Introduction
As practitioners dedicated to improving outcomes for children with autism spectrum disorder (ASD), we understand the importance of reliable and valid assessment tools. The Gilliam Autism Rating Scale-Second Edition (GARS-2) is a widely used instrument designed to aid in the identification and diagnosis of autism. A recent study titled "Factor Structure, Internal Consistency, and Screening Sensitivity of the GARS-2 in a Developmental Disabilities Sample" provides valuable insights into the efficacy of this tool. This blog post will explore the key findings of the study and discuss how practitioners can leverage these insights to enhance their assessment practices.
Understanding the GARS-2
The GARS-2 is a 42-item informant rating scale that helps identify autism and assess symptom severity. It comprises three subscales: Stereotyped Behaviors, Social Interaction, and Communication, each containing 14 items. This tool is completed by individuals familiar with the child's behavior, such as parents, teachers, or clinicians. Despite its widespread use, the GARS-2 has faced criticism regarding its factor structure and item placement.
Key Findings from the Study
The study conducted an exploratory factor analysis on the GARS-2 using ratings from special education teaching staff for 240 individuals with autism or other developmental disabilities. The analysis revealed a correlated three-factor solution, aligning with the original GARS structure. However, more than a third of the GARS-2 items were assigned to the wrong subscale, indicating potential areas for revision.
- Factor Structure: The study identified three factors: Stereotyped and Repetitive Behaviors, Social Avoidance and Withdrawal, and Atypical Language and Communication. These factors showed reasonable correspondence to the GARS-2 subscales but highlighted discrepancies in item placement.
- Internal Consistency: The internal consistency estimates for the factor-based scales were higher than previous studies, meeting or exceeding standards for screening purposes.
- Screening Sensitivity: The study reported a sensitivity of 0.65 and specificity of 0.81 for the Autism Index using a cut score of 85. This suggests that while the GARS-2 is a useful tool, it should be used with caution and not in isolation.
Implications for Practitioners
For practitioners, these findings underscore the importance of critically evaluating the tools we use in practice. Here are some recommendations based on the study:
- Review Item Placement: Consider the factor structure findings when interpreting GARS-2 results. Be aware of items that may not align with their intended subscales.
- Use as Part of a Comprehensive Assessment: Given the moderate sensitivity and specificity, the GARS-2 should be used alongside other diagnostic tools and clinical observations.
- Advocate for Instrument Revision: Engage with researchers and stakeholders to support revisions that improve the alignment of items with their intended constructs.
Encouraging Further Research
The study highlights the need for ongoing research to refine and validate assessment tools like the GARS-2. Practitioners can contribute by participating in research studies, providing feedback on assessment tools, and staying informed about the latest developments in the field.
To read the original research paper, please follow this link: Factor Structure, Internal Consistency, and Screening Sensitivity of the GARS-2 in a Developmental Disabilities Sample.
