Exploring the diagnostic ability of the ADOS in special needs schools in the greater eThekwini area : a blinded study.

Abstract

Autism Spectrum Disorders (ASDs) are increasing in prevalence worldwide, including in developing countries like South Africa. If the assumption that ASDs manifests similarly across all cultures, then the Autism Diagnostic Observation Schedule (ADOS), the western gold standard for diagnosing ASDs, will be able to accurately discriminate those children that have ASDs from those that do not. The ADOS was designed to increase the likelihood of children displaying ASD type behaviours to facilitate a diagnosis, but this may negatively impact on scores obtained by African children which are socialised to be respectful as opposed to spontaneous.

This research study formed part of the larger KwaZulu-Natal-ASD1 (K-ASD) study, and aimed to explore the diagnostic ability of the ADOS in special needs schools in the greater eThekwini area.

The study design used a matched blinded sample comprising of an atypically developing ASD and non-ASD group from Black, White and Indian ethnicities. The sample came from special needs schools. The experimental group thus comprised people with ASD and the control group was a learning disabled group that did not have ASD. This study compared Autism Diagnostic Observation Schedule (ADOS) algorithm scores of a sample of 26 children (6-11 years of age) who were administered modules 1-3 of the ADOS with the clinical diagnoses for each of these children.

Using McNemar’s Westlake Schuirmann Test of equivalence it was found that the clinician diagnoses and the ADOS coding algorithm results were statistically equivalent. Thus, no significant difference existed between the two methods of diagnosis. The ADOS showed greater sensitivity in identifying symptoms associated with ASD than did the clinician diagnoses. An ANOVA revealed significant differences in the communication and the reciprocal social interaction algorithm’s. This indicates a cultural variation in behaviours, since Black participants behaved in various gestural ways that were significantly different to the manner in which Whites behaved to the ADOS testing.