.

Results: The sensitivity of the CDT in the detection of dementia in the general community was 76%. The specificities of the CDT against normal elderly and depressed elderly was 81% and 77% respectively. Higher sensitivity and specificity were achieved by the MMSE.

Conclusions: The use of the CDT in the detection of dementia syndromes is likely to be more relevant in the primary care context than in specialist settings. The CDT provides good sensitivity and specificity but may not be as sensitive or specific in the general community as previous studies have suggested, particularly in mild dementia. Community-based late life depression does not appear to alter the specificity of the CDT.