Bayley Scales Of Infant and Toddler Development

Definition/Introduction

Bayley Scales of Infant and Toddler Development is an extensive formal developmental assessment tool for diagnosing developmental delays in early childhood. BSID is the commonly used abbreviation for Bayley Scales of Infant and Toddler Development. BSID scores are from a norm-referenced assessment of early childhood development. Nancy Bayley published the first BSID in 1969. The current BSID in use is BSID 4, published in 2019. BSID 4 is time-saving and has greater clinical sensitivity and accuracy when compared to BSD 3. It takes about 30 to 70 minutes to complete the test. 

Infant and Childhood Development 

Infant and childhood development comprises physical, cognitive, social-emotional, linguistic, and behavioral milestones. The differences in cultural, environmental, and genetic factors influence development. The development process is rapid and cumulative. Developmental disabilities are common and are reported in 1 in 6 children in the United States. The number of children with select developmental disabilities (autism, attention deficit hyperactivity disorder, and other developmental delays) has increased, requiring more health and education services.[1]

Developmental Assessments 

An estimated 5 to 10% of the pediatric population has a developmental disability.[2] There are 3 different strategies to detect developmental delay. 

1. Routine developmental surveillance is where the health care professional takes a short history and briefly examines it to elicit any developmental delay. Identification of developmental delay is ineffective when based solely on routine surveillance.[2]
2. A developmental screening tool is a systematic and structured tool to identify developmental delay. Although screening tools are cost and time-efficient, they are not diagnostic and have less utility in high-risk populations.[3]
3. Formal developmental tests are widely accepted and have a diagnostic utility. 

Formal Developmental Assessment Tools

The purpose of the assessment and the age groups decide the type of tool used for formal development assessment. The evaluation varies depending on the clinician's skill and the family's needs and concerns. Some are norm-referenced, and some are criterion-referenced. 

• A norm-referenced test is a standardized process of evaluating an individual against the performance of their peers.[4]
• A criterion-referenced test evaluates the development of a child against pre-specified criteria. It helps to measure whole-group performance like in school. 

Following is the list of developmental assessment tools commonly used in practice. 

1. Norm-referenced 
• BSID-4 - Bayley Scales of Infant Development-4 
• Battelle Developmental Inventory 3rd edition 
• DAYC-2: Developmental Assessment of Young Children-2 
2.  Criterion-referenced
• AEPS - Assessment Evaluation & Programming System 
• ELAP - Early Learning Accomplishment Profile 
• IDA-2: Infant Toddler Developmental Assessment -2 
3. Brigance Inventory of Early Development III (both)

The Bayley Scales of Infant and Toddler Development 

The Bayley Scales has been in practice for several decades as a useful tool for detecting early developmental delay in clinical and research settings.[5] In 1969, Nancy Bayley published the first BSID. The first BSID assessed motor and mental domains in the age group from 3 to 28 months. BSID 2nd edition, published in 1993, added a behavior rating scale and widened the age group from 1 to 42 months. BSID-III, published in 2006, assessed development from 1 to 42 months in 5 domains - cognition, motor, language, socio-emotional, and adaptive behavior. BSID 4 was published in 2019 and is currently in use. BSID 4 retained the 5 domains from BSID III.

Difference between BSID III versus BSID 4 

1. Scoring is Dichotomous (1, 0) in BSID III, whereas scoring is polytomous (2,1,0) in BSID4. 
2. Compared to BSID III, BSID 4 takes approximately 30% less time to complete the assessment. 
3. BSID 4 has questions for the caregiver.
4. Scoring is software-based in BSID III. BSID 4 scores need web-based administration.
5. BSID 4 retains the same 5 domains as BSIDIII. However, the number of items in each section has decreased. 
   1. BSID III has the following number of items in each domain 
      • Cognitive scale - 91 items 
      • Language scale - 49 items in the receptive and 48 items in the expressive domain 
      • Motor scale - 66 items in the fine motor and 72 items in the gross motor domain 
      • Social-Emotional Scale derived from Greenspan Chart.
      • Adaptive behavior scale derived from ABAS (Adaptive behavior assessment system) 
   2. BSID4 has the following number of items 
      • Cognitive scale - 81 items 
      • Language scale - 42 items in the receptive and 37 items in the expressive domain 
      • Motor scale - 46 items in the fine motor and 58 items in the gross motor domain 
      • Social-Emotional Scale is unmodified from Bayley III.
      • The adaptive behavior scale utilizes the Vineland behavior assessment system.

Purpose

The BSID determines children's developmental functioning and plans management for kids with developmental delays. BSID helps in the following ways. 

1. Early identification of intellectual delay. Re-assessments can help to monitor progress over time.
2. To individualize the management and to accommodate a child's developmental and learning needs.
3. To assess individual domains of development, such as cognitive delay,
4. To help researchers as a research tool. 

Pediatric professionals are critical in diagnosing developmental disabilities early.[6] BSID helps to detect developmental delay early and also to initiate early developmental intervention. 

Target Age Group

BSID III and BSID -4 are used for the age group starting from 16 days to 42 months.

BSID Kit 

Each BSID kit has a manual, forms, a booklet for the motor response, Social-Emotional, Adaptive Behavior domain questionnaires, caregiver reports, an observation Checklist, and a manipulative set. Cognitive, Language, and Motor scores assessment needs a web-based device. The questionnaire for caregivers includes socio-emotional and adaptive domains. Scores are given as polytomous, ranging from 0 to 2. In BSID-4 scoring, 2 are Mastery, 1 is emerging, and 0 means absent. After the assessment, the assessor summarizes standard and scaled scores. BSID administration requires training, which happens through webinars and workshops. 

Preparation 

The examiner explains to the caretaker what happens during the assessment. This helps establish rapport with the child and avoid parental concerns during the evaluation. The caretaker is advised not to talk or aid the child during the assessment, thereby avoiding skewed deviation. 

Issues of Concern