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Figure 6 In this example, pretest probability is estimated by standard coronary heart disease (CHD) risk factor measurements in a multivariable model, such as the Framingham risk score, to predict a future event (dashed line). The solid and dotted lines represent curves generated, depending on whether the subsequent test result is positive (solid line) or negative (dotted line). The arrows represent how a patient with a 15% pre-test probability would have markedly different post-test probabilities depending on whether the additional noninvasive test was positive or negative. In this example, an individual who undergoes a screening evaluation that suggests a 15% chance of having a CHD event in the next 10 years undergoes a second test, and the 15% prediction is modified upward and becomes more than 35% if the test is positive, or is modified downward and becomes less than 5% if the second test is negative. This figure demonstrates how additional test results can either substantially increase or decrease the probability estimate of a future CHD event by increasing the chance that a positive result is a true positive, or that a negative result is a true negative. (Adapted from Greenland et al. [10]).
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