For the flowchart, the first tier of mutually exclusive diagnoses can be expanded to three or more branches. The next tier can be expanded to include each possible result and the number of patients in each diagnostic category with each possible test result. For the tabular approach, a new row is added for each additional mutually exclusive diagnosis considered, and a section is added for each possible test result. ECGs show no ST-segment elevations or Q waves, although the T waves are inverted anteriorly. A serum cardiac troponin I level can help differentiate these diagnoses.
Mathematical analysis helps quantify probability.
Assume that the conditional probabilities are those shown in Table 295-2. Table 295-3 shows how Bayes theorem is used to interpret these findings. An intermediate level modestly decreases the likelihood of MI and increases the likelihood of unstable angina, whereas the likelihood of noncardiac disease drops sharply. A high level of cardiac troponin I increases the likelihood of MI and virtually excludes noncardiac disease. All rights reserved.