A randomised controlled trial of an early preventative care program for infants born very preterm: the role of social risk on cognitive outcomes throughout early childhood

Background and Objective(s): Infants born very preterm (<32wks’ gestation) are at increased risk of a range of neurodevelopmental impairments including cognitive impairments, which are exacerbated for preterm children raised in socially disadvantaged environments. Early intervention is effective in improving the cognitive and behavioural outcomes for preterm survivors, as well as the mental health of their mothers. However, it is unclear whether the benefits of early intervention vary according to family social risk. The objective of this study was to examine the effects of an early preventative care program aimed at improving infant development, parent-infant attachment and parent mental health on cognitive outcomes at 2, 4 and 8 years in relation to social risk of the family. Study Design: Randomised controlled trial reported according to CONSORT guidelines. Study Participants & Setting: 120 infants born at <30 weeks’ gestation recruited at term equivalent age from two tertiary neonatal intensive care units. Materials/Methods: Following informed consent by parents, infants were randomised to intervention (n=61) or control group (n=59). Infants in the intervention group received a preventative care program over the first 12 months of life delivered by a physiotherapist and psychologist over 9-sessions in the home. The control group received standard care. Infants were classified as high social risk using the Social Risk Index. Cognitive outcome was assessed at 2 years’ using the Bayley Scales of Infant and Toddler Development-3rd edition and The General Conceptual Ability score of the Differential Ability Scale-2nd edition at 4 and 8 years. Assessments were completed by a blinded assessor using corrected age. Outcomes between groups were analyzed using linear regression adjusted for the stratification factors of multiple birth and brain injury. Models were fitted using generalized estimating equations to allow for correlations between twins, with an interaction term for social risk. Results: At 2, 4 and 8 years, 96%, 89% and 85% of children returned for follow-up. There was a interaction effect between intervention group and social risk on cognitive outcomes at 2 (p=0.05) and 4 years (p=0.02). Children of higher social risk in the intervention group had better cognitive outcomes at 2 years compared with the higher social risk control group children (mean difference 11.2; 95% confidence interval [CI] 1.6 to 20.8; p=0.022). This improvement in cognitive outcomes in the higher social risk intervention group remained at 4 years compared with the higher social risk control group children (mean difference 12.8; 95% CI 0.2 to 25.5; p=0.047) but was not sustained at 8 years (mean difference=6.1; 95% CI −5.1 to 17.4; p=0.29). There were no differences in cognitive outcomes at any time point in early childhood for the lower social risk groups. Conclusions/Significance: A preventative care program over the first year of life for very preterm children and their families improved cognitive outcomes at 2 and 4 years of age for those children at higher social risk compared with standard care, although these benefits were not sustained at 8 years. There were no cognitive benefits of the intervention program for children classified as lower social risk. Intervention programs to improve cognitive outcomes should be targeted towards preterm children with higher social risk. Further randomised controlled trials of interventions to improve cognitive outcomes at preschool and school age are recommended.