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Epidemiology Night School: Introduction to Outbreaks (or “Don’t expect Dr. Jay to understand all this stuff”)

23 Aug

With EpiRen offline, I feel a bit of a void. In his blogging he was taking on an educational project: using current topics to discuss important topics in epidemiology. EpiWonk is also offline, but his body of work remains. EpiWonk also took on describing topics and terminology in epidemiology. Since I find these efforts valuable, I’ve decided to lift some of EpiRen’s “Epidemiology Night School” posts to preserve here. Below is one from March 25, 2011. I picked this somewhat at random, so don’t read too much into the selection.

From here on out, it is in EpiRen’s voice. As he is offline, don’t expect him to respond to comments directed at him.

If you’ve been reading me for a while, you know that I absolutely detest having to attack someone personally. Sure, I may point out the stupidity in some statements by people like Christina England, some homeopath here and there, and even Ms. Jennings was a subject of several postings. But I try not to inject my personal opinions about a person (much) because discussions of science should leave personal feelings out of it. (Sorry it was too late for you, Galileo.) Doing this avoids all that background noise. Know what I mean?

Still, there are those times when someone just somehow manages to get under my skin with comments so outrageous (in my opinion) that I am forced to think ill of them. (Not wish them ill, though. Even I am not that big of a bastard so as to wish others ill.) So I’m going to weave in some comments from the twitter feed of one Dr. Jay Gordon, just to show you how someone who doesn’t understand epidemiology can come off as crass and uncaring (in the opinion of many). All, of course, after the jump…

You see a monkey. I see flying Ebola.

MINNESOTA

Todd W. over at “Harpocrates Speaks” has a great series covering the development of the current outbreak of measles in Minnesota. Here are the facts as I am writing this:

  • 11 confirmed cases of measles as of 3/23/11
  • 4 of 11 too young to be vaccinated against measles
  • 5 of 11 of age to be vaccinated but are not
  • 2 of 11 with an unknown vaccine status
  • All are epidemiologically linked to one another. (We’ll cover what this means in a little bit.)
  • Minnesota had not seen these many cases since 1997, when they had 8 total cases throughout the year. Here is the table from their statistics web page:

  • Furthermore, 5 of the 11 cases have been hospitalized.
  • Finally, several of the cases are part of a community of Somali ex-patriots (or refugees) that has been targeted by Andrew Wakefied and his friends with anti-vaccine propaganda.

    • WHAT IS AN OUTBREAK?
    Traditionally, an outbreak has been defined as “one case over the expected rate (or number) of cases for a given location in a period of time.” In Minnesota, they have seen 22 cases over the last 14 years (22/14=1.6 cases per year in all Minnesota). Rounding up, we can say that two cases per year is what is expected. Three cases in 2011 would mean an outbreak. What was that in 2010, you ask? Well, 19 cases in 13 years give us a rate of 1.5 cases per year. It would also be an outbreak situation, especially if the three cases were epidemiologically linked. That information is not yet available from the MDH, but it will be interesting to read later on.

    YES. YES, IT'S AN OUTBREAK. IT'S A FRIGGIN' OUTBREAK!!!


    YES. YES, IT’S AN OUTBREAK. IT’S A FRIGGIN’ OUTBREAK!!!

    EPIDEMIOLOGICALLY LINKED?
    When two or more people develop a disease or condition, and they have similar exposures, they are said to be epidemiologically linked. For example, if two people ate at the same place in the hours before their onset of the same illness, then they are epidemiologically linked regardless of whether or not the food they shared is found to be the culprit. Some links are stronger than others, but this concept is not lost in outbreak investigations. During the outbreak of what is now known as Legionnaires’ Disease in Philadelphia in 1976, the fact that all those men were coming down with pneumonia raised some flags… The fact that they were all staying at the same hotel AND were all members of the American Legion was a cause for alarm. (It would be a while before the bacteria that caused the outbreak was discovered, but their epidemiological link proved to be an enormous clue.)

    BACK TO MINNESOTA

    So, eleven cases, all epidemiologically linked, is that an outbreak?

    You Lost Me at Porn

    YOU LOST ME AT PORN.

