Autism Occurrence by MMR Vaccine Status Among US Children With Older siblings With and Without autism (study)

AutismThe JAMA 2015 study, “Autism Occurrence by MMR Vaccine Status Among US Children With Older siblings With and Without Autism,” (which you can read here… ) concludes, “receipt of the MMR was not associated with increased risk of ASD, regardless of whether older siblings had ASD”.  They go on to state “these findings indicate no harmful association between MMR vaccine receipt and ASD even among children already at higher risk for ASD.  I would add that given the lack of significance in their findings, and study design issues, this study also does not clarify at all whether the MMR was associated with an increased risk of autism or not.

This study of almost 100,000 children used administrative claims data only, and for unknown reasons excluded all but one large commercial health plan. It is not explained why Medicare children were excluded. The results reported in the abstract had P values of .22, .052, .05 and .55 (hardly worth reporting on since they are not significant).  In fact the only statement with significance that they reported is that of those with older siblings with ASD, 6.9% had ASD vs 0.9% of the children with unaffected siblings (P<.001).  So we can say that if you have one child with autism or ASD, you are at higher risk of having another child with autism or ASD. Why did their study design exclude those with only one diagnosis claim for autism or ASD? What did that data show?  It would be nice to see the data that included those children.  It is not clear why those with “neuromuscular, cardiovascular, respiratory, renal, gastrointestinal. hematologic or immunologic, metabolic, other congenital or genetic defects, and malignant neoplasms” were excluded.  Several fancy statistical analyses were done adding little to the understanding of this data.  Using the data they present in table 2, I calculate for you the autism rates that were found and present them here:





2 Year Olds               

1   MMR                      1/1,468                                                            1/199
No MMR                      1/1,173                                                            1/86

3 Year Olds

1   MMR                      1/333                                                               1/38
No MMR                      1/285                                                               1/25

4Year Olds

1   MMR                      1/200                                                               1/23
No  MMR                     1/184                                                               1/15

5 Year Olds 

2   MMR’s                   1/186                                                               1/26
1   MMR                      1/119                                                               1/16
No MMR                      1/138                                                               1/11


So skip the hazard ratios, the Cox proportional hazards models, and the Yates-corrected X2 test.  The above data show clearly the following points:

  1. Your risk of autism or ASD goes up significantly based on the age of children you are looking at.  In low risk populations (most families who do not already have an autistic child) your risk of having an autistic child is as low as 1/1,468 at age 2 to as high as 1/119 at age 5.
  2. If you have an older sibling with autism or ASD, your risk of your next child having autism is as low as 1/199 at age 2 to as high as 1/11 by age 5.
  3. If you have one autistic child you are about 10 times more likely to have another when compared to those families who do not have an autistic child.
  4. For each age group, having not given the MMR results in a much higher risk of having an autistic child.  How can that be?  The authors acknowledge this problem saying “this pattern is driven by selective parental decision making around MMR immunization, i.e., parents who notice social or communication delays in their children decide to forestall immunization. Because, as a group, children with recognized delays are likely to be at higher risk of ASD, such selectivity could result in a tendency for some higher-risk children to be “unexposed” (to the MMR).  Do you think?


This is exactly what I see in my practice where intelligent parents are absolutely waiting on vaccines if they see developmental delays in their child. The experience I have had in my practice, is that for siblings of autistic children, when parents do no vaccines, I have had a rate of autism that is 1/87 when I last looked at those who were ages 3-5 in my practice. Compare this to the study rates here of 1/11 for 5 year olds, 1/15 for 4 year olds, 1/25 for 3 year olds who didn’t get the MMR and it becomes clear that there is a design flaw in this study, or that vaccines are involved in the causation of autism.  Compare this with the published data on the risk of having a second child with autism that ranges from 6.4% (1/15) to 1/4 (25%). I have placed some links at the end of this blog for you to see the published data. The 1/87 (1.15%) in my practice becomes a goal against which all other approaches can be compared.

This study adds wonderful data to the world literature on autism rates in this population based on having at least two diagnoses and factoring in the multitude of exclusions.  Clearly the ASD diagnosis rate climbs significantly as children get older and this illustrates the difficulty when comparing autism or ASD rates between studies since they often have different ages of diagnosis or different ages of children being studied.

We need straight forward studies that compare apples to apples, compare vaccinated to non-vaccinated or to selectively vaccinated populations.  Factoring in family history is clearly the most important variable and just looking at siblings who are already autistic is like closing the barn door after the horse has bolted.  It is time we acknowledge that epigenetic vulnerability to environmental toxins is critical, and that vaccines are part of the environmental toxic puzzle.  Let’s get some real studies that get to the heart of the mater. This study leaves me as uninformed as I was before I read it, on the issue they claim to address: autism rates and their relationship to MMR.


The familial risk of autism

Recurrence risk for autism spectrum disorders: a Baby Siblings Research Consortium study

Recurrence of autism spectrum disorders in full- and half-siblings and trends over time: a population-based cohort study


Dr. Paul



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