Should you follow The Science or the Yellow Brick Road? (episode 2)
The path to knowledge is paved with only the best of intentions, and what more exemplifies knowledge than The Science and its handmaidens, clinical studies Unfortunately, not all scientists are putting out good science, even if their statistical analyses are impeccable.
Case Study Four – COVID shots protect you from traffic accidents?
Another great study, this time out of Toronto, Canada. Researchers decided to look for a link between “vaccine hesitancy” and “traffic crashes,” because
... we theorized that individual adults who tend to resist public health recommendations might also neglect basic road safety guidelines.
And they were right! They found that out of the over 11 million adults studied, unvaccinated people accounted for 1682 crashes, whereas vaccinated people accounted for 6682. Since 84 percent of those studied were vaccinated, this meant that unvaccinated people had an increased relative risk of 72 percent of being involved in a traffic crash. (For statistics fans, P was <0.001, which is considered very, very significant.)
For those who were reading our last Yellow Brick Road and remember what we wrote about adjusting the data for confounding factors, rest assured that these Torontonian scientists had no flies on them there. They adjusted for sleep apnea, age, sex, home location, socioeconomic status, and medical diagnoses. P was still <0.001 but the increased risk of crashes in the unvaccinated dropped to 48 percent.
(As an aside, it didn’t seem to matter what kind of vaccine you got. Pfizer, Moderna, or Aunt Jemima’s were all equally effective at protecting you from traffic accidents.)
The researchers admitted that finding a connection between COVID vaccine hesitancy and increased traffic risks was “surprising,” but still concluded (how could they not?) that,
These data suggest that COVID vaccine hesitancy is associated with significant increased risks of a traffic crash.
Understandably they couldn’t resist adding that,
An awareness of these risks might help to encourage more COVID vaccination ... Coronavirus disease (COVID) vaccination uptake has stalled despite being safe, effective, and free ... Physicians counseling patients who decline COVID vaccination could consider safety reminders to mitigate traffic risks.
Given that “vaccine hesitancy” is a rather unscientific term, let’s take a look at what the researchers mean when they describe it.
Coronavirus disease (COVID) vaccine hesitancy is defined by the World Health Organization as a delay in acceptance or refusal of vaccination against an important contagious disease despite supply (distribution), access (availability), and awareness (albeit with possible misinformation).
Clearly they are not describing people who are merely hesitant. What they are describing would better be called “perversity” — people who refuse a (safe, effective, and free) treatment for an “important” (i.e. dangerous) disease, for no good reason at all. However, what they actually studied are people who decided not to be injected, not people who were hesitant, perverse, stupid, illiterate, deplorable, or even intelligent.
Nonetheless, the researchers did go so far as to suggest some reasons why people might be “hesitant” about getting jabbed:
One possibility relates to a distrust of government or belief in freedom that contributes to both vaccination preferences and increased traffic risks...
A different explanation might be misconceptions of everyday risks, faith in natural protection, antipathy toward regulation, chronic poverty, exposure to misinformation, insufficient resources, or other personal beliefs...
Alternative factors could include political identity, negative past experiences, limited health literacy, or social networks that lead to misgivings around public health guidelines.
Did the researchers have any misgivings? After all, they themselves admitted that, “Simple immune activation against a coronavirus, for example, has no direct effect on traffic behavior or the risk of a motor vehicle crash.” Were the causes really all down to reckless driving by people who recklessly discounted their own and others’ health in general?
As noted above, the researchers did make some attempt to adjust the data for all the other possible causes of traffic crashes which might have skewed their results. One factor that they didn’t properly account for, however, is what is known as the “healthy vaccinee bias.” In a nutshell, what this means (and has been observed in many studies for many vaccines) is that people who are more health-conscious in general are more likely to follow doctors’ advice and get a shot, while people who pay less attention to their health (for whatever reason) are less likely to follow doctors’ advice.
Adjusting data for healthy vaccinee bias is not easy to do with any degree of accuracy. The Toronto researchers did make an attempt to test their data for general accuracy, but failed to incorporate their findings in their conclusions. This is what they did:
They write: “The purpose of the second propensity score analysis was to be stringent when matching an unvaccinated individual 1-to-1 with a vaccinated individual and excluding cases where any person had a medical diagnosis.”
Had they emerged with an odds ratio of 1, you would know that they had accounted for bias. But they didn’t. What they got was 1.63 (adjusted) instead of 1.72 (unadjusted).
As Prof. Eyal Shahar notes, “Relying on measured variables can fail to remove the bias, and that’s all that we need to know.”
But there’s more.
The researchers write that,
Another limitation of our study is the lack of direct data on driving exposure in different groups ... [or] why the increased risks extended to pedestrians.
Why might the increased risks extend to pedestrians? As the table below shows, unvaccinated pedestrians had an increased relative risk of 1.38 of being involved in a traffic crash, as compared to vaccinated pedestrians. Well, perhaps they were recklessly jaywalking or ignoring traffic signals or sleepwalking...
What the researchers don’t mention, although they include the results in the table, is that passengers who were unvaccinated seemed to be just as likely as drivers (and more likely than pedestrians) to be involved in car crashes. How can that be explained? Perhaps they were sitting next to the driver and telling him, “Hey, see that red light? Ignore it! It’s just government propaganda...” Well, you never know...
But think twice before trusting clinical trials coming out of Toronto.
Case Study Five – Drinking coffee increases your chances of getting lung cancer?
This time we bring you a study from Shanghai. Researchers decided to investigate a putative link between coffee consumption and lung cancer risk. Why? Apparently, epidemiologic studies have already taken a look at this interesting idea but “the results were inconsistent.” So they conducted a meta-analysis, which involved searching through PubMed and EMBASE databases from 1966 till 2009.
The Chinese researchers came up with 13 studies on links between coffee and lung cancer, giving them a pool of just over 5,000 cancer cases and almost 105,000 non-cancer cases.
The combined results indicated a significant positive association between highest coffee intake and lung cancer [relative risk (RR)=1.27, 95% confidence interval (CI)=1.04-1.54). Furthermore, an increase in coffee consumption of 2 cups/day was associated with a 14% increased risk of developing lung cancer (RR=1.14, 95% CI=1.04-1.26).
So there you go — drinking coffee could give you lung cancer. Or could it? There was just one little problem:
In stratified analyses, the highest coffee consumption was significantly associated with increased risk of lung cancer ... but borderline significantly associated with decreased risk of lung cancer in non-smokers. In addition, decaffeinated coffee drinking was associated with decreased lung cancer risk...
Could it be that the “significant positive association” was actually an association with smoking rather than coffee?
The researchers seemed hesitant (or perhaps too perverse) to admit that, noting only that,
In conclusion, results from this meta-analysis indicate that high or an increased consumption of coffee may increase the risk of lung cancer. Because the residual confounding effects of smoking or other factors may still exist, these results should be interpreted with caution.
Stay tuned for more of the best of the Yellow Brick Road.
The information contained in this article is for educational and information purposes only and is not intended as health, medical, financial or legal advice. Always consult a physician, lawyer or other qualified professional regarding any questions you may have about a medical condition, health objectives or legal or financial issues.
For Yellow Brick Road (episode 1) click here
