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February 2022

COVID And Heart Disease—It’s All Relative

A new COVID study recently reported in Nature got the attention of your aging scrivener. It reported that COVID-19 increases risk for cardiovascular disease for at least a year after infection.  This was a large study of US veterans that found that the risk of having a heart attack, stroke or several other cardiovascular events was higher for those who had COVID-19 the year prior compared to those who weren’t infected. The risk was highest for those who had been hospitalized but was still elevated for those not admitted.

But when you read about elevated risk in the news or especially on social media, what does it mean? Hint: the media usually will not tell you this.

In order to understand the significance of such risk, we need to know both the relative and absolute risks. Relative risk is what we often see reported in alarming headlines—for example in this case, the risk of a heart attack was reported to be 63% higher in those who had had COVID-19. That is relative risk and it sounds pretty bad, right? Relative risk tells us that a risk is higher in one group than in another, but it doesn’t tell us the whole story. To put relative risk in perspective, we also need to know the absolute risk of the bad thing happening.

For example: let’s say that in a group of 100,000 “normal” people, one is expected to develop a rare cancer. But in people who were recently x-rayed, two people in 100,000 develop the cancer. The headlines would scream that x-rays caused a 100% increase of the cancer. The risk doubled after being x-rayed. Pretty chilling. Yet, the absolute risk in this example is extremely small—only one extra person out of 100,000 who are x-rayed gets the cancer.

Compare that to a situation where 10,000 out of 100,000 typically develop this cancer and x-rays again double the risk. That means 20,000 out of 100,000 people getting x-rays will get the cancer. In the two scenarios, the relative risk is identical—x-rays are associated with a doubling of cancer cases—a 100% increase in cancer risk. But in the second example, the absolute risk is much, much greater. Instead of causing cancer in only one out of 100,000 people (0.001%) as in the first example, the second example has x-rays causing cancer in 10,000 of every 100,000 people, or 10%.

Going back to the study in Nature, remember having COVID led to a 63% increased chance of having a heart attack. The data showed that the absolute risk of heart attack was 4.67/1000 for uninfected people compared to 7.59/1000 for those who had COVID-19 in the previous year. So, in absolute risk terms, an extra 3 people out of 1000 had a heart attack after having COVID-19. That puts the 63% increased relative risk in perspective.

Now that relative vs absolute risk have been explained, we are still left with the question of whether these extra three heart attacks are concerning. Like many other things, it depends how you look at it.

With tens of millions of people getting infected with COVID-19, an increase of three heart attacks for every thousand people can add up fast. Looking at the population level, this could lead to a noticeable rise in cardiovascular disease burden and lead health experts to begin planning for a wave of heart attacks. But, looking at the individual level, most COVID infected peoples’ risk of having a heart attack in the next year is pretty low. So, if you have COVID, you do not need to begin planning your funeral.

Bottom line: These alarming headlines need to be understood in terms of relative vs absolute risk and then looked at in terms of the effect on the population vs on the individual. Way too often during this pandemic, I have seen folks abusing both. For example, how often do you hear people saying that COVID is overblown because <1% die from it. This totally ignores the absolute risk (how many deaths is that) and focuses only on the individual effect while totally ignoring the population level effect (1% of 100 million is a lot of people).

It is all relatively absolute and absolutely relative.

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Another Unexpected Pandemic Consequence: Undiagnosed Cancer

In these pages, your humble bloggeur (that would be me) has written about several unusual consequences of the COVID-19 pandemic. Most of these were on the ironically funny side, such as farmed fish being too large for restaurant plates, rattlesnakes climbing in plane landing gears, and the ketchup packet shortage. But, not all of these odd aftermaths of the pandemic are humorous. The topic of this post is very unfunny.


It seems that as healthcare providers were swamped with COVID cases, or were at reduced capacity because staff became ill, or because service slowed in order to prevent CoV-2 spread, many people have missed routine medical care for non-COVID problems. It is feared that this will create a crisis in coming years involving increased diagnosis of cancers that were caught later than usual. As we deal with the fourth wave of COVID-19 caused by the Omicron variant, we are learning that the pandemic dramatically disrupted routine health screenings for cancer and other chronic diseases. Some now predict that the next crisis that could overwhelm the US health system will be a surge in advanced chronic diseases like cancer that went undiagnosed and untreated for too long.

Screenings for several major cancers and new cancer diagnoses fell significantly during 2020, according to a study published in December 2021 in the journal Cancer. This was not because there was less cancer in the world. It was because fewer patients were seeing their doctors.

A co-author of the Cancer study, and who is a professor at the University of Maryland School of Medicine, said that we have never before seen screening rates drop so dramatically in such a short time.

In one case, a Hispanic man in his 40s first noticed rectal bleeding in early 2020 that his doctor said was probably due to hemorrhoids. The man was unable to get a timely colonoscopy to rule out cancer because the local hospitals were overwhelmed with COVID-19 patients, and he also feared catching COVID if he went to a hospital swamped with COVID patients. Eighteen months later, he finally got a colonoscopy, which revealed advanced rectal cancer. Those 18 months likely were the difference between being cured by a simple polyp removal vs dealing with a cancer that had metastasized throughout his body.

At this point, nobody knows how many cases like this are out there. We will find out.  

This patient, as thousands of others like him, had the misfortune to notice symptoms that needed followup amid the biggest disruption of medical care in US history. In 2020, while hospitals curtailed services in order to prepare for the COVID surge, the number of colonoscopies plummeted 93 percent. By the end of the year, there had been 133,231 fewer colonoscopies performed compared to 2019. There also were 62,793 fewer chest CT scans, 49,334 fewer fecal blood tests, and prostate biopsies dropped 25%.

This drop in screenings has created a huge backlog that will take months to clear. A gastroenterologist at a small community hospital in the Middle-of-No-Where, Kansas was recruited by a larger hospital in Kansas City to do nothing but colonoscopies from 7 in the morning to “whenever at night.” They had a backlog of 1000 patients—a certain percentage of whom have cancer already growing in their colons while waiting to be told they had colon cancer. And that backlog begets a fresh one of new patients who also need to be scoped because they just noticed something like rectal bleeding, but will have to wait for those who have already been waiting.

This backlog creates a subtle form of medical rationing. It forces doctors to make hard choices about which patients to prioritize. "Lucky" are the serious patients who are moved to the head of the line. Not so lucky are those whose colonoscopies or mammograms or biopsies are then further delayed.

I would rather deal with rattlesnakes in my plane's landing gear or forgo mustard on my brat (which would be pushing the limit) than delay a needed medical test or procedure. It seems that your humble bloggeur (me again) has been caught in the backlog. I am scheduled to have an enlarged parathyroid gland removed next week, but COVID can still derail that. I won’t be certain that the surgery will happen until the day before I am to be operated on and that depends, in part, on everyone, including me, being COVID-free, and the OR not being diverted for use as a COVID ICU. If it proceeds as scheduled, I will have waited several months since the initial diagnosis for the surgery. An additional routine diagnostic test I need in order to determine how the fractious organ might have affected my bone health was scheduled six months out. Six months for a routine scan?