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Extremely Preterm Born Children Are at Very High Risk for Developing Autism Spectrum Disorder
Advances in neonatal and perinatal care have increased the survival rate of extremely preterm children, children born before 28 weeks of gestation. Although this is a positive evolution, follow-up studies have shown that these children are at an increased risk of developmental problems in various domains. Recent evidence also suggests a link between prematurity and autism spectrum disorder (ASD) (Johnson et al., 2010; Limperopoulos, 2009; Moore et al., 2012; Stephens et al., 2012). It appears that ASD is an under-recognized problem in this group of children.
Objectives:
Our study aims to investigate the prevalence of ASD in a cohort of extremely preterm children who are now in their early teens. Previous prevalence studies were predominantly based on screening instruments and did not include diagnostic confirmation. By using diagnostic instruments in addition to screening instruments to determine the prevalence of ASD, we want to provide a more reliable picture.
Methods:
We conducted a follow-up study of the EPIBEL children. EPIBEL is an acronym of a study investigating Extremely Preterm Infants in BELgium. Perinatal data of all the surviving children born between 22 and 26 completed weeks of gestation in a two-year period (January 1, 1999 to December 31, 2000) in Belgium were collected (Vanhaesebrouck et al., 2004). At 3 years of age, the cognitive, language and motor development of the 95 Flemish children was re-assessed by our research group (De Groote et al., 2007). This group was visited again between the ages of 11 and 13. In the first part of this study, parents were asked to complete the Social Communication Questionnaire (SCQ; Rutter, Bailey & Lord, 2003) and the Social Responsiveness Scale (SRS; Constantino & Gruber, 2005). In the second part, diagnostic evaluation of the children who already received a clinical diagnosis and of the positive screens included the Autism Diagnostic Observation Schedule (ADOS; Lord, Rutter, DiLavore & Risi, 1999). Parents are currently being interviewed with the Autism Diagnostic Interview – Revised (ADI-R; Rutter, Le Couteur & Lord, 2008).
Results:
Results suggest that the prevalence of ASD is very substantially higher in this group than in the general population. Of the participating children, 24.4% were clinically diagnosed with ASD. In addition, 13.3% of the children scored above the cut-off of the ADOS. Significant correlations with the ADOS severity score were found for birth weight, the 5 minute Apgar score and for the Mental and Psychomotor Developmental Indexes of the Bayley Scales of Infant Development (BSID-II; Bayley, 1993) at age three. Male gender was also significantly associated with being diagnosed with ASD.
Conclusions:
This study confirms findings of previous research which suggested an elevated rate of ASD in extremely preterm born children. In this Flemish cohort of children born before 26 completed weeks of gestation, the prevalence of ASD was found to be 37.8% after a screening procedure and a clinical diagnostic evaluation and/or a research evaluation with the ADOS. It is clear that extreme preterms are a high-risk group for developing ASD that deserves increased clinical and research attention.