Elsevier

The Journal of Pediatrics

Volume 161, Issue 2, August 2012, Pages 222-228.e3
The Journal of Pediatrics

Original Article
Are Outcomes of Extremely Preterm Infants Improving? Impact of Bayley Assessment on Outcomes

https://doi.org/10.1016/j.jpeds.2012.01.057Get rights and content

Objectives

To compare 18- to 22-month cognitive scores and neurodevelopmental impairment (NDI) in 2 time periods using the National Institute of Child Health and Human Development's Neonatal Research Network assessment of extremely low birth weight infants with the Bayley Scales of Infant Development, Second Edition (Bayley II) in 2006-2007 (period 1) and using the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley III), with separate cognitive and language scores, in 2008-2011 (period 2).

Study design

Scores were compared with bivariate analysis, and regression analyses were run to identify differences in NDI rates.

Results

Mean Bayley III cognitive scores were 11 points higher than mean Bayley II cognitive scores. The NDI rate was reduced by 70% (from 43% in period 1 to 13% in period 2; P < .0001). Multivariate analyses revealed that Bayley III contributed to a decreased risk of NDI by 5 definitions: cognitive score <70 and <85, cognitive or language score <70; cognitive or motor score <70, and cognitive, language, or motor score <70 (P < .001).

Conclusion

Whether the Bayley III is overestimating cognitive performance or whether it is a more valid assessment of emerging cognitive skills than the Bayley II is uncertain. Because the Bayley III identifies significantly fewer children with disability, it is recommended that all extremely low birth weight infants be offered early intervention services at the time of discharge from the neonatal intensive care unit, and that Bayley scores be interpreted with caution.

Section snippets

Methods

This was a retrospective cohort study of ELBW infants with a birth weight of 401-1000 g and born at a GA of <27 weeks who were admitted to one of 20 neonatal intensive care units in the NRN and underwent comprehensive neurologic and developmental assessments at 18-22 months corrected age (CA) during calendar years 2006-2011. The infants were categorized into 2 groups, those assessed during period 1 using the Bayley II (n = 1012) and those assessed during period 2 using the Bayley III (n =

Results

Maternal and infant characteristics are presented in Table II (available at www.jpeds.com). There were slight differences between the study periods for the samples before matching. Study period 2 included slightly more educated mothers, 3% more children who received antenatal steroids, and 5% fewer children with ROP or sepsis. In unadjusted analyses, Bayley III Cog scores were significantly higher than Bayley II MDI scores, and fewer children were classified as impaired, regardless of whether a

Discussion

Our findings support our hypothesis that Bayley III Cog scores are higher than Bayley II MDI scores. This is not surprising, given that the Bayley III manual states that the Cog scores are 7 points higher than the Bayley II MDI; in our cohort, they were 11 points higher. This difference of 4 points is small but represents one-quarter SD and thus is potentially clinically significant.

The reasons for this difference are not clear. The Bayley III separation of language and Cog scores was developed

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    Supported by grants from the National Institutes of Health and the Eunice Kennedy Shriver National Institute of Child Health and Human Development. Data collected at participating sites of the National Institute of Child Health and Human Development's Neonatal Research Network were transmitted to RTI International, the data coordinating center for the network, which stored, managed, and analyzed the data for this study. The authors declare no conflicts of interest.

    A list of members of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network is available at www.jpeds.com (Appendix).

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