    I learned in grade school that 11 cases (to date) in the current outbreak is 9 cases over the expected 2. I also learned that it’s over 5 times the expected rate. I then learned in epidemiology school (a master’s level degree) that the fact that all these cases are somehow related to each other pretty much makes this an outbreak. Am I – or anyone working on that outbreak – being obsessive about “a few extra cases of measles”?

    If it means stopping a disease that can do this to a child, then YES, YES I AM OBSESSED.

    I want to emphasize the fact that they are all related to each other. If they had absolutely nothing to do with each other and were found in different corners of planet Earth, I wouldn’t obsess. But they’re all in one region of Minnesota. There’s nothing random about that, is there?

    You can lead the horse to the water, but…
    RANDOM, I DO NOT THINK YOU UNDERSTAND WHAT THAT WORD MEANS

    As I’ve stated before, there are clearly defined guidelines on what constitutes an outbreak and what doesn’t. If you look at the definition, there are factors of person, place, and time. How many people, where, and when? As I’m writing this, the answer is 11 people, in one region of Minnesota, in the last two to three weeks. That’s an outbreak, my friends. It’s a clean and clear situation.

    What the hell does Noro have to do with measles?
    REMEMBER YOUR TRAINING

    Pop quiz. What is the definition of incidence? Yep. You got it. It’s the number of new cases divided by the population at risk. Vaccine coverage for measles is estimated at 85% in Minnesota (maybe lower or higher, but certainly not enough for herd immunity now). That means that about 780,000 people in Minnesota are at risk for measles because they’re not considered immune. (Others who have been immunized, but whose immune system didn’t “take” the vaccine are too low in number to make an impact. The vaccine is really quite good, giving immunity to 99.7% of those who get their two doses and to 95% of those who get at least one dose.) That little quip about 15% norovirus? It’s a GUIDELINE on when to call an elevated number of cases of norovirus symptoms on a cruiseship an outbreak. (It appears that Dr. Gordon wants to go with one guideline but not another.)

    Not a dangerous epidemic? Would he say that to the mothers of those sick children?

    TELEVISION AND REALITY

    I don’t know about you folks, but I have never based an epidemiological decision or observation on a television show. I am yet to hear anything on television (or in any other media) and take it as gospel. What I have done is look at books about epidemiology that build upon a couple of centuries of knowledge and scientific experimentation. Maybe the Brady Bunch didn’t succumb to measles because – and I’m only taking a wild guess here – THEY WERE A FICTIONAL FAMILY! Moreover, they were a fictional family that caught measles in 1969 and then mumps in 1973. I would NEVER take my medical or epidemiological advice from such a careless bunch.


    The guy isn’t even wearing gloves!

    I’d never use them as an example for such a serious situation. Heck, if I used stuff on television to justify my thinking on epidemiological matters, I would be laughed out of a profession… I mean, imagine if I advocated to call in the US Army to wipe out a town because they had an outbreak of hemorrhagic fever? (“Outbreak“, 1995)

    RECAP

    Alright, so we learned that an outbreak is defined by person, place, and time. (If you remember one of the first lessons of the night school was descriptive epidemiology, and the example there was learning to recognize an outbreak.) There are certain situations where you have a group of people who are sick at the same time, but they were never in the same place. We call that a cluster in time.


    Not to be confused with a cluster OF time.

    There are other situations when a group of people who live in the same area get sick from the same pathogen (or condition) but at different times. We call that a cluster in space.


    We call this “Lost in Space”

    To be an outbreak, you need to establish associations between person, place, and time. Sure, the cluster in time may turn out to be an outbreak once you find out through questionnaires and interviews that they all bought the same brand of milk, albeit from different retailers. Or the cluster in space may turn out to be an outbreak once you notice that something has been leaking into the environment over a long period of time.

    So, when trying to determine if something is an outbreak, consider how many cases you’re looking at compared to previous years (or other periods of time), consider their geographic spread, consider common exposures of attributes (like gender, race, ethnicity, social status, grade in school, etc.), and consider them all human beings worthy of your caring and best honest effort to bring the outbreak under control and prevent it from ever happening again – like with vaccines and stuff.

