Clock Drawing Test Ratings by Dementia Specialists: Interrater Reliability and Diagnostic Accuracy

Le résumé fourni par la source

The authors aim to study subjective ratings of clock drawing test by clinicians and determine interrater reliability and diagnostic accuracy. The clock drawing test has been advocated over the Mini-Mental State Examination as an office screening test for dementia, but use of the clock drawing test by neurologists and dementia specialist clinicians has not been validated. The authors conducted a study of clock drawing test scoring by dementia specialists. The authors randomly assigned 25 clocks from each of six predetermined groups based on consensus diagnosis (cognitive comparison subjects, subjects with a memory complaint but with normal neuropsychological testing, subjects with probable and possible mild cognitive impairment, and subjects with possible and probable Alzheimer’s disease) to dementia specialists for blinded scoring using a binary yes/no impairment system and a 0–10 scale as subjectively determined by each individual clinician rater. The authors collapsed the six groups into three (comparison subjects, mild cognitive impairment patients, and Alzheimer’s disease patients) and analyzed interrater reliability, sensitivity, and specificity for consensus diagnosis of mild cognitive impairment, and Alzheimer’s disease. The authors found excellent interrater reliability, sensitivity, and specificity for predicting consensus diagnosis. The 0–10 clock drawing test rating scale was more predictive of consensus diagnosis than the binary impairment scale. Based on the five clinicians’ average dichotomous rating, the clinicians differentiated comparison and Alzheimer’s disease participants with a sensitivity of 0.75 and a specificity of 0.81. For three of the four comparisons, a cutoff score of two or greater resulted in the maximization of sensitivity and specificity for differentiating diagnostic groups. A cutoff score of four or greater maximized sensitivity (0.54) and specificity (0.74) for differentiating Alzheimer’s disease from mild cognitive impairment. Based on rating systems, clock drawing test scoring by dementia clinicians had excellent interrater reliability and sensitivity for differentiating the mild Alzheimer’s disease subjects from comparison subjects. When utilizing a binary rating scale for the clock drawing test in the absence of clinical information, dementia specialist clinicians at the Boston Medical Center were moderately sensitive and highly specific in separating mild cognitive impairment from healthy comparison subjects. These dementia clinicians were also highly sensitive and less specific in differentiating mild cognitive impairment from Alzheimer’s disease.

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