Prevalence of Autism Spectrum Disorder and Autistic Symptoms in a School-Based Cohort of Children in Kolkata, India

Alokananda Rudra
Matthew K Belmonte
Parmeet Kaur Soni
Saoni Banerjee
Shaneel Mukerji
Bhismadev Chakrabarti

This is a preprint of an article published in Autism Research 10(10):1597-1605 (October 2017).
Copyright © 2017 The Authors

SCIENTIFIC ABSTRACT Despite housing ~18% of the world’s population, India does not yet have an estimate of prevalence of autism. This study was carried out to estimate the prevalence of autism in a selected population of schoolchildren in India. N = 11,849 children (mean age = 5.9 [SD = 1.3], 39.5% females) were selected from various school types from three boroughs in Kolkata, India. Parents/caregivers and teachers filled in the Social and Communication Disorders Checklist (SCDC). Children meeting cutoff on parent-reported SCDC were followed up with the Social Communication Questionnaire (SCQ). SCQ-positive children were administered the Autism Diagnostic Observation Schedule (ADOS). Teacher report on SCDC was available on all 11,849 children. Parent-report SCDC scores were obtained for 5,947 children. Mean scores on teacher SCDC were significantly lower than parent SCDC. Out of 1247 SCDC-positive children, 882 answered the SCQ, of whom 124 met the cutoff score of 15. Six of these children met criteria for autism, autism spectrum disorder (ASD), or broader autism spectrum on the ADOS. The weighted estimate of supra-threshold SCQ scores was 3.54% (CI: 2.88-4.3%). The weighted prevalence estimate of positive scores (for broader autism spectrum + ASD + autism) was 0.23% (0.07-0.46%). As ~20% children in this state are known to be out of the school system, and ASD prevalence is likely to be higher in this group, this estimate is likely to represent the lower bound of the true prevalence. This study provides preliminary data on the prevalence of broader-spectrum autism and supra-threshold autistic traits in a population sample of school children in Eastern India.

LAY ABSTRACT Despite India's being the second most populous country in the world with over 1.2 billion people, there is no estimate of how many people in the country have an Autism Spectrum Disorder (ASD). Such an estimate is crucial in fixing policy and guiding allocation of resources for individuals and families affected by ASD, in a way that accommodates the cultures and norms of the country and its people. We measured autism-related symptoms in 11849 school-going children aged between 3 and 8, in one major city of India (Kolkata). Data were taken from surveys of parents and teachers, followed up with our own in-person assessments. In comparison to teachers, parents as a group tended to over-report autism-related symptoms in their children. As a result, many children underwent follow-up screening, which took place via a detailed diagnostic assessment. After accounting for drop-outs at various stages, our estimate of school-children affected by ASD or broader autism spectrum was 0.23%. Since >20% children in this state are known to be out of the school system, this estimate is likely to represent the lower limit of the true estimate of ASD prevalence in this age group. Potential sources for cultural/geographic differences in ASD prevalence are discussed.

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