Controversial issues in hyperbaric oxygen therapy: a European Committee for Hyperbaric Medicine Workshop

22 Aug

After writing the post on the University of California HBOT paper (Brief Report: Hyperbaric Oxygen Therapy (HBOT) in Children with Autism Spectrum Disorder: A Clinical Trial) this new abstract came out: Controversial issues in hyperbaric oxygen therapy: a European Committee for Hyperbaric Medicine Workshop.

It covers a discussion of applications of HBOT which were not yet considered in their previous workshop. This includes autism as a condition to treat with HBOT. Their conclusion: rate HBOT for autism as “not-accepted”.

Every few years, the European Committee for Hyperbaric Medicine (ECHM) publishes its recommendations concerning the clinical indications for hyperbaric oxygen therapy (HBOT). The last recommendations were issued during the 7th European Consensus Conference on Hyperbaric Medicine in 2004. Since then, several publications have reported on the use of HBOT in some indications in which it has not yet been recommended routinely, namely aseptic bone necrosis, global brain ischaemia and autism. Patients or their families push physicians and staff of hyperbaric facilities to use hyperbaric treatment regardless of the quality of the scientific evidence. Therefore, the ECHM Workshop “Controversial issues in hyperbaric oxygen therapy” was convened as a satellite meeting of the 2010 European Underwater and Baromedical Society Annual Scientific Meeting in Istanbul, Turkey in 2010. For each topic, a set procedure was used: first came a general report by specialists in the topic, incorporating a review of current pathophysiological, experimental and clinical evidence. Then, there were reports from hyperbaric facilities that had gained clinical experience in that condition, followed by a general discussion with specialists present in the audience. Finally, statements regarding each topic were proposed and voted on by the audience and these were presented to the ECHM Executive Board for consideration and possible approval. In conclusion, the use of HBOT in femoral head necrosis will be proposed during the next ECHM Consensus Conference to become an ‘accepted’ indication; whilst the use of HBOT in global brain ischaemia and autism should retain its current ECHM recommendations, that it should be ‘optional’ and ‘non-accepted’ respectively.

Brief Report: Hyperbaric Oxygen Therapy (HBOT) in Children with Autism Spectrum Disorder: A Clinical Trial

22 Aug

Hyperbaric Oxygen Therapy (HBOT) is a popular offering in the alternative medical community. It is a therapy that has proven and approved uses (most notably treatment for decompression sickness or carbon monoxide poisoning). It has been proposed as a therapy for autism, and there is already a mixed body of literature on the subject, most with small and/or uncontrolled studies. The most recent study found no benefit.

Another study has now been released, this time from the University of California (UC San Francisco and UC Davis). Brief Report: Hyperbaric Oxygen Therapy (HBOT) in Children with Autism Spectrum Disorder: A Clinical Trial is a small, uncontrolled study. The measure of benefit, at least by the abstract, is the CGI-I (Clinical Global Impression, Improvement scale), which is not particularly objective. Measures of cytokine levels were made, and no changes were observed. So, if any behavioral changes were derived from the HBOT, they were not correlated with cytokine levels.

We sought to determine whether HBOT leads to parental reported behavioral changes and alterations in cytokines in children with ASD. Ten children completed 80 sessions of HBOT and all improved by 2 points on the clinician-rated CGI-I scale (much improved) as well as several parent-completed measures of behavior. The lack of a control group limits the ability to determine if improvements were related to HBOT. Enrolled children did not exhibit abnormal cytokine levels at baseline and no significant changes in mean cytokine levels were observed. Although this study was limited by the small sample size and by the variable nature of cytokines, we found no evidence that HBOT affects cytokine levels or that cytokine levels were associated with behavioral changes.

In general, not a particularly strong study. I’ll note that UCSF’s recent MB12 study put a rather positive spin on a negative result. The fact that these researchers rated the children as improved is not really impressive to me. We don’t need more weak studies on alternative medicine. Those will never really answer any questions.

Teaching Medical Students About Disability: The Use of Standardized Patients.

20 Aug

If you haven’t heard about “standardized patients” before, they are an interesting (and important) part of medical training. Basically think of an actor (often literally an actor looking for some extra money) who portrays a patient with a given malady. He may or may not give all the information needed to the doctor in training. As in, “I’m coughing a lot lately” without saying “I smoke three packs a day”.

