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Prevalence of Autism in China: A Mainstream-School Population National Study in 3 Cities
Our previous study utilising a Mandarin Chinese translation of the Childhood Autism Spectrum Test (CAST) in mainstream schools reported a prevalence of Autism Spectrum Conditions (ASC) in Beijing of 119 per 10,000 (95%CI: 53, 265). The results from the Beijing study suggested an under-diagnosis of autism in a mainstream-school population, which laid the groundwork for the current large population-based prevalence study of ASC in mainland China.
Objectives:
(1) To conduct a pilot study in one city in China to test the feasibility of the measures for the main study. (2) To compare these results to two other cities in China.
Methods:
Pilot Study: We sampled one school district in the urban area of Jilin city. All students in Grades 1 to 4 (6-10 years old) in 13 mainstream primary schools and two special schools in the district were invited to participate. Each screening package included the Mandarin CAST and questions on parents’ background. After screening, the children were divided into 3 groups according to their CAST score: 1) the high-score group, also known as screen-positive group: CAST score≥15; 2) the borderline group: CAST score 12-14; and 3) the low-score group: CAST score ≤11. Study in Two Cities: We repeated the same process in Shenzhen city, Guangdong province, in the south of China, and Jiamusi city, Heilongjiang Province, in the north of China. Children were given diagnosis of ASC after clinical assessments and research diagnostic assessments using the ADOS and the ADI-R.
Results:
Pilot Study: Seventy-seven cases were identified among a total study population of 7,258 in the district in the urban area of Jilin City, resulting in a prevalence estimate for autism of 108 per 10,000 (95% CI: 89, 130). Study in Two Cities: Shenzhen city: Of 21,420 children screened in mainstream primary schools (age 6-10), 122 children were given a clinical diagnosis of “ASC” or “suspected ASC”. After research diagnosis, the direct raw prevalence estimate for the population was 42.3 per 10,000 children (95% CI 20.1-88.6). Jiamusi city: 16,358 questionnaires were distributed to 27 mainstream primary schools, with 100% response. 24 children were given a clinical diagnosis of “ASC” or “suspected ASC”. The direct raw prevalence estimate for the population was 19.0 per 10,000 children age 6-10 (95% CI 9.7-37.5). The differences between the two regions were not significant either as a crude effect (OR=0.45 95% CI 0.16-1.23, p=0.12) or after adjusting for age, sex, income and education differences between the two regions (OR=0.39, 95% CI 0.12-1.30, p=0.13).
Conclusions:
This study shows that screening and diagnostic instruments developed in the West can be adapted for use in non-Western countries. In particular, the CAST can be used for a national prevalence study in China. Our results confirmed the under-diagnosis of ASC in the mainstream-school population in China. The current results will be compared to results from ongoing screening studies in seven other provinces. This type of epidemiological survey is essential for the assessment of service needs and the choice of the best model of service delivery.