Overdiagnosis. The Danger of Calling People Sick, Who Aren’t
I'm an Instructor at Harvard, a consultant in risk perception and risk communication, author of How Risky Is it, Really? Why Our Fears Don't Always Match the Facts, and principal co-author of RISK, A Practical Guide for Deciding What's Really Safe and What's Really Dangerous in the World Around You. I run a program called Improving Media Coverage of Risk. I was the Director of Risk Communication at the Harvard Center for Risk Analysis, part of the Harvard School of Public Health, for 4 years, prior to which I was a TV reporter, specializing in environmental issues, for a local station in Boston for 22 years.
If a doctor looked at you or me thoroughly enough, with all the diagnostic tools now at her disposal, she could almost certainly find something wrong. A spot here, a shadow there, blood pressure a little too high, insulin a little too low. The result quite likely would be some additional procedure or test, or some kind of drug to manage our “condition”, some kind of intervention to find out or treat what’s wrong. Only there is a good chance that nothing would actually be wrong at all.
Sometimes the imperfections that CAT scans and whole body MRIs and DNA testing can reveal are no more than that; imperfections, not medical problems that warrant any further investigation or treatment. Sometimes a slightly elevated cholesterol level or blood pressure or blood sugar or Body Mass Index is beyond the recommended number, but not really enough to worry about. Yet millions of people diagnosed with these suspicious lumps and shadows, or who fall outside the range of some metric that has been deemed “healthy”, are subjected to additional poking around or biopsies or other invasive investigative procedures, or to surgery or other treatments, or they are put on medication. And some of us who weren’t sick in the first place, get sick, or even die.
This problem is known as overdiagnosis, the concept articulated by Drs. Gilbert Welch, Lisa Schwartz, and Steve Woloshin in their 2011 e book Overdiagnosed, Making People Sick in the Pursuit of Health. The idea is simple; millions of people are being diagnosed with medical conditions that will never cause any symptoms, or death. As Welch and colleagues argue, overdiagnosis happens for a number of reasons;
-- Advanced new tests and equipment let us find more. Unfortunately those tests have outpaced our understanding of what all those shadows and bumps and test results actually mean for our health. We can see lots more, but don’t yet know the medical ramifications of what we’re looking at.
-- Experts, all of whom care about public health but many of whom also have strong financial incentives, set more stringent numeric thresholds for what officially qualifies as needing treatment, turning millions of asymptomatic people into paying patients.
-- A litigious society is ready to pounce on any health care provider who fails to diagnose anything that can be blamed for subsequent medical problems.
I would add one more factor. Curiously, it’s our relatively good health. We live longer healthier lives than ever, in large part because many major threats have been brought under control. But we are instinctively always on the alert for whatever can do us harm. So with many of the big threats out of the way, we can look at a finer level for smaller signs of possible trouble. Only we now have the ability to look at such a fine level that some of what we find and worry about, won’t turn into trouble at all.
Here are some examples of overdiagnosis;
-- Millions of men have prostate cancer, which can be detected with blood tests or biopsies, that will never be symptomatic.
-- Millions of women have bumps or lumps in their breasts that are not, and never will be, breast cancer or anything else harmful.
-- 40% of people with no knee pain or problems have ‘damage’ that shows up in an MRI.
-- In 10% of people with no symptoms of gallbladder disease, ultrasounds find gallstones.
-- An MRI of the spine of anyone over 45 is almost sure to find ‘problems’, even in people who are fit and fine.
-- Tens of millions of people are on medication for high or low blood pressure, or high total cholesterol levels, or low bone density, who weren’t candidates for that medicine before “expert panels” set new lower thresholds for who officially qualified for those conditions.
And here are the ramifications of overdiagnosis. Medication has side effects. Biopsy-ing and radiological scanning and a host of follow-up procedures to investigate an overdiagnosis can have side effects. Certainly surgery and other treatments for overdiagnosed conditions that will never cause ill health or death have all kinds of side effects, including severe ill health, and death. And all that medical intervention costs the health care system billions of dollars, which raises the costs of health care for you and me and the whole economy.
The idea of overdiagnosis challenges a fundamental tenet of modern medicine, which rests on the foundational human instinct for precaution and self-preservation. We assume that it’s best to find and take care of anything that might be a problem as early as possible, hopefully before it becomes a problem. The only problem is, we can now find things that meet some medical criterion for ‘problem’, that aren’t in fact problems at all, and never will be.
But it is also a fundamental tenet of medicine to Do No Harm. And our instinct for precaution and self-preservation doesn’t mean we should completely abandon reason and prudence. So the real challenge of overdiagnosis, for all of us, is to see it for the threat that it is, and recognize that in our eagerness to keep ourselves healthy and safe, in many cases we are doing ourselves more harm than good.
What do we see from watching birds move across the country?
- A total of eight billion birds migrate across the U.S. in the fall.
- The birds who migrate to the tropics fair better than the birds who winter in the U.S.
- Conservationists can arguably use these numbers to encourage the development of better habitats in the U.S., especially if temperatures begin to vary in the south.
