Validating the RAADS-R Scale for Autism Diagnosis in Adults

Key Takeaways

Study FocusRitvo Autism Asperger Diagnostic Scale-Revised (RAADS-R)
PurposeTo assist the diagnosis of Autism Spectrum Disorders in adults
MethodInternational validation study
Participants779 subjects (201 ASD, 578 comparisons)
ResultsHigh sensitivity (97%), specificity (100%), and test-retest reliability (r = .987)
ConclusionRAADS-R is a useful adjunct diagnostic tool for ASD in adults

Introduction to RAADS-R

The Ritvo Autism Asperger Diagnostic Scale-Revised (RAADS-R) is an essential instrument developed to bridge the gap in screening services for adults with autism spectrum disorders (ASD). It serves as a clinical tool for the diagnosis of higher functioning individuals in adulthood. The scale, consisting of 80 questions, underwent an international validation study involving nine centers across three continents.

The Need for RAADS-R

With the prevalence of ASD on the rise, adults are increasingly seeking services or diagnosis. The RAADS-R, a revised version of the original RAADS, was developed to provide a clinical adjunct diagnostic tool, particularly for adults with average or above-average intelligence.

The Development and Validation Process

The original RAADS, with 78 questions, showed high accuracy in differentiating ASD from non-ASD subjects. The revised RAADS-R added two questions and a fourth symptom area, “circumscribed interests,” to enhance its diagnostic capability.

Methodology of the Validation Study

Research Centers and Participants

Nine centers were selected for a diverse sample. The study population included subjects with Autistic Disorder, Asperger’s Disorder, no previous DSM-IV-TR diagnosis, and those with other DSM-IV-TR diagnoses.

Inclusion Criteria

ASD subjects had to meet DSM-IV-TR criteria, have ADI/ADOS diagnoses, and standardized IQ testing with a Full Scale IQ score of 80 or above.

Results of the RAADS-R Study

Diagnostic Accuracy

The RAADS-R scores ranged significantly, with a threshold score of 65 effectively distinguishing ASD from non-ASD subjects. The accuracy of the RAADS-R score in diagnosing ASD was remarkably high.

Group Comparisons

Mean RAADS-R scores for ASD subjects were significantly different from comparison groups across all nine research centers.

Validity and Reliability of RAADS-R

Subscale Analysis

Cronbach alpha coefficients for subscales and derived factors were good, indicating high internal consistency.

Factor Analysis

Factor analysis revealed four factors: Social Relatedness, Circumscribed Interests, Sensory Motor, and Social Anxiety.

Clinical Implications

RAADS-R Score Interpretation

A score of 65 or greater suggests a clinical diagnosis of ASD, while a score of 64 or lower suggests otherwise. However, clinical judgment should always be considered.

Limitations and Considerations

Self-report scales have inherent limitations, including the potential for subjects to misunderstand or misrepresent symptoms.

Conclusion and Future Directions

The RAADS-R has proven to be a highly specific and sensitive tool for diagnosing ASD in adults. It is recommended for use in clinical settings to assist clinicians. Further studies are warranted to expand the database and validate the scale in different populations.


  1. What is the RAADS-R scale?
    • The RAADS-R is a diagnostic tool designed to assist in diagnosing adults with Autism Spectrum Disorders.
  2. How accurate is the RAADS-R scale?
    • The RAADS-R has shown a sensitivity of 97% and a specificity of 100% in diagnosing ASD.
  3. Can the RAADS-R scale be self-administered?
    • No, it is designed to be administered by a clinician in a clinical setting.
  4. What is the significance of a RAADS-R score of 65?
    • A score of 65 or higher is consistent with a clinical diagnosis of ASD.
  5. Are there any limitations to the RAADS-R scale?
    • Yes, self-report scales can be limited by subjects’ understanding and representation of their symptoms.

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