Equation for calculation of theoretical sensitivity and specificity of simple list of items rule with cut-off value at one item.

<p>Equation for calculation of theoretical sensitivity and specificity of simple list of items rule with cut-off value at one item.</p

Characteristic of variables used in the clinical decision rules to distinguish ABM from pAVM.

*<p>Probability of ABM (pABM).</p

Characteristics of the 129 patients in this study.

<p>Characteristics of the 129 patients in this study.</p

Accuracy comparison of clinical rules.

#<p>Thresholds indicated by the authors of the rules.</p>⊕<p>Thresholds computed by ROC analysis to achieve 100% sensitivity.</p>*<p>Probability of ABM (pABM).</p><p>Numbers in boldface indicate rule with 100% sensitivity.</p

Explanation for calculation of theoretical sensitivity and specificity.

<p>The theoretical sensitivity is the likelihood of sensitivity of the clinical rule after combining <i>n</i> tests, thus its values is depend on the individual sensitivity of each test. For example, a clinical rule combining two tests with sensitivities at 90% and 80%, respectively, the likelihood of the combined sensitivity (of the clinical rule of two tests) is calculated as 1–(1–0.90)×(1–0.80) = 0.98 or 98%. Therefore, combination of several tests will enhance the rule's sensitivity. In contrast, a clinical rule combining two tests with specificities at 80% and 70%, the likelihood of the combined specificity (of the clinical rule of two tests) will be decreased as the follow calculation: 0.80×0.70 = 0.56 or 56%.</p