A comparison of C/B ratios from studies using receiver operating characteristic curve analysis

In receiver operating characteristic (ROC) curve analysis, the optimal cuto ff value for a diagnostic test can be found on the ROC curve where the slop e of the curve is equal to (C/B) X (1-p[D])/p[D], where p[D] is the disease prevalence and C/B is the ratio of net costs of treating nondiseased indiv iduals to net benefits of treating diseased individuals: We conducted a str uctured review of the medical literature to examine C/B ratios found in ROC curve analysis. Only two studies were found in which a C/B ratio was expli citly calculated; in another 11 studies, a C/B ratio was based on a sa call ed holistic estimate, an all-encompassing educated estimate of the relative costs and benefits relevant to the clinical situation. The C/B ratios rang ed from 0.0025 (tuberculosis screening) to 2.7 (teeth restoration for cario us lesions). Clinical scenarios that are directly life threatening but cura ble had C/B ratios of less than 0.05. This analysis led us to construct a t able of ordered C/B ratios that may be used by investigators to approximate C/B ratios for other clinical situations in order to establish cutpoints f or new diagnostic tests. J CLIN EPIDEMIOL 52;9:885-892, 1999. (C) 1999 Else vier Science Inc.