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Study: Overuse of Risky Screening Colonoscopies in Elderly

Health Letter, July 2013

A recent study in JAMA Internal Medicine demonstrated that colonoscopies to screen for colorectal cancer are being performed in the elderly (those over 75) despite robust evidence that routine colonoscopy screenings do more harm than good in that

For those between the ages of 50 and 75, colonoscopy screening can be life-saving. However, the procedure can cause serious complications and is not recommended routinely for those older than 75.

Study overview

The JAMA Internal Medicine study examined the records of almost 75,000 Texas Medicare beneficiaries age 70 and older who underwent colonoscopy in that state between October 2008 and September 2009. The authors looked at claims data to determine whether a colonoscopy had been performed for the purposes of routine screening for colorectal cancer in a person who appeared healthy, rather than to assist in the diagnosis or treatment of another suspected condition (including suspected colon cancer, based on symptoms or on the results of a recommended screening test). Such routine “screening” colonoscopies are not recommended in healthy patients 70 to 75 years old if they have already had a negative colonoscopy within the past 10 years, and they are not recommended at all in patients 75 and older. The authors therefore considered all routine screening colonoscopies to be potentially inappropriate if they were conducted in patients 76 and older. For patients 70 to 75 years old, the screening was considered potentially inappropriate if the patient had already had a negative colonoscopy between 2001 (the date of the oldest record in the study) and the date of the screening.

The authors found that 23 percent of all screening colonoscopies were potentially inappropriate. Approximately 10 percent of all screening colonoscopies in those ages 70 to 75 were considered potentially inappropriate because they were conducted too soon after a previous clean bill of health from a prior colonoscopy. Much higher rates of inappropriate colonoscopies were found in the age groups of 76-85 (39 percent) and 86 and older (25 percent).

Surgeons and more senior physicians were slightly more likely to perform a large number of inappropriate colonoscopies, while more recent medical school graduates and those trained in a nonsurgical specialty (e.g., gastroenterology) were less aggressive in this regard.

Federal recommendations

The U.S. Preventive Services Task Force (USPSTF), a quasi-governmental body tasked with formulating evidence-based federal diagnostic Elderlyand therapeutic recommendations, concluded in 2008 that although routine screening colonoscopies every 10 years are recommended and potentially life-saving for adults between the ages of 50 and 75, they are contraindicated for those 76 and older.

The USPSTF detailed its reasoning in a report accompanying its 2008 recommendations on colorectal cancer screening. The group explained that the “lead time,” or the time between detecting a small, early-stage tumor (known as a colonic polyp) and the transformation of that polyp into a life-threatening cancer, is long — on the order of years, or even decades, into the future. As a person gets older, his or her life expectancy decreases, and death from other causes becomes more likely before the transformation to cancer occurs. Therefore, the benefit of removing any polyps diminishes with age. By age 76, the USPSTF concluded, this diminishing benefit becomes outweighed by the myriad risks of colonoscopies, which increase with age.

Risks and costs

The 2008 USPSTF report found that serious complications of the colonoscopy itself occur in 25 of every 10,000 colonoscopies performed. Such complications include “deaths attributable to colonoscopy or adverse events requiring hospital admission, including perforation, major bleeding, diverticulitis, severe abdominal pain, and cardiovascular events. …”

These risks are compounded by the anesthesia increasingly administered to some patients to help them tolerate the procedure. Traditionally, patients have been administered a mild sedative, such as a benzodiazepine or narcotic, for the duration of the procedure. This medication allows a patient to tolerate the procedure more comfortably, usually not remembering it, but does not induce a state of unconsciousness. Though no medication is risk-free, such a one-time dose of a short-acting benzodiazepine or narcotic, administered under supervised conditions, is relatively innocuous.

Over the past decade, however, an increasing number of patients have opted instead for general anesthesia, preferring to remain unconscious during the colonoscopy. According to a 2012 study of Medicare and privately insured patients, use of general anesthesia for either colonoscopies or upper endoscopies (an imaging study similar to a colonoscopy, but of the stomach and esophagus) increased from 14 percent in 2003 to 30 percent by 2009. More than two-thirds of general anesthesia use was in low-risk patients who did not warrant this treatment.

