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What’s Causing The Increase In Autism Prevalence? A Critical Analysis

Two recent studies concerning the prevalence of autism in the US have been getting a lot of attention, because they indicate that autism prevalence may be higher than previously estimated. This, of course, fuels the debate over whether or not there are environmental triggers of autism.

One study was conducted by the CDC but has yet to be published. The results were announced ahead of publication by the US Health and Human Services Secretary Kathleen Sebelius to the autism community. She reports that the new prevalence of autism spectrum disorder (ASD) is now estimated at 1% or 100 in 10,000 children. This is an increase over the last few years. In 2002 the prevalence was estimated to be 66 per 10,000.

The second study was published in the journal Pediatrics and is a phone survey of 78,037 parents. They asked if they had any children who had ever been diagnosed with an ASD. Here are the results:

The weighted current ASD point-prevalence was 110 per 10,000. We estimate that 673,000 US children have ASD. Odds of having ASD were 4 times as large for boys than girls. Non-Hispanic (NH) black and multiracial children had lower odds of ASD than NH white children. Nearly 40% of those ever diagnosed with ASD did not currently have the condition; NH black children were more likely than NH white children to not have current ASD. Children in both ASD groups were less likely than children without ASD to receive care within a medical home.

These are slightly higher numbers than the CDC data. This is to be expected, however, since the Pediatrics study is a phone survey. Diagnoses were not confirmed by a clinician.

There is no question that the number of ASD diagnoses has been steadily increasing for the last two decades. The burning question has been – is this a real increase in the disorder or an artifact of increased surveillance and an expanded diagnosis. I have reviewed the evidence in depth previously – the evidence strongly supports the conclusion that the increasing autism prevalence is due to increased efforts to make the diagnosis and a broadening of the definition of autism. The evidence is not sufficient to conclude that there is not also a real increase in ASD incidence, but nor is there data to support this conclusion.

Further, since I wrote my last summary, there has been more data to support the conclusion that autism rates are really flat. The National Health Service also has recently published a survey of autism prevalence. While the US studies looked at children from 3 to 17, the NHS study looked at all age groups. Their question was this – is the prevalence of ASD the same or different among various age groups? If the incidence of ASD is truly increasing, then younger age groups should have more ASD than older age groups.

They found a consistent prevalence of 1% in all age groups they surveyed. This is remarkable for two reasons – first, they found the exact same 1% figure as the CDC US survey (assuming the CDC data is more accurate than the phone survey published in Pediatrics). This supports the conclusion that the 1% figure may be close to the true prevalence of ASD in the population.

Second, the NHS study found that the prevalence of autism was the same in all age groups, strongly suggesting that true ASD incidence has not been increasing over recent decades and supporting the increased surveillance and definition hypothesis.

Of course, the anti-vaccine community is exploiting these two new studies (the US studies – they have already found excuses and conspiracies to dismiss the implications of the NHS study). David Kirby, writing for Age of Autism, a notorious anti-vaccination site, wonders aloud why there is no alarm about these new ASD prevalence numbers. He is still playing his coy “conspiracy of silence” card.

It is also interesting that Kirby and others in the anti-vaccine community were predicting that autism rates should decrease following the near complete removal of thimerosal form the childhood vaccine schedule by 2002 in the US. Autism rates continued to rise at a steady rate, essentially killing the hypothesis that thimerosal is a significant contributor to autism. Now Kirby is citing the same evidence (continued rising autism rates) that punctured his previous hypothesis as support for his new hypothesis – the HepB vaccine.

That’s right – the anti-vaccine community has moved from the MMR vaccine to thimerosal to other “toxins” in vaccines and are now focusing their sites on the HepB vaccine. As each claim fails to be supported by scientific evidence, they simply migrate over to another claim – all with the core feature that vaccines are always to blame.

Meanwhile, the strong consensus of evidence is that ASD rates are not truly increasing at all.

