(AP) -- Many older Americans get repeat colon cancer tests they don't need and Medicare is paying for it, suggests a study that spotlights unnecessary risks to the elderly and a waste of money.
Almost half of the Medicare patients in the study had had a colonoscopy less than seven years after getting normal results from an earlier test. The test is recommended just every 10 years, starting at age 50, for people at average risk whose initial test is normal.
The study showed that among those 80 and older, one-third had a repeat exam within seven years of the previous colonoscopy. That's an age group that can skip the test altogether if no problems have been spotted before.
The U.S. Preventive Services Task Force recommends against routine colon cancer screening for most people 76 to 85 - and says for those older than 85, screening risks outweigh the benefits.
The older you are, the more likely you are to die from other causes before cancer becomes deadly, which means the screening procedure's risks may outweigh its benefits in many aged patients, the study authors said.
"I was surprised by the magnitude of the issue," said lead author Dr. James Goodwin, a geriatrician and researcher at University of Texas Medical Branch in Galveston.
In the study, researchers chose a random national sample of Medicare claims and enrollment data from more than 200,000 patients over 65 who received colonoscopies between 2001 and 2008. The number of patients in the sample totaled 24,071 - all people considered at normal risk for colon cancer.
The results suggest most of the repeat exams were unnecessary; only 27 percent of all study patients with frequent exams had symptoms that might have raised suspicion of cancer, including abdominal pain, change in bowel habits, and weight loss. The study appears in Monday's Archives of Internal Medicine.
The colonoscopy is considered one of the most effective screening tests available, and it's credited with saving thousands of lives by catching cancer early. The doctor uses a thin flexible tube to examine the intestines. It can snip off suspicious-looking growths.
The exam is generally pretty safe, but does have risks that occur more often with older patients, including complications from sedation, accidental perforation of the colon and bleeding.
Medicare covers colonoscopies every 10 years - more frequently for high-risk patients, including those with a family history of colon cancer. But in this study, the authors excluded high-risk patients.
Colonoscopy costs vary widely but typically exceed $1,000. While Medicare rules say the government won't pay for too-frequent colonoscopies, only 2 percent of the study claims were denied for repeat exams in people without symptoms.
The results suggest the Medicare regulation "is not working," Goodwin said.
Excessive colonoscopies are not just economically costly, he said, noting they can pose a real harm to patients, especially older ones.
Robert Smith, director of cancer screening at the American Cancer Society, said some doctors may recommend more frequent colonoscopies because they think 10-year intervals are too risky. Some may think, incorrectly, that finding any growths, even non-suspicious polyps, means a repeat exam should be done within less than 10 years, Smith said.
Some doctors also order repeat tests "because they want to bring in income," he said.
Besides being risky and costly, too-frequent screenings make colonoscopy resources less available for people who really need them, Smith said.
But, he pointed out, while colonoscopies may be overused in the elderly, the exams and other colon cancer screening methods are underused among some groups, including the uninsured, blacks and Hispanics.
The government's Centers for Medicare & Medicaid Services issued a statement in response to the study, saying the agency recognizes the importance of effective screening as well as "the importance of ensuring Medicare beneficiaries only get screened at appropriate intervals."
Medicare covers the exams every two years for high-risk patients, but if the study results are true, "then we need to further validate the accuracy of our payments," said agency spokeswoman Ellen Griffith.
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