A Review of a CDC study on COVID-Induced Myocarditis Finds a Questionable Use of Statistics and False Medical Theory

Originally published on Wordpress Nov 14, 2021

This document is a review (fact check) of a summary conclusion by Tegan Boehmer et al, published by the CDC on their website on September 03, 2021, titled:  Association Between COVID-19 and Myocarditis Using Hospital-Based Administrative Data — United States, March 2020–January 2021.   Link to the Study.

In their summary conclusions they wrote: 

“These findings underscore the importance of implementing evidence-based COVID-19 prevention strategies, including vaccination, to reduce the public health impact of COVID-19 and its associated complications.”

I rate that statement as FALSE.

Their study analyzed inpatient admissions data from over 900 hospitals that represented approximately 20% of inpatient admissions in the United States.  The authors reported an elevated risk for myocarditis among people who tested positive for COVID-19 in the period March 2020 - January 2021.

The authors did not present any medical theory that supports their claim that vaccination is the correct course of action to avoid myocarditis associated with COVID-19.   I further have multiple concerns with the way the authors interpreted the data which lead me to say that their statistical claims are invalid as reported.  I’ll begin with their statistics.

The authors claimed that the risk of myocarditis was 15.7 times higher for those who had COVID versus those who did not have COVID.  The authors presented this statistic as if the risk of vaccine-induced myocarditis had been eliminated from their statistic.   First let’s look at where they get the statistic of 15.7 X. Below is a table where they reported some of the data used to calculate this statistic.

The 15.7 X elevated risk factor is a simple calculation: The rate of myocarditis while COVID Positive is divided by the rate of COVID Negative. 

The rate of myocarditis while COVID Positive is 2,116 / 1,452,773. This rate = .00145652. 

The rate of myocarditis while COVID Negative is 2,953 / 34,552,521. This rate = .00008546.

These are the two rates. Divide the COVID Positive rate by the COVID Negative rate. (00145652 / 00008546) and you get 17.0433 by my math. This is the increased elevated risk of myocarditis due to COVID, according to the data provided by the authors. The authors in turn "adjust" the 17.04 number downward by a formula to reach their 15.7 number. Although the authors did not provide the formula they used to adjust the data, I do not take issue with their adjustment.

I just want the reader to see where the statistic came from. The following text is where I do find issues. 

The data used to create the 15.7 X (adjusted) elevated risk of myocarditis from COVID was taken from the period March 2020 - January 2021.  The first COVID reports begin in the hospital admissions data in March 2020. The data set the authors analyzed actually began in January 2019, however.   I have taken a chart provide by the authors and divided the data into 3 groups for ease of view for the reader:

The authors could have taken the baseline of risk of myocarditis from the period January 2019 - February 2020 (Period 1) in a period without COVID.  That would avoid any complicating factors from trying to isolate the baseline of risk of myocarditis in the period March 2020 - January 2021 (Periods 2 and 3) that could have been due to COVID.  I don’t understand why they wouldn’t use the period before COVID to determine the baseline risk of myocarditis.  But that's not the main problem.

Vaccinations began in December 2020 according to the authors.  There was no need for the authors to include the period December 2020 to January 2021 (Period 3) in their study.  The authors were aware that vaccinations themselves can cause myocarditis:  “Since the introduction of mRNA COVID-19 vaccines in the United States in December 2020, an elevated risk for myocarditis among mRNA COVID-19 vaccine recipients has been observed…” 

The data available from March 2020 - November 2020 (Period 2) was sufficient to calculate the risk of myocarditis attributable to COVID without falsely attributing any vaccine-induced myocarditis to COVID in the period December 2020 and January 2021 (Period 3).  Why include the period that included vaccinations in the study, knowing that it could be a complicating factor?  With a total number of 5,069 observations of myocarditis (both COVID Negative and Positive), any vaccine-induced myocarditis included in the 15.7 X statistic could greatly skew the statistic.   

The authors gave the appearance that they compensated for vaccine-induced myocarditis:   “To minimize potential bias from vaccine-associated myocarditis (6), 277,892 patients with a COVID-19 vaccination record in PHD-SR during December 2020–February 2021 were excluded.” 

The authors do not say that they removed all the vaccinated individuals from the study, only that they “minimized” the bias by removing 277,892 from a total number of vaccinated individuals that was not disclosed by the authors. 

The study’s implied purpose (they don’t actually state it) was to compare the risk of myocarditis with and without COVID, not including the major complicating variable of vaccine-induced myocarditis. Because the authors did not publish data on the number of people who were vaccinated in their study, this fact alone is enough to invalidate the conclusions of their study.  

To regain public confidence in their study, the authors of the study should clarify how many vaccinated individuals were included in their study, if any, and why they chose to include the period December 2020 - January 2021 at all when there was no need.

Here is another major problem with the data:  “In addition, 37,896 patients for whom information on sex was missing were excluded.”

Again, the authors reported 5,069 cases of myocarditis in the period from March 2020 to January 2021.  With a number as low as 5,069, you can’t just throw away 37,896 observations for “sex” without further explanation and expect anyone to respect your conclusions.  How many among the 37,896 had myocarditis?  They authors did not publish their data or even summarize the nature of the 37,896 observations they omitted.  

If the 37,896 omitted observations that did not include sex were randomly generated over time and had the same rough percentage of myocarditis as the rest of the data, and the authors had been transparent about that, I could accept the omission of the data without questioning the validity of the entire study.  As it is, I cannot accept this omission without further explanation.  What if the omitted data contains a great deal of vaccine-induced myocarditis in the period December 2020 - January 2021, for instance?  I’m not saying that’s what happened, but you can’t just throw away 37,896 observations for “sex” in a data set that has only 5,069 myocarditis observations total and not expect me to question it.  The nature of this omission alone is enough to invalidate the authors’ conclusions.  (I do not question that there is an elevated risk COVID-induced myocarditis; I dispute that the authors established a need for vaccinations to counteract COVID-induced myocarditis. A further explanation of this dispute follows in the "MEDICAL THEORY" section). 

