Alternate scoring of the Bayley-III improves prediction of performance on Griffiths Mental Development Scales before school entry in preschoolers with developmental concerns.

BACKGROUND: The Bayley-III is widely used as an assessment tool in young children; however, its standard composite scores appear to under-estimate delay, severe and profound delay cannot be identified, and the lack of an overall score makes it difficult to compare results with later assessments. AIMS: To explore the use of Bayley-III quotient subtest and average scores, compared with composite subtest and average scores for both clinical and research purposes, comparing their ability to predict performance on the Griffiths Mental Development Scales (Griffiths) before school entry. METHOD: One hundred preschoolers referred for a diagnosis were assessed on the Bayley-III before 3.5 years. They were reassessed before school entry on the Griffiths. Composite and quotient scores were calculated and their ability to predict outcome compared across the score range. RESULTS: Averaging the three subscale quotient scores (Bayley-AQS) gave a similar mean score for this sample (61.1, SD 16.2) as for the Griffiths general quotient (Griffiths-GQ) (61.1, SD 19.6). The average composite scores (Bayley-ACS) had a significantly higher mean (74.2, SD 12.1). Correlations between the average scores on the Bayley-III and the Griffiths-GQ (0.8) were at least as strong as any of the individual subscale scores. Kappa coefficients showed that Bayley-AQS was superior to Bayley-ACS for predicting moderate and severe delay. Average change in scores was -0.1 for Bayley-AQS, and -13.2 for Bayley-ACS. Improvement in category of delay was seen in 28% of children using Bayley-AQS, and deterioration in 22%. In contrast, 5% improvement was seen using Bayley-ACS, and 65% deterioration. CONCLUSIONS: The three directly assessed subscales of the Bayley-III can be averaged to give an overall score. Bayley-AQS are a better measure of development in young children with delay than Bayley-ACS, and most children maintain their developmental classification using this method of scoring when re-assessed before school entry.