Screening for autism in extremely preterm infants: problems in interpretation

Abstract

AIM The aim of this article was to report the prevalence of, and risk factors for, positive autism screens using the Modified Checklist for Autism in Toddlers (M-CHAT) in children born extremely preterm in England.METHOD All children born at not more than 26 weeks' gestational age in England during 2006 were recruited to the EPICure-2 study. At 2 years of age, postal questionnaires incorporating the M-CHAT and additional developmental questions were sent to the parents of each survivor (n=1031; 499 male, 532 female), of which 523 (266 male, 257 female; 51%) were returned completed. RESULTSThe prevalence of positive M-CHAT screens in this extremely preterm population was 41% (216 ⁄ 523; 130 male; 86 female). Severe bronchopulmonary dysplasia, administration of postnatal steroids, late-onset bacteraemia, and being male were statistically significantly associated with a positive screen. Coexisting disabilities were present in 320 (62%) children. Of 200 children without disability, 16.5% screened positive. In contrast, 63 (95.5%) of those with severe motor impairment (odds ratio 42; 95% confidence interval [CI] 12.9-135) and 175 (55.9%) of those with cognitive impairment (odds ratio 5.3; CI 3.5-8) screened positive. All children with a significant vision or hearing impairment screened positive. INTERPRETATIONThe prevalence of positive M-CHAT screens in extremely preterm children is high, especially in children with neurodevelopmental impairment. Positive screens should be interpreted in the light of other neurodevelopmental sequelae in clinical practice to avoid falsepositive referrals.Preterm birth is an established risk factor for psychiatric disorders including autism spectrum disorders (ASDs). In a recent whole-population study, we reported that 8% of 219 children born at not more than 25 completed weeks of gestation met the diagnostic criteria for ASD in middle childhood. 1,2 This is markedly higher than the 0.2 to 0.7% prevalence reported in the general population. 3,4 As early diagnosis and behavioural intervention for ASD significantly improves outcome, 5,6 screening may be particularly important in high-risk groups such as extremely preterm children. The advent of autism screening tools, such as the Modified Checklist for Autism in Toddlers (M-CHAT), 7 has facilitated screening in infancy, and the use of this parentreport questionnaire is increasing in both clinical and research outcome evaluations. A high prevalence of positive autism screens in extremely preterm infants has been reported in selected American cohorts, 8,9 but concerns have been raised regarding the interpretation of such results in light of the high prevalence of other neurodevelopmental impairments. 8,10 In order to advance our understanding of screening for early symptoms of autism in extremely preterm children, we used the M-CHAT in a postal questionnaire format as part of a national population-based study of extremely preterm infants born in England. We investigated the prevalence of and neurodevelopmental associations with positiv...

Extremely Preterm Born Children at Very High Risk for Developing Autism Spectrum Disorder

“…Two recent studies even found a gradual increased risk of traits of ASD with shorter gestation (18,19). Screening studies in early childhood revealed that features of ASD have a disproportionally higher prevalence in the preterm compared to the general population (20)(21)(22)(23). Studies with the Modified-Checklist for Autism in Toddlers (M-CHAT) (24,25) found screening percentages between 21 and 41% (20)(21)(22).…”

“…Since several studies indicated that the high frequency of neurological, cognitive and sensory difficulties may give rise to false-positive screening classifications for ASD (21,22,26,31), a diagnostic evaluation to confirm true rates of ASD is indicated. To our knowledge, only one study confirmed a positive ASD screen with a further assessment in late childhood: of the 15.8% children with a positive screen on the Social Communication Questionnaire (SCQ) (32), 8% was diagnosed with ASD following a psychiatric evaluation at 11 years (33).…”

Behavioural outcomes and psychopathology during adolescence

“…This was fuelled in part by reports of a markedly high prevalence of autistic features in preterm infants, with up to 25% of very preterm/VLBW [42,43] and 41% of extremely preterm infants [44] screening positive for the risk of ASD using the Modified Checklist for Autism in Toddlers (M-CHAT). Caution should be observed when interpreting such reports as the specificity of screening for ASD in infancy is particularly confounded in preterm populations in which there is a high prevalence of neurodevelopmental impairment and global developmental delay.…”

Autism in Toddlers Born Very Preterm

“…3,4,6 These impairments also are associated with the high positive screen rates reported in the preterm population. 5,8,[13][14][15][16] Although these screening studies overestimate diagnostic outcome, children born preterm often demonstrate a profile of early social communication and emotional difficulties consistent with ASD characteristics. 4,14 The variability in the rates of ASD in these studies is likely influenced by the eligibility of the preterm population, age assessed, loss to follow-up, and the specific assessment tool used.…”