Effect of workup strategy on the cost-effectiveness of fecal occult blood screening for colorectal cancer.

Physicians respond to a positive fecal occult blood test with a variety of workup strategies. To study the effect of the choice of strategy on the net costs and health benefits of colorectal cancer screening using this test, we used a decision analysis model to compare seven strategies that physicians might choose to examine a positive "screenee." Strategies using rigid or flexible sigmoidoscopy alone are not only insensitive, but also have high cost-effectiveness ratios. The strategy of air contrast barium enema alone had the lowest cost-effectiveness ratio. Rigid sigmoidoscopy combined with barium enema had a lower cost-effectiveness ratio than primary colonoscopy, but the strategy of primary colonoscopy could have an equal or better ratio depending on assumptions about test costs and the benefit of removing benign polyps. The primary colonoscopy strategy is both more effective and less costly than the combination of flexible sigmoidoscopy and barium enema. The optimal strategy will vary with local factors, and with the perspective of the decision-maker.

The pros and cons of fecal occult blood testing for colorectal neoplasms.

Testing feces for occult blood is widely recommended as a means of detecting subclinical colorectal tumors. Guaiac tests such as Hemoccult are the most widely used, but chemical sensitivity is relatively low and the tests are affected by dietary peroxidases, the state of fecal hydration, and certain drugs. The newly devised HemoQuant and immunologic techniques appear more sensitive and specific, but they require further evaluation before widespread clinical usage can be recommended. Occult blood screening has both merits and weaknesses. Testing does uncover subclinical colorectal cancer, often at a relatively early stage, but whether this actually improves the prognosis remains to be proven. Benign neoplastic polyps are also detected, although it is debatable whether this is a valid rationale for screening. Test sensitivity for malignancy varies from good to moderate, but is poor for benign polyps. Specificity is usually around 97%-98%, yet the predictive value of a positive test for cancer is only about 10%; hence most test-positive individuals are needlessly subjected to invasive colonic investigations. Reported figures on public compliance with occult blood testing vary widely from excellent to poor. Published costs of screening are usually quite low, but these overlook important indirect and hidden expenses and are therefore misleading. On balance, the problems of occult blood testing currently appear to outweight the merits. This could change, however, with the newer testing techniques and with awaited mortality data from controlled clinical trials now underway.

Fecal blood levels in health and disease. A study using HemoQuant.

We tested HemoQuant, a quantitative assay of fecal blood based on the fluorescence of heme-derived porphyrin, in 106 healthy volunteers, 170 patients with gastrointestinal symptoms but with normal diagnostic studies, 44 patients with gastrointestinal cancer, 75 patients with benign polyps, and 374 patients with a variety of other benign gastrointestinal lesions, including ulcers and erosions. In 98 per cent of the healthy volunteers, fecal hemoglobin concentrations were less than 2 mg per gram of stool. Levels were similarly low in stools from patients with symptoms and normal studies and in patients with relatively minor benign lesions. Within these groups, levels were slightly higher in those who had ingested red meat or aspirin. The fecal hemoglobin concentration was higher in patients with gastrointestinal cancer than in any other group, and 97 per cent of those with colorectal cancer had levels above 2 mg per gram. The sensitivity of HemoQuant was significantly greater than that of the guaiac test Hemoccult, particularly when heme was degraded or stools were dry. Intestinal degradation of heme to porphyrin can be measured separately by HemoQuant, and was greater when bleeding was from proximal lesions rather than distal ones. We conclude that HemoQuant is a more sensitive measure of gastrointestinal bleeding than Hemoccult, and that its capacity to measure degraded heme may be useful in indicating the anatomic site of bleeding.

[Haemoccult and Colorectal: a comparative prospective study on the detection of occult blood in the feces]. / Haemoccult und Colorektal: eine vergleichende prospektive Studie zum Nachweis von okkultem Blut im Stuhl.

Comparison of Colorektal and Haemoccult in 600 stool samples from 200 ambulatory, non-selected patients over the age of 40 revealed an equal number of positively reacting specimens (Colorektal 5.8%, Haemoccult 5.7%). Comparison of the results in relation to patients showed 28 positive cases with Colorektal and 18 with Haemoccult. Diagnostic workup disclosed a lesion potentially responsible for the bleeding in 67% of the cases with Haemoccult-positive and 54% with Colorektal-positive stool samples.

[Occult blood in feces--a prospective study for the comparison of Hemoccult and Fecatest]. / Okkultes Blut im Stuhl-eine prospektive Studie zum Vergleich von Haemoccult und Fecatest.

Stool samples of 150 unselected patients were tested for occult blood by the Haemoccult test and the Fecatest. The results show that the Haemoccult test is more suitable for screening for cancerous and precancerous colonic lesions than the Fecatest. Less than 10% of the patients had positive stool samples with the Haemoccult test, while bleedings lesions were subsequently found in about 2/3 of the cases. In contrast, the Fecatest was positive in 50% and in 70% after storage. These findings show clearly that the Fecatest cannot be recommended for the screening of colonic tumors.

Gastrointestinal blood loss. Effect of aspirin, fenoprofen, and acetaminophen in rheumatoid arthritis as determined by sequential gastroscopy and radioactive fecal markers.

The feasibility of determining the exact site and amount of drug-induced gastric bleeding was tested. Fourteen patients with rheumatoid arthritis received equivalent therapeutic doses of the antinflammatory drugs aspirin, 4 gm/day, and fenoprofen calcium, 2.4 gm/day, in randomized order for seven days. Acetaminophen was given for 14 days just prior to each of these periods. By fiberoptic gastroscopy, antral ulceration and acute mucosal lesions were found in seven patients following aspirin ingestion, in one taking fenoprofen, and in none taking acetaminophen. Fecal blood loss in four-day stool collections, quantitated by autologous chromium 51-labeled erythrocytes shed into the stool averaged 5.0 ml/day while taking aspirin, 2.2 ml/day while taking fenoprofen calcium, and 0.8 ml/day while taking acetaminophen. The mean blood loss was greater for those in whom gastric lesions developed while taking aspirin than for those in whom lesions did not develop. The short-term risk of erosive gastritis was greater for aspirin than fenoprofen.