"Epilepsy was reported to co-occur in 8.6 % of ASD [autism spectrum disorder] cases."
That was the headline conclusion reported by Shiny Thomas and colleagues  as they drew on data from "the most recent U.S. National Survey of Children's Health, 2011-2012" to add to the extensive literature looking at how common epilepsy is when it comes to autism.
Including some 1600 children/young adults diagnosed with autism - equivalent to a prevalence of 1.8% of the entire 85,000-strong cohort - researchers "examined parent-reported prevalence of co-occurring epilepsy" and eventually came up with that 8-9% figure. Further, they also observed that: "the co-occurrence of epilepsy was associated with increasing child age, female gender, intellectual disability, speech problems and lower socioeconomic status."
This is important work. Epilepsy or seizure disorder is not something to be taken lightly under any circumstances; more so when applied to autism and the 'burden' of medical comorbidity that seems to be over-represented following a diagnosis (see here). The use of the U.S. National Survey of Children's Health (NSCH), 2011-2012 also has some significant strengths in terms of numbers of participants and has previously informed quite a few areas of autism research (see here for example).
There is another important detail attached to the Thomas paper that is also worthy of comment in relation to how their prevalence figure compares with other independent studies in terms of epilepsy appearing comorbid to autism (readers should click on the 'Supplementary material' attachment shown here). Bearing in mind their data was derived from children "ages 2-17" and includes the term 'parent-reported' (as opposed to medical records reported) the 8.6% figure seems to be quite a conservative one. I say this on the basis that previous data from NSCH has observed slightly higher rates of epilepsy (see here) and other data sources have even talked about 1 in 5 children on the autism spectrum manifesting with a seizure or seizure disorder (see here). I of course realise that the word 'epilepsy' covers quite a bit of diagnostic ground and seizures/seizure disorder can present for a variety of reasons, but nonetheless I stand by the 8.6% comorbidity figure as perhaps being one of the lower values published in the peer-review domain.
The additional observations that 'increasing age' and presence of intellectual (learning) disability might influence the presence of epilepsy in relation to autism are interesting but by no means novel findings. They do however offer something of a roadmap to monitoring those on the autism spectrum who may be at some enhanced risk of developing epilepsy and indeed, implementing the relevant strategies in a timely fashion to ensure that epilepsy is managed safely.
Many questions still remain concerning the hows and whys of epilepsy intersecting with autism (and indeed, autism intersecting with epilepsy) including those related to more 'non-traditional' aspects (see here for example). What however is abundantly clear from the peer-reviewed and other literature in this area is that epilepsy is an important part of life for quite a few people on the autism spectrum and as many resources as possible should be pumped into looking at the relationship and offsetting / averting the potentially life-changing consequences that epilepsy can have on a person and their loved ones (see here).
To close, when one mentions 'God Save the Queen' one should really specify which version one requires?
 Thomas S. et al. Brief Report: Prevalence of Co-occurring Epilepsy and Autism Spectrum Disorder: The U.S. National Survey of Children's Health 2011-2012. J Autism Dev Disord. 2016 Oct 17.
Thomas S, Hovinga ME, Rai D, & Lee BK (2016). Brief Report: Prevalence of Co-occurring Epilepsy and Autism Spectrum Disorder: The U.S. National Survey of Children's Health 2011-2012. Journal of autism and developmental disorders PMID: 27752862