Reliability and validity analysis of the Chinese version of the Quick Dementia Rating System (QDRS)

Alzheimer's disease (AD) is one of the most common chronic diseases among the elderly. The Quick Dementia Rating System (QDRS) is a recognized cognitive assessment tool. The purpose of the current study was to evaluate the Chinese version of the QDRS (C-QDRS) as an early screening tool for elderly individuals.

The QDRS was translated into Chinese and its reliability and validity were assessed. A total of 366 people were recruited for the study, and all participants completed comprehensive neuropsychological tests. For reliability analysis, internal consistency was calculated using Cronbach's alpha coefficient. For validity analysis, the exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were carried out. Receiver operating characteristic (ROC) curve analyses were performed to evaluate the discriminative ability of the C-QDRS to identify cognitive impairment.

C-QDRS scores increased progressively across groups: normal controls, objective subtle cognitive decline (obj-SCD), mild cognitive impairment (MCI), and AD. The C-QDRS demonstrated strong consistency, with a Cronbach's alpha of 0.923. The EFA showed a two-factor structure, and the CFA indicated that the model fit was satisfactory (χ²/df = 2.81, P < 0.001). There were strong correlations between the C-QDRS and standardized neuropsychological tests, indicating that the C-QDRS exhibited concurrent validity (all P < 0.001). ROC analyses showed optimal cutoff values of 1.0 for obj-SCD, 2.5 for MCI, and 5.0 for AD, with AUCs of 0.802, 0.840, and 0.907, respectively. The C-QDRS showed statistically superior discriminative ability compared to ACE-III and MoCA-B in detecting obj-SCD (both P < 0.05).

The C-QDRS is a precise and effective tool for screening both AD and preclinical AD in China.