We conducted a systematic review and meta-analysis to determine the effect of changes to the Diagnostic and Statistical Manual (DSM)-5 on autism spectrum disorder (ASD) and explore policy implications. We identified 418 studies; 14 met inclusion criteria. Studies consistently reported decreases in ASD diagnosis (range 7.3–68.4 %) using DSM-5 criteria. There were statistically significant pooled decreases in ASD [31 % (20–44), p = 0.006] and DSM-IV-TR subgroups of Autistic disorder [22 % (16–29), p < 0.001] and pervasive developmental disorder-not otherwise specified (PDD-NOS) [70 % (55–82), p = 0.01]; however, Asperger’s disorder pooled decrease was not significant [70 % (26–94), p = 0.38]. DSM-5 will likely decrease the number of individuals diagnosed with ASD, particularly the PDD-NOS subgroup. Research is needed on policies regarding services for individuals lacking diagnosis but requiring assistance.
