# probability

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## Probability

The relative likelihood of a particular outcome among all possible outcomes.

## probability

the likelihood of a particular uncertain event occurring, measured on a scale from 0.0 (such an event is impossible) to 1.0 (such an event is certain to occur). People generally estimate probabilities on the basis of the relative frequency with which an event has occurred in the past, under given circumstances, and generalize from this past experience. In some circumstances it is easy to estimate the proportion of occasions on which an event occurs; for example, the probability of getting ‘heads’ when flipping a balanced coin is 0.5 because with such a coin in the long run we would get 50% ‘heads’ and 50% ‘tails’. In estimating probabilities in business situations, though, there may be no or only a few previous experiences that can be used to gauge the relative frequency of an event occurring. See also RISK AND UNCERTAINTY.
Collins Dictionary of Economics, 4th ed. © C. Pass, B. Lowes, L. Davies 2005
References in periodicals archive ?
Kearon et al, (16) demonstrated the utility of D-dimer testing alone in excluding PE in low pretest probability patients, however, that alone cannot be used to exclude PE in patients with moderate to high risk of developing PE.
Situations Test preferred Test not preferred Cyclic Cushing's syndrome [21] UFC or LNSC DST Mild Cushing's syndrome [21] LNSC or DST UFC Pseudo Cushing's syndrome [21] LNSC or DST UFC CS patients on antiepileptics [21] UFC or LNSC DST Adrenal incidentaloma [21] DST UFC or LNSC Pregnancy [21] UFC DST, LNSC Severe chronic kidney disease [21] DST or LNSC UFC Low pretest probability [15] UFC High pretest probability [15] LNSC UFC: urinary free cortisol; LNSC: late-night salivary cortisol; DST: dexamethasone suppression test.
In the most extreme scenario, where every negative level III test is followed by an in-lab test to confirm a diagnosis of OSA, our analysis still demonstrates that the HM pathway has a cheaper per-patient cost than the SL pathway in a population with a moderate pretest probability of OSA.
It was found in the study that coronary CT angiogram based strategy was safe for the evaluation of acute pain chest presumably of cardiac origin with low and intermediate pretest probability of coronary artery disease.
For a patient with a solid nodule >8 mm to 3 cm, ACCP guidelines suggest that physicians estimate the pretest probability of malignancy qualitatively using their clinical judgment and/- or quantitatively by using a validated model, such as the Mayo model described above.
Therefore the clinical profile of the patient and the pretest probability are important in assessing the test result.
Using LRs, one can calculate the posttest probability for any given pretest probability [25].
Tool for estimating pretest probability of coronary heart disease Variable Score Example: 52- year-old woman Age (male/female): -Under 40/under 50 3 -40 to 50/50 to 64 6 6 -55 or older/65 or older 9 Estrogen status positive (F) -3 -3 Estrogen status negative (F) 3 Angina history typical * 5 Angina history atypical 3 Angina history nonanginal 1 1 Diabetes 2 2 Hyperlipidemia 1 1 Hypertension 1 Smoking (any) 1 First-degree family history 1 1 of coronary artery disease Obesity (BMI >27 kg/[m.sup.2]) 1 1 Total score 9 Risk according to total score Low: 0 to 8 Intermediate: 9 High: 16 or to 15 greater Source: Morise AP, Jalisi F.
This is because the level of clinical suspicion or pretest probability may be low in this racial group.
Tips for teachers of evidence-based medicine: clinical prediction rules (CPRs) and estimating pretest probability. J Gen Intern Med 2008; 23: 1261-8.
Using electronic records and chart review, they sought to identify differences in the use of stress testing based on patient demographics and comorbidities, pretest probability of coronary artery disease, and house staff coverage.

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