Selective improvement in cognitive test scores of extremely low birthweight infants aged between 2 and 5 years

Predictive value of developmental testing in the second year for cognitive development at five years of age

There is mixed evidence about the predictive validity of the Griffiths mental developmental scales. This study aimed to assess the predictive value of developmental assessments of children in their second year using the Griffiths mental development scales for neuro-developmental status at five years using the Wechsler preschool and primary scale of intelligence, revised (WPPSI-R). In a longitudinal study 253 children were assessed in their second year of life using the Griffiths scales and again at five years using the WPPSI-R. The scores were compared and the predictability of the WPPSI-R outcome on the basis of Griffiths scores was assessed. The WPPSI-R full scale IQ and the performance IQ at age five could be predicted moderately by the Griffiths general quotient (GQ) and by the personal/social scale. The Griffiths GQ was not a significant predictor of verbal IQ at age 5. The Griffiths performance scale predicted subsequent WPPSI-R performance IQ, and marginally the Full Scale IQ. For the early identification of children at risk for language delay, the Griffiths scales may not be suitable. However, a shortened form would be useful to predict overall cognitive development from the second year to school entry, focussing on the personal-social and performance scales.

Chronic lung disease and developmental delay at 2 years of age in children born before 28 weeks' gestation

INTRODUCTION

Extremely low gestational age newborns (ELGANs) are at increased risk of chronic lung disease (CLD) and of developmental delay. Some studies have suggested that CLD contributes to developmental delay.

PATIENTS AND METHODS

We examined data collected prospectively on 915 infants born before the 28th week of gestation in 2002-2004 who were assessed at 24 months of age with the Bayley Scales of Infant Development-2nd Edition or the Vineland Adaptive Behavior Scales. We excluded infants who were not able to walk independently (Gross Motor Function Classification System score < 1) and, therefore, more likely to have functionally important fine motor impairments. We defined CLD as receipt of oxygen at 36 weeks' postmenstrual age and classified infants as either not receiving mechanical ventilation (MV) (CLD without MV) or receiving MV (CLD with MV).

RESULTS

Forty-nine percent of ELGANs had CLD; of these, 14% were receiving MV at 36 weeks' postmenstrual age. ELGANs without CLD had the lowest risk of a Mental Developmental Index (MDI) or a Psychomotor Developmental Index (PDI) of <55, followed by ELGANs with CLD not receiving MV, and ELGANs with CLD receiving MV (9%, 12%, and 18% for the MDI and 7%, 10%, and 20% for the PDI, respectively). In time-oriented multivariate models, the risk of an MDI of <55 was associated with the following variables: gestational age of <25 weeks; single mother; late bacteremia; pneumothorax; and necrotizing enterocolitis. The risk of a PDI of <55 was associated with variables such as single mother, a complete course of antenatal corticosteroids, early and persistent pulmonary dysfunction, pulmonary deterioration during the second postnatal week, pneumothorax, and pulmonary interstitial emphysema. CLD, without or with MV, was not associated with the risk of either a low MDI or a low PDI. However, CLD with MV approached, but did not achieve, nominal statistical significance (odds ratio: 1.9 [95% confidence interval: 0.97-3.9]) for the association with a PDI of <55.

CONCLUSIONS

Among children without severe gross motor delays, risk factors for CLD account for the association between CLD and developmental delay. Once those factors are considered in time-oriented risk models, CLD does not seem to increase the risk of either a low MDI or a low PDI. However, severe CLD might increase the risk of a low PDI.

Poor predictive validity of the Bayley Scales of Infant Development for cognitive function of extremely low birth weight children at school age

OBJECTIVE

The Bayley Scales of Infant Development, Second Edition (BSID II) are commonly used to assess outcomes of extremely low birth weight (ELBW) infants. We sought to assess the predictive validity of the BSID II Mental Developmental Index (MDI) for cognitive function at school age.

DESIGN/METHODS

Of 330 ELBW infants admitted in 1992-1995, 238 (72%) survived to the age of 8 years, of whom 200 (84%) were tested at both 20 months' corrected age (CA) and 8 years. Mean birth weight was 811 g, mean gestational age was 26.4 weeks, 41% were boys, and 60% were black. Measures included the BSID II at 20 months' CA and the Kaufman Assessment Battery for Children (KABC) Mental Processing Composite (MPC) at 8 years' postnatal age. BSID II MDI and MPC scores were compared and the predictive validity calculated for all 200 ELBW children and for the 154 ELBW neurosensory-intact subgroup. Predictors of stability or change in cognitive scores were examined via logistic regression adjusting for gender and sociodemographic status.

RESULTS

For all ELBW children, the mean MDI was 75.6 +/- 16 versus a mean KABC of 87.8 +/- 19. For the neurosensory-intact subgroup, the mean MDI was 79.3 +/- 16 and the mean KABC was 92.3 +/- 15. Rates of cognitive impairment, defined as an MDI or KABC of <70, dropped from 39% at 20 months' CA to 16% at 8 years for the total ELBW population and from 29% to 7% for the neurosensory-intact subgroup. The positive predictive value of having an MPC of <70 given an MDI of <70 was 0.37 (95% confidence interval [CI]: 0.27, 0.49) for all ELBW infants, 0.20 (95% CI: 0.10, 0.35) for the neurosensory-intact subgroup, and 0.61 (95% CI: 0.42, 0.77) for the neurosensory-impaired subgroup. The negative predictive values were 0.98, 0.99, and 0.85 for the 3 groups, respectively. Neurosensory impairment at 20 months' CA predicted lack of improvement of cognitive function (odds ratio: 6.9; 95% CI: 2.4, 20.2). Children whose cognitive scores improved between 20 months and 8 years had significantly better school performance than those whose scores stayed at <70, but they did less well than those whose scores were persistently >70.

CONCLUSIONS

The predictive validity of a subnormal MDI for cognitive function at school age is poor but better for ELBW children who have neurosensory impairments. We are concerned that decisions to provide intensive care for ELBW infants in the delivery room might be biased by reported high rates of cognitive impairments based on the use and presumptive validity of the BSID II MDI.

Neurosensory outcome at 5 years and extremely low birthweight. The Victorian Infant Collaborative Study Group

OBJECTIVE

To establish the stability of neurosensory outcome at 5 years of age compared with 2 years of age, and to determine whether the improving survival rate of extremely low birthweight (ELBW) (500-999 g) children has been accompanied by an increase in the number of severely impaired and disabled children in the community.

METHODS

A geographically determined cohort study was made of consecutive ELBW survivors born in the state of Victoria during 1985-7, and during 1979-80, inclusive. Rates of neurosensory impairments and disabilities at 2 and 5 or more years of age were measured.

RESULTS

Of 212 children surviving to 5 years of age born during 1985-7, 211 (99.5%) had been assessed at 2 years of age, and 209 (98.6%) were assessed at 5 or more years of age. Of the 208 children seen at both 2 and 5 years, 32 children had deteriorated, 23 children had improved, and 153 were unchanged, compared with their 2 year assessment. The major reason for a change in classification was an alteration in psychological test results. Compared with ELBW children born in 1979-80, those born in 1985-7 had significant reductions in hearing and intellectual impairment. The rate of severe neurosensory disability in the 1985-7 cohort was 5.7% compared with 12.4% in children born in 1979-80.

CONCLUSIONS

The age of 2 is too early to be sure of neurosensory outcome in ELBW infants. The additional survivors born in the mid 1980s, compared with the late 1970s, are free of severe neurosensory disability at 5 years of age, with no increase in the absolute number of ELBW children surviving with severe neurosensory disability.