1,300 mg of aspirin daily does not cause positive fecal hemoccult tests.

Journal of Clinical Gastroenterology (Impact Factor: 3.19). 05/1983; 5(2):123-5. DOI: 10.1097/00004836-198304000-00006
Source: PubMed

ABSTRACT Americans 50 years of age and older are advised to test their stools for occult blood to detect colorectal neoplasms. Many will be taking 1,300 mg of aspirin daily because of cerebrovascular disease or smaller amounts for cardiovascular disease. To determine if 1,300 mg of aspirin causes positive hemoccult II tests, 27 healthy volunteers ate a red meat-free, high-fiber diet. Their stools were negative for occult blood during a 3-day control period and remained negative while they took 1,300 mg aspirin daily for an additional 7 days. This indicates that 1,300 mg aspirin daily for 1 week does not cause positive hemoccult II testing. Those taking this dose of aspirin probably need not interrupt therapy to perform hemoccult II testing.

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    ABSTRACT: To determine the effect of anticoagulants and antiplatelet medications on the positive-predictive-value of fecal occult blood test (FOBT). All patients who underwent a colonoscopy at our institution from 1995 to 2006 for a positive FOBT were identified. Medical records were searched, and patients were stratified into five groups selected a priori: low-dose aspirin, NSAIDs, warfarin, clopidogrel, or controls. The positive-predictive-value of FOBT for advanced colonic neoplasia was computed for each group. During the study period, 1,126 patients underwent colonoscopy for a positive FOBT and met entry criteria. The average age of study participants was 69 years and most were men. The positive-predictive-value of FOBT for advanced colon neoplasia was significantly higher in the control group (30.5%) when compared to those on low-dose aspirin (20.5%; p = 0.003), NSAIDs (19.7%; p = 0.003), clopidogrel (7.3%; p = 0.002), or warfarin (20%; p = 0.05). The positive-predictive-value of FOBT was significantly lower for those on clopidogrel than those on low-dose aspirin (p = 0.04) and NSAIDs (p = 0.05), but not warfarin (p = 0.08). The positive-predictive-value for FOBT was similar for those on aspirin, NSAIDs, and warfarin. There was a linear trend between the number of number of positive FOBT cards and prevalence of advanced colon neoplasia (p = 0.01). Anticoagulants and antiplatelet medications lower the positive-predictive-value of FOBT for advance colonic neoplasia and should be stopped if clinically feasible prior to stool collection.
    Digestive Diseases and Sciences 03/2010; 55(6):1637-42. DOI:10.1007/s10620-010-1150-4 · 2.55 Impact Factor
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    ABSTRACT: To determine whether medication interventions enhance the sensitivity and specificity of guaiac-based fecal occult blood testing (FOBT) when screening for colorectal cancer (CRC). We searched PubMed-MEDLINE, CINAHL, and the Cochrane databases using the MeSH headings occult blood, feces/analysis, and guaiac/analysis, linking them to variations of anticoagulants, heparin, warfarin, iron, aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), clopidogrel, cyclooxygenase-2 inhibitors, and ascorbic acid (vitamin C). Study selections were limited to English studies involving humans. All resulting titles and abstracts were reviewed for studies that included manipulation of medications associated with guaiac-based FOBT. If the study's relevance was unclear from the abstract, the full article was reviewed. The search resulted in 31 pertinent studies. No studies addressed the effects of medication interventions on the sensitivity or specificity of FOBT screening. Randomized controlled trials, however, showed no increase in the rate of positive results among those taking NSAIDs. The literature is mixed regarding the effect of NSAIDs on the positive predictive value of a positive FOBT result, although no change in positive predictive value has been shown for warfarin. Iron will not affect FOBT results in vivo. Ascorbic acid might inhibit positive FOBT results both in vitro and in vivo, but it has not been studied in screening populations. Studies evaluating the effects of medication intervention on FOBT screening for CRC are limited by their lower quality and because they do not address sensitivity and specificity. Available evidence, however, does not suggest a benefit from withholding NSAIDs, anticoagulant medications, or iron during the screening period. These recommendations should be abandoned in order to maximize adherence to screening. Positive FOBT results obtained among patients taking these medications deserve full evaluation for CRC. Until further studies clarify the effect of ascorbic acid on FOBT screening, withholding this medication before testing seems prudent.
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