Developing correction factors for premature infants

• In Event: Creating Global Developmental Norms for Young Children: Opportunities and Challenges

Abstract

The third paper addresses challenges in using developmental norms for children born preterm. Healthy preterm infants are believed to attain early developmental milestones at times more consistent with their gestational age than their chronologic age (D’Augustino, 2009). Accordingly, adjustments for age are made when conducting developmental evaluations in both research and clinical settings (American Academy of Pediatrics (AAP), 2020). Current practice is to subtract the number of weeks/days the infant was born prior to 37 weeks, 0 days from their chronologic age and use this “adjusted age” for scoring of age-normed developmental tools. Despite widespread practice, there is little comprehensive data to inform several important questions.

1) How long should age adjustment for developmental evaluations continue for premature infants?
The AAP recommends 2 years, and this is generally accepted in clinical practice in high resource contexts (AAP, 2020; Ionio et al., 2016). Both shorter and longer durations of adjustment (e.g., Aylward, 2020; D’Augustino, 2009) or alternative methods (Wilson, 1987) have been suggested, and a systematic review concluded research on the most appropriate means for age adjustment is inconclusive (Wilson & Cradock, 2004).

2) Should the amount of adjustment remain constant over time (e.g., for the first two years of life)?
One longitudinal study found that unadjusted developmental scores of preterm infants were lower than average at 1, 4 and 8 months, at the lower end of average by 12 and 18 months, and in the average range at both 24 and 36 months (Harel-Gadassi et al., 2018). In a study of Dutch infants, van Buuren & Eekhout (2021) find support for a full age correction up to 24 months, but caution that a partial correction factor works better for very young children.

3) How does a correction factor function without fine-grained data on child gestational age?
Most age correction relies on accurate gestational ages to calculate the number of days and weeks a child is born early. In widespread use of a tool in the Global South, accurate estimates might not be possible. Instead, this global norming works seeks to explore how a single correction factor applied to all moderate to late premature children (32 to <37 weeks gestational age at birth) functions across the 0-3-year age range.

To investigate these questions, this study will recruit a sample of moderate-to-late premature children in a similar manner explained in Paper 1. This restricted (non-representative) sample diverse global contexts and will be recruited using the same criteria (apart from gestational age and birth weight). These data will be used to both explore how an age-dependent correction factor functions, provide insight into outstanding questions around duration of adjustment for prematurity, and how well an age correction factor performs to late- to moderate preterm infants on average, dependent on age.

Group Authors

GSED Team

Authors

• Susanne P Martin Herz, University of California - San Francisco
  Presenting Author

• Maureen Black, University of Maryland School of Medicine

• Stef van Buuren, 1) TNO, Leiden 2) Utrecht University

• Melissa Gladstone

• Magdalena Z Janus, McMaster University

• Jonathan Seiden, Harvard University