The Impact of DSM-5 Social Communication Disorder Diagnosis on Autism: Results from Two Systematic Literature Reviews and Meta-Analyses

Background: Social Communication Disorder (SCD) is a new behaviorally-defined developmental communication disorder diagnosis in the Fifth Edition of the Diagnostic and Statistical Manual (DSM-5). It was initially described as potentially capturing individuals with a DSM-IV, Text-Revised (DSM-IV-TR) diagnosis of autism, perhaps those with pervasive developmental disorder-not otherwise specified (PDD-NOS), who would no longer meet the more stringent DSM-5 ASD criteria. To date, limited studies have examined SCD, and its impact remains unknown.

Objectives: As part of two systematic literature reviews and meta-analyses, the first conducted prior to DSM-5 implementation and a recently completed five-year follow-up, we assessed the potential of an alternative diagnosis of SCD for individuals who met DSM-IV-TR but not DSM-5 autism spectrum disorder (ASD) diagnostic criteria.

Methods: We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines in conducting these reviews. We searched the literature for studies published between January 2011 and March 2013 (first review) and April 2013 and July 2018 (second review) that applied DSM-IV-TR and DSM-5 ASD criteria to study samples and, for those who did not meet DSM-5 ASD criteria, applied SCD criteria. Scientific rigor was rated using the Quality Appraisal of Reliability Studies. We pooled study data by extracting the number of individuals who met DSM-IV-TR ASD criteria but no longer met criteria for an ASD diagnosis under DSM-5 and, of those, the number who would alternatively meet SCD criteria. We estimated a pooled effect for the proportion of individuals meeting SCD criteria, and we investigated model heterogeneity and publication bias.

Results: Nine studies (four from the first review and five from the second review) representing data from 555 individuals assessed for SCD were included. Of these, 5 studies specifically examined ASD subtypes. There was no evidence of publication bias. While statistical significance was not achieved, the pooled effect suggests that less than one-third [28.8%; (95%CI 13.9-50.5), p=0.06] of those who met DSM-IV-TR but not DSM-5 ASD diagnosis would meet criteria for SCD. Heterogeneity was greater than expected by chance alone (Cochran’s Q = 57.5, p<0.001, I² = 86.1). In studies which examined ASD subtypes, those with PDD-NOS (23 of 47 individuals; 49%) were less frequently captured by SCD compared to either Autistic Disorder or Asperger's Disorder.

Conclusions: Overall, SCD does not appear to capture the majority of those with ASD diagnosis using DSM-IV-TR but who no longer maintain their diagnosis under DSM-5. While subtype data are limited, SCD appears least likely to capture those with DSM-IV-TR PDD-NOS who do not meet DSM-5 ASD diagnostic criteria. The impact of SCD as a new, independent diagnosis from ASD, and its potential to serve as a gateway for services, are important areas for future research.