Parkinson's disease in China: prevalence in Beijing, Xian, and Shanghai.

A cross-sectional prevalence study of Parkinson's disease in China was undertaken in 1997-98. We assessed 29?454 residents aged > or =55 years from 79 rural and 58 urban communities in Beijing, Xian, and Shanghai, who were selected through stratified, multistage, cluster sampling. With a standardised diagnostic protocol, we identified 277 people with the disease. Prevalence of Parkinson's disease for those aged > or =65 years was 1.7% (95% CI 1.5-1.9). We estimate that 1.7 million people in China have the disease (aged > or =55 years). Our findings suggest that prevalence of Parkinson's disease in China is similar to that in developed countries.