A Comparison of C/B Ratios from Studies Using Receiver Operating Characteristic Curve Analysis

In receiver operating characteristic (ROC) curve analysis, the optimal cutoff value for a diagnostic test can be found on the ROC curve where the slope 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 individuals to net benefits of treating diseased individuals. We conducted a structured 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 explicitly calculated; in another 11 studies, a C/B ratio was based on a so-called holistic estimate, an all-encompassing educated estimate of the relative costs and benefits relevant to the clinical situation. The C/B ratios ranged from 0.0025 (tuberculosis screening) to 2.7 (teeth restoration for carious lesions). Clinical scenarios that are directly life threatening but curable had C/B ratios of less than 0.05. This analysis led us to construct a table 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 for new diagnostic tests.