In a recently released article in Pediatrics, Dr. Glen Aylward discusses “correction for prematurity” with respect to developmental testing. This topic is fascinating and a lot more complicated than I realized (10.1542/peds.2022-057857). Dr. Aylward brings multiple case examples that illuminate the shortcomings of a rote approach to correction of raw developmental testing scores based on weeks of prematurity. He points out that differences between raw scores (the actual result based on test performance) and corrected scores (a calculated score that adjusts the raw score based on chronological age and weeks of prematurity) are greatest among babies born at <28 weeks gestation, and this is the very population for whom assessing development may be most important. He also notes that “correction for prematurity” may essentially mislabel a developmental deficit, which will not resolve, as a (temporary) developmental delay, which would be expected to resolve with time and intervention.
In this well written article, you will learn about the details of how developmental scoring works with respect to chronological age, and the pitfalls then associated with correcting for prematurity. Since children are rarely actually tested on their birthdays, each age has “age bands” for scoring, which are the “wiggle room” associated with testing before or after the child’s birthday – the bands are narrower at younger ages and wider at older ages because developmental growth is quicker at younger ages. These bands vary between tests even for children of the same age, and Dr. Aylward notes that choosing band width is both an art and a science. When correcting for prematurity, a day or two difference in chronological age can lead to one child “staying down” at a lower age level and perhaps scoring as within normal, while another who is one day older may “jump up” to a higher band and score as delayed.
Dr. Aylward leads us through these challenges, with several more to uncover as you read this excellent short article. He then proposes a solution, while acknowledging that research and clinical work may have differing needs. The proposed solution is a technique called “continuous norming” that uses linear regression and does not assume that development is static or somehow stalled within an age band, but rather is continuous and a (nonlinear) function of age. Hopefully even with my brief and perhaps even clunky explanation you are able to see how this approach could be valuable. There’s just so much in this incredibly informative article, and I think your bands of understanding regarding how to interpret developmental testing in preterm infants will advance nicely as you read it!