How can a doctor learn about the special needs of patients with disabilities? Especially those which may not be obvious, or those which make it difficult to obtain information from the patient? In Teaching Medical Students About Disability: The Use of Standardized Patients the authors consider programs which use standardized patients (SP’s) with disabilities and those portraying disabled subjects.

Standardized patients (SPs), now a mainstay of the undergraduate medical education experience, are beginning to play larger roles in helping students build competencies to better serve patients who have disabilities, in educating students about the lived experiences of persons with disabilities, and in testing students’ understanding of disability-related issues. In this article, the authors discuss several U.S. training programs that involve SPs who have disabilities or SPs who do not have disabilities but who portray patients who do. The authors review the goals of each program (e.g., to provide students with opportunities to gain experience with patients with disabilities), describe their commonalities (enhancing students’ interview skills) and differences (some programs are educational; some are evaluative), and summarize the evaluative data of each. The authors also explore the benefits and challenges of working with SPs with disabilities and of working with SPs without disabilities. Finally, they consider the practical issues (e.g., recruiting SPs) of developing and implementing such programs.

Honestly, I haven’t read the full paper. I’ve been putting off writing about this until I find the time, but that hasn’t happened and I find the subject too interesting to let it just fall by the wayside. I am encouraged to think that training programs include disability in their SP’s, and hope that is is more the rule than the exception.

Alleged Cases of Vaccine Encephalopathy Rediagnosed Years Later as Dravet Syndrome

19 Aug

A case study released this week looks at 5 children who were considered to have vaccine encephalopathy caused by pertussis vaccinations. In this case study, all five children were found to have Dravet Syndrome, a genetic condition involving how the brain uses sodium.

The phrasing of “alleged cases” will likely draw some critique. Parents are very sensitive to the accusation that they didn’t see what happened, in this case seizures and regression following vaccination. Alleged in this case doesn’t challenge what the parents saw, but what it means. It appears that individuals with Dravert syndrome don’t get through childhood without regression (there don’t appear to be cases with the mutation and no syndrome in adults). In the words of the vaccine court, these individuals would have Dravert’s syndrome in any event, making it impossible to show that vaccines are the causation in fact.

Dr. Vincent Ianelli reports over at pediatrics.about.com that the cases include:

14-year-old mentally retarded boy with autistic features, who was a healthy infant until he got his vaccines when he was 7 months old
20-year-old with delayed development and autistic-like features who began having seizures right after getting vaccines at 2 months
2-year-old with a mild expressive speech delay who developed seizures after getting vaccines at age 4 months
4-year-old with “slowing development” who began having seizures after the six month vaccines
3-year-old regressed development and autistic-like features who began having seizures after getting vaccines at age 4 months

In these five case, genetic testing resulted in a diagnosis of Dravet Syndrome.

From Dr. Ianelli:

Dravet syndrome is a rare, genetic cause of encephalopathy that causes seizures that are hard to control and developmental delays.

Since fever is the usual trigger of the first seizure and subsequent seizures, it is important that children with Dravet syndrome get all of their vaccines, since natural infections will cause more fever and put them at risk for more seizures. In another study, “A retrospective study of the relation between vaccination and occurrence of seizures in Dravet syndrome,” only 16% of patients with Dravet syndrome had a vaccine related seizure as their first manifestation.

The researchers also state “that although vaccination might trigger an earlier onset of the presenting symptoms of Dravet syndrome, there is no evidence that the outcomes, in terms of subsequent seizure types or intellect, are any different between those patients with Dravet syndrome whose symptoms started within 2 days of vaccination and those whose symptom onset was not related temporally to vaccination.”

Here is the abstract:

Dravet syndrome is a rare epileptic encephalopathy linked to mutations in SCN1A (neuronal sodium channel ?1 subunit) and characterized by an onset in infancy with polymorphous seizure types and developmental decline. It was reported recently that a proportion of patients previously diagnosed with alleged vaccine encephalopathy might possess SCN1A mutations and clinical histories that enabled a diagnosis of Dravet syndrome, but these results have not been replicated. We present here the cases of 5 children who presented for epilepsy care with presumed parental diagnoses of alleged vaccine encephalopathy caused by pertussis vaccinations in infancy. Their conditions were all rediagnosed years later, with the support of genetic testing, as Dravet syndrome. We hope that these cases will raise awareness of Dravet syndrome among health care providers who care for children and adolescents and aid in earlier recognition and diagnosis.

