BOX S-2
Important Definitions
Analytical Validation: “assessing [an] assay and its measurement performance characteristics, determining the range of conditions under which the assay will give reproducible and accurate data.”a
Biomarker: “a characteristic that is objectivelyb measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacologic responses to a[n] … intervention.”c Example: cholesterol level.
Chronic Disease: a culmination of a series of pathogenic processes in response to internal or external stimuli over time that results in a clinical diagnosis/ailment and health outcomes. Example: diabetes.
Clinical Endpoint: “a characteristic or variable that reflects how a patient [or consumer] feels, functions, or survives.”c Example: death.
Fit-for-Purpose: being guided by the principle that an evaluation process is tailored to the degree of certainty required for the use proposed.
Qualification: “evidentiary process of linking a biomarker with biological processes and clinical endpoints.”d
Surrogate Endpoint: “a biomarker that is intended to substitute for a clinical endpoint. A surrogate endpoint is expected to predict clinical benefit (or harm or lack of benefit or harm) based on epidemiologic, therapeutic, pathophysiologic, or other scientific evidence.”c Example: blood pressure for trials of several classes of antihypertensive drugs.e
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NOTES:
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b The committee defines “objectively” to mean “reliably and accurately.”
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e Please see Chapter 2 for discussion of this biomarker.
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SOURCES:
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a Wagner (2002);
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c Biomarkers Definitions Working Group (2001); and
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d Wagner (2008).
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