To regain public confidence in their study, the authors of the study should publish the data set they analyzed, including the data they omitted for “sex”, and provide further analysis of the omitted data.

There is yet another problem with the data:  “Patients with myocarditis were defined as those who had their first of at least one inpatient encounter, at least two outpatient encounters, or at least one outpatient encounter with a relevant specialist** with a myocarditis ICD-10-CM code during March 2020– February 2021.” 

Thus the authors excluded patients with one “outpatient encounter” from their definition of who did and did not have myocarditis.  If you’re making a study on myocarditis rates, and discard myocarditis observations without explanation, that’s simply unacceptable to me and to any statistician.  The authors should at least publish the omitted observations and say why they excluded them, and not just hide the fact that they eliminated myocarditis observations in a paragraph that doesn’t even directly state that they eliminated the observations.  

To regain public confidence in their study, the authors of the study should publish the data set they analyzed, including the data they omitted for “one outpatient encounter” with myocarditis and provide further analysis of the omitted data.

MEDICAL THEORY

Boehmer et al, wrote:  "On June 23, 2021, the Advisory Committee on Immunization Practices concluded that the benefits of COVID-19 vaccination clearly outweighed the risks for myocarditis after vaccination (6). The present study supports this recommendation by providing evidence of an elevated risk for myocarditis among persons of all ages with diagnosed COVID-19." 

This statement is also FALSE.   Evidence of elevated myocarditis risk in COVID patients does not support the recommendation of the Advisory Committee on Immunization Practices that the total benefits of vaccination outweigh the risks of vaccine-induced myocarditis.  The evidence presented in the study, flawed as it was, only establishes an elevated COVID-induced myocarditis risk that could be made greater or less by vaccination.    

The study Boehmer et al referenced in (6) is by Gargano et al: Use of mRNA COVID-19 Vaccine After Reports of Myocarditis Among Vaccine Recipients: Update from the Advisory Committee on Immunization Practices — United States, June 2021. Link to the study.

The purpose of this review is not to review the study of Gargano et al. Briefly, however, the Gargano study is an analysis of the total benefits of COVID vaccines versus myocarditis risk:  “The benefits (prevention of COVID-19 disease and associated hospitalizations, ICU admissions, and deaths) outweighed the risks (expected myocarditis cases after vaccination) in all populations for which vaccination has been recommended.”  

Gargano et al do not say that elevated risk of COVID-induced myocarditis creates a need for vaccinations.  Instead, they say that the total benefits of vaccinations outweighed the risk of vaccine-induced myocarditis.  Further, neither Boehmer et al or Gargano et al report any data or analysis on the interaction of COVID and vaccines on myocarditis rates.

By presenting an elevated COVID-associated myocarditis “risk” which may be higher or lower after vaccination, the findings of Boehmer et al do not support the Advisory Committee on Immunization Practices conclusion that the total benefits of vaccinations outweigh the risk of vaccine-induced myocarditis.  (There seems to be an implied, unsubstantiated premise in Boehmer et al's logic that vaccinations stop the transmission and acquisition of COVID and thus COVID-induced myocarditis, but I'll let them explain that). That's one major criticism in their medical theory; another is the lack of consideration of the combined effect of COVID and vaccines on myocarditis rates.

TOPICS FOR FURTHER RESEARCH:  STATISTICAL

What is the combined elevated risk of myocarditis for those who are both COVID Positive and vaccinated?   

There are 4 rates of myocarditis that could have been analyzed by these authors.  The two variables that increase myocarditis rates are COVID (C) and vaccine (V).  Let Positive be represented by P Negative by N, signifying the presence or absence of both variables.    The 4 myocarditis rates are thus:  CPVP,  CPVN,  CNVP, and CNVN.   The authors only reported 2 rates from this data set:  CNVN and CPVN.  They did not report rates on myocarditis after vaccination (CPVP and  CNVP) despite discarding 277,892 vaccination observations.  The elephant in the room here is of course the comparison of myocarditis rates of vaccinated individuals who are COVID positive to unvaccinated individuals who are COVID positive (CPVN to CPVP).  

The authors say that their evidence of elevated risk of myocarditis due to COVID supports the need for vaccinations.  If it is determined later that the authors had evidence that vaccinations after COVID compounded the risk of myocarditis from COVID alone, and yet the authors reported that the correct course of action was to get vaccinated anyway, I will consider it to be a serious breach of professional ethics.  

TOPICS FOR FURTHER RESEARCH:  MEDICAL

Gargano et al wrote:  "Both Pfizer-BioNTech and Moderna vaccines are mRNA vaccines encoding the stabilized prefusion spike glycoprotein of SARS-CoV-2, the virus that causes COVID-19."  Why do COVID and COVID mRNA spike protein based vaccines both increase the risk of myocarditis?

It seems that there are at least two common denominators of COVID and COVID mRNA spike protein based vaccines:  (1) myocarditis and (2) the spike proteins of coronavirus.  Do the spike proteins cause myocarditis?  

SUMMARY

Boehmer et al used questionable and nontransparent statistical methods and senseless medical theory to report findings that an elevated risk of myocarditis associated with COVID created a need for mass vaccinations with COVID mRNA spike protein vaccines.

Author:  Charles Wright

November 14, 2021