Published 3 November 2009, doi:10.1136/bmj.b3823
Cite this as: BMJ 2009;339:b3823

Practice

Diagnosis in General Practice

Using probabilistic reasoning

¹ Faculty of Health Sciences and Medicine, Bond University, Gold Coast, QLD 4029, Australia

Having a sense of the accuracy of diagnostic tests will help general practitioners to interpret and use the tests appropriately and, as in the example of chest pain, avoid unnecessary testing (doi:10.1136/bmj.b4117)

The first 150 words of the full text of this article appear below.

Diagnostic tests—whether clinical signs, imaging, or laboratory tests—are imperfect: there is always a possibility that test results are inaccurate and our diagnosis is wrong. However, we need to make decisions about whether to treat or not to treat patients, and so we need to feel confident that our diagnosis is above a certain threshold before we decide to treat a patient and below a certain threshold if we decide to withhold treatment. The threshold depends on the disease and the potential harms and benefits of treating or not treating patients. Unless we have clear strategies to cope with the uncertainties of testing, false positive results mislead us to treat some patients unnecessarily and false negative results lead us to fail to treat some patients adequately or in time.

Probabilistic reasoning is used when we consider the diagnostic accuracy of tests in our clinical decisions. It is also called Bayesian reasoning, . . . [Full text of this article]

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    StumbleUpon    Technorati    What's this?

Relevant Articles

Chest pain

Michael Jelinek and Kevin Barraclough
BMJ 2009 339: b4117. [Extract] [Full Text]

Clinical prediction rules

Gavin Falk and Tom Fahey
BMJ 2009 339: b2899. [Extract] [Full Text]

Diagnostic strategies used in primary care

C Heneghan, P Glasziou, M Thompson, P Rose, J Balla, D Lasserson, C Scott, and R Perera
BMJ 2009 338: b946. [Extract] [Full Text]

Diagnostic tests 4: likelihood ratios

Jonathan J Deeks and Douglas G Altman
BMJ 2004 329: 168-169. [Extract] [Full Text] [PDF]

This article has been cited by other articles:

• Jelinek, M., Barraclough, K. (2009). Chest pain. BMJ 339: b4117-b4117 [Full text]  

Rapid Responses:

Read all Rapid Responses

Measurement of uncertainty

John T Callahan
bmj.com, 4 Nov 2009 [Full text]

True or False? - you still have to decide

Harry Hall
bmj.com, 4 Nov 2009 [Full text]

Probabilistic reasoning in diagnosis

Huw Llewelyn
bmj.com, 10 Nov 2009 [Full text]

Online poll

Find out more>>