Evaluation of predictive capacities of biomarkers based on research synthesis

The objective of diagnostic studies or prognostic studies is to evaluate and compare predictive capacities of biomarkers. Suppose we are interested in evaluation and comparison of predictive capacities of continuous biomarkers for a binary outcome based on research synthesis. In analysis of each study, subjects are often classified into two groups of the high‐expression and low‐expression groups according to a cut‐off value, and statistical analysis is based on a 2 × 2 table defined by the response and the high expression or low expression of the biomarker. Because the cut‐off is study specific, it is difficult to interpret a combined summary measure such as an odds ratio based on the standard meta‐analysis techniques. The summary receiver operating characteristic curve is a useful method for meta‐analysis of diagnostic studies in the presence of heterogeneity of cut‐off values to examine discriminative capacities of biomarkers. We develop a method to estimate positive or negative predictive curves, which are alternative to the receiver operating characteristic curve based on information reported in published papers of each study. These predictive curves provide a useful graphical presentation of pairs of positive and negative predictive values and allow us to compare predictive capacities of biomarkers of different scales in the presence of heterogeneity in cut‐off values among studies. Copyright © 2016 John Wiley & Sons, Ltd.