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Tools for Decision Making Sections
Author Bio
Introduction
Probability Theory
Case Study 1: Patient History
Bayes' Theorem
Methods for Estimating Pre-test Probability
Estimating Likelihood Ratios
Sensitivity and Specificity
Currently selected section: Interpreting Test Results
Calculating Post-test Probabilities
Post-test Probabilities in Clinical Practice
Conclusions: Case Study 1
Part II
Part III
References


Chapter 14: Tools for Decision Making: Interpreting Test Results
        

Here is some information about the performance of two tests for patients with suspected coronary artery disease. Your goal is to determine which of these two tests is preferable.

Table 1.8.1: Interpreting Test Results
Test Sensitivity Specificity Likelihood ratio positive Likelihood ratio negative Cost(1994dollars)
Dobutamine echo .89 .80 4.5 .14 $194
Exercise ECG .68 .77 3.0 .42 $116

Your answer will require two steps that are described in the sections that follow:

Step 1: Calculate the post-test probability of disease for all results of each test.

Step 2: Decide if the difference in post-test probability would make a difference to the treatment of the patient.


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