The migration of birds — and we didn't even used to know that birds migrated; we assumed they hibernated; the modern understanding of bird migration was established when a white stork landed in a German village with an arrow from Central Africa through its neck in 1822 — draws us in the direction of having an understanding of the world. A bird is here and then travels somewhere else. Where does it go? It's a variation on the poetic refrain from The Catcher in the Rye. Where do the ducks go? How many are out there? What might it encounter along the way?
While there is a yearly bird count conducted every Christmas by amateur bird watchers across the country done in conjunction with The Audubon Society, the Cornell Lab of Ornithology recently released the results of a study that actually go some way towards answering heretofore abstract questions: every fall, as per cloud computing and 143 weather radar stations, four billion birds migrate into the United States from Canada and four billion more head south to the tropics.
"In the spring," the lead author Adriaan Dokter noted, "3.5 billion birds cross back into the U.S. from points south, and 2.6 billion birds return to Canada across the northern U.S. border."
In other words: the birds who went three to four times further than the birds staying in the U.S. faired better than the birds who stayed in the U.S. Why?
Part of the answer could be very well be what you might hear from a conservationist — only with numbers to back it up: the U.S. isn't built for birds. As Ken Rosenberg, the other co-author of the study, notes: "Birds wintering in the U.S. may have more habitat disturbances and more buildings to crash into, and they might not be adapted for that."
The other option is that birds lay more offspring in the U.S. than those who fly south for the winter.
What does observing eight billion birds mean in practice? To give myself a counterpoint to those numbers, I drove out to the Joppa Flats Education Center in Northern Massachusetts. The Center is a building that sits at the entrance to the Parker River National Wildlife Refuge and overlooks the Merrimack River, which is what I climbed the stairs up to the observation deck to see.
Once there, I paused. I took a breath. I listened. I looked out into the distance. Tiny flecks Of Bonaparte's Gulls drew small white lines across the length of the river and the wave of the grass toward a nearby city. What appeared to be flecks of double-crested cormorants made their way to the sea. A telescope downstairs enabled me to watch small gull-like birds make their way along the edges of the river, quietly pecking away at food just beneath the surface of the water. This was the experience of watching maybe half a dozen birds over fifteen-to-twenty minutes, which only served to drive home the scale of birds studied.
Explore how alcohol affects your brain, from the first sip at the bar to life-long drinking habits.
- Alcohol is the world's most popular drug and has been a part of human culture for at least 9,000 years.
- Alcohol's effects on the brain range from temporarily limiting mental activity to sustained brain damage, depending on levels consumed and frequency of use.
- Understanding how alcohol affects your brain can help you determine what drinking habits are best for you.
If you want to know what makes a Canadian lynx a Canadian lynx a team of DNA sequencers has figured that out.
- A team at UMass Amherst recently sequenced the genome of the Canadian lynx.
- It's part of a project intending to sequence the genome of every vertebrate in the world.
- Conservationists interested in the Canadian lynx have a new tool to work with.
If you want to know what makes a Canadian lynx a Canadian lynx, I can now—as of this month—point you directly to the DNA of a Canadian lynx, and say, "That's what makes a lynx a lynx." The genome was sequenced by a team at UMass Amherst, and it's one of 15 animals whose genomes have been sequenced by the Vertebrate Genomes Project, whose stated goal is to sequence the genome of all 66,000 vertebrate species in the world.
Sequencing the genome of a particular species of an animal is important in terms of preserving genetic diversity. Future generations don't necessarily have to worry about our memory of the Canadian Lynx warping the way hearsay warped perception a long time ago.
Artwork: Guillaume le Clerc / Wikimedia Commons
13th-century fantastical depiction of an elephant.
It is easy to see how one can look at 66,000 genomic sequences stored away as being the analogous equivalent of the Svalbard Global Seed Vault. It is a potential tool for future conservationists.
But what are the practicalities of sequencing the genome of a lynx beyond engaging with broad bioethical questions? As the animal's habitat shrinks and Earth warms, the Canadian lynx is demonstrating less genetic diversity. Cross-breeding with bobcats in some portions of the lynx's habitat also represents a challenge to the lynx's genetic makeup. The two themselves are also linked: warming climates could drive Canadian lynxes to cross-breed with bobcats.
John Organ, chief of the U.S. Geological Survey's Cooperative Fish and Wildlife units, said to MassLive that the results of the sequencing "can help us look at land conservation strategies to help maintain lynx on the landscape."
What does DNA have to do with land conservation strategies? Consider the fact that the food found in a landscape, the toxins found in a landscape, or the exposure to drugs can have an impact on genetic activity. That potential change can be transmitted down the generative line. If you know exactly how a lynx's DNA is impacted by something, then the environment they occupy can be fine-tuned to meet the needs of the lynx and any other creature that happens to inhabit that particular portion of the earth.
Given that the Trump administration is considering withdrawing protection for the Canadian lynx, a move that caught scientists by surprise, it is worth having as much information on hand as possible for those who have an interest in preserving the health of this creature—all the way down to the building blocks of a lynx's life.
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