Table 1

Overview of outcomes, tools and definitions

OutcomeToolDefinitionUnit of measurement
(Neuro)developmentAges and Stages QuestionnaireTotal problem scoreMean (SD)
Five domains:

  • Communication

  • Gross motor

  • Fine motor

  • Problem solving

  • Personal social

Mean (SD)
Mildly abnormal:
≥1 and <2 SD in one domain below mean
Abnormal:
≥2 SD in any domain or multiple domains <1 SD below mean
BehaviourStrength and Difficulties QuestionnaireTotal Difficulties ScoreMean (SD)
Mildly abnormal:
>80th centile below mean
Abnormal:
>90th centile below mean
Five subscales:

  • Conduct problems

  • Emotional symptoms

  • Hyperactivity

  • Peer relationships

  • Prosocial behaviour

Mean (SD)
Subscales:*

  • Emotional problem score

  • Conduct problem score

Abnormal:
>90th centile
MortalityMedical records, Dutch population registerPerinatal death and child death up to 4 years of ageNumber (%)
All randomised children as the denominator
General health and sociodemographic informationGeneral health and sociodemographic informationFor example, the need for a medical specialist and/or developmental care, medication use in the past and present, hospital admissions and need for surgeryNumber (%)
Follow-up population as the denominator
GrowthGrowth book from Child Healthcare Centres

  • Height of child

  • Height of biological parents for calculation of target height

Mean (SD)
Abnormal:
1.6 SDS above or below target height range
BMI (kg/m2)Mean (SD)
Abnormal:

  • Underweight

  • Overweight

  • Obesity

Composite of mortality and abnormal outcomeTools as described aboveComposite of:

  1. Perinatal death and child death up to 4 years corrected age

  2. Abnormal (neuro)development

  3. Problem behaviour

Components as defined above

  • *There are no definitions of an abnormal score of the subscales hyperactivity, peer relationships and prosocial behaviour, and the validity of these separate subscales is unknown.

  • ASQ, Ages and Stages Questionnaire; BMI, body mass index; SDQ, Strength and Difficulties Questionnaire; SDS, Standard Deviation Score.