Cognitive outcome of early intervention in preterms at 7 and 9 years of age: a randomised controlled trial

OBJECTIVE: Examine the effect of an early intervention programme on cognitive outcome at 7 and 9 years in children with birth weight (BW) <2000 g. DESIGN: A randomised controlled trial of a modified version of the Mother-Infant Transaction Program. SETTING: A single tertiary neonatal unit. PATIENTS: 146 infants were randomised into a preterm control group (74) or a preterm intervention group (72). INTERVENTIONS: The intervention consisted of eight sessions shortly before discharge and four home visits by specially trained nurses focusing on the infants' unique characteristics, temperament, developmental potential and the interaction between infants and parents. MAIN OUTCOME MEASURES: Outcomes were assessed with the Wechsler Intelligence Scale for Children (WISC-III). RESULTS: Mean BWs were 1396 (429) g in the intervention group and 1381(436) g in the control group. After adjusting for the possible clustering effects of twin pairs and maternal education, there were no significant differences in WISC-III scores at age 7 or 9. The mean difference was 4.1 points (95% CI -1.5 to 9.8 points) in favour of the intervention group at 7 years and 2.2 points (95% CI -3.4 to 7.6 points) at 9 years. At 7 years, a 6.8 points difference in the Verbal Comprehension Index (95% CI 0.5 to 13.0 points) was found in favour of the intervention group. Loss to follow-up at age 7 and 9 was 11% and 14%, respectively. CONCLUSIONS: This intervention programme did not have a sustained significant effect on overall cognitive outcomes in preterm children at age 7 and 9. TRIAL REGISTRATION NUMBER: The trial has been registered at http://www.clinicaltrials.gov (identifier NCT00222456).