In an article being early released this week in Pediatrics, Dr. Nicole Baumer and colleagues from Harvard University used data from their hospital-based clinic population at Boston Children’s Hospital to create a new developmental milestone assessment tool for children and young adults with Down syndrome (10.1542/peds.2023-065402). This pragmatic clinical tool predicts the probability of achieving specific milestones across academic, adaptive, language, and motor milestones by age, with a range of probabilities from 15% through 90%.
In my mind, this article is a “must read” for practicing pediatricians because of the key help it provides with developmental assessment. The AAP Clinical Report “Health Supervision for Children and Adolescents with Down Syndrome” is invaluable for monitoring for potential medical problems and preventing medical complications that are most likely among those with Down syndrome. With respect to development and behavior, however, the Clinical Report guidance is very general. In this article the authors give us specific age norms that parents and clinicians can use to guide expectations for milestone achievement and evidence-based timing regarding when milestone delay warrants an evaluation.
The clinical tool is pictorial, with bar graphs expressing the 15–30%, 30–45%, 45–60%, 60–75%, and 75–90% for 25 unique milestones, graphed by age and sorted by domain. For those who used the Denver Developmental Screen Test, the format is (intentionally) very familiar.
The authors used March 2018–2023 data from the Boston Children’s Hospital Down Syndrome Program that included a developmental intake form, the Neurodevelopmental Parent Report for Outcome Monitoring, the Physical Therapy Clinical Form, and the electronic medical record for 842 patients, ranging in age from 2 months to 24 years.
Notable findings for prediction of milestone attainment among children with Down syndrome, presented for the 75% to facilitate comparison with the current CDC and AAP Milestones for neurotypical children, included:
- Reading 10 or more words was predicted with 75% probability by age 14.2 years.
- Daytime toilet training was predicted with 75% probability by 9.0 years.
- Independent walking was predicted with 75% probability by age 4.5 years.
- Use of 2-word phrases was predicted with 75% probability by age 7.7 years.
Far wider ranges in milestone attainment as compared to neurotypical children were noted. For example, first words were achieved by children with Down syndrome with 75% probability by age 1.5 years and then with 90% probability by 4.1 years. This finding is just one of many clinical pearls in this excellent article.
An accompanying commentary by Dr. Marilyn J Bull, the lead author of the AAP Clinical Report noted above, emphasizes that the work by Dr. Baumer and colleagues provides a unique framework for understanding developmental trajectories, and establishes the basis for much needed larger studies that can advance the care of children and young adults with Down syndrome.
While larger prospective studies that include international cohorts, children with specific comorbidities including autism, and children from a broader range of social and family environments will be needed, this article provides a critical and solid foundation for future research.
Let the work begin!
