An Epidemiological Review Study on the Prevalence and Incidence Rate of Autism Spectrum Disorder in Ethnic Chinese Population

Background: Recent data from the West suggest that autism spectrum disorder (ASD) is becoming more prevalent. In Asia, the latest study from Korea reported a high rate of 2.64 percent.(1) It is not known whether there is an increasing trend of ASD among Chinese.

Objectives: To present the findings of a systemic review of epidemiologic data (prevalence and incidence) of ASD from major studies conducted in Chinese populations.

Methods: We conducted a systemic review on studies that reported the prevalence and/or incidence of ASD among Chinese populations (mainland China, Hong Kong, Taiwan, Singapore, and Malaysia).

Results: There is no national wide survey data on ASD in mainland China. Local data are available only in recent years and the reported prevalence ranged from 0.28‰ to 7.54‰.(2-4) The latest study reported an overall prevalence of 7.54‰ among preschool children in mainstream kindergartens. The rate for autism, Asperger syndrome and pervasive developmental disorder-not otherwise specified was 2.95‰, 4.1‰ and 0.49‰ respectively.(5)

In Hong Kong, Wong et al calculated the incidence and prevalence of autism spectrum disorder for the period of 1986 to 2005 based on registry data and population demographics. The estimated incidence of autism spectrum disorder was 5.49 per 10,000 person-Years. The average prevalence rate was 1.61‰ and there was a steady increase of the prevalence rate over the 20 years period.(6)

In Taiwan, Chien and colleagues reported that the cumulative prevalence of ASD increased from 0.18 to 2.87‰ from 1996 to 2005. The annual incidence rate increased from 0.91 to 4.41 per 10,000 per year from 1997 to 2005.(7)However, the rates were calculated based on health insurance database and may not reflect the real frequency in the population.

 There is a large Chinese resident population in Singapore (approximately 3.8 million) and Malaysia (approximately 5.6 million) respectively. Currently there is no published data on the prevalence and incidence of ASD among Chinese Singaporeans and Chinese Malaysian.

Conclusions: There are limited studies reporting on ASD prevalence and incidence rates in ethnic Chinese population in Asia. This is further limited by the differing study methodologies making the data comparison challenging. While existing data appear to suggest, it remains unclear whether there is a true rise in the prevalence of ASD in ethnic Chinese population across geographic sites. A collaborative multi-site population-based epidemiologic study being planned would be able to yield much needed information for service planning.