When Guidelines, Evidence, and Expert Opinion Collide

What Should We Make of the Colonoscopy Headlines?

No one loves having a colonoscopy, but we have been told that the procedure can dramatically reduce our chances of developing colon (large intestine) and rectal cancer and of dying from colorectal cancer. In fact, the United States Preventive Services Task Force (USPSTF) guidelines recommend a colonoscopy for adults 45 years old and up every 10 years. During the procedure, a long flexible scope is passed up through the large intestine, allowing the trained endoscopist to visualize and biopsy abnormal tissue. Since most cancerous lesions in the small intestine start out as polyps, removing them during colonoscopy can prevent the development of colorectal cancer. Detecting cancer during the colonoscopy permits the initiation of treatment, which can be lifesaving.

         Since colorectal cancer is the second leading cause of cancer death in the U.S. for men and women combined, it would seem to make a lot of sense to follow the guidelines for colonoscopy screening. Hence, it came as quite a shock when media headlines blared out the news that a new study seemed to show that colonoscopy is not as effective in reducing risk for cancer or cancer-related death as expected. The study was published in the New England Journal of Medicine in October and reported the results of research conducted in four European countries, although only results from three countries (Poland, Norway, and Sweden) were reported. In the study, men and women aged 55 to 64 years old were randomized either to be invited to have a colonoscopy or not to be invited to have a colonoscopy. There were 28,220 people in the invited group and 56,365 in the usual-care (no invitation for colonoscopy) group. The participants were then followed for ten years. The researchers found an 18% decrease in risk for colorectal cancer in the invited-for-colonoscopy group and no difference in cancer-related death between groups. That finding contradicts earlier, smaller studies, that found a much larger benefit for colonoscopy and thus the immediate media attention, declaring that the study had failed to find colonoscopy to be of much benefit.

During a colonoscopy, the examiner passes a long, flexible scope through the rectum and large intestine (colon), enabling detection and biopsy of abnormal tissue (image: Shutterstock).

         “Such news coverage has ignited controversy,” wrote Franklin G. Berger, a cancer research scientist, “and created some confusion about the study and its implications, leading people to question whether the results suggest that reevaluation of the utility and need for a colonoscopy is warranted.” Dr. Franklin went on to state, however, that “Many of these news reports mistakenly interpreted the study…Such misinterpretations have grave consequences with regard to efforts aimed at screening and preventing a form of cancer that affects the health and well-being of so many.”

         It is unknown at this point whether the study and its loud media coverage will dissuade people from undergoing colonoscopy. The preparation for a colonoscopy is unpleasant and the procedure has risks like bowel perforation, which, although rare, are serious. It would seem likely that anything that calls the procedure into question might be capable of influencing some people to avoid it. Would they be making a wise decision? After all, the study that ignited these questions was large, carefully done, and published in the world’s most prestigious medical journal. What happens and what should we do when guidelines get called into question by studies that are immediately reported to us in the media?

Taking a Closer Look at the Colonoscopy Study

         If we look a bit more closely at the study, we can see why many experts are pushing back against the conclusion that the findings decrease confidence in the benefits of colonoscopy. Only 42% of the people who were invited to have a colonoscopy actually had one. When the researchers restricted their analyses to just those people who underwent colonoscopy, they found a 31% decrease in cancer risk and a 50% decrease in cancer-related deaths, rates that certainly meet the standard of being clinically significant. A gastroenterologist pointed out two other aspects of the study of note. First, it is more common for skilled gastroenterologists to perform colonoscopy in the U.S. than in other countries and this may increase the rate of detection of abnormal, precancerous tissues. Second, one in four of the colonoscopies in the study were performed without any anesthesia, something rarely done in the U.S. Without anesthesia, colonoscopy can be quite painful, leading the examiner to terminate the procedure earlier without sufficient probing to detect abnormalities.

