Neurocognitive testing of very low birth weight infants at an age of 4 years

Aims: Very low birth weight infants (VLBWI, birth weight <1500g) are known to have increased risks for developmental delay. In order to describe long-term outcome in these children German quality control programs have introduced neurocognitive testing at an corrected age of 24 months. The long-term predictive value of test results in this age group, however, is known to be poor. We report on the results of a follow-up program of VLBW infants until age of 4 years using the Kaufman-Assessment Battery for Children-I (K-ABC) at our institution.

Methods: 62 children born between 2003 and 2006at our perinatal center with a birth weight below 1500g were tested with the K-ABC-I (mean birth weight 1075g (SD: 316); mean gestational age 29 weeks (SD: 2)) at an age of 4 years. In 47 children test results of the Bayley testing at corrected age of 36 months were available.

Results: The overall cognitive score was 94.1 (SD: 11.7). The mean within the sequential processing subscale was significantly higher than the mean of the simultaneous processing subscale (96.0 (13.9) vs. 86.5 (15.8), p<0.0001).

2 Children (3.2%) had values below 70, another 5 (8.1%) showed values between 70 and 84, 4 children (6.4%) scored higher than 120.

There was no correlation with either birth weight or gestational age and K-ABC test results.

The correlation between Bayley test results at an corrected age of 36 months and K-ABC results at 48 months was weak (r=0.21).

Conclusion: 11% of all VLBW infants showed lower than average intelligence at an age of 48 months. The individual predictive value of the Bayley Scale testing at an age of 36 months was poor. Neurocognitive testing beyond early childhood in VLBW infants seems necessary in order to describe better deficits, risk factors and needs for special care.

K-ABC - development VLBWI