People with developmental disabilities often have additional medical issues at rates higher than the general population. For example, heart problems are more common in the Down Syndrome population and Timothy Syndrome. Hip dislocation is common among those in the Fragile X community. Mental health conditions and neurological disorders are very common in autistics (but somehow those are rarely mentioned in discussions of autism and comorbidities).
When it comes to autism parents online, perhaps the most talked about autism comorbidity is gastrointestinal disease. And, in specific, inflammatory bowel disease. This is a lasting legacy of Andrew Wakefield’s attempt to link the MMR vaccine and autism (an effort which set back work on autism and GI disease by a decade or more–see Blame Wakefield For Missed Autism-Gut Connection).
Mr. Wakefield’s assertion was that the MMR vaccine leads to a unique form of IBD (he dubbed it autistic enterocolitis, a condition which doesn’t appear to exist) and this somehow leads to autism. The model also asserts that autism rates have climbed with the introduction of the MMR in the UK (an argument that fails when when considers when the MMR was introduced in the U.S., but I digress). Given the Wakefield model, including the claim that the MMR has played a major role in the “autism epidemic”, we would expect a large fraction of autistics should have IBD.
With apologies to autistics with IBD for taking so long on this introduction–this all begs the question of what is the prevalence of IBD in the autistic population? Well, a recent study discusses this:
Before we get to the prevalence let’s consider the important points. First–IBD does exist in autistics. Given communication issues and sensory issues, any medical condition is serious in the autistic population. Second–IBD is more prevalent in the autistic population. What this may say about the biology of autistics and the developmental trajectory is not discussed in the abstract of this study.
Finally let’s ask how big is the prevalence of IBD in the autistic population? The study looked at two sample populations. In one population 7 out of 2728 (0.26%) autistics had IBD. For another, 16 of 7201 (0.22%). Just because the prevalence is small doesn’t mean this isn’t an important issue for the autism communities. But, let’s face it, the claims of high and rising IBD prevalence in the autism community–the claims by Mr. Wakefield to support his attack on the MMR vaccine–are just not true. And, yes, this also means that people who think that all or most autistic kids should be treated for IBD are also not doing a service. Yes, treat people with IBD. But no, don’t assume autism = person with IBD.
The fact that IBD is not that common in autistics is not really that new. I recall the press conference for the MMR/autism study by Hornig et al.. One thing that slowed the study was the fact that there weren’t that many autistic kids whose symptoms really indicated the need for a colonoscopy. Contrary to some practitioners who seem to believe that all autistics should be ‘scoped.
The objective of this study was to measure the prevalence of inflammatory bowel disease (IBD) among patients with autism spectrum disorders (ASD), which has not been well described previously.
The rates of IBD among patients with and without ASD were measured in 4 study populations with distinct modes of ascertainment: a health care benefits company, 2 pediatric tertiary care centers, and a national ASD repository. The rates of IBD (established through International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] codes) were compared with respective controls and combined using a Stouffer meta-analysis. Clinical charts were also reviewed for IBD among patients with ICD-9-CM codes for both IBD and ASD at one of the pediatric tertiary care centers. This expert-verified rate was compared with the rate in the repository study population (where IBD diagnoses were established by expert review) and in nationally reported rates for pediatric IBD.
In all of case-control study populations, the rates of IBD-related ICD-9-CM codes for patients with ASD were significantly higher than that of their respective controls (Stouffer meta-analysis, P < 0.001). Expert-verified rates of IBD among patients with ASD were 7 of 2728 patients in one study population and 16 of 7201 in a second study population. The age-adjusted prevalence of IBD among patients with ASD was higher than their respective controls and nationally reported rates of pediatric IBD.
Across each population with different kinds of ascertainment, there was a consistent and statistically significant increased prevalance of IBD in patients with ASD than their respective controls and nationally reported rates for pediatric IBD.
By Matt Carey