Saturday, August 27, 2011

Assessment Tools for ASD: Diagnostic Validity


Diagnostic validity is an especially important psychometric characteristic to consider when evaluating the quality and usefulness of a test or screening instrument. It refers to an instrument’s accuracy in predicting group membership (e.g., ASD versus non-ASD). Diagnostic validity can be expressed through metrics such as sensitivity and specificity, and positive predictive value (PPV) and negative predictive value (NPV).  Sensitivity and specificity are measures of a test's ability to correctly identify someone as having a given disorder or not having the disorder. Sensitivity refers to the percentage of cases with a disorder that screen positive. A highly sensitive test means that there are few false negative results (individuals with a disorder who screen negative), and thus fewer cases of the disorder are missed. Specificity is the percentage of cases without a disorder that screen negative. A highly specific test means that there are few false positive results (individuals without a disorder who screen positive). False negatives decrease sensitivity, while false positives decrease specificity.  An efficient assessment tool should minimize false negatives as these are individuals with a likely disorder who remain unidentified.  Sensitivity and specificity levels of .80 or higher are generally recommended.
Positive Predictive Value (PPV) and Negative Predictive Value (NPV) are also important validity statistics that describe how well a screening tool or test performs. The probability of having a given disorder, given the results of a test, is called the predictive value. PPV is interpreted as the percentage of all positive cases that truly have the disorder. PPV is a critical measure of the performance of a diagnostic or screening measure, as it reflects the probability that a positive test or screen identifies the disorder for which the individual is being evaluated or screened. NPV is the percentage of all cases that screened negative that are truly without the disorder. The higher the PPV and NPV values, the better the instrument at correctly identifying cases. It is important to recognize that PPV is determined by the sensitivity and specificity of the test and the prevalence of disorder in the population being tested. For example, an ASD-specific screening measure may be expected to have a higher PPV when utilized with a known group of high-risk children who exhibit signs or symptoms of developmental delay, social skills deficits, or language impairment. In fact, for any diagnostic test, when the prevalence of the disorder is low, the positive PPV will also be low, even using a test with high sensitivity and specificity.
Practitioners should carefully review the psychometric properties of assessment tools and select those with high sensitivity and PPV values. For example, rating scales such as the Autism Spectrum Rating Scales (ASRS) and Social Communication Questionnaire (SCQ) have, on average, high sensitivity and PPV, while instruments such as the Gilliam Autism Rating Scale (GARS) underestimate the likelihood of children with autism being classified as having autism, indicating poor sensitivity.
Lecavalier L. (2005). An evaluation of the Gilliam Autism Rating Scale. Journal of Autism and Developmental Disorders, 35, 795-805.
Norris, M. & Lecavalier, L. (2010). Screening accuracy of level 2 autism spectrum disorder rating scales: A review of selected instruments. Autism, 14, 263-284.

© Lee A. Wilkinson, PhD

Thursday, August 25, 2011

Autism Advocacy Workshop


Palm Beach County School District psychologist, Lee A. Wilkinson, PhD, will be present a workshop, Autism Spectrum in Schools: Assessment and Advocacy, at the fifth annual STatewide Advocacy Network on Disabilities (STAND) Pinellas Accessing Resources Conference (SPARC) on September 24th, in Largo, FL. The SPARC 2011 Conference brings together exhibitors from across the nation to showcase the best resources available to special education advocates. Professional educators, therapists, psychologists, and parents alike will have an opportunity to learn about resources beneficial to special needs students as well as all children. Attendees can choose from 60 different breakout sessions, browse more than 150 different exhibitors, earn credit toward professional license recertification, and meet representatives from state, regional and local organizations.
Dr. Wilkinson is the author of the award-winning book, A Best Practice Guide to Assessment and Intervention for Autism and Asperger Syndrome in Schools, from Jessica Kingsley Publishers. His work was honored with a gold medal in the 2011 Next Generation Book Awards Education/Academic Category and finalist awards for the 2011 National Association for Special Educational Needs (NASEN) Educational Needs/Academic Book of the Year and 2010 National Best Book Awards.


Monday, August 15, 2011

High Recurrence Risk for Autism in Siblings

A research study published in the journal Pediatrics suggests that nearly 1 in 5 children who have an older sibling with autism will also develop the disorder at a rate much higher than previously thought. Earlier estimates put the risk at between 3 and 10%, but a new study found a substantially higher risk rate of 18.7%, on average.
Researchers in the U.S., Canada and Israel followed 664 infants from 12 US and Canadian sites who had at least one older brother or sister with an autism spectrum disorder. Overall, 132 infants or approximately 19% received an autism diagnosis by their third birthday.
The highest rates were in infants who had at least two older siblings with autism – 32% also developed the disorder. Boys were nearly three times as likely to develop autism as girls, with a recurrence rate of 26.2% versus 9.1%.
The study’s lead author Sally Ozonoff, a psychiatry and behavioral sciences professor with the Mind Institute at the University of California at Davis, noted that 80% of siblings studied did not develop autism, and that the prevalence rate was an “average.” According to Ozonoff, “It’s important to recognize that these are estimates that are averaged across all of the families. So, for some families, the risk will be greater than 18 per cent, and for other families it would be less than 18 per cent.”  “At the present time, unfortunately, we do not know how to estimate an individual family’s actual risk.”
The study has important implications for both parents and professionals.  Families and primary care professionals should be especially observant with infants whose older siblings have been diagnosed with an autism spectrum disorder. Early identification and intervention are critically important to outcome. Ozonoff and her colleagues comment, “The red flags identified should be followed by immediate referral for infant intervention rather than adopting a 'wait-and-see' attitude because early specialized intervention is considered best practice for ASD and may represent the best hope for reducing symptoms and overall disability in high-risk infants who are developing ASD."
Reference:
Ozonoff S, et al. Recurrence risk for autism spectrum disorders: a baby siblings research consortium study. Pediatrics 2011; DOI: 10.1542/peds.2010-2825.

