Epidemiological Study of Autism in Tianjin, China

Background: Recent studies have suggested a significantly higher prevalence rate for autism spectrum disorders (ASD). Kogan et al (2009) reported that about 110 per 10,000 children ages 3 to 17 in US have ASD, an increase over previous estimates. However, there is very few large scale epidemiological research about the prevalence and incidence of autism in China and there is no such a registry for autism to collect and store all the inpatient data from all public hospitals either. We collected and analyzed and reviewed all the hospital and school records of children diagnosed with autism in Tianjin, one of four provincial-level cities in China since early 1990s.

Objectives: This study aims to investigate the epidemiology of autism in children in Tianjin, China.

Methods: We collected all the inpatient data from all public hospitals and rehabilitation centers and schools in Tianjin and computerized them and conducted statistical analysis. Diagnoses were confirmed or ruled out following a multidisciplinary assessment including standard psychometric tests of IQ, Japanese S-M Social Living Ability Scale (SM), Child Behavior CheoKlist (CBCL), Sensory Integration Rating Scale, Children Temperament Scale (CTS), Toddler Temperament Scale (TTS), Gesell Development Schedules (GDS), Autism Behavior Checklist (ABC), Childhood Autism Rating Scale (CARS), International Classification of Diseases 10 Edition (ICD-10), Diagnostic and Statistic Manual of Mental Disorders (DSM-IV), Chinese Classification of Mental Disorders (CCMD-3), etc. The incidence and prevalence of autism have been calculated for the period of 1993 to 2008 using the population statistics available in the government for children less than 15 years old and less than 5 years old respectively in Tianjin City.

Results: 1769 children 0-14 years old with diagnoses of autism were identified from 1993 to 2008 in Tianjin City, including 1375 boys and 394 girls (the male to female ratio was 3.49: 1). 1316 children 0-4 years old were identified with autism from 1993 to 2008 in Tianjin City. The estimated incidence of autism was 5.3 per 10 000. The prevalence was 43.87 per 10 000 for children less than 15 years old for the same period.

Conclusions: The incidence rate is similar to those reported in Hong Kong, Australia and North America, but lower than Europeans. The prevalence is higher than that reported in Hong Kong, but still lower than those reported from year 2000 onward in North America and Europe. The results of this study supported the previous research on the ratio of male to female. Although it is possible that unidentified environment factors have contributed to an increase in autism, the timing of the increase suggests that it may be due to improved awareness, changes in diagnostic criteria, and availability of services, leading to identification of previously unrecognized young children with autism. It was also noticed that the diagnosed ages became younger in the past decades, so there is an urgent need for early diagnosis and intervention.