Prospective study of New Zealand very low birthweight infants: outcome at 7-8 years

Abstract

Objective: To determine the survival and sensorineural outcome at 7-8 years in very low birthweight (VLBW) infants born in New Zealand in 1986.

Methodology: In 1986 all VLBW New Zealand infants admitted to neonatal units were enrolled in a prospective study of acute retinopathy of prematurity. Surviving infants were traced and were assessed at a home visit. Parents were asked a comprehensive questionnaire, and children underwent a visual assessment including photorefraction and were tested with the Revised Wechsler Intelligence Scale for Children (WISC-R).

Results: Four hundred and thirteen VLBW infants were admitted to neonatal units in 1986, 338 (81.8%) surviving to discharge, 12 children died after discharge, 17 were traced to overseas, seven declined to participate and four were untraced, leaving 298 (96% survivors resident in New Zealand) who were assessed at a mean age of 7.6 (+/- 0.4 years, 15 children (5.0%) had severe disability, 14 (4.7%) moderate disability, and 46 (15.4%) mild disability. Blindness (vision worse than 6/60) occurred in eight children (2.7%), deafness requiring aids in four (1.3%), any form of cerebral palsy in 17 (5.7%), and an JQ score on the WISC-R > 1 SD below the mean in 62 (20.8%). There was no significant difference in outcome for children with birthweight < 1000 g and 1000-1499 g.

Conclusions: Long-term (7-8 year) survival and disability rates in this national cohort of VLBW infants is comparable with that reported from other populations. Although a majority of children have no disability a sizeable proportion do perform poorly on the WISC-R. This may relate in part to problems such as a short attention span and poor visual-motor integration.