Though more comfortable for patients, general anesthesia is far riskier than sedatives, particularly for patients with a history of cardiovascular or pulmonary disease or those who smoke. In addition, because it requires the services of an anesthesiologist, general anesthesia typically adds about $150 (for Medicare patients) to $500 (for privately insured patients) to the cost of a colonoscopy or endoscopy. The overall cost of general anesthesia services for these procedures in the U.S. more than tripled from 2003 ($0.4 billion) to 2009 ($1.3 billion), with most of this cost ($1.1 billion, or 85 percent in 2009) for “potentially discretionary” use in low-risk patients.

Advice for patients

Colonoscopy is not the only method to screen for colon cancer, and screening is not recommended for all age groups. Table 1 below provides the most current recommendations from the USPSTF regarding colorectal cancer screening. Table 2, also below, describes three screening options,  including colonoscopy screening.

If you are between the ages of 50 and 75 and have never been screened for colorectal cancer or were last screened more than 10 years ago, make an appointment with your doctor to get screened as soon as possible. If you are between the ages of 76 and 85, you no longer need to be routinely screened, unless your doctor determines otherwise after a detailed discussion of the risks and benefits, as well as any history of an abnormal colonoscopy or other test. No one 86 or older should be screened under any circumstances. Colonoscopy, flexible sigmoidoscopy and fecal occult blood testing are the only screening procedures recommended at this time.

Table 1: Current USPSTF recommendations for colorectal cancer screening (using colonoscopy, sigmoidoscopy or fecal occult blood testing [FOBT])*

Patients Recommendation
Adults 50 to 75 years old Recommend screening for colorectal cancer using one of three procedures in Table 2.
Adults 76 to 85 years old Against routine screening for colorectal cancer. There may be considerations that support colorectal cancer screening in an individual patient, after detailed discussions with a physician of the benefits and risks of the screening and history.
Adults older than 85 Against routine screening for colorectal cancer in all circumstances.

* Last updated October 2008. These recommendations apply only to routine colorectal cancer screening in healthy patients and not to cases in which a colonoscopy is necessary to assist in the diagnosis or treatment of another suspected condition (including suspected colon cancer based on symptoms or on another screening test listed in Table 2).


Table 2: Current USPSTF-recommended options for colorectal cancer screening*

Recommended Procedures Description Recommended Interval** Pros Cons
Colonoscopy A camera is inserted into the colon via the rectum and visualizes the entire colon and rectum Every 10 years
  • Most sensitive technique for finding a tumor anywhere in the colon or rectum
  • Highest-risk of all procedures
  • Colonic perforation, bleeding and risks from general anesthesia, if given
  • Most expensive
sigmoidoscopy*** (must be done in combination with fecal occult blood testing (FOBT)
A camera is inserted into the last part of the colon (sigmoid colon) via rectum and visualizes only the sigmoid colon and rectum Every five years (with FOBT every three years)
  • Sensitive for visualizing tumors within the sigmoid colon and rectum
  • Less invasive, lower rates of serious complications compared to colonoscopy
  • Colonic perforation and bleeding (but less likely than with a colonoscopy) and risks of general anesthesia, if given
  • If used alone, without FOBT, may miss tumors in the rest of the colon (66-72 percent of all colonic tumors)
FOBT*** Stool samples are collected at different times and examined for blood that might indicate a potential tumor somewhere in the colon or rectum Annually (if alone) or every three years (if in combination with flexible sigmoidoscopy)
  • Lowest-risk and lowest-cost among all three procedures
  • Can be done from home
  • Highest chance among all three procedures of missing a tumor
  • Least specific of all three procedures (highest rate of false positives)

* Two other procedures, CT colonography and fecal DNA testing, are not currently recommended by the USPSTF due to a lack of evidence assessing the benefits and harms of these procedures in screening for colorectal cancer.
** Assuming negative initial tests. If a tumor or malignant polyp is found, repeat tests may need to be performed more frequently.
***A positive result on either the flexible sigmoidoscopy or the fecal occult blood test warrants a colonoscopy to further investigate the results.