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.
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