{Reference Type}: Journal Article
{Title}: Summary concordance index for meta-analysis of prognosis studies with a survival outcome.
{Author}: Hattori S;Zhou XH;
{Journal}: Stat Med
{Volume}: 40
{Issue}: 24
{Year}: 10 2021 30
{Factor}: 2.497
{DOI}: 10.1002/sim.9121
{Abstract}: In prognosis studies to evaluate association between a continuous biomarker and a survival outcome, investigators often classify subjects into two subclasses of the high- and low-expression groups and apply simple survival analysis techniques of the Kaplan-Meier method and the logrank test. The high- and low-expressions are defined according to whether or not the observation of the biomarker is higher than the cut-off value, which is heterogeneous across studies. The heterogeneous definitions of the cut-off value make it difficult to apply the standard meta-analysis techniques. We propose a method to estimate the concordance index for a survival outcome synthesizing published prognosis studies, in which the Kaplan-Meier estimates for the high- and low-expression groups are reported. We illustrate our proposed method with a real dataset for meta-analysis of prognosis studies evaluating Ki-67 in early breast cancer and evaluate its performance with a simulation study.