         Delving into the details of the New England Journal of Medicine report thus leads to different conclusions than may have been apparent from reading the media headlines. It is unlikely, at least for the time being, that the USPSTF or any other medical guideline-producing organization will downgrade their colonoscopy recommendations based on the study. So why did media outlets rush to tell us about the study? Should they have restrained their reporting of it, recognizing that how they presented the findings might lead to adverse health consequences for some people?

Medical Guidelines are Not Infallible

         While we definitely advocate for greater care by journalists and their editors in how they report the results of hot-off-the-press research studies, it is also important to recognize that medical guidelines are far from impervious to the need for change as new research emerges. Last year, a group of physicians wrote in the Annals of Internal Medicine that “Studies of guidelines unfortunately have reported a high proportion of recommendations—including strong recommendations—based on evidence that is low quality and hypothesis generating rather than high quality and hypothesis confirming…” One of the group’s main complaints was “the lack of regular updates” of guidelines. While it is doubtful that the colonoscopy study published last October will justify guideline changes, it certainly is the case that in many other instances guideline recommendations become out of date as new research emerges that indicate changes are needed. For example, the authors of the Annals of Internal Medicine article point to guidelines that once recommended that postmenopausal women receive hormone replacement therapy to reduce the risk of cardiovascular disease and breast cancer even though “large randomized controlled trials subsequently proved precisely the opposite.”

         Right now, a controversy appears to be brewing over new USPSTF guidelines for who should take statin medications that are prescribed to reduce blood levels of LDL (bad) cholesterol. Data are clear that when given to the right patient these medicines can significantly reduce the risk for cardiovascular disease and stroke. The new guidelines were published in the Journal of the American Medical Association last August and recommend that adults aged 40 to 75 years who have 1 or more cardiovascular risk factors and an estimated 10-year cardiovascular disease risk of 10% or greater be prescribed a statin medication. What is the problem with this recommendation? “The USPSTF recommendation excludes many individuals who would otherwise likely benefit from a statin,” concluded a group of physicians who pointed out that the new recommendation is more conservative than a 2018 guideline issued jointly by the American Heart Association, the American College of Cardiology, and other medical societies. In fact, they estimated that “Approximately 16 million fewer adults from 2017 to 2020 would have been eligible for statin therapy” under the USPSTF guideline.

         The reasons for the difference in recommendations here are very complex, but clearly could potentially make an enormous difference in people’s lives. Although this controversy does not seem to have ignited the same degree of media attention as the colonoscopy study, it does seem like something people ought to know about. It is possible that, following the USPSTF guideline, physicians have told millions of people they don’t need statin medication who, according to the alternative 2018 guideline, might benefit from them. Shouldn’t people be aware of this, especially given the fact that health guidelines are hardly infallible?

Statins are a class of medication that reduce the level of low-density lipoprotein (LDL or bad) cholesterol in the blood and decrease the risk of having a heart attack or stroke (image: Shutterstock).

      So here we have a case in which too much media coverage might harm people, while in another case too little media coverage might also cause harm.  

         Challenges to guidelines confuse healthcare providers and their patients and can result in decisions that are not in people’s best interests. We see the need for two solutions. First, we need a better-informed and more careful cadre of journalists and editors who understand how to report on new studies and opinions in balanced, non-sensationalized ways that will really be helpful to their consumers. Second, it is imperative that the medical/scientific community do a better job of communicating to the public the significance of new findings that may necessitate reconsideration of what is in a health guideline.. When differences of opinion emerge among experts so that true consensus is lacking, these need to be reported to the public so that they can seek personalized advice from their own healthcare professionals. In the case of the colonoscopy study, media outlets should have pushed pause before reporting the results, giving time for experts to explain clearly why the new study does not mean we should stop following colonoscopy guidelines, at least for now. In the case of the statin guidelines, reporters should now delve into this potential difference of opinion and if it really represents a lack of expert consensus the public should be informed so that individuals can decide with their own doctors whether a statin is advisable. Better management of health guidelines is therefore required from multiple sources.

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