Trends of prevalence and mortality of dementia over 17 years in rural areas of Xi'an City

Objective By comparing the prevalence and mortality of dementia among rural people in Xi'an in 1997 and 2014 to clarify the epidemiological changes of dementia among rural people in the city over 17 years. Methods In 1997 and 2014, people aged 55 and above in villages in Xi'an were selected by random cluster sampling method, and face-to-face questionnaire survey was conducted by combining centralized and home visits. Dementia and its subtypes were diagnosed by “the three-step method”；the changes of dementia prevalence and mortality were compared between the two surveys. Results The prevalence of dementia among rural residents aged 55 and above in Xi'an was 3.49% in 1997, with age-gender standardized prevalence of 2.08%.In 2014, the prevalence of dementia was 4.25%, with age-gender standardized prevalence of 2.78%.Over the 17 years, the prevalence of dementia increased by 1.79 times (OR=1.79, 95%CI ：1.20-2.65, P=0.004), with a 1.9-fold increase in females and a 1.67-fold increase in males.The mortality of dementia patients was 61.76‰and age-gender standardized mortality was 60.20‰in 1997, while the mortality was 35.71‰ and age-gender standardized mortality was 34.18‰in 2014. The mortality of dementia decreased by 33% over the 17 years (HR=0.33, 95%CI ：0.15-0.74, P=0.007) .Conclusion The prevalence of dementia in rural areas of Xi'an increased significantly over the 17 years, but the mortality rate decreased, and this trend was more obvious in women.