Incidence and prevalence of amyotrophic lateral sclerosis in urban China: a national population-based study

Amyotrophic lateral sclerosis (ALS) is a severe neurodegenerative disease and information on disease burden of ALS in mainland China was limited. We aimed to estimate the prevalence and incidence of ALS in China.We used 2012-2016 data from China's Urban Employee Basic Medical Insurance and Urban Residence Basic Medical Insurance, covering approximately 0.43 billion individuals. ALS cases were identified by the primary diagnosis (International Classification of Diseases code or text of diagnosis) in the insurance database.The crude prevalence and incidence in 2016 were 2.91 per 100 000 person-years (95% CI 2.31 to 3.58) and 1.65 (95% CI 1.33 to 2.01), respectively. The standardised prevalence and incidence based on 2010 Chinese census data were 2.97 (95% CI 2.91 to 3.03) and 1.62 (95% CI 1.58 to 1.67), respectively. The annual prevalence between 2013 and 2016 remained relatively constant, ranging from 2.91 (95% CI 2.31 to 3.58) in 2016 to 3.29 (95% CI 2.51 to 4.17) in 2014 (linear regression: β=-0.129, p=0.104). Both rates peaked in the group aged 75-79 years.The prevalence and incidence of ALS in mainland China were lower than those in developed countries, and maintained a relatively stable trend. The age at onset and age at diagnosis for ALS patients were younger than those in developed countries. Further research is expected to clarify the potential pathophysiological mechanism of ALS.