Evidence of increasing recorded diagnosis of autism spectrum disorders in Wales, UK: An e-cohort study.

The study counted autism only when it appeared in GP or hospital records, so people with autism who never used these services may be missed. GP records before 2000 are sparse, so earlier diagnoses may be missing, and the rise from 2001 may partly reflect better record coverage. The diagnoses were not verified, and the code set could include conditions such as Rett's syndrome that are not representative of autism as a whole. Private diagnoses may not have been reported into NHS records, so adult diagnoses could be underestimated. The study cannot show why rates rose. The authors suggest better recognition and access, but that is interpretation. No race or ethnicity, socioeconomic status, education, or deprivation data were extracted, so differences in those groups cannot be assessed. This is a record-based cohort study, not a treatment trial, so it cannot tell therapists whether any intervention helps.

One author, J.H., reported grants from Takeda for work unrelated to this project. The other authors declared no competing interests. The project was funded by a Wellcome Trust ISSF Clinical Primer award and a Wellcome Trust GW4-CAT Clinical Doctoral Fellowship to J.F.G.U. Several authors were also supported by Healthcare Research Wales through the National Centre for Mental Health and by MRC Pathfinder grants.

Do not read the rising rates as proof that autism itself is more common. They are counts of diagnoses recorded in GP and hospital records, which may miss people without recorded diagnoses and cannot verify each diagnosis.