Prevalence of dementia in an urban population aged ≥75 years in Guangzhou / 中华老年医学杂志

ABSTRACT

Objective To obtain an accurate prevalence of dementia and Alzheimer's disease (AD) in large sample of ≥75 year old elderly living in Guangzhou city. Methods From August 1994 to December 1995, the study was conducted in Liwan District of Guangzhou, China. A two stage cluster sampling design was used to obtain a large sample. ‘Jiedao’ (resident unit in China) was the primary sampling units (PSU),‘Jumin Xiaozu’ (resident group) was the secondary sampling units (SSU). Systematic sampling and simple random sampling procedures were used for the first and second stages, respectively. The study was divided into two phases a door to door survey of the entire sample aged ≥75 years (4 735 persons), followed by a clinical examination of suspected cases for positive and differential diagnosis. In the first phase, mini mental status examination (MMSE) was used as screening method for dementia. In the second phase, dementia and AD were clinically diagnosed according to the criteria of Diagnostic and Statistical Manual for Mental Disorders (DSM III R) , National Institute of Neurological and Communicative Disorders (NINCDS) and Stroke Alzheimer's Disease and Related Disorders Association (ADRDA). Results The sensitivity and specificity of MMSE were 0 7451 and 0 7496 respectively while the positive predictive value was 0 2251. The prevalence of dementia in individuals aged 75 years and over was 8 90%, in which male and female were found to be 2 91% and 13 11%, and that of AD was 7 49%, male and female found to be 2 01% and 11 36% respectively. The prevalence of vascular dementia (VD) was 1 16%. Of the subjects with dementia, 84 24% was diagnosed Alzheimer's disease, 13% VD, and 2 76% dementia with other causes. The proportion of AD increased obviously by every 5 years. Conclusions The prevalence of dementia in ≥ 75 year persons was lower in Guangzhou than that in Shanghai, but was higher than that in other regional studies within China. In ≥75 year male and/or poorly educated female were more easily suffered from AD. The proportion of AD in dementia was higher in this study than that in others. These figures indicated that as a screening tool for dementia MMSE need improving and should be combined with ADL and POD together.