Definitions of the levels of evidence (I—III) and grades of the recommendation (A, B, C, I) are presented at the end of the "Major Recommendations" field.
Note from the National Academy of Clinical Biochemistry (NACB) and the National Guideline Clearinghouse (NGC): The Laboratory Medicine Practice Guidelines (LMPG) evidence-based practice for point-of-care testing sponsored by the NACB have been divided into individual summaries covering disease- and test-specific areas. In addition to the current summary, the following are available:
Does annual or biennial guaiac-based fecal occult blood test (FOBT), in the average-risk asymptomatic outpatient population older than 50 years (no family history or other risk factors for colorectal cancer [CRC]), reduce mortality from colorectal cancer compared to no FOBT screening?
Guideline 134. The guideline developers strongly recommend that clinicians routinely provide guaiac-based FOBT for asymptomatic individuals older than 50 years at least biennially to reduce mortality from colorectal cancer. Three large randomized controlled trials have illustrated a 15% to 33% reduction in mortality from annual or biennial FOBT. FOBT is easy and inexpensive and poses no risk to the patient.
Strength/consensus of recommendation: A
Level of evidence: I and II (randomized controlled trials and case-control studies)
Does annual or biennial guaiac-based FOBT, in the asymptomatic population older than 50 years, significantly decrease the incidence of CRC?
Guideline 135. The guideline developers cannot currently recommend for or against the use of guaiac-based FOBT to reduce the incidence of CRC. Randomized control studies addressing this question are conflicting; however, the differences in length of follow-up make it difficult to draw direct comparisons. More studies need to be performed to resolve this question.
Strength/consensus of recommendation: I
Level of evidence: I and II (randomized controlled trials and case-control studies)
Should FOBT be performed in the central laboratory or at the point of care for asymptomatic patients who require screening for CRC?
Guideline 136. The guideline developers cannot recommend for or against FOBT performed in the central laboratory or at the point of care to screen for CRC in asymptomatic patients. Experts suggest that home collection of specimens with analysis either in the physician office or laboratory is recommended over traditional point-of-care testing (POCT) for occult blood by digital rectal examination (DRE). In addition, the randomized controlled trials illustrating CRC mortality reduction used the central laboratory to perform FOBT. However, no trials have compared these methodologies and addressed the benefits of POCT, which include convenience and an increase in compliance.
Strength/consensus of recommendation: I
Level of evidence: III (retrospective trial, expert opinion)
Which FOBT method, guaiac-based, heme-porphyrin assay, or immunological, is the most accurate (sensitivity, specificity, positive predictive value [PPV]) in an outpatient setting for the detection of CRC in asymptomatic individuals older than 50 years?
Guideline 137. The guideline developers cannot currently recommend an ideal fecal occult blood method for the detection of CRC according to the current literature and available methodology. Although guaiac-based testing is not extremely sensitive, it is reasonably specific, cheap, and easy to use and poses no risk to the patient. In addition, 3 large randomized controlled trials used guaiac-based methods to illustrate a reduction in CRC mortality. Although guaiac-based methods are widely used in the United States, there is insufficient evidence to recommend guaiac-based methods over other types of assays.
Strength/consensus of recommendation: I
Level of evidence: II and III (prospective comparative trials, descriptive studies, and opinion)
Is FOBT useful in symptomatic patients to differentiate bleeding caused by upper gastrointestinal lesions (including gastroesophageal cancer) from bleeding caused by lower gastrointestinal lesions?
Guideline 138. The guideline developers cannot currently recommend FOBT to differentiate upper from lower sources of gastrointestinal bleeding. A limited number of cohort and case-control studies have demonstrated that FOBT can detect bleeding caused by upper gastrointestinal lesions, but there is no evidence to support that guaiac-based FOBT can determine the origin of bleeding.
Strength/consensus of recommendation: I
Level of evidence: II (case-control and cohort studies)
Can guaiac-based FOBT be used in patients receiving therapeutic anticoagulation to predict whether a patient is at high risk for gastrointestinal bleeding?
Guideline 139. The guideline developers cannot currently recommend for or against the use of guaiac-based FOBT to predict gastrointestinal bleeding in patients receiving anticoagulation. Although the current literature is sparse, it suggests that positive fecal occult blood results do not correlate with the level of anticoagulation. From these data, it can be extrapolated that FOBT would not be predictive of bleeding risk. More studies need to be done to directly address this issue.
Strength/consensus of recommendation: I
Level of evidence: II and III (prospective trials and expert opinion)
Can Gastroccult testing of gastric fluid from a nasogastric tube be used to detect gastrointestinal bleeding in high-risk intensive care unit (ICU) patients receiving antacid prophylaxis?
Guideline 140. The guideline developers cannot currently recommend for or against the use of Gastroccult to detect gastric bleeding in ICU patients receiving antacid prophylaxis. Only 1 study to their knowledge has indirectly addressed this issue. No randomized controlled trials have been performed.
Strength/consensus of recommendation: I
Level of evidence: III (small study and clinical evidence)
Definitions:
Levels of Evidence
- Evidence includes consistent results from well-designed, well-conducted studies in representative populations.
- Evidence is sufficient to determine effects, but the strength of the evidence is limited by the number, quality, or consistency of the individual studies; generalizability to routine practice; or indirect nature of the evidence.
- Evidence is insufficient to assess the effects on health outcomes because of limited number or power of studies, important flaws in their design or conduct, gaps in the chain of evidence, or lack of information.
Strength of Recommendations
A - The National Academy of Clinical Biochemistry (NACB) strongly recommends adoption; there is good evidence that it improves important health outcomes and concludes that benefits substantially outweigh harms.
B - The NACB recommends adoption; there is at least fair evidence that it improves important health outcomes and concludes that benefits outweigh harms.
C - The NACB recommends against adoption; there is evidence that it is ineffective or that harms outweigh benefits.
I - The NACB concludes that the evidence is insufficient to make recommendations; evidence that it is effective is lacking, of poor quality, or conflicting, and the balance of benefits and harms cannot be determined.
