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Do You Really Need That Colonoscopy? 

Some older Americans are being screened  too often, others not enough

En español l These days most people have gotten the message about the importance of colorectal cancer screening: After we turn 50, nearly everyone ought to undergo a colonoscopy every 10 years. But say you're 79 and in good health with no family history of colon disease; do you really need another colonoscopy if you got one at 70? Probably not.

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Man sitting on examination table in hospital gown, Potentially unnecessary colonoscopies

Christie & Cole/Corbis

Colonoscopies performed on Medicare recipients age 70 and older may be inappropriate.

Turns out a number of older people are having these invasive, uncomfortable tests too often. New research shows that almost a quarter of the tests are performed on those who don't really need them.

On the other hand, while some older adults are being screened too often, other groups are not getting screened enough. Underscreening remains a problem for racial and ethnic minorities and those in lower socioeconomic populations.

A valuable test

During a colonoscopy, a doctor can find and remove precancerous polyps before they grow and spread. But colonoscopies are invasive procedures that carry small but real risks, such as bleeding, bowel perforations or complications from sedation, particularly in older people.

Groups like the U.S. Preventive Services Task Force (USPSTF), the American Cancer Society and the American College of Gastroenterology agree that routine screening colonoscopies should be carried out every 10 years starting at age 50.

Colorectal cancer is the third most commonly diagnosed cancer among men and women and the second leading cause of cancer death. An estimated 143,000 new cases will be diagnosed this year, according to the National Cancer Institute, and nearly 51,000 people will die from the disease. But the five-year survival rate is about 90 percent if it is caught early, which is why cancer screening is highly recommended.

The USPSTF says screening colonoscopies should be performed on a case-by-case basis for people between the ages of 76 and 85, and it recommends no screening for people over age 85. The benefit of early cancer detection in very old people is offset by the risk of complications.

But some doctors and patients aren't getting the message. A recent study published in JAMA Internal Medicine suggests that almost a quarter of colonoscopies are either performed too often or given to patients who are too old to benefit.

"It looks like some patients are getting screened inappropriately," says Kristin Sheffield, Ph.D., an epidemiologist at the University of Texas Medical Branch in Galveston who led the study.

The study didn't fault colonoscopies doctors performed because a patient had a problem or worrisome symptom, such as blood in the stool or abdominal pain. Nor does it address colonoscopies to check patients who previously have had colorectal cancer or precancerous growths. The remaining colonoscopies were classified as potentially inappropriate when they were performed in people over the age of 76, or if they were carried out less than 10 years after a previous normal colonoscopy.

Big city vs. country

The researchers found that overall, people on the East Coast and upper Midwest were more likely to have questionable colonoscopies than those living in the Southwest and on the West Coast. And those in big cities were somewhat more likely to have inappropriate colonoscopies than those in rural areas.

Physicians performing the highest percentage of potentially inappropriate colonoscopies tended to be surgeons, U.S. medical school graduates, people who had graduated from medical school before 1990 and those who performed a high volume of procedures, the study found.

Douglas Rex, M.D., a professor at the Indiana University School of Medicine and past president of the American College of Gastroenterology, says overuse of screening colonoscopies may not be as common as Sheffield's research suggests.

For example, it is wise to repeat colonoscopies at five-year intervals in a patient who previously has had cancer — yet the study design has no way of spotting those cases, he says.

"They really can't tell whether these colonoscopies are inappropriate or not," Rex says. "We don't want the public to think that 25 or 30 percent of colonoscopies are inappropriate when these authors just can't know that based on claims data."

Rex acknowledges that some areas of the country tend to test more than is recommended.

"You have places where almost all of the doctors do colonoscopy every five years," Rex says. "They say, 'That's the standard of care in our region.' That sort of thing is part of the explanation for why there's so much regional variation in health care costs in the United States."

Knowing when to test

Sheffield and her University of Texas colleagues adopted the USPSTF standards in determining which colonoscopies for older patients should be classified as potentially inappropriate, but Rex points out that other professional organizations disagree.

"A lot of groups don't accept that," says Rex, who has helped draft colonoscopy practice guidelines. Instead, these groups recommend that doctors consider a patient's overall health and only stop screening when life expectancy is less than 10 years.

Among younger patients, more frequent screening colonoscopies might be justified when a patient has a first-degree relative who was diagnosed with colorectal cancer before age 60 or two first-degree relatives who have had the disease, Rex says.

He says if a patient has previously had colon cancer or if abnormal growths are detected, it also makes sense to follow up with a colonoscopy after three years. If those results are normal, patients should be tested every five years, Rex says.

Given that the average age for colon cancer diagnosis is 70, if someone were treated for the cancer at that age, then had a normal follow-up colonoscopy at age 75, another test at age 80 would be classified as "too soon" by the University of Texas study, Rex notes.

Why so many?

John Inadomi, M.D., a professor at the University of Washington School of Medicine and chair of the American Gastroenterological Association's clinical practice and quality management committee, cites a number of factors that may lead doctors to perform more colonoscopies than necessary.

Some physicians may simply disagree with the recommended intervals, although they are based on substantial research. Others, recognizing the difficulty in performing a visual examination of the colon, worry that they may overlook a polyp and figure that more frequent examinations provide a greater margin of safety.

"I think a lot of us look for reasons to bring back people early, because we know we miss things," Inadomi says.

Meanwhile, financial incentives may be at work, Inadomi adds.

As is the case with other physicians, gastroenterologists are paid for how many procedures they perform, not based on whether their patients have a healthy outcome.

"We get paid for doing more," he says. "There is an inherent conflict here."

As part of the Choosing Wisely campaign with Consumer Reports and the American Board of Internal Medicine Foundation, Inadomi's committee is working to reduce the overuse of colonoscopies by recommending the procedure once every 10 years for patients at average risk, and by discouraging screening within less than three years if polyps have been found and completely removed.

"We recognize that overuse occurs and we want to own this problem ourselves," he says.

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