This isn’t the first work linking alleged vaccine encephalopathy with Dravet syndrome in some cases. Last year a study in The Lancet, Effects of vaccination on onset and outcome of Dravet syndrome: a retrospective study (also summarized in Pertussis Vaccination Triggers Dravet Syndrome in Predisposed Children) came to the conclusion:

Vaccination might trigger earlier onset of Dravet syndrome in children who, because of an SCN1A mutation, are destined to develop the disease. However, vaccination should not be withheld from children with SCN1A mutations because we found no evidence that vaccinations before or after disease onset affect outcome.

The anchor author on that study has a previous study, De-novo mutations of the sodium channel gene SCN1A in alleged vaccine encephalopathy: a retrospective study. They found 11 of 14 patients with alleged vaccine encephalopathy had Dravet syndrome (SMEI). Here is the abstract:

BACKGROUND:
Vaccination, particularly for pertussis, has been implicated as a direct cause of an encephalopathy with refractory seizures and intellectual impairment. We postulated that cases of so-called vaccine encephalopathy could have mutations in the neuronal sodium channel alpha1 subunit gene (SCN1A) because of a clinical resemblance to severe myoclonic epilepsy of infancy (SMEI) for which such mutations have been identified.

METHODS:
We retrospectively studied 14 patients with alleged vaccine encephalopathy in whom the first seizure occurred within 72 h of vaccination. We reviewed the relation to vaccination from source records and assessed the specific epilepsy phenotype. Mutations in SCN1A were identified by PCR amplification and denaturing high performance liquid chromatography analysis, with subsequent sequencing. Parental DNA was examined to ascertain the origin of the mutation.

FINDINGS:
SCN1A mutations were identified in 11 of 14 patients with alleged vaccine encephalopathy; a diagnosis of a specific epilepsy syndrome was made in all 14 cases. Five mutations predicted truncation of the protein and six were missense in conserved regions of the molecule. In all nine cases where parental DNA was available the mutations arose de novo. Clinical-molecular correlation showed mutations in eight of eight cases with phenotypes of SMEI, in three of four cases with borderline SMEI, but not in two cases with Lennox-Gastaut syndrome.

INTERPRETATION:
Cases of alleged vaccine encephalopathy could in fact be a genetically determined epileptic encephalopathy that arose de novo. These findings have important clinical implications for diagnosis and management of encephalopathy and, if confirmed in other cohorts, major societal implications for the general acceptance of vaccination.

A recent study out of Germany took a bit more cautious interpretation: A retrospective study of the relation between vaccination and occurrence of seizures in Dravet syndrome. But the abstract does not address the question of whether outcome depends upon whether the first seizure is possibly vaccine related or not.

At least two cases of have been heard in the vaccine court claiming vaccine injury in children with Dravet syndrome. Both cases (here and here) were denied compensation.

More information about Dravet syndrome can be found at the NIH website, and dravet.org

Autism Science Foundation issues new request for scientific grant proposals

18 Aug

The Autism Science Foundation funds research. They have funded predoctoral and postdoctoral researchers and are seeking proposals for this year’s round of grants. Personally, I like this focus. I like the idea of bringing good new people into autism research.

Here is the press release:

AUTISM SCIENCE FOUNDATION ISSUES NEW REQUEST FOR SCIENTIFIC GRANT PROPOSALS
Grants will fund pre- and postdoctoral autism research fellowships

(August 18, 2011—New York, NY)–The Autism Science Foundation, a not-for-profit organization dedicated to supporting and funding autism research, today announced that it had issued a new request for scientific proposals. ASF is inviting applications for Pre- and Postdoctoral Training Awards from graduate students, medical students and postdoctoral fellows interested in pursuing careers in basic and clinical research relevant to autism spectrum disorders. In the past two years, ASF has funded over $400,000 in pre and postdoctoral grants.

