Estimates of Autism Spectrum Disorder Prevalence May Be Lower Under Revised Diagnostic Criteria

Estimates of autism spectrum disorder (ASD) prevalence may drop under recently revised diagnostic criteria in the “Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition” (DSM-5) published by the American Psychiatric Association in 2013, according to a study by Matthew J. Maenner, Ph.D., of the National Center on Birth Defects and Developmental Disabilities at the Centers for Disease Control and Prevention, Atlanta, and colleagues.

DSM-5 criteria differ from the older DSM-IV-TR (fourth edition, text revision) criteria in several ways, including: DSM-5 does not distinguish subtypes of ASD (such as autistic and Asperger disorders); it recognizes only two domains of impairment: social communication and restricted, repetitive patterns of behavior interests or activities; and all three items in the social communication domain are required, the authors write in the study background. Also, the DSM-5 specifies seven diagnostic criteria but some describe more general principles and behaviors than in DSM-IV-TR and the DSM-5 criteria allow historical behaviors to be considered in addition to current behaviors.

The authors evaluated the potential effects the new criteria for diagnosing ASD by applying them to 8-year-olds who are part of a large ASD surveillance system in the United States.

Among 6,577 children classified as having ASD based on DSM-IV-TR criteria, 81 percent (5,339) met the DSM-5 criteria for ASD. Using the DSM-5 criteria, ASD prevalence in 2008 would have been 10 per 1,000 people compared with the reported prevalence of 11.3 based on DSM-IV-TR criteria, according to the study results.

“Autism spectrum disorder prevalence estimates will likely be lower under DSM-5 than under DSM-IV-TR diagnostic criteria, although this effect could be tempered by future adaptation of diagnostic practices and documentation of behaviors to fit the new criteria,” the authors conclude.

(JAMA Psychiatry. Published online January 22, 2014. doi:10.1001/jamapsychiatry.2013.3893.