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Stability of Bayley Motor Scale scores in the first year of life
J Coryell1, B Provost, I J Wilhelm
1Department of Physical Therapy, Sargent College of Allied Health Professions, Boston University, MA 02215.
Insights
Bayley Motor Scale scores in infants showed rank stability but significant score variations, with 4-month scores potentially inflating results. Scores at 3 and 8 months best predicted outcomes.
Area of Science:
- Developmental Pediatrics
- Infant Motor Development Assessment
Background:
- Assessing infant motor development is crucial for early identification of potential delays.
- The Bayley Scales of Infant Development Motor Scale is a widely used tool for this purpose.
- Understanding score stability is essential for accurate interpretation of developmental assessments.
Purpose of the Study:
- To evaluate the stability of Bayley Motor Scale scores in infants during their first year of life.
- To determine if individual infant scores remain consistent across multiple testing ages.
- To identify patterns of score variation and their relationship to developmental outcomes.
Main Methods:
- Longitudinal study involving 23 infants (15 low-risk, 8 high-risk).
- Collected Bayley Motor Scale scores at 2, 3, 4, 8, and 12 months.
- Assessed developmental outcomes at 24 or 36 months for most participants.
Main Results:
- Infant ranks remained stable overall and for those with normal outcomes, but scores varied significantly between tests.
- Infants with non-normal outcomes showed less score variability.
- A notable peak in scores at 4 months was observed in most variation patterns.
- Scores at 3 and 8 months demonstrated the strongest predictive accuracy for outcomes.
Conclusions:
- A single Bayley Motor Scale score may not fully represent an infant's motor abilities due to score fluctuations.
- The 4-month assessment may potentially inflate scores, requiring careful consideration.
- Scores at 3 and 8 months are more reliable indicators for predicting later developmental outcomes.
Abstract:
The purpose of this study was to determine whether Bayley Motor Scale scores were stable in infants during the first year of life, that is, whether each individual infant's score was essentially the same at each of the five test ages. Subjects were 15 low-risk and 8 high-risk infants with Bayley Scales of Infant Development Motor Scale scores at 2, 3, 4, 8, and 12 months. All high-risk and most low-risk infants also had outcome scores at either 24 or 36 months. For the group as a whole, and for all infants with "normal" outcomes, subjects did not change ranks over the six test ages (ie, high-scoring infants' ranks remained high and low-scoring infants' ranks remained low), but scores varied significantly from test to test. Scores of infants with "non-normal" outcomes did not vary significantly from test to test. The highest and lowest scores of 75% of the infants with normal outcomes and 57% of the infants with non-normal outcomes differed significantly. Four patterns of variations of Bayley Motor Scale scores over the five test ages of the first year after birth were identified. The first pattern included three infants with the most stable scores. The three remaining patterns were different from each other, but a consistent feature of each was a peak at 4 months. Finally, scores at 3 and 8 months were best able to correctly identify outcome. A single Bayley Motor Scale score may not reflect an infant's true abilities; some factor may be inflating scores at age 4 months.