“This is one of our most important funding mechanisms” said Alison Singer, president of the Autism Science Foundation. “The pre- and postdoctoral fellowships not only build our knowledge about what causes autism and how best to treat it, but also build our future by encouraging outstanding young investigators to dedicate their careers to autism research.”

“Outstanding research is the greatest gift we can offer our families” said Karen London, ASF co-founder. “We are so grateful to all our donors and volunteers who have come together to support autism research and who make these grants possible.”

The proposed training must be scientifically linked to autism. Autism Science Foundation will consider for training purposes all areas of related basic and clinical research including but not limited to: human behavior across the lifespan (language, learning, communication, social function, epilepsy, sleep, repetitive disorders), neurobiology (anatomy, development, neuro-imaging), pharmacology, neuropathology, human genetics/genomics, immunology, molecular and cellular mechanisms, studies employing model organisms and systems, and studies of treatment and service delivery. Applications must be received by November 18, 2011.

Additional information about the RFA can be found at www.autismsciencefoundation.org/ApplyForaGrant.html
The Autism Science Foundation is a 501(c)(3) public charity. Its mission is to support autism research by providing funding to scientists and organizations conducting, facilitating, publicizing and disseminating autism research. The organization also provides information about autism to
the general public and serves to increase awareness of autism spectrum disorders and the needs of individuals and families affected by autism.
Grant applications will be reviewed by members of ASF’s Scientific Advisory Board (SAB) and other highly qualified reviewers. Current SAB members include Dr. Joseph Buxbaum (Mt. Sinai School of Medicine); Dr. Emanuel DiCicco-Bloom (UMDNJ-Robert Wood Johnson Medical School); Dr. Sharon Humiston (University of Rochester); Dr. Bryan King (University of Washington, Seattle); Dr. Ami Klin (Emory University); Dr. Harold Koplewicz (The Child Mind Institute); Dr. Eric London (New York Institute for Basic Research); Dr. Catherine Lord (New York Institute for Brain Development); Dr. David Mandell (University of Pennsylvania/CHOP); and Dr. Matthew State (Yale Medical School).

To learn more about the Autism Science Foundation’s grant programs, and to read about projects funded through this mechanism in prior years, visit www.autismsciencefoundation.org/ApplyForaGrant.html

Media Contact Info:

Dawn Crawford
Autism Science Foundation
dcrawford@autismsciencefoundation.org

The Autism Science Foundation has posted this to their blog: ASF Issues New Request for Scientific Grant Proposals: Grants will fund pre- and postdoctoral autism research fellowships

Study Recurrence Risk for Autism Spectrum Disorders: A Baby Siblings Research Consortium Study

16 Aug

It is known that the chances of having an autistic child are higher for families who already have an autistic child. This is the “recurrence risk”. In the past, the recurrence risk has been estimated at between 3 and 10%. A study just out (and discussed somewhat yesterday) puts the risk at something closer to 20% (18.7%). This is a fairly large study, where they monitored the baby siblings in families with an autistic child. They were watching these baby sibs and testing them to see which ones had an autism spectrum disorder (ASD). This makes this study much more powerful in that they are much less likely to miss any ASD baby sibs.

Here is the abstract:

OBJECTIVE: The recurrence risk of autism spectrum disorders (ASD) is estimated to be between 3% and 10%, but previous research was limited by small sample sizes and biases related to ascertainment, reporting, and stoppage factors. This study used prospective methods to obtain an updated estimate of sibling recurrence risk for ASD.
METHODS: A prospective longitudinal study of infants at risk for ASD was conducted by a multisite international network, the Baby Siblings Research Consortium. Infants (n=664) with an older biological sibling with ASD were followed from early in life to 36 months, when they were classified as having or not having ASD. An ASD classification required surpassing the cutoff of the Autism Diagnostic Observation Schedule and receiving a clinical diagnosis from an expert clinician.
RESULTS: A total of 18.7% of the infants developed ASD. Infant gender and the presence of >1 older affected sibling were significant predictors of ASD outcome, and there was an almost threefold increase in risk for male subjects and an additional twofold increase in risk if there was >1 older affected sibling. The age of the infant at study enrollment, the gender and functioning level of the infant’s older sibling, and other demographic factors did not predict ASD outcome.
CONCLUSIONS: The sibling recurrence rate of ASD is higher than suggested by previous estimates. The size of the current sample and prospective nature of data collection minimized many limitations of previous studies of sibling recurrence. Clinical implications, including genetic counseling, are discussed.

