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

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.