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Field Trials Suggest New Criteria for Diagnosing Autism 'Reliable'

American Psychiatric Association approves DSM-5 changes; autism advocates call for further study 

Autism experts and families have long been concerned about inconsistencies in how clinicians diagnose autism spectrum disorders (ASD). Though U.S. doctors and therapists use the same checklist of symptoms, they tended to vary in how they applied them. What one clinician diagnosed as autistic disorder, another would call Asperger syndrome or pervasive developmental disorder not otherwise specified (PDD-NOS). Some clinicians misdiagnosed autism in children with related conditions such as language disorder, or vice versa.

So the American Psychiatric Society assembled a committee of experts to improve the criteria used to diagnose ASD. The committee developed a diagnostic definition of autism that they judged to be less subjective and more reliable. Those changes are now slated to become part of the fifth edition of the Diagnostic Statistical Manual of Mental Disorders (DSM-5), scheduled for publication in May 2013.

The proposed revision – which generated tremendous public comment throughout 2012 – introduced two fundamental changes.

* First, it collapsed previously distinct autism subtypes – including autistic disorder and Asperger syndrome – into one unifying diagnosis of ASD.

* Second, the current three symptom domains of social impairment, communication deficits and repetitive/restricted behaviors were folded into two – social communication impairment and repetitive/restricted behaviors.

“The changes have a strong scientific rationale,” said Autism Speaks Chief Science Officer Geraldine Dawson, Ph.D. “However, they are more than an academic exercise. They will impact how ASD is diagnosed, can affect access to services and will influence how the prevalence of ASD is measured.” 

Indeed, some research suggested that certain individuals currently diagnosed with ASD might lose their diagnosis under the new system. For this reason, the National Institutes of Health (NIH) and Autism Speaks funded studies to better gauge the effects of the proposed changes. (See Autism Speaks DSM-5 study grants, here.)   

In October, the American Journal of Psychiatry published the results of the first NIH study to analyze a large number of records of individuals diagnosed with ASD using the DSM-IV. It explored whether the cases examined would retain their diagnosis of ASD based on the DSM-5. While preliminary, the results were reassuring.

The study involved an expert review of more than 5,000 case files of children who had been evaluated for ASD under the DSM-IV criteria.  The team, led by psychologist Catherine Lord, Ph.D., of New York’s Weill Cornell Medical College, applied the DSM-5 criteria to the symptoms recorded in the children’s records. This included both children diagnosed with autism and some who were not.

The study found that the new DSM-5 criteria did not miss a significant number of previously diagnosed children.  However, the study was based on a retrospective analysis of medical records. Still needed was a prospective study – with clinicians applying both old and new criteria to the diagnosis of actual children.

November brought the results of the first DSM-5 field trial. The three-part report likewise appeared in the American Journal of Psychiatry.

This field trial involved the evaluation of 63 school age children in Massachusetts and California. It, too, found diagnoses using the DSM-5 criteria to be reliable. When one clinician diagnosed a child with ASD using the new criteria, the second clinician was very likely to do so as well.  The study also showed that the large majority of children who met the DSM-IV criteria for a disorder on the autism spectrum would retain a diagnosis of ASD.

The results are promising, but more studies need to be conducted to ensure that affected individuals don’t lose access to services, Dr. Dawson said. “This is a relatively small sample of school age children from largely Caucasian backgrounds,” she noted. “Adults with autism were not included, so we don’t know how the proposed diagnostic criteria might affect them. We also don’t know how the proposed changes will affect diagnosis of very young children.”

Dr. Dawson and other autism experts agree it’s crucial to gain a better understanding of how the DSM-5 criteria will affect autism prevalence estimates – which in turn could influence the nation’s public health priorities. Autism Speaks is currently funding a study, in collaboration with the Centers for Disease Control and Prevention (CDC), to better address this issue.

“As these new diagnostic criteria come into use, we need to closely monitor how they affect people in our communities,” Dr. Dawson concluded. “At Autism Speaks, we remain committed to getting answers to these questions and ensuring that all individuals receive the interventions and services they need.”

Huerta M, Bishop SL, Duncan A, Hus V, Lord C. Application of DSM-5 Criteria for Autism Spectrum Disorder to Three Samples of Children With DSM-IV Diagnoses of Pervasive Developmental Disorders. Am J Psychiatry. 2012; 169(10): 1056-64. 

Regier DA, Narrow WE, Clarke DE, et al. DSM-5 Field Trials in the United States and Canada, Part II: Test-Retest Reliability of Selected Categorical Diagnoses. Am J Psychiatry. Advance online 30 Oct 2012.

Narrow WE, Clarke DE, Kuramoto SJ, et al. DSM-5 Field Trials in the United States and Canada, Part III: Development and Reliability Testing of a Cross-Cutting Symptom Assessment for DSM-5. Am J Psychiatry. Advance online 30 Oct 2012.

Clarke DE, Narrow WE, Regier DA, et al. DSM-5 Field Trials in the United States and Canada, Part I: Study Design, Sampling Strategy, Implementation, and Analytic Approaches. Am J Psychiatry. Advance online 30 Oct 2012.

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