The full paper is free online.

Since this was already presented here and elsewhere, I’ll point out a few findings that I found interesting:

1) 41% of the baby sibs received autistic disorder diagnoses. The remaining 59% received PDD-NOS diagnoses.
2) The recurrence risk did not depend on the “functioning status” or “severity” of the autism for the first child. They used ADOS and IQ scores to measure “severity”.
3) the gender of the first autistic child does not increase the recurrence risk. So, if a family has an autistic daughter, the recurrence risk is the same as if the autistic child is a son. My recollection is that previous studies indicated a high recurrence risk if the older sibling was a daughter.

Autism Baby Siblings Study: recurrence risk 19%

15 Aug

Results of the MIND Institute’s baby sibling study have been published in the journal Pediatrics. The study puts the recurrence risk of autism at 19%. In other words, a family with one autistic child has, on average, a 19% chance that a subsequent child will be autistic. The study authors stress that the risk may be higher in some families and lower in others.

More discussion can be found in various news outlets carrying the story, including

http://m.heraldextra.com/news/science/health-med-fit/article_a90c6549-3444-5b6a-800a-85aba7234914.html

The Association of Autism Diagnosis With Socioeconomic Status

4 Aug

The CDC’ autism prevalence estimates are probably the most quoted values. Not too long ago, the estimate was 1 in 166. Then 1 in 150. About a year ago, the estimate was revised to 1 in 100.

But, these numbers are estimates. And, more importantly, these estimates spam a wide range. Autism prevalence estimates vary by state and by ethnicity.

The state with the highest prevalence estimate is New Jersey. A team in New Jersey has analyzed the most recent data for the relationship on factors such as race/ethnicity and household income.

What did they find? Kids from high income families are twice as likely to get an autism designation as kids from less affluent areas.

The prevalence estimate in wealthy areas? 17 per 1000. Or 1 in 59.

Here is the abstract:

Background: In 2007 the Centers for Disease Control and Prevention (CDC) reported a higher prevalence of autism spectrum disorder (ASD) in New Jersey, one of the wealthiest states in the United States, than in other surveillance regions. Objective: To examine the association of socioeconomic status (SES) with ASD prevalence. Methods: Information on eight-year-olds with ASD from four counties was abstracted from school and medical records. US Census 2000 provided population and median household income data. Results: 586 children with ASD were identified: autism prevalence was 10.2/1000, higher in boys than girls (16 vs. 4/1000); higher in white and Asian non-Hispanics than in black non-Hispanics and Hispanics (12.5, 14.0, 9.0, and 8.5/1000, respectively); and higher (17.2/1000 (95% CI 14.0-21.1)) in tracts with median income >US$90,000 than in tracts with median income ?US$30,000 (7.1 (95% CI 5.7-8.9)). Number of professional evaluations was higher, and age at diagnosis younger, in higher income tracts (p < .001), but both measures spanned a wide overlapping range in all SES levels. In multivariable models race/ethnicity did not predict ASD, but the prevalence ratio was 2.2 (95% CI 1.5-3.1) when comparing highest with lowest income tracts. Conclusions: In the US state of New Jersey, ASD prevalence is higher in wealthier census tracts, perhaps due to differential access to pediatric and developmental services.

Listeners prefer the laughs of children with autism to those of typically developing children.

4 Aug

When you see a paper with a title like that, you have to read the abstract. OK, I have to. I didn’t expect this to be profound. It is interesting, though. Right up the the last ( and in my opinion unfortunate) sentence.

The purpose of this study was to investigate the impact of laugh sounds produced by 8- to 10-year-old children with and without autism on naïve listeners, and to evaluate if listeners could distinguish between the laughs of the two groups. Results showed that listeners rated the laughs of children with autism more positively than the laughs of typically developing children, and that they were slightly above chance levels at judging which group produced the laugh. A subset of participants who reported listening for “uncontrolled” or “longer” laughs were significantly better at discriminating between the laughs of the two groups. Our results suggest that the laughs of children with autism have the potential to promote the formation of relationships.

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