Clinical Reasoning and Probability—Bayes' Theorem at the Bedside—
- VernacularTitle:診断推論と確率—ベッドサイドでのベイズの定理—
- Author:
Haruki Sasaki
- Publication Type:Journal Article
- From:An Official Journal of the Japan Primary Care Association
2013;36(3):191-197
- CountryJapan
- Language:Japanese
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Abstract:
Likelihood ratios (LRs) have emerged as one of the most useful means to describe the implications of probabilistic reasoning. Unfortunately, at the bedside, many clinicians have difficulty relating LRs to the more familiar concept of pretest and posttest probability. I propose an easier two-step calculation ; the first uses the prevalence of a particular disease as the pretest probability. If the pretest probability is <10%, it is chosen among 0.1%, 1%, 2%, and 5%, then multiplication by LRs of 110, 11, 5.5 and 2.2 respecively makes the probability 10%.
The second way (McGee‘s method) is to add the pretest probability of 10% to the converted probability from LRs. If the pretest probability is >10%, the second way is appropriate for calculating the probability without the first step.
I hope the simplicity of this method, with no need to use a calculating device, will increase adoption of probabilistic reasoning at the bedside