Friday, August 12, 2011

Best Practice Conference: STAND-Pinellas Accessing Resources Conference (SPARC)


September 24th, 2011 
Saturday, 8:00am - 4:30pm
Fitzgerald Middle School 
6410 118th Ave N, Largo, FL
The fifth annual STatewide Advocacy Network on Disabilities (STAND) Pinellas Accessing Resources Conference (SPARC) brings together exhibitors from across the nation to showcase the best resources available to special education advocates. Professional educators, therapists, psychologists, counselors and parents alike will have an opportunity to learn about resources beneficial to special needs students as well as all children.
  •  Choose from 60 different breakout sessions     
  •  Earn credit toward professional license sessions. 
  •   Browse more than 150 different exhibitors. 
  •  Earn credit toward professional license recertification.               
  •  Meet representatives from state, regional and local organizations to answer your  questions. 

                     Register online now!

          Because every child deserves a voice!


Thursday, August 4, 2011

Legally Appropriate Educational Services for Students with ASD

Since Congress added autism as a disability category to the Individuals with Disabilities Education Act (IDEA) in 1990, the number of students receiving special education services in this category has increased over 900 percent nationally. It’s critically important that educators understand the provisions for providing legally and educationally appropriate programs and services for students identified with ASD.
 Research indicates that education is the most effective treatment/intervention for children with ASD. The most recent reauthorization of the Individuals with Disabilities Education Act (IDEA 2004) <http://idea.ed.gov/explore/home >entitles all students with disabilities to a free, appropriate public education (FAPE). FAPE encompasses both procedural safeguards and the student’s individual education program (IEP). The IEP is the cornerstone for the education of a child with ASD. When a student is determined eligible for special education services, an IEP planning team is formed to develop the IEP and subsequently determine placement.
Although clinical diagnoses, psychiatric reports, and treatment recommendations can be helpful in determining eligibility and educational planning, the provisions of IDEA are the controlling authority with regard to decisions for special education. While clinical information is professionally helpful, it is neither legally required nor sufficient for determining educational placement. Therefore, it’s especially important for administrators, parents, advocates, teachers and non-school professionals to keep in mind that when it comes to special education, it is state and federal education codes and regulations (not clinical criteria) that determine eligibility and IEP planning decisions. Legal and special education experts recommend the following guidelines to help school districts meet the requirements for providing legally and educationally appropriate programs and services to students with ASD.
1. School districts should ensure that the IEP process follows the procedural requirements of IDEA. This includes actively involving parents in the IEP process and adhering to the time frame requirements for assessment and developing and implementing the student’s IEP.  Moreover, parents must be notified of their due process rights. It’s important to recognize that parent-professional communication and collaboration are key components for making educational and program decisions.
2. School districts should make certain that comprehensive, individualized evaluations are completed by school professionals who have knowledge, experience, and expertise in ASD. If qualified personnel are not available, school districts should provide the appropriate training or retain the services of a consultant.
3. School districts should develop IEPs based on the child’s unique pattern of strengths and weaknesses. Goals for a child with ASD commonly include the areas of communication, social behavior, adaptive skills, challenging behavior, and academic and functional skills. The IEP must address appropriate instructional and curricular modifications, together with related services such as counseling, occupational therapy, speech/language therapy, physical therapy and transportation needs. Evidence-based instructional strategies should also be adopted to ensure that the IEP is implemented appropriately.
4. School districts should assure that progress monitoring of students with ASD is completed at specified intervals by an interdisciplinary team of professionals who have a knowledge base and experience in autism. This includes collecting evidence-based data to document progress towards achieving IEP goals and to assess program effectiveness.
5. School districts should make every effort to place students in integrated settings to maximize interaction with non-disabled peers. Inclusion with typically developing students is important for a child with ASD as peers provide the best models for language and social skills. However, inclusive education alone is insufficient, evidence-based intervention and training is also necessary to address specific skill deficits. Although the least restrictive environment (LRE) provision of IDEA requires that efforts be made to educate students with special needs in less restrictive settings, IDEA also recognizes that some students may require a more comprehensive program to provide FAPE. 
6. School districts should provide on-going training and education in ASD for both parents and professionals. Professionals who are trained in specific methodology and techniques will be most effective in providing the appropriate services and in modifying curriculum based upon the unique needs of the individual child.
References and further reading:
Individuals with Disabilities Education Improvement Act of 2004. Pub. L. No. 108-446, 108th Congress, 2nd Session. (2004). 
Mandlawitz, M. R. (2002). The impact of the legal system on educational programming for young children with autism spectrum disorder. Journal of Autism and Developmental Disorders, 32, 495-508.
National Research Council (2001). Educating children with autism. Committee on Educational Interventions for Children with Autism. C. Lord & J. P. McGee (Eds). Division of Behavioral and Social Sciences and Education. Washington, DC: National Academy Press.
Twachtman-Cullen, D., & Twachtman-Reilly, J. (2003). How Well Does Your Child's IEP Measure Up? Quality Indicators for Effective Service Delivery. London: Jessica Kingsley Publishers.
Wilkinson, L. A. (2010). Best practice in special needs education. In L. A. Wilkinson, A best practice guide to assessment and intervention for autism and Asperger syndrome in schools (pp. 127-146). London: Jessica Kingsley Publishers. 
Yell, M. L., Katsiyannis, A, Drasgow, E, & Herbst, M. (2003). Developing legally correct and educationally appropriate programs for students with autism spectrum disorders. Focus on Autism and Other Developmental Disabilities, 18, 182-191.
©Lee A. Wilkinson, PhD

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