Glossary


Glossary of terms (terminology and key principles).

Browse the glossary using this index

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P

Positive predictive value

The proportion of individuals with a positive test result who truly have the target condition.

Entry link: Positive predictive value

Predictive biomarker

In individuals with a confirmed diagnosis, the presence of a predictive biomarker is used to identify individuals who are more likely to experience a favorable or unfavorable effect from a specific intervention or exposure than individuals where the biomarker is absent.  Predictive biomarkers may be used to refine criteria for disease classification.

Example

  • Tumour estrogen receptor status in women with breast cancer, to identify those who will respond to endocrine therapy such as tamoxifen.
Entry link: Predictive biomarker

Prognostic biomarker

In individuals with a confirmed diagnosis, the presence or level of a prognostic biomarker is used to identify the likelihood of a clinical event, disease recurrence or progression, independent of the effects of a specific intervention. 

Prognostic biomarkers may be used to refine criteria for disease diagnosis or staging. A biomarker may be both prognostic and predictive.


Example

  • CD4+ lymphocyte count in individuals with human immunodeficiency virus, to identify those at elevated risk of progression to Acquired Immunodeficiency Syndrome.
Entry link: Prognostic biomarker