Researchers at NHS Forth Valley, Larbert and NHS Lothian University Hospitals Division, Edinburgh have published the findings of an audit of autism spectrum disorder (ASD) diagnoses by paediatricians in one health board area in the years 2011-2019 using electronic case records and analysed the data according to the year of birth.
For birth years 2009-2013, a total of 211 children were diagnosed before their sixth birthday, and the cumulative incidence rose from 0.6 per cent to 1.85 per cent. This equates to a reported prevalence of 1.77 per cent for those aged 5-6 years in 2018.
The diagnostic process was highly compliant with the recommendations of the Scottish Intercollegiate Guidelines Network. Nearly all children had documented assessments of physical health and general development, specialist speech and language therapy and multidisciplinary consensus regarding the diagnosis.
A large majority were diagnosed by the International Classification of Diseases, 10th Revision, criteria for childhood autism. The number of girls increased over time, and the sex ratio averaged around 5:1 for birth years 2010-2013.
Despite the increased service capacity, neither waiting time for diagnosis (>6 months) nor median age at diagnosis (>42 months) decreased significantly over time, and there was no obvious change in the severity of associated speech disorders.
The majority of children had delayed speech and language development, and around one in four were non-verbal (less than five words) at the time of diagnosis.
With no evidence of over-reporting, the authors say the rise in ASD remains unexplained, and paediatricians may be witnessing a real increase in the true incidence.