April 2016

The ups and downs of preventive medicine

Look, death comes for us all. In the words of the inimitable Dr. Cox from Scrubs—“Everything we do here—everything—is a stall. We’re just trying to keep the game going, that’s it.” We’ve gotten much better at stalling over the years (life expectancy in the United States has doubled since 1880), but there’s still plenty of question as to how best to stall, for the longest amount of time, with the best results.

In recent years, focus has increasingly shifted to offense rather than defense with the rise of “preventive medicine.” Rather than doing our best to treat conditions once they arise, preventive medicine means getting out in front of the problems—promoting healthy behavior, screening for diseases, trying to remove environmental and economic barriers to care. Preventive medicine was a key tenet of the Affordable Care Act, which created the National Prevention Strategy and a National Prevention, Health Promotion, and Public Health Council to implement it.
But how exactly can we catch diseases early, or, better yet, keep people from getting sick in the first place? How can we “increase the number of Americans who are healthy at every stage of life,” as the National Prevention Strategy aims to? What strategies work?

The first step is to raise awareness. The public needs to be educated, prepared, and vigilant.

How many people out there seem unaware of things like cancer, though?

“Awareness” is a big buzzword in public health, and it’s hard to argue against—sure, it’s probably good for people to be aware of diseases and health risk factors. But do these awareness campaigns—the nearly 200 official U.S. “health awareness days” and the scores of others put on by companies and organizations—actually translate to any real-world action? Do they inspire people to eat better, exercise, or get tested?

They may inspire people to donate to research or to advocacy organizations. And that’s not nothing. But a literature review published last year in the American Journal of Public Health found that there haven’t been many studies done evaluating the efficacy of awareness days, and the few that have been done weren’t designed very well. One recent study analyzed the Great American Smokeout (an anti-smoking awareness day held on the third Thursday of November) and found that on the day, there were 61 percent more news stories about quitting smoking, 13 percent more tweets, 42 percent more calls to quitting hotlines, and 25 percent more quitting-related Google searches, than would be expected on a normal day.

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So if the point is to get attention, that particular awareness day seems to be successful. But how many people actually quit smoking because of the Great American Smokeout? We don’t know.

There are cases where public awareness, or I might prefer to call them “information campaigns,” are totally needed—in the case of emerging diseases for example, or ongoing outbreaks. During the Ebola outbreak, people needed to know how the disease was spread, how to protect themselves, and where to go to seek care. The current outbreak of Zika is a case where medical knowledge about the disease is still developing, and so updates on what we’re learning are particularly valuable.
But awareness for the sake of awareness is a goal that seems, at least, questionable.

One concrete thing we can do is encourage people to get screened for diseases. If we catch them early, we can save lives.

Do the benefits of testing always outweigh the harms?

At first blush, it’s hard to see what the harms could be. You’re being proactive about your health! You’re giving doctors more time to treat and help you if they do find something. But false positives are a real danger with many kinds of screening tests, and they can lead not only to unnecessary stress and anxiety for a patient who is actually fine, but to invasive follow-up tests like biopsies. And for some cancers—even if there is a tumor there, it may be one that’s never likely to grow, that a patient can live with indefinitely with no ill effects.

In his book on medical uncertainty, Snowball in a Blizzard, Steven Hatch, an assistant professor of medicine at the University of Massachusetts Medical School, writes that false positives are more likely than false negatives, because humans are wired to look for patterns, and are also more likely to focus on possible threats. And using even a very accurate test on a population with lower risk for the disease can lead to more false positives, he writes.

In recent years, several old trusty screening tests have come into question, and recommendations have been revised to advise using them less often. Mammograms for women under 50 are no longer recommended and neither is using the prostate-specific-antigen test to screen for prostate cancer. Women are supposed to get pap smears only once every three years instead of annually, and annual pelvic exams have also been deemed unnecessary for healthy women who aren’t pregnant, by the American College of Physicians.

The U.S. Preventive Services Task Force studies and rates screening tests, giving them grades based on their likelihood of being beneficial. An A recommendation means there’s high certainty of substantial benefit—Hepatitis B screening for pregnant women and HIV screening are examples of A-level tests. Bs are for high certainty of moderate benefit or moderate certainty of high benefit; B tests include depression screening and mammograms for women 50 to 74. Cs are for moderate certainty of a small benefit (like mammograms for women 40 to 50), Ds are for moderate or high certainty that there are no benefits, or that the harms outweigh the benefits (like PSA prostate screenings).
So all of that is to say, the benefit of screening depends heavily on the test, and the patient.

Well, at the very least, we can promote the three simplest rules of good health: Eat healthy, exercise, and don’t smoke.

How do you get people to do these things?

A healthy diet, regular exercise, and keeping your lungs free of cigarette smoke reduce people’s risk for so many conditions, but actually changing people’s behavior is notoriously difficult. A recent study found that only 3 percent of Americans met four qualifications for a “healthy lifestyle”—being a non-smoker, having a healthy diet, exercising 150 minutes a week, and having a healthy body fat percentage.

Part of the reason it may be so hard for people to adopt healthier habits could be because they don’t have the right motivation. Some research suggests that intrinsic motivation (doing things for their own sake, because you enjoy them and you want to do them) is the best way to keep at something, and it can be hard to drum up that kind of love for running or eating broccoli if you haven’t already got it. Shame, on the other hand, while it can be motivating, may not be enough to get someone to commit to healthy habits long-term.

If doctors shame patients who smoke, or who have an unhealthy diet or weight, they may not get good results. It seems to depend on the person—33 percent of people who felt shamed by a doctor took it as motivation to try to do better, in one study, while 45 percent were motivated only to avoid their doctors, or lie to them.

In a recent interview I did with Hatch, he told me he thought shaming was not a great strategy: “I can cheer you on, if you want to try to quit smoking,” he said. “But I’m not going to sit here and lecture you. I’m not going to be your moral scold.”


There are many, many other questions one could ask about how to prevent disease before it starts, and a lot of them are not about targeting a specific condition or a specific individual, but about improving society.

How can we increase access to necessary care? How can we reduce the number of uninsured people, increase the number of doctors in rural areas, and keep drug prices from spiraling out of control?

How can we get fresh, healthy, and affordable produce into food deserts?

How can we design cities to be conducive to walking, biking, and other kinds of physical activity?


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