pretest probability

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(1) The number of people with a specific condition or attribute at a specified time divided by the total number of people in the population.
(2) The number or proportion of cases, events or conditions in a given population.
A term defined in the context of a 4-cell diagnostic matrix (2 X 2 table) as the amount of people with a disease, X, relative to a population.

Veterinary medicine
(1) A clinical estimate of the probability that an animal has a given disease, based on current knowledge (e.g., by history of physical exam) before diagnostic testing.
(2) As defined in a population, the probability at a specific point in time that an animal randomly selected from a group will have a particular condition, which is equivalent to the proportion of individuals in the group that have the disease. Group prevalence is calculated by dividing the number of individuals in a group that have a disease by the total number of individuals in the group at risk of the disease. Prevalence is a good measure of the amount of a chronic, low-mortality disease in a population, but is not of the amount of short duration or high-fatality disease. Prevalence is often established by cross-sectional surveys.

pretest probability

An estimate of a patient's likelihood of illness. It is based on or derived from the prevalence of disease in a community.
See also: probability
References in periodicals archive ?
Stress ECHO is appropriate for symptomatic patients with an intermediate pretest probability of CAD and contraindication to regular treadmill stress testing.
Yes Yes No No TABLE II: Causes of Increased D-dimer Athersclerosis Trauma Hepatic disease Disemminated in travasuclar coagulation Infection Pregnancy Inflammation Age of the patient Cancer DVT Thrombolytic therapy PE TABLE III: How best fo use d-dimer assays Clinical Policy from College Emergency Physicians, 2003 Patient Management Recommendation Level A (High Clinical Certainty) No Recommendation specificied Level B (Moderate)-Low Pretest probability Use 1.
Hair analysis should be used with caution to make decisions regarding overexposure or need for treatment in patients with nonspecific symptoms and a low pretest probability of metal toxicity based on medical history, exposure history, and physical examination.
The most crucial factor governing pretest probability for Lyme disease is exposure history.
In 2013 ESC Guidelines on the management of SCAD (2013G), the indications of CCTA for patients with SCAD should be considered an alternative to stress tests in patients with ejection fraction (EF) >50% and pretest probability between 15% and 50%.
But mounting evidence (the recent admissions of cyclist Lance Armstrong (2), the words of cyclist Floyd Landis (3), and the US government's Mitchell report (4) on baseball doping, to name a few sources) indicates that the pretest probability of doping, at least in some sports, is very high.
Patients with high pretest probability should undergo immediate scanning, foregoing the D-dimer--which should be reserved for patients who have a low or moderate pretest probability but sufficient reason to suspect PE or DVT.
This means that one can effectively rule out CRS (post test probability of less than 17%) if the pretest probability is less than 50% and if endoscopy is not suggestive of the diagnosis.
Two patients with the same pretest probability of SIHD may prefer different approaches because of variations in personal beliefs, economic considerations, or stage of life," said Dr.