Neurodevelopmental Impairment : Who Defines It?
Neurodevelopmental impairment (NDI) is a key neonatal outcome measure- often the primary outcome. It is frequently included in composite outcomes such as “death or NDI,” which raises significant ethical and scientific concerns.
Why Use NDI as a Primary Outcome is Problematic
NDI itself is a composite measure, encompassing:
- Developmental delay (often assessed by the Bayley Scales).
- A permanent motor disorder, cerebral palsy (CP).
- Significant hearing or visual impairment.
This classification was developed by clinicians and researchers to quantify the neurological impact of prematurity. However, it has several limitations:
- Change in classification: A low developmental score at 2 years does not necessarily predict long-term intellectual disability. In the CAP study, only 18% of children with a low Bayley score at 18 months had a low IQ at 5 years.
- A child diagnosed with CP at 2 years may have a different classification as they grow.
- Unequal criteria: Some impairments (e.g., blindness, severe hearing loss) are more permanent but represent a small portion of NDI.
Additionally, grouping NDI with death as a composite outcome implies they carry the same weight. This can skew the interpretation of medical interventions, making a treatment that reduces mortality appear ineffective if survivors have lower Bayley scores.
Parents’ Perception of NDI
Extremely preterm infants, when they come back to follow-up at 18-24 months are classified in one of 4 categories: no NDI, mild, moderate and severe NDI. A new Canadian study (Richter et al., 2025, Pediatrics) examined how parents perceive their child’s neurodevelopment. We asked parents in which category they would classify they child, without telling them the medical classification (and before investigation during follow-up). Over 1,000 extremely preterm infants were evaluated using standard NDI criteria. Before the formal assessment, parents were asked if they believed their child had a developmental impairment.
Results revealed a striking disconnect between medical classification and parental perception:
Toward a New definition of describing outcomes
Traditional research often relies on binary outcome measures (yes/no), but the real impact on children and families is far more nuanced.
Instead of using overly simplistic composite measures (“death or NDI””), we should:
- Consider parents’ priorities and the diversity of developmental trajectories.
- Assess overall child functioning, including behavior, feeding, and sleep.
- Adopt more flexible outcome measures that better reflect the complexity of prematurity’s long-term effects.
Diagnoses are important, we all wish to decrease the incidence of cerebral palsy, on the other hand, function is also important. We wish function will be measured in large networks and described in future trials.
Learn more: https://pubmed.ncbi.nlm.nih.gov/39786567/