Aaron Carroll is the president and chief executive of AcademyHealth.
In 2002, my wife and I had our first child. In his early months, she worried about everything that might affect his health. She considered radically restricting her diet because two years earlier, the American Academy of Pediatrics recommended that nursing mothers avoid allergenic foods. But the recommendation wasn’t based on trial evidence. It was based on expert opinion and cautious logic. I was skeptical enough to co-author a systematic review showing there was no known relationship between early solid food introduction and children developing allergies.
It didn’t matter. Caution won. Between 1997 and 2008, the prevalence of peanut allergies in the United States rose by about 250 percent. Rates of food allergies overall increased sharply as well.
The advice didn’t simply fail to work. It contributed to the problem everyone was trying to avoid. Research conducted in the last decade has shown that early introduction of allergens to children protects them against developing food allergies. Withholding allergens makes reactions more common. Expert advice caused more allergies than would have developed if those experts had remained quiet.
To its credit, the academy began to reverse course on this issue in 2008. Guidelines in Australia, the United States and Europe have since been updated to recommend that children be exposed to allergenic foods in infancy rather than avoid them. A study recently published in JAMA Pediatrics shows that these new guidelines are working. The prevalence of egg allergies in Australia has dropped from 9.2 percent to 7.6 percent in recent years, a 17 percent relative decline. This is a massive improvement in a short time, and given that just over half of Australian parents followed the guidelines, there is still plenty of room for improvement.
Unfortunately, the problem of overcautious guidelines is not limited to egg and peanut allergies. It’s a pattern I have been writing about for years. Doctors advised patients not to eat egg yolks or shrimp because that would raise cholesterol levels. But later studies showed that consumption of cholesterol makes almost no difference in cholesterol levels for most people. Margarine was thought to be better than butter. Turns out, trans fats — which margarine is full of — are linked to heart attacks and strokes. Experts have pushed supplements, standing desks and milk consumption on similarly thin evidence. When confidence in a recommendation is unwarranted, and later evidence contradicts it, lives are not the only things that are harmed — trust in the experts is, too.
That trust is important, because sometimes we really do need to be told what to do. The covid-19 pandemic is the most recent example. One of the hardest parts of leadership is making difficult decisions with imperfect information when no option will please everyone. Decisions need to be made. They cannot all be made with the same surety, however.
Instead of the years experts usually get to accumulate evidence, update guidelines and shift practice, during that emergency they got weeks. I do not fault leaders who made decisions that later turned out to be questionable. But it would have been better if those decision-makers admitted publicly what they were guessing about and updated their positions when evidence shifted. I tried to do that with school closures. I tentatively supported them in March 2020. By summer I was arguing that camps should open. By fall I was pleading that schools should be the last thing to close, not the first.
That’s what following the evidence looks like in practice. It’s uncomfortable to acknowledge your limitations and invite debate, but the alternative is worse. When institutions issued guidance with more confidence than the data could support — for instance, the six-foot rule, which appears to have been based on old studies rather than knowledge of covid — they painted themselves into a corner. Walking the recommendation back would have meant admitting that previous confidence was unwarranted. Public health agencies — including the Centers for Disease Control and Prevention — chose not to for too long, and the guidance lingered, skepticism deepened, and the institutions that might have led Americans through the next crisis spent down the credibility they need to do it.
One institution gets this right. The U.S. Preventive Services Task Force issues a letter grade with every recommendation, from “A” for a high certainty of substantial benefit to “I” for insufficient evidence to make a call. Only the strongest grades require insurance coverage. Periodically, the group reviews the evidence and updates its recommendations accordingly. But the Department of Health and Human Services has recently fired the task force’s leadership and left it dormant for over a year, threatening one of the few institutions in American medicine that gets this right.
The task force provides a model for all health recommendations. Institutions should not only tell people what to do. They should tell the public how sure they are and why. They should update their recommendations when the evidence changes. And if there’s no emergency or the evidence is weak, they should say so clearly — or, better yet, say nothing at all.
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