There's a traditional Chinese belief that sweeping with a broom on New Year’s brings bad luck.
But how do we know if these things are actually linked or if they're just randomly associated?
How do public health officials, medical doctors, and patients themselves determine if there's a cause-and-effect relationship between aluminum and brain decline or glyphosate and fertility challenges?
Correlation or Causation?Sir Austin Bradford Hill was a medical statistician in Great Britain. In 1965, Hill established a set of nine “viewpoints” to determine when data demonstrated causation.
Hill’s work is still the foundation of showing cause and effect in epidemiology, as well as of showing statistically valid causation across the sciences.
You have heard the caution that “correlation is not causation.” This is a phrase repeated many times over, especially by industry spokespeople trying to defend the safety of pharmaceutical medications or other products.
The idea behind insisting that correlation doesn't equal causation is that just because two things happen together, it doesn’t mean that one caused the other.
A quick example: Let’s say a lot of people named Ashley drive Priuses. That doesn’t mean that Prius drivers must be named Ashley or that people named Ashley necessarily prefer Priuses. The observation can be true without there being any real connection between the name Ashley and Priuses beyond simple random chance.
The Bradford Hill CriteriaIn 1965, long before cigarette manufacturers acknowledged there was any connection, Hill applied his criteria to smoking and cancer.
While everyone now recognizes the connection, it’s important to remember that smoking and lung cancer don't have a 1:1 correlation.
However, the Bradford Hill criteria point to smoking as a cause of lung and other cancers, including rare cancers that are found more frequently in smokers.
- Strength: The more two things occur together, the more likely the causality, even for rare events.
- Consistency: Studies find the same correlation in different places and populations.
- Specificity: A single cause produces a specific effect. (True of diseases like tuberculosis, for example, which is caused by a bacterium called “Mycobacterium tuberculosis”; not so simple for cancer, which appears to have multiple causes.)
- Temporality: The cause must come before (precede) the effect.
- Biological gradient: More exposure leads to more frequent consequences.
- Plausibility: Is there a plausible mechanism for how one thing causes the other?
- Coherence: Is the same effect found in both epidemiological studies of the population and in laboratory work?
- Experiment: Can the correlation observed in the population be reproduced in a laboratory experiment?
- Analogy: Is this cause-effect relationship similar to others we already understand?
Meeting Even One Criterion Enough to Show CausationAccording to Hill, you don't need to satisfy all of his criteria in order to show a clear cause-and-effect relationship between two things.
Myocarditis in Young Men Post-COVID-19 InjectionCases of myocarditis in young men who had received mRNA COVID-19 vaccines made UK health officials concerned that the risk of myocarditis may be as great or greater to young men than the risks of COVID-19 itself. Because of a risk-benefit analysis that showed that cases are higher in men who get the Pfizer vaccine, the UK's National Health Service now recommends young men get the Moderna injection.
“This analysis found that there is an 84% increase in the relative incidence of cardiac-related death among males 18–39 years old within 28 days following mRNA vaccination. With a high level of global immunity to COVID-19, the benefit of vaccination is likely outweighed by this abnormally high risk of cardiac-related death among men in this age group. Non-mRNA vaccines were not found to have these increased risks.
“As such, the State Surgeon General recommends against males aged 18 to 39 from receiving mRNA COVID-19 vaccines. Those with preexisting cardiac conditions, such as myocarditis and pericarditis, should take particular caution when making this decision.”
Research is now being done to look at plausible biological mechanisms to explain why the mRNA vaccines are causing heart inflammation.
Since this specific condition was virtually unheard of before the vaccines, six cases in women between the ages of 18 and 48 were enough to get the attention of the public health authorities. Several Bradford Hill criteria were fulfilled, including temporality and strength. The CDC recommends using other vaccines against COVID-19. As they explain on their website:
Pharmaceutical Expert Weighs InA former pharmaceutical executive, Sasha Latypova, spent her career founding several companies focusing on clinical trial reviews.
“What else do you need as proof?” Latypova asked rhetorically. “All the Bradford Hill criteria have all been met for all of this.”
There's a definite correlation between COVID-19 injections and adverse events, including declining birth rates, stillbirths, and other poor health outcomes. In most cases, if a drug is shown to cause harm by meeting just two Bradford Hill criteria, it would no longer be recommended. In this case, all nine Bradford Hill criteria are met.