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Colonoscopy Riskier in Older Age
By Crystal Phend, MedPage Today
June 16, 2009
Colonoscopy complication risks rise with age in the Medicare population, a population-based study revealed.
Despite low overall adverse event risk with colonoscopy, every age group 70 and older was at elevated risk of adverse gastrointestinal and cardiovascular events from the procedure, Joan L. Warren, Ph.D., of the National Cancer
Institute in Bethesda, Md., and colleagues found.
The risk of GI bleeding or perforation was 75% higher at age 80 to 84 than at age 66 to 69, they reported in the June 16 Annals of Internal Medicine.
The findings, from the Medicare claims database, support the controversial upper age limit for screening colonoscopy set by the U.S. Preventive Services Task Force, Dr. Warren's group said.
Because competing causes of mortality often outweigh the potential benefit from detecting colon cancer at progressively older ages, guidelines do not recommend screening past age 75 and recommend against it after 85. (See Task Force Recommends End to Colon Cancer Screening at 75)
However, no studies have looked specifically at risks of colonoscopy in this older age group.
So, Dr. Warren's group examined risks in a cohort of 53,220 Medicare beneficiaries age 66 to 95 who had outpatient colonoscopy over a four-year period. They compared them to a matched cohort of beneficiaries who did not have colonoscopy.
Their Medicare claims indicated that 10.1% of the colonoscopies were done as screening procedures, 33.6% as diagnostic procedures, and 56.3% for polyp removal.
The overall adjusted risk of screening colonoscopy was not significantly elevated for serious GI events -- bleeding or perforation -- compared with no colonoscopy (2.8 per 1,000 persons, 95% confidence interval 1.2 to 4.3, versus 1.8, 95% CI 1.4 to 2.1).
Nor did screening colonoscopy carry increased risks of other GI events (6.5 per 1,000, 95% CI 4.2 to 8.9, versus 5.7, 95% CI 5.0 to 6.3), or increased risk of cardiovascular events resulting in a hospitalization or emergency department visit within 30 days (12.5 per 1,000, 95% CI 9.1 to 15.8, versus 15.9 per 1,000, 95% CI 14.8 to 16.9).
However, the adjusted predictive risk for a serious GI event was significantly greater with diagnostic colonoscopy and colonoscopy with polypectomy than with no colonoscopy (4.2 per 1,000 procedures, 95% CI 3.3 to 5.2, and 9.4, 95% CI 8.2 to 10.5, versus 1.8, 95% CI 1.4 to 2.1).
The polypectomy group had significantly elevated risk for other GI events and cardiovascular events (13.0 per 1,000, 95% CI 11.7 to 14.4, versus 5.7 without colonoscopy, 95% CI 5.0 to 6.3, and 23.8, 95% CI 21.6 to 25.1, versus 15.9 without colonoscopy, 95% CI 14.8 to 16.9).
Risks also rose with age.
Colonoscopy in Medicare beneficiaries age 66 to 69 did not carry increased risk except nonserious GI events (6.9, 95% CI 5.6 to 8.2, versus 3.7 per 1,000 persons, 95% CI 2.9 to 4.4).
For all age groups 70 and older, though, the event rate per 1,000 was significantly elevated for serious GI events (5.8 per 1,000 with colonoscopy versus 1.5 per 1,000 without colonoscopy at age 70 to 74, up to 12.1 versus 3.2 at age 85 and beyond). The findings were similar for other GI events (8.7 per 1,000 versus 4.7 at age 70 to 74 up to 19.0 versus 10.2 for those 85 and older).
One factor appeared to be comorbid conditions, since both types of GI risks were elevated with colonoscopy in those who had a history of stroke, chronic obstructive pulmonary disease, or congestive heart failure, compared to those without the conditions.
The reason for the increased complication risk in older persons and those with these conditions may be related to the preparation, sedation, or the procedure itself, the researchers noted.
"Certain preparations, such as sodium phosphate, can increase the likelihood of electrolyte imbalances, especially in elderly persons," they wrote. "In addition, persons taking ACE inhibitors, angiotensin-receptor blockers, diuretics, and nonsteroidal anti-inflammatory drugs -- all of which are commonly used in elderly persons -- may have more adverse events related to the bowel preparation for colonoscopy."
They cautioned that the use of administrative claims data to determine complication risks -- rather than medical record review -- might have underestimated the true risk of adverse events.
But Dr. Warren's group concluded that the study results should be incorporated into physician-patient discussions about the risks associated with colonoscopy.
"Our findings should aid clinicians in making age- and health status-appropriate recommendations to elderly patients for colorectal cancer screening, especially given the availability of Medicare coverage for alternative colorectal cancer screening tests that are less risky than colonoscopy," they wrote.
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