Nearly half of all Medicare beneficiaries receive screening colonoscopies more frequently than current guidelines recommend, while older adults with the best life expectancy were less likely to experience a negative effect on their health from fecal occult blood testing, indicating that clinicians could better target use of that test.
Together, those findings from two studies published May 9 in Archives of Internal Medicine suggest that "there is much room for improvement in the way we measure proper utilization of screening colonoscopy, ensure adequate follow-up, and evaluate net benefit among those who screen positive," noted Dr. Patrick G. O’Malley, chief of internal medicine at Walter Reed Army Medical Center, Washington, noted in an accompanying editorial (Arch. Intern. Med. 2011 May 9 [doi:10.1001/archinternmed.2011.198]).
"Many questions about proper processes, who to screen, when to stop screening, and what defines the proper interval for screening have not been adequately studied," Dr. O’Malley said.
No guidelines recommend a colonoscopy screening interval of fewer than 10 years after a negative examination result, but Dr. James S. Goodwin and his colleagues at the University of Texas Medical Branch, Galveston, found that many patients are undergoing screening colonoscopies at much shorter intervals than once every decade.
The researchers examined a 5% national sample of Medicare beneficiaries from 2000 through 2008 to identify average-risk patients who underwent screening colonoscopy and then followed those with a negative screening result for the next 7 years (Arch. Intern. Med. 2011 May 9 [doi:10.1001/archinternmed.2011.212]).
Among 24,071 beneficiaries who had a negative screening result, 46% underwent screening colonoscopy again within 7 years, they found. In 43% of those patients, the records showed no clear indication for the early repeated examination.
When broken down by age, 46% of patients aged 75-79 years received repeat colonoscopies within the study period, as did a third of those 80 years and older.
Men, patients with more comorbidities, and those treated by high-volume colonoscopists or in an office setting received early repeat examinations more often without a clear reason, the researchers found.
They also found marked geographic variations, with more than 50% of patients in some regions receiving a repeat exam within 7 years, while fewer than 5% of patients in other areas received repeat exams in that time frame.
Overall, more than 57% of the repeat colonoscopies performed during the study period were tagged with a diagnosis that might indicate a legitimate reason for the early examination, the researchers wrote.
But they also noted an "inflection point" at 60 months, where only about 38% of the colonoscopies performed were accompanied by a potentially explanatory diagnosis.
"The rapid increase in colonoscopies in the period around 60 months suggests that those might have been routinely scheduled," the researchers wrote.
Even though Medicare regulations preclude reimbursement for screening colonoscopy within 10 years of a negative screening result, only 2% of the claims for nonindicated, early repeat colonoscopies were denied, the researchers found.
In the second study, Dr. Christine E. Kistler of the University of North Carolina at Chapel Hill and her colleagues looked at long-term outcomes following a positive fecal occult blood test (FOBT) in 212 adults aged 70 years and older who were treated at four Veteran Affairs facilities.
They found that 56% of those patients received follow-up colonoscopies, which revealed 34 significant adenomas and 6 cancers. One in 10 patients experienced complications from the colonoscopy or from their cancer treatments (Arch. Intern. Med. 2011 May 9 [doi:10.1001/archinternmed.2011.206]).
Meanwhile, 46% of those without follow-up colonoscopy died of other causes within 5 years of their positive FOBT results, while three died of colon cancer within 5 years.
The researchers calculated the net survival benefit from FOBT screening along with the potential burdens, which can include complications from additional testing and/or treatment. Previous trials of FOBT suggest that a person needs a life expectancy of at least 5 years to derive survival benefits from screening; if that person isn’t expected to live 5 years or more, then he or she only risks the potential burdens.
Dr. Kistler and her associates found that 87% of those with the worst life expectancy experienced a negative burden from screening, as did 70% of those with average life expectancy and 65% of those with the best life expectancy. This negative burden could be reduced by better targeting FOBT screening and follow-up to healthy older adults, they said.
"Our study supports guidelines that recommend using life expectancy to guide colorectal cancer screening decisions in older adults and argues against one-size-fits-all interventions that simply aim to increase overall screening and follow-up rates," the study concluded.