Childhood Autism Screening Test (CAST) As a Screening Tool for ASD: Utility in a Community Population in Lagos, Nigeria

Background:

Autistic spectrum disorder (ASD) is routinely screened during childhood in developed countries but still missed in developing countries. With increasing awareness about ASD, it has become pertinent for us to use simple tool to assist in early identification due to scarcity of manpower especially in our rural communities.

Childhood Autism Screening Test (CAST) a screening instrument developed as a combination of behavioural symptom of ASD according to International Classification of Disease (ICD-10) and Diagnostic and Statistical Manual fourth edition (DSM-IV) has been widely used in western societies. A few studies have reported use among African-American but none among Africans.

Objectives: To determine the utility of CAST for screening for ASD among individuals with neuro-developmental disorders in Lagos state, Nigeria.

Methods:

Participant were recruited during an annual community screening for autism and other neuro-developmental disorders which is a collaboration between a bank, Blazing Trail International USA (a Non-Governmental Organization) and Centre for Autism and Neuro-developmental Disorders (CANDo) of the College of Medicine, University Lagos. Participants were reached via mails, radio jingles word of mouth and text messages. They were screened in stages using a sociodemographic questionnaire, CAST for those aged 4 and above and diagnosis was based on DSM V criteria for ASD.

Results:

A total of 268 participants attended the screening exercise. Two hundred and eighteen individuals were attending for the first time (81.3%). More than three quarters were eligible for CAST (76.9%) and majority of them (83%) completed CAST. Sensitivity is 70.8%, specificity 60.4% and positive predictive value 52.3%.

Conclusions:

CAST was found to be a user friendly instrument with high specificity and sensitivity in diagnosis of ASDs. It should be considered for larger validation study for autism in Africa.