Results at age 8 years of early intervention for low-birth-weight premature infants. The Infant Health and Development Program

Abstract

OBJECTIVE: To reevaluate at age 8 years children who had participated during the first 3 years of life in a randomized clinical trial of special services for low-birthweight (LBW) premature infants. DESIGN: Follow-up of a randomized controlled trial of premature infants (< or = 37 weeks' gestation), stratified by 2 LBW groups (lighter [< or = 2000 g] and heavier [2001-2500 g]) and divided into intervention (n=377) and follow-up only (n=608) groups. SETTING: Eight sites serving diverse populations. PARTICIPANTS: At age 8 years, 874 children were assessed: 336 in the intervention group and 538 in the follow-up only group. INTERVENTION: The 3-year intervention consisted of home visits (birth to 3 years), child development center services (ages 1 to 3 years), and parent group meetings (ages 1 to 3 years). PRIMARY OUTCOME MEASURES: Cognitive functioning (Weschler Intelligence Scale for Children-III; Peabody Picture Vocabulary Test-Revised); academic achievement (Woodcock-Johnson Tests of Achievement-Revised); and parental reports of school performance, behavior (Child Behavior Checklist), and health (Child General Health Survey). RESULTS: At age 8 years, in the entire cohort and in the lighter LBW stratum, the intervention and follow-up only groups were similar on all primary outcome measures. Differences favoring the intervention group were found within the heavier LBW group: full-scale IQ score (4.4 points higher, P=.007), verbal IQ score (4.2 points higher, P=.01), performance IQ score (3.9 points higher, P=.02), mathematics achievement score (4.8 points higher, P=.04), and receptive vocabulary score (6.7 points higher, P=.001). On a physical functioning subscale, the whole intervention group received less favorable ratings, while the lighter LBW intervention group had lower maternal ratings assessing social limitations caused by behavior. CONCLUSION: Although at age 8 years there were modest intervention-related differences in the cognitive and academic skills of heavier LBW premature children, attenuation of the large favorable effects seen at 3 years was observed in both the heavier and lighter LBW groups. This indicates a need to develop additional intervention strategies for LBW premature children that can provide sustained benefits.