[The likelihood ratio: estimation of the impact of a diagnostic test on treatment decision].

Likelihood ratios (LRs) can be used to assess in an efficient manner the change of a pre-test probability to the post-test probability of a disease based on a given test result. For any clinical question or condition of interest, the diagnostic benefit can be calculated for each diagnostic test allowing to compare the performance of different diagnostic tests. Urologists should become familiar with the use of LR to promote a more evidence-based application of diagnostic test for different clinical scenarios. This review provides insights in the calculation and use of LR.