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Fecal Occult Blood Tests Can Do More Harm Than Good in the Elderly

Among elderly men, 87% with the worst life expectancy and 65% with the best life expectancy experienced more burden than benefit from fecal occult blood testing.

The U.S. Preventive Services Task Force recommends that colorectal cancer (CRC) screening be discontinued after age 85 and that decisions to perform screening be individualized for patients aged 75 to 85. Several other guidelines recommend against CRC screening if individual life expectancy is &lt;10 years, but supporting evidence is mostly from short-term follow-up studies.

To assess the benefit versus burden of fecal occult blood test (FOBT) screening in the elderly, researchers conducted a 7-year longitudinal study involving 212 patients (age range, 70–84; 99.5% men) who received positive FOBT results at four Veterans Affairs medical centers. Net benefit was defined as detection of CRC or "significant adenoma" (adenoma ≥1 cm, 3 or more adenomas, or an adenoma with villous features), followed by treatment and survival for ≥5 years. Net burden encompassed false-positive tests, deaths within 5 years of FOBT screening, and undetected cancers when patients declined follow-up. Researchers analyzed benefit status by life expectancy, which they classified as follows, using the Charlson-Deyo comorbidity index (CCI) as a measure of comorbidity:Best: age range, 70–79 and CCI, 0 (life expectancy, &gt;10 years)
Average: age range, 70–84 and CCI, 1–3; or age ≥80 and CCI, 0 (life expectancy, 5–10 years)
Worst: age range, 70–84 and CCI ≥4; or age ≥85 and CCI ≥1 (life expectancy, &lt;5 years)
Of all participants, 16% experienced net benefit from FOBT screening, and 70% experienced net burden; benefit status was indeterminate in 14%. The percentage of patients who experienced a net burden varied by life expectancy: best, 65%; average, 70%; and worst, 87%. Net benefit also varied by life expectancy: best, 20%; average, 15%; and worst, 10%.

Comment:&nbsp;This study is somewhat hampered by ambiguous definitions of screening burdens. For example, a net burden from FOBT screening in patients who had cancer but did not undergo colonoscopy would seem to result from failure to follow up the positive screening test, not the screening test itself. Appropriate follow-up would have shifted a net burden to a net benefit. Also, although a positive FOBT without a follow-up colonoscopy in a person without cancer might constitute a net burden, the burden seems minimal. Nevertheless, the study provides some quantitative data on CRC screening benefit by patient life expectancy. These issues might be even more relevant to colonoscopy screening, since the costs and risks of colonoscopy and polypectomy are incurred at the initial decision to screen. However, with FOBT screening, a positive test can still be followed by a decision to forgo colonoscopy if substantial morbidities or advanced age are factors. In that case, of course, the initial decision to perform the FOBT was probably inappropriate.

—&nbsp;Douglas K. Rex, MD

Published in&nbsp;Journal Watch Gastroenterology&nbsp;June 3, 2011

Citation:
Kistler CE et al. Long-term outcomes following positive fecal occult blood test results in older adults: Benefits and burdens.&nbsp;Arch Intern Med&nbsp;2011 May 9; [e-pub ahead of print].&nbsp;[Medline® Abstract]

Copyright © 2011. Massachusetts Medical Society. All rights reserved.The above message comes from&nbsp;Journal Watch, who is solely responsible for its content.