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Med J Aust. 2004 May 3;180(9):449-54.

Generating pre-test probabilities: a neglected area in clinical decision making.

Author information

1
Centre for Clinical Epidemiology and Biostatistics, Level 3, David Maddison Building, University of Newcastle, Newcastle, NSW 2300, Australia.

Abstract

OBJECTIVE:

To assess the accuracy and variability of clinicians' estimates of pre-test probability for three common clinical scenarios.

DESIGN:

Postal questionnaire survey conducted between April and October 2001 eliciting pre-test probability estimates from scenarios for risk of ischaemic heart disease (IHD), deep vein thrombosis (DVT), and stroke.

PARTICIPANTS AND SETTING:

Physicians and general practitioners randomly drawn from College membership lists for New South Wales and north-west England.

MAIN OUTCOME MEASURES:

Agreement with the "correct" estimate (being within 10, 20, 30, or > 30 percentage points of the "correct" estimate derived from validated clinical-decision rules); variability in estimates (median and interquartile ranges of estimates); and association of demographic, practice, or educational factors with accuracy (using linear regression analysis).

RESULTS:

819 doctors participated: 310 GPs and 288 physicians in Australia, and 106 GPs and 115 physicians in the UK. Accuracy varied from about 55% of respondents being within 20% of the "correct" risk estimate for the IHD and stroke scenarios to 6.7% for the DVT scenario. Although median estimates varied between the UK and Australian participants, both were similar in accuracy and showed a similarly wide spread of estimates. No demographic, practice, or educational variables substantially predicted accuracy.

CONCLUSIONS:

Experienced clinicians, in response to the same clinical scenarios, gave a wide range of estimates for pre-test probability. The development and dissemination of clinical decision rules is needed to support decision making by practising clinicians.

PMID:
15115422
[Indexed for MEDLINE]

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