*This blog post was originally published at Science-Based Medicine*


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Richmond, VA – In an effort to simplify inpatient medical billing, one area hospitalist group has determined that “altered mental status” (ICD-9 780.97) is the most efficient code for use in any patient work up.

“When you enter a hospital, you’re bound to have some kind of mental status change,” said Dr. Fishbinder, co-partner of Area Hospitalists, PLLC. “Whether it’s confusion about where your room is located in relationship to the visitor’s parking structure, frustration with being woken up every hour or two to check your vital signs, or just plain old fatigue from being sick, you are not thinking as clearly as before you were admitted. And that’s all the justification we need to order anything from drug and toxin screens, to blood cultures, brain MRIs, tagged red blood cell nuclear scans, or cardiac Holter monitoring. There really is no limit to what we can pursue with our tests.”

Common causes of mental status changes in the elderly include medicine-induced cognitive side effects, disorientation due to disruption in daily routines, age-related memory impairment, and urinary tract infections.

“The urinalysis is not a very exciting medical test,” stated Dr. Fishbinder. “It doesn’t matter that it’s cheap, fast, and most likely to provide an explanation for strange behavior in hospitalized patients. It’s really not as elegant as the testing involved in a chronic anemia or metabolic encephalopathy work up. I keep it in my back pocket in case all other tests are negative, including brain MRIs and PET scans.”

Nursing staff at Richmond Medical Hospital report that efforts to inform hospitalists about foul smelling urine have generally fallen on deaf ears. “I have tried to tell the hospitalists about cloudy or bloody urine that I see in patients who are undergoing extensive work ups for mental status changes,” reports nurse Sandy Anderson. “But they insist that ‘all urine smells bad’ and it’s really more of a red herring.”

Another nurse reports that delay in diagnosing urinary tract infections (while patients are scheduled for brain MRIs, nuclear scans, and biopsies) can lead to worsening symptoms which accelerate and expand testing. “Some of my patients are transferred to the ICU during the altered mental status work up,” states nurse Anita Misra. “The doctors seem to be very excited about the additional technology available to them in the intensive care setting. Between the central line placement, arterial blood gasses, and vast array of IV fluid and medication options, urosepsis is really an excellent entré into a whole new level of care.”

“As far as medicine-induced mental status changes are concerned,” added Dr. Fishbinder, “We’ve never seen a single case in the past 10 years. Today’s patients are incredibly resilient and can tolerate mixes of opioids, anti-depressants, anti-histamines, and benzodiazepines without any difficulty. We know this because most patients have been prescribed these cocktails and have been taking them for years.”

Patient family members have expressed gratitude for Dr. Fishbinder’s diagnostic process, and report that they are very pleased that he is doing everything in his power to “get to the bottom” of why their loved one isn’t as sharp as they used to be.

“I thought my mom was acting strange ever since she started taking stronger pain medicine for her arthritis,” says Nelly Hurtong, the daughter of one of Dr. Fishbinder’s inpatients. “But now I see that there are deeper reasons for her ‘altered mental status’ thanks to the brain MRI that showed some mild generalized atrophy.”

Hospital administrators praise Dr. Fishbinder as one of their top physicians. “He will do whatever it takes to figure out the true cause of patients’ cognitive impairments.” Says CEO, Daniel Griffiths. “And not only is that good medicine, it is great for our Press Ganey scores and our bottom line.”

As for the nursing staff, Griffiths offered a less glowing review. “It’s unfortunate that our nurses seem preoccupied with urine testing and medication reconciliation. I think it might be time for us to mandate further training to help them appreciate more of the medical nuances inherent in quality patient care.”

Dr. Fishbinder is in the process of creating a half-day seminar on ‘altered mental status in the inpatient setting,’ offering CME credits to physicians who enroll. Richmond Medical Hospital intends to sponsor Dr. Fishbinder’s course, and franchise it to other hospitals in the state, and ultimately nationally.

***

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