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Evid Based Nurs 11:122 doi:10.1136/ebn.11.4.122
  • Prognosis

Chorioamnionitis, gestational age, male sex, birth weight, and illness severity predicted positive autism screening scores in very-low-birth-weight preterm infants

C Limperopoulos

Dr C Limperopoulos, Montreal Children’s Hospital, Montreal, Quebec, Canada; catherine.limperopoulos{at}childrens.harvard.edu

QUESTION

What are the prevalence and risk factors of early autistic features in young children who had very low birth weights?

METHODS

Design:

inception cohort of preterm infants followed up to 18–24 months of age adjusted for prematurity.

Setting:

{a hospital in Boston, Massachusetts, USA}.*

Patients:

consecutive series of 103 preterm infants with birth weights <1500 g (median gestational age 26 wks, 60% boys, median birth weight 890 g). Exclusion criteria were known or suspected cerebral dysgenesis, dysmorphic syndromes, or chromosomal disorders. 8 infants died, and 4 were lost to follow-up.

Prognostic factors:

maternal age and temperature, acute intrapartum or antepartum haemorrhage, preterm labour, placental infection, gestational age at birth, birth weight, sex, admission Score of Neonatal Acute Physiology II (SNAP-II), duration of oxygen requirement, and abnormal magnetic resonance imaging studies.

Outcomes:

included positive screening for early autistic features (failure on ⩾2 critical items or any 3 items on 23-item Modified Checklist for Autism in Toddlers [M-CHAT]), externalising and internalising behaviour problems (T scores ⩾60 on Child Behavior Checklist), and functional delays (<2 standard deviations of normative mean on Vineland Adaptive Behavior Scale).

MAIN RESULTS

At a mean corrected age of 22 months, 25% of 91 children had a positive screen for early autistic features, 29% had problems with internalising behaviours and 13% with externalising behaviours, and 19–29% had functional difficulties. Multivariate analysis identified predictors of early autistic features (table).

Independent predictors of abnormal M-CHAT scores in preterm, very-low-birth-weight infants at 18–24 months of age adjusted for prematurity*

CONCLUSIONS

25% of preterm infants with very low birth weights had positive autism screening scores at a mean corrected age of 22 months. Male sex, chorioamnionitis, gestational age, lower birth weight, and illness severity predicted positive autism screening scores.

*Information provided by author.

ABSTRACTED FROM

Limperopoulos C, Bassan H, Sullivan NR, et al. Positive screening for autism in ex-preterm infants: prevalence and risk factors. Pediatrics 2008;121:758–65.

Clinical impact ratings: Neonatal intensive care 7/7; Paediatrics 5/7; Psychiatry 5/7

Footnotes

  • Source of funding: LifeBridge Fund; Caroline Levine Foundation; Trust Family Foundation; Canada Research Chairs Program.

Commentary

The study by Limperopoulos et al contributes new information to our knowledge of the effects of prematurity. As the authors indicate, there is consistent evidence of a higher incidence of behavioural problems throughout childhood in preterm infants compared with those born at term. However, evidence is conflicting for behavioural outcomes in adolescence and young adulthood.

Although data from the study by Limperopoulos et al suggest a higher incidence of positive autism screening scores in infants <1500 grams at birth, these findings should be considered in light of the study limitations. The M-CHAT is a screening instrument and is not diagnostic of autism disorders or even autism spectrum disorder (ASD) symptoms. The M-CHAT has a positive predictive value of about 10% in community samples of low-risk children,1 and thus, a follow-up interview is required2 to determine which children truly screen positive. An M-CHAT item may be scored “abnormal” simply because a physical limitation prevents a child from demonstrating a “normal” behaviour; this is a possible source of bias in this study given that 29% of children had functional delays in motor abilities. In addition, the sample was recruited from a previous study and was described as being consecutive; no information was provided about representativeness of the population of preterm infants for that region. With further follow-up, many of these children will not be diagnosed with any behavioural disorder or may be diagnosed with a behavioural disorder other than ASD.

As clinicians, the information from this study heightens our awareness of the potential for increased social-behavioural disorders in this vulnerable population. However, further studies are needed to establish the prevalence of ASD and its associated risk factors in preterm infants.

References

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