How Has DSM-5 Affected Autism Diagnosis? a Five-Year Follow-up Systematic Literature Review and Meta-Analysis
Objectives: The purpose of this systematic literature review and meta-analysis were to: (1) determine the changes in frequency of ASD diagnosis in the first five years after publication of the revised DSM-5 ASD criteria, and (2) identify the DSM-IV-TR autism subtypes most affected by these new diagnostic criteria.
Methods: Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we searched the literature for studies published between April 2013 and July 2018 that applied both DSM-IV-TR and DSM-5 ASD diagnostic clinical criteria to study samples. Scientific rigor was rated using the Quality Appraisal of Reliability Studies. Data on sample size, individuals meeting DSM-IV-TR ASD criteria, and those no longer meeting an ASD diagnosis under DSM-5 criteria were extracted. Pooled effects were estimated for ASD and DSM-IV-TR subtypes of autistic disorder (AD), Asperger’s Disorder, and pervasive developmental disorder-not otherwise specified (PDD-NOS) using random effects meta-analysis models. Heterogeneity of each model, subtype analyses to explore reasons for heterogeneity if present, and publication bias was assessed.
Results: Of 898 studies identified, 33 met inclusion criteria for the review and meta-analysis; of these, 19 studies specifically examined DSM-IV-TR subtypes (AD n=17; Asperger’s Disorder n=14; PDD-NOS n=18). Overall risk of bias across studies was unclear. Most studies utilized the Autism Diagnostic Interview–Revised (ADI-R) and the Autism Diagnosis Observation Schedule (ADOS) as evaluation tools. There were statistically significant pooled decreases in ASD diagnoses under DSM-5 criteria [20.8% (95%CI 16-27), p<0.001] and for the DSM-IV-TR subtypes of AD [10.1% (95%CI 6.2-16.0), p<0.001] and Asperger’s [23.3% (95%CI 12.9-38.5), p=0.001]; however, the pooled decrease for PDD-NOS was not significant [46.1% (95%CI 34.6-58.0), p=0.52]. Two variables contributed to heterogeneity across ASD and subtype models: age group and type of clinician who made the diagnosis. Notably, when the diagnosis was made by a team of a physician and a psychologist, the decrease in diagnosis rates between DSM-IV-TR and DSM-5 was lowest.
Conclusions: While all previous literature reviews that examined this topic found ASD rates could decrease by at least one-third, findings from this five-year follow-up demonstrated smaller pooled decreases for ASD and all DSM-IV-TR subtypes. Nevertheless, future research is needed as concerns remain for impaired individuals without a specific diagnosis as well as to stratify for future clinical intervention studies.