Concordance Between DSM-IV and DSM-5: Results from a Large-Scale Epidemiological Surveillance Study

Background:   In 2013 the American Psychiatric Association made significant revisions to the diagnostic criteria for Autism Spectrum Disorder (ASD), including moving from a series of related Pervasive Developmental Disorder (PDD) diagnoses in DSM-IV-TR to one ASD diagnosis in DSM-5. Changes were based on research suggesting poor distinction among DSM-IV-TR subtypes, and that social communication deficits and restricted repetitive behaviors are both core symptom domains in ASD.  However there has been concern that the revised criteria may exclude more mildly affected children from clinical diagnosis. 

Objectives:   To determine concordance between DSM-IV-TR and DSM-5 ASD diagnoses among school-aged children at risk for ASD. 

Methods:   Data for this study is from the South Carolina Children’s Educational Surveillance Study (SUCCESS), which is designed to assess the prevalence of ASD through population-based screening and evaluation.  School-aged children 8-11 years of age were identified as being at risk for ASD using the Social Communication Questionnaire (SCQ). Participants (n=292) completed developmental assessments to determine ASD case status according to both DSM-IV-TR and DSM-5 criteria. Clinical best estimate diagnoses were based on lifetime history of ASD symptoms. Participants were 65% male, 42% white non-Hispanic, 35% black non-Hispanic, 9% non-native English speakers, and 62% from Title 1 public schools (schools with a high percentage of low income students).  Average IQ was 93.97 (SD=19.03). 

Results:   All participants who met criteria for DSM-5 ASD (n=52) also met criteria for one of three DSM-IV-TR PDD diagnoses (Autistic Disorder, Asperger’s Disorder, PDD-NOS). Forty percent of those with DSM-IV-TR PDD diagnoses did not meet criteria for DSM-5 ASD. Most discordant participants (30/35; 86%) had a DSM-IV-TR diagnosis of PDD-NOS. Demographic characteristics including gender, race, ethnicity, non-native English speaker status, and Title 1 school status were not associated with DSM-IV-TR/DSM-5 discordance. Those participants who were concordant for DSM-IV-TR PDD and DSM-5 ASD had significantly higher scores on autism-related assessment instruments (ADOS-2, SRS-2, & SCQ), and had significantly lower adaptive scores (Vineland-2). IQ was not significantly different between the two groups. Among those who met DSM-IV-TR but not DSM-5 criteria, 40% failed to fulfill at least 2 restricted repetitive behavior criteria, while 94% failed to fulfill all 3 social communication criteria for ASD. 

Conclusions:   Results suggest that, among school-aged children, DSM-5 ASD captures participants who have greater severity of ASD symptoms and more functional impairment than those captured under DSM-IV-TR. Individual demographics (SES, race, gender, ethnicity, IQ) do not appear to impact concordance. The majority of discordant participants met DSM-IV-TR criteria for PDD-NOS, a diagnosis that has been criticized for being overly broad and non-specific to ASD, and of these very few had a diagnosis of a PDD/ASD prior to participation in this study. Nonetheless, the fact that 40% of discordant participants met the autism/ASD threshold on the ADOS-2 suggests that some children with symptoms of ASD may not meet DSM-5 criteria for ASD. Particularly in regards to revisions in the social communication criteria, children with milder or fewer symptoms in this subdomain are less likely to be diagnosed with ASD under DMS-5 criteria.