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




b The committee defines “objectively” to mean “reliably and accurately.”


e Please see Chapter 2 for discussion of this biomarker.




a Wagner (2002);


c Biomarkers Definitions Working Group (2001); and


d Wagner (2008).

taneously measured “signatures,” or patterns of co-occurring sets, of genetic sequences, peptides, proteins, or metabolites as biomarkers. These signatures can also be combinations of several of these types of measurements; ideally, each component of a signature is identified.

Biomarkers are used to describe risk, exposures, intermediate effects of treatment, and biologic mechanisms; as surrogate endpoints, biomarkers are used to predict health outcomes. Biomarkers can provide information about risk and physiological parameters that is useful in a variety of contexts: (1) insight into the health and well-being of patients and consumers, (2) the status of patient and consumer response to an intervention, (3) a basis for interpreting research results and comparing results across studies, (4) indications of health status and disease risk in population groups, and (5) important data for planning and evaluating public health programs. Biomarker measurements support the practice

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