Reliability and concurrent validity of Alzheimer’s disease assessment scale - Cognitive subscale, Chinese version (ADAS-Cog-C) among Chinese community-dwelling older people population

Abstract

Objective To evaluate reliability and concurrent validity of the Alzheimer’s Disease Assessment Scale - Cognitive Subscale, Chinese Version (ADAS-Cog-C) among Chinese community older adults. Method Three groups, comprising of 1,276 community-dwelling older adults, were included in this study: a normal control (NC), a mild cognitive impairment (MCI), and an Alzheimer’s disease (AD) group. All participants were assessed through ADAS-Cog-C, clinical interviews, physical examinations, Mini Mental State Examination (MMSE), and the Clinical Dementia Rating Scale (CDR). Internal consistency was assessed to evaluate the reliability of ADAS-Cog-C. Pearson and Spearman correlation coefficients were calculated to evaluate the concurrent validity between ADAS-Cog-C, MMSE, and CDR. Results Overall, the Cronbach’s alpha coefficients of ADAS-Cog-C for the AD and MCI groups were 0.843 and 0.554, respectively. The split-half reliability coefficients for the AD and MCI groups were 0.860 and 0.539, respectively. ADAS-Cog-C scores were negatively correlated with MMSE scores (r = −0.706, p < 0.001) and positively associated with CDR scores (r = 0.546, p < 0.001). After excluding the MCI group from the analysis, the internal consistency of ADAS-Cog-C for the total population improved (α = 0.813, r hh = 0.852, all p < 0.001), as did the correlation between ADAS-Cog-C and MMSE (r = −0.828, p < 0.001) and CDR (r = 0.429, all p < 0.001) scores. Conclusions ADAS-Cog-C has good internal consistency and concurrent validity for assessing Chinese community older adults with AD, but poor consistency, good concurrent validity with the MMSE while moderate concurrent validity with the CDR for MCI.