Use of Likelihood Ratios in Evidence-based Clinical Decision Making

초록

During the clinical decision making practitioners are often faced with performing diagnostic tests to solveterms such as sensitivity, specificity, and positive (PPV) and negative predictive value (NPV). Although well known,clinicians are frequently unclear about the concept and application of these terms in everyday evidence-based clinicaldecision making. Sensitivity and specificity, which are intrinsic properties of diagnostic tests, sumarizes thecharacteristics of the test over a population. The PPV and NPV are greatly dependent on the population prevalenceof disease, and thus they do not transferable to different patients or clinical settings. Besides, considering the factthat clinicians more often interested in knowing the extent to which a test result could confirm or exclude of a condition(LR) using the information contained in sensitivity and specificity are becoming increasingly popular for reportingthe usefulness of diagnostic tests because this term provide an indication of posttest probability as a function of thepretest probability. In this article, clinical applications of LR are illustrated with some practical examples. Discussionis also included of the inherent limitations regarding diagnostic test characteristics.

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