Validity of clinical use of the clock-drawing test in Thai elderly patients with memory problems

Forty eight elderly Thai patients, 12 demented, 36 non-demented who consecutively attended a geriatric clinic, at Chulalongkorn University Hospital, with a memory problem were recruited in the study which aimed to determine the validity of the clock-drawing test (CDT) and Chula mental test (CMT). Subjects took the Chula Mental Test (CMT) and were asked to draw a clock on a preprinted 12 centimeters circle showing the time of 11:10. Clocks were scored using the Chula Clock-drawing Scoring System (CCSS). Ten subjects voluntarily participated and completed the WAIS test. The best cutoff score of the CMT and the CDT using diagnosis of dementia as a gold standard were 15 and 7 respectively. Sensitivity and specificity for detecting dementia by the CDT were 100 per cent and 94.1 per cent respectively. Sensitivity and specificity for detecting dementia by the CMT were 83.3 per cent 91.7 per cent. The likelihood ratio (95% confidence interval) of the CMT and the CDT were 10 (3.3-30.4) and 17 (4.4-65.2) respectively. There was a good correlation of the CDT score and the CMT score with the WAIS score. Although the CDT was better than the CMT in literate patients, the CDT had limitation of use among illiterate patients but not the CMT. The benefits of simultaneously application on dementia screening was shown. This study showed that the CDT was a valuable, brief method of dementia screening in elderly Thai patients with memory problems.