The reliability and validity of the Alzheimer's Disease Assessment Scale Cognitive Subscale (ADAS-Cog) among the elderly Chinese in Hong Kong.
BACKGROUND
The Alzheimer's Disease Assessment Scale cognitive subscale (ADAS-cog) was reported to be a sensitive cognitive function assessment scale for Alzheimer's Disease (AD). The English, Greek, Spanish but not Chinese versions had been validated previously.


OBJECTIVE
The objectives of the present study were to investigate the reliability and validity of an adapted Chinese version of the ADAS-cog among Chinese elderly AD patients in Hong Kong.


METHODS
Thirty-nine subjects were recruited during the period July to December 1998. Twenty were AD patients while 19 were non-demented normal subjects. Two raters administered the ADAS-cog scale thrice on different occasions.


RESULTS
The internal consistency (Cronbach's alpha) of the ADAS-cog were 0.91, 0.88 and 0.65 for the whole group, the AD and normal (i.e. non-demented) subjects respectively. The test-retest reliability as measured by the Spearman's rho correlation coefficients were 0.96, 0.86 and 0.86 for the whole group, AD and normal subjects, respectively, (all P < 0.001). The Spearman's rho correlation coefficients for inter-rater reliability were 0.95 (P < 0.001), 0.91 (P < 0.001) and 0.65 (P = 0.003) for the whole group, AD and normal subjects, respectively. The ADAS-cog score was inversely related to the Mini-Mental Status Examination (MMSE) score (Spearman's rho = -0.91; P < 0.001). The ADAS-cog score was directly proportional to the Clinical Dementia Rating (CDR) (rho = 0.89; P < 0.001). Forward stepwise discriminant function analysis between AD and normal subjects yielded a canonical discriminant function with 3-question items (i.e. word recall test, orientation and comprehension of speech; P < 0.001). This short version had a sensitivity of 90%, specificity of 94.7% and overall accuracy of 92.3%.


CONCLUSIONS
The Chinese version of ADAS-cog subscale is both reliable and valid among the elderly Chinese in Hong Kong.
Chu
L W
LW
Division of Geriatrics, University Department of Medicine, Queen Mary Hospital, Hong Kong SAR. lwchu@hkucc.hku.hk
Chiu
K C
KC
Hui
S L
SL
Yu
G K
GK
Tsui
W J
WJ
Lee
P W
PW
D000367:Age Factors; D000368:Aged; D000544:Alzheimer Disease / Q000145:classification / Q000175:diagnosis* / Q000208:ethnology; D016022:Case-Control Studies; D002681:China / Q000208:ethnology; D003071:Cognition; D016002:Discriminant Analysis; D004522:Educational Status; D005260:Female; D015577:Geriatric Assessment; D006723:Hong Kong; D006801:Humans; D008297:Male; D008609:Mental Status Schedule / Q000592:standards; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales / Q000592:standards*; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D012737:Sex Factors; D018709:Statistics, Nonparametric