Why medical research is constantly changing your mind – Harvard Health Blog

Have you ever wondered why medical research seems to be flipping so often? Eggs used to be terrible for your health; now they are not that bad. Gastric ulcers were thought to be due to stress and a “type A personality”, but that has been proven. I was taught that every postmenopausal woman should take hormone replacement therapy to prevent heart disease and bone loss; now it is considered far too risky. It can cause you to question every bit of medical news that you hear.

But maybe that’s not so bad. Asking questions about what you read or hear is reasonable. And perhaps medical reversals – when new research leads to a complete reversal with regard to a widespread medical practice or treatment – are not as common as they seem. Maybe they get more attention than they deserve and drown out the consistent and ‘non-reverse’ medical research that is available. For example, it seems unlikely that the health benefits of exercising regularly, quitting smoking or maintaining a healthy weight will ever be reversed.

A new study investigates medical reversals

A remarkable new study investigated the phenomenon of medical reversals to determine how often they occur and to find out which types of disorders were most involved.

Researchers collected more than 3,000 randomized controlled trials; these are considered to be the most reliable types of research because they randomly assign otherwise similar subjects to different treatment groups and try to control (control) factors other than those that may affect the results. For example, a study comparing two treatments to prevent heart attacks should have a similar percentage of people with high cholesterol or high blood pressure, as they can affect the risk of having a heart attack.

In this new study, the analysis was limited to three of the best medical journals in the world: JAMA (formerly known as the Journal of the American Medical Association), The Lancet and the New England Journal of Medicine. For each identified medical reversal, the authors searched for later studies that refuted the findings and only counted those who had stood the test of time (until now!).

This is what they found:

  • Of the 3,017 studies analyzed over the past 15 years, 396 came to conclusions that reversed previous treatments or practice recommendations. This represented about 13% of randomized controlled trials that appeared in these journals and about 6% of their original study reports.
  • The most common conditions were cardiovascular disease, preventive medicine and medicines for critical care (such as care in an intensive care unit).
  • Medications, procedures and vitamins accounted for around two-thirds of the reversals.

Examples of medical reversals

Among the nearly 400 medical treatments or practices that were reversed during the years of this new study, here are some notable examples.

  • Wearable technology for weight loss. When fitness trackers became widely available for the first time, recommendations for using them when losing weight were common. But a 2016 study found that they were no more effective (and perhaps less) than a standard weight loss program that did not use an activity tracker.
  • Hormone replacement therapy (HRT). For more than 50 years, HRT was thought to prevent chronic women, such as cardiovascular disease, in menopausal women. A number of more recent (and more powerful) studies have shown that HRT does not offer such benefits and that some combinations of hormonal therapy may increase the risk of certain types of cancer, stroke and blood clots. HRT can still be recommended for women with significant menopause symptoms, such as hot flashes, but is no longer prescribed to prevent chronic diseases.
  • Surgery for a meniscal (cartilage) tear with osteoarthritis of the knee for adults 45 years and older. This combination of problems is common in middle-aged adults and is often detected when MRI scans are performed to evaluate knee pain. Although surgery was often recommended and performed to remove or repair the ruptured meniscus, it was uncertain whether this was really necessary. A 2013 study found that initial physiotherapy treatment was just as effective as immediate surgery. Guidelines quickly changed to recommend non-surgical treatment as the first approach for most middle-aged or older patients with meniscus tears and knee osteoarthritis.

Medical myth or medical fact?

Myth and misconception are common in the field of health and medical practice. But it is also true that medical fact is a moving target. Things that we accepted as fact years ago sometimes turn out to be wrong, as these medical reversals show. Meanwhile, certain myths can have credibility if well-designed research concludes so much.

The reason why this research on medical reversal is so important is that it indicates how important rigorous research is, not only for new treatments or innovative procedures, but also for evaluating older, established methods of doing things.

What’s next?

Medical experts hear flip-flop about their recommendations or conclusions about medical news seems common – but is 6% of the original study or 13% of all randomized controlled trials “too high”? I would argue that that is not the case. Rather than questioning all research, this new study on medical reversal should serve as a measure of reassurance that skepticism is alive and healthy in the research community, and that “inexpensive medical practices” are discovered when the right investigation is set up , funded and implemented.

You can be sure that there will be more bewildering, bewildering medical reversals in the future. Keep in mind that most of this is simply a reflection of how researchers continue to clarify what works in medicine – and what doesn’t. The best thing they can do is stick to it. The best thing we can do is to critically review medical news and be open.


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