In the last year or so there has been a glut of studies comparing DSM-IV and DSM-5. I've listed below all the ones I know of, but there may be even more. In the article, I focus on three of these: the Yale study from earlier this year that I covered here and here; the recent Cornell study that I critiqued earlier this week; and another newish study from Autism Spectrum Australia that, unlike other studies, actually looked at DSM-5 in a clinical context, rather than re-coding old data.
We're still waiting for the results of the official DSM-5 field trials. But, to be honest, the more studies I read, the less convinced I am that we can predict DSM-5's impact in advance. The obvious problem is that there is no objective test of whether or not someone is autistic, so it's difficult to say whether DSM-5 is an improvement on DSM-IV. But much will also depend on the interpretation of the new rules by clinicians; the reaction of governments and insurers to resulting changes in autism numbers and to new diagnoses such as Social Communication Disorder; and ultimately the extent to which an autism diagnosis continues be a stepping stone to services. These are all in themselves difficult to predict.
There is also the broader question of whether it makes sense to base research and clinical practice on the notion of an autism "syndrome". We have the strange situation where, for example, someone can be denied support for social and communication difficulties because they don't have sufficient repetitive behaviours for an autism diagnosis. Or, as one commenter noted, a child with specific language difficulties is unable to access speech therapy that is available to an autistic child without language difficulties. From the research perspective, we're still all just relying on an intuition that the behaviours that define autism actually constitute a coherent syndrome. As scientists we should be always challenging our intuitions but in effect the DSM serves only to formalise and reinforce them.
Emily Singer has a comprehensive review of DSM-5 issues as part of a free supplement in Nature.
Frazier TW, Youngstrom EA, Speer L, Embacher R, Law P, Constantino J, Findling RL, Hardan AY, Eng C (2012). Validation of proposed DSM-5 criteria for autism spectrum disorder. Journal of the American Academy of Child and Adolescent Psychiatry, 51, 28–40
Gibbs V, Aldridge F, Chandler F, Witzlsperger E, Smith K (2012). Brief Report: An Exploratory Study Comparing Diagnostic Outcomes for Autism Spectrum Disorders Under DSM-IV-TR with the Proposed DSM-5 Revision. Journal of Autism and Developmental Disorders, 42, 1750-1756.
Huerta M, Bishop SL, Duncan A, Hus V, Lord C (2012). Application of DSM-5 Criteria for Autism Spectrum Disorder to Three Samples of Children With DSM-IV Diagnoses of Pervasive Developmental Disorders. American Journal of Psychiatry, 169, 1056-64.
McPartland JC, Reichow B, Volkmar FR: Sensitivity and specificity of proposed DSM-5 diagnostic criteria for autism spectrum disorder. Journal of the American Academy of Child and Adolescent Psychiatry, 51, 368–383.
Matson JL, Kozlowski A, Hattier MA, Horovitz M, Sipes M (2012). DSM-IV vs DSM-5 diagnostic criteria for toddlers with Autism. Developmental Neurorehabilitation, 15, 3, 185-190.
Mattila ML, Kielinen M, Linna SL, Jussila K, Ebeling H, Bloigu R, Joseph RM, Moilanen I (2011). Autism spectrum disorders according to DSM-IV-TR and comparison with DSM-5 draft criteria: an epidemiological study. Journal of the American Academy of Child and Adolescent Psychiatry, 50, 583–592.
Mazefsky CA, McPartland JC, Gastgeb HZ, Minshew NJ. (in press). Comparability of DSM-IV and DSM-5 ASD Research Samples. Journal of Autism and Developmental Disorders
Worley JA, Matson JL (2012). Comparing symptoms of autism spectrum disorders using the current DSM-IV-TR diagnostic criteria and the proposed DSM-V diagnostic criteria. Research in Autism Spectrum Disorders, 6, 965-970.