%0 Journal Article
%T Analysis of Predictive Values Based on Individual Risk Factors in Multi-Modality Trials
%A Katharina Lange
%A Edgar Brunner
%J Diagnostics
%D 2013
%I MDPI AG
%R 10.3390/diagnostics3010192
%X The accuracy of diagnostic tests with binary end-points is most frequently measured by sensitivity and specificity. However, from the clinical perspective, the main purpose of a diagnostic agent is to assess the probability of a patient actually being diseased and hence predictive values are more suitable here. As predictive values depend on the pre-test probability of disease, we provide a method to take risk factors influencing the patient¡¯s prior probability of disease into account, when calculating predictive values. Furthermore, approaches to assess confidence intervals and a methodology to compare predictive values by statistical tests are presented. Hereby the methods can be used to analyze predictive values of factorial diagnostic trials, such as multi-modality, multi-reader-trials. We further performed a simulation study assessing length and coverage probability for different types of confidence intervals, and we present the R-Package facROC that can be used to analyze predictive values in factorial diagnostic trials in particular. The methods are applied to a study evaluating CT-angiography as a noninvasive alternative to coronary angiography for diagnosing coronary artery disease. Hereby the patients¡¯ symptoms are considered as risk factors influencing the respective predictive values.
%K positive predictive value
%K negative predictive value
%K diagnostic trials
%K coronary artery disease
%U http://www.mdpi.com/2075-4418/3/1/192