Simple to Complex: A Comparison of Clock Drawing Test Scoring Systems

The popularity of the Clock Drawing Test (CDT) is paralleled by the multitude of scoring systems ranging from brief and subjective to complex.

To compare the properties and classification accuracy of different scoring approaches, the CDT was scored using 14 published scoring systems and one simplistic four-point scale using a military veteran sample.

Among the scoring approaches, eight displayed acceptable discrimination between profiles classified as cognitively intact versus cognitively impaired based on neuropsychological test scores, with areas under the receiver operating characteristic curve (AUCs)=.709 to .797. Analyses within individual cognitive domains revealed excellent discrimination for the Framingham (visuospatial: AUC=.850, and executive: AUC=.808) and Shulman (language: AUC=.811) scoring approaches.

Simpler and even subjective approaches were on par with highly detailed procedures for scoring the CDT. With many scoring approaches being capable of detecting overall impairment, a total score may be most useful as a screening indicator.