Screening for autism spectrum disorder in young children with trisomy 21

Abstract

Children with trisomy 21 are at increased risk for autism spectrum disorder. A prevalence between 9 and 42% is reported. Early diagnosis has multiple potential benefits for the child and its environment.

Several screening tools have been developed for children with intellectual disabilities. The PDD-MRS scale (Pervasive Developmental Disorder in Mentally Retarded Persons Scale) was originally designed and validated in Dutch. We aimed to evaluate the accuracy of this scale as screening test.

Method

22 children (11 girls, 11 boys) with trisomy 21, aged 24-84 months (mean 56,2 months) were included and screened with the PDD-MRS. After screening all children completed a comprehensive multidisciplinary diagnostic evaluation at the Centre for Developmental Disorders. The results of the PDD-MRS screening test and the full multidisciplinary evaluation were compared.

Results:

Autism spectrum disorder was diagnosed with multidisciplinary diagnostic evaluation in 59% of our population. The PDD-MRS results in two outcome scores: a clean points score based on the parents’ answers to the questionnaire and a clinical score based on both the answers and the observation of the child’s behaviour by the examiner. The sensitivity and specificity of PDD-MRS were: clean points score: sensitivity 0.69, specificity 0.56; clinical score: sensitivity 0.92, specificity 0.67. The feasibility of the PDD-MRS was good.

Conclusion:

In our population, the accuracy of the PDD-MRS scale as screening test is moderate. The sensitivity of the clinical score, combining parents’ answers and functional observation, is clearly better than the clean score, but that might be determined by the examiner’s experience.