The DARB was developed by researchers from the Stanford Autism Center to enable detailed assessment of key types of restricted and repetitive behaviors and interests (RRB) clinical domain. These include repetitive sensory motor behaviors, insistence on sameness, restricted interests, unusual interests, sensory sensitivity, self-injurious behaviors, obsessions and compulsive behaviors and repetitive language. These RRB are primarily seen in people with autism spectrum disorder, however, they also occur in a range of other neurodevelopmental (e.g., attention-deficit hyperactivity disorder), neurogenetic (e.g., Fragile X) and in certain neuropsychiatric conditions (e.g., obsessive compulsive disorder). Therefore, DARB allows researchers and clinicians to gain a detailed insight into a wide range of distinct RRB subdomains not simultaneously captured by any of the existing instruments.
DARB was developed, refined and validated through several iterative steps.
Development: RRB are a complex and multifaceted clinical domain. Thus, it was first necessary to identify all relevant RRB subdomains that need to be captured by the DARB. This was achieved through a conceptual and data-driven integration including meta-analysis of the RRB factor analytic studies published to date. This process enabled us to identify RRB structure that encompassed the following eight distinct subdomains: repetitive sensory-motor behaviors , insistence on sameness, restricted interests (interests typical in terms of their content but atypical in terms of their intensity and/or inflexibility), unusual interests (interests atypical in terms of content [e.g., interest in traffic lights]), self-injurious behaviors, sensory sensitivity, obsessive-compulsive behaviors, and repetitive language. Following this, we have generated multiple items for each of the targeted RRB constructs (≥ 15 per construct) to ensure in-depth coverage. Concepts guiding item development included (i) coverage of the full range of symptom severity and presentations and (ii) applicability across the cognitive functioning range and lifespan.
Refinement: Preliminary list of DARB items was evaluated by 40 experts and 19 parents for the content validity, developmental appropriateness, and clinical relevance. Experts in RRB and/or measurement evaluated DARB items in terms of their clarity and were asked to suggest whether any of the potential RRB subdomains were missed and whether additional items were needed. In addition, experts rated (on a 5-point Likert scale) how well each of the items measures each of the specific scales. Suggested improvements or clarifications of item wording were incorporated. Quantitative ratings provided strong evidence for face validity. Parents of youth with autism evaluated items for clarity and were asked to indicate whether any potentially relevant RRB were missed. Adjustments were made to 11 items to improve the clarity or simplify reading level; two items were removed and one item nominated by four parents was added.
Validation: Parents of 1,892 parents of youth with autism (Mage= 10.81 years, SDage= 4.14; 22.4% females) completed the DARB and several other instruments to evaluate convergent and divergent validity. A subsample of 450 parents completed the DARB after two weeks to evaluate test-retest stability. Factor analysis indicated that the following eight-factor structure closely matching hypothesized factors provided the best fit to the data: (CFI= .932; TLI=.922; RMSEA= .044, close fit test p= .937; SRMR =.036):
- repetitive sensory-motor behaviors (example item, “Does your child rock body, either when standing or sitting?”)
- insistence on sameness (example item, “Does your child insist that particular activities have to take place at the exact same time of the day regardless of the situation or context?”)
- restricted interests (example item, “Does your child show interest in fictional characters [Examples: from cartoons, movies, comics, etc.]?”);
- unusual interests (example item, “Does your child have a fascination with dates and/or time [Examples: they memorize everyone’s date of birth or memorizes timetables, etc.]?”);
- self-injurious behaviors (example item, “Does your child Pull eyebrows or eyelashes?”);
- sensory sensitivity (example item, “Does your child react more strongly than other people to loud or sudden noises?”);
- obsessive-compulsive behaviors (example item, “Does your child avoid touching items or objects touched by other people?”); and
- repetitive language (example item, “Does your child Immediately repeat/echo what you or others have said?”).
The derived eight-factor showed invariance across sex, age and IQ. Importantly, item response theory (IRT) analysis provided strong evidence for unidimensionality of each subscale. Internal consistency, indicated by Ω, ranged from good to excellent for all DARB factors. IRT analyses indicated excellent conditional reliability for the DARB total score and all subscales from very low (theta -2) to extremely high scores (theta +5). Two-week test-retest stability was excellent (ICC ranging from 0.89 (RSMB) to 0.91 (OC). Associations between the DARB subdomains and the corresponding Repetitive Behavior Scale-Revised, Repetitive Behaviour Questionnaire-2 and Sensory Experience Questionnaire subscales had large effect sizes. DARB subscales showed distinct pattern of associations with key demographic cognitive and clinical correlates.
Where can I found out more about the research using the DARB
The following paper provides more detailed information on DARB development and validation:
Uljarević, M., Frazier, T. W., Jo, B., Scahill, L., Youngstrom, E. A., Spackman, E. K., Phillips, J. M., Billingham, W., & Hardan, A. Y. Dimensional Assessment of Restricted and Repetitive Behaviors: Development and Preliminary Validation of a New Measure. Journal of American Academy of Child and Adolescent Psychiatry (early online).
To keep up to date with the most recently published papers that used the DARB, please click on the “Research using DARB” tab below.