18599
Prevalence of Autism Spectrum Conditions in Mainland China: Pilot and a Whole Population Study
The majority of recent prevalence studies of the Autism Spectrum Conditions (ASC) in developed countries have adopted a combination of prospective and retrospective approaches, using standardized diagnostic instruments for case identification. Previous reported prevalence estimates of ASC in mainland China have been much lower than Western estimates (around 1%). This may be partly due to the differences in: 1) study methodology; 2) screening and diagnostic instruments; 3) clinical diagnostic criteria; 4) under-diagnosis of milder subtypes of the spectrum: most children diagnosed are those with classic autism. A recent validation of the Mandarin Chinese Childhood Autism Spectrum Test (CAST) suggested there is an under-estimation of the prevalence of ASC in the general population in Beijing.
Objectives:
1) To apply validated screening and standardized diagnostic instruments to an entire district population in a moderately developed city to establish a prevalence estimate of ASC in an unselected population in mainland China. 2) To conduct a pilot study to test the feasibility of a national prevalence study of ASC in China.
Methods:
Based on the residential records, the Mandarin CAST was distributed to all children aged 6 to 11 years old (N = 7,258 children) in Fengman district in Jilin province. The study had 3 stages. Stage 1: All children between 6 and 11 years old in mainstream primary schools were screened. Stage 2: All screened children who scored highly (at or above the cut-off of 15 on the CAST) were assessed by experienced child psychiatrists using DSM-IV criteria, and then further assessed using the ADOS and the ADI-R. A consensus diagnosis was made between instruments’ examiners and psychiatrists. Stage 3: All children (age 6 to 11) in special schools, intervention centres, communities, or at home with an existing diagnosis of ASC, were screened with diagnostic records checked. A random selection of 10 children with an existing diagnosis of ASC who met the cut-off were examined by clinicians and examiners to confirm their diagnostic status. The prevalence estimate was generated after adjusting and imputing for missing values using inverse probability weighting.
Results:
A total of 6,149 questionnaires (participation rate: 85.8%) from mainstream primary schools (Stage 1) and 91 questionnaires (participation rate: 100%) from children with a diagnosis of ASC (Stage 3) were available for analysis. A total of 477 children (7.8%) in mainstream schools met the cut-off of the CAST, and 72 children (79.1%) with a diagnosis met the cut-off. 9 children from mainstream primary schools and 68 children from other settings in this district were found to meet the consensus diagnostic criteria for ASC (78.5% after adjustment). After adjustment and data imputation, the prevalence in this primary school population in China was 108 per 10,000 (95%CI: 86, 135). The sex ratio (boys: girls) of children with ASC was 7:1.
Conclusions:
Using a comparable method, the prevalence estimate of ASC in a moderately developed city in mainland China is similar to those estimates in developed countries. This study confirms it is feasible to conduct a large population-based epidemiological study for ASC in China.