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

This large Welsh study looked at autism diagnosis records for over 3.6 million people from 2001-2016. They found autism diagnoses have more than tripled over this period, especially among women and adults over 35. However, only 0.51% of the population has a recorded autism diagnosis, which is lower than expected based on other research. This suggests many autistic people still haven't been identified by health services.

This large-scale e-cohort study analyzed healthcare records from over 3.6 million people in Wales, UK to examine autism diagnosis trends from 2001-2016. The study found an overall autism prevalence of 0.51% in healthcare records, which is lower than population survey estimates but consistent with other administrative datasets. New autism diagnoses increased substantially from 0.188 per 1000 person-years in 2001 to 0.644 per 1000 person-years in 2016, representing a >150% increase during 2008-2016. The increase was particularly notable among women and adults over 35 years.

Despite expanded adult autism services and increased societal awareness, the findings suggest many individuals remain unrecognized by healthcare services.

Results suggest substantial underdiagnosis of autism, particularly among women and older adults. Expanding diagnostic services and awareness campaigns may help identify previously missed cases. Healthcare systems should prepare for continued increases in autism diagnoses and ensure adequate service capacity.

Study relies on healthcare records which may miss undiagnosed individuals. No comparison group or control for diagnostic criteria changes. Cannot distinguish between true prevalence increases versus improved recognition. Administrative data may have coding inconsistencies.

Autism spectrum disorders (autism) are thought to be relatively common, with analyses estimating 1% in the population could meet diagnostic criteria. New services for adult diagnosis have been set up in Wales, UK; however, no studies have examined for the proportion of adults with autism in Wales. In this study, we take anonymised healthcare record data from more than 3.6 million people to produce a national estimate of recorded autism diagnoses. We found the overall prevalence rate of autism in healthcare records was 0.51%.

The number of new-recorded cases of autism increased from 0.188 per 1000 person-years in 2001 to 0.644 per 1000 person-years in 2016. The estimate of 0.51% prevalence in the population is lower than suggested by population survey and cohort studies, but comparable to other administrative records. From 2001 to 2016, the number of autism services for adults has increased, and autism is more widely known in society, while concurrently in healthcare records, there was a >150% increase autism diagnoses in the years 2008-2016. An increasing number of diagnoses were among women and those aged over 35 years.

This study suggests that while the number of people being diagnosed with autism is increasing, many are still unrecognised by healthcare services.