Neurocognitive testing in West African children 3-6 years of age: Challenges and implications for data analyses.

OBJECTIVE: When testing African children with developmental and cognitive standardized tests from high-income countries (HIC), investigators are uncertain as to whether to apply the HIC norms for these tests when standardizing a child's raw-score performance on the basis of age. The present study compared the construct validity of both raw and HIC-based standardized scores for the Mullen Scales of Early Learning (MSEL) and the Kaufman Assessment Battery in Children - 2nd edition (KABC-II) for Beninese children in a rural setting from three to six years of age.
METHODS: Seventy-four children 3-4 yrs of age were assessed with the MSEL, and 61 eligible older children (5-6 yrs of age) were assessed with the KABC-II. Assessors spoke the instructions to the children and caregivers for the assessment items in the local language. The developmental quality of the home environment was evaluated with the Caldwell Home Observation for Measurement of the Environment (HOME) inventory, and a material possessions and housing quality checklist was used as a measure of socio-economic status (SES). Children's mothers were given the Raven's Progressive Matrices test (nonverbal cognitive ability), and the Edinburgh Postpartum Depression Scale (EPDS) (emotional wellbeing).
RESULTS: For the MSEL, the 4-yr old group performed significantly better than the 3-yr old group on both the raw and standardized score comparisons for all scales. These differences were attenuated when using standardized scores, although the MSEL standardized cognitive composite score was still highly significant between years of age. When comparing 5- to 6-yr olds on KABC-II subtest and global scale performance, comparisons between the raw and standardized mean score performances were much less consistent. Generally, 6-yr olds performed significantly better than 5-yr olds on the raw score comparisons on the KABC-II subtests, but not so for standardized scores. Parent-child interactions assessed through the HOME measure was associated with both raw and standardized MSEL cognitive composite score outcomes on a multiple regression analysis. SES was the only significant predictor for KABC-II raw and standardized outcomes.
CONCLUSION: Standardization using HIC norms was not optimal, resulting in minimal impact to account for age when using the MSEL, and lower scores for oldest children compared with youngest children when using the KABC2. This is likely due to children in Benin drifting away from HIC-based norms with each passing year of age, systematically lowering standardized performance measures. These findings support the importance of having a local comparison group of reference or control children to allow for adjusted (for age, HOME, and SES) raw score comparisons when using western-based tests for developmental and neuropsychological evaluation.