We analyse an issue when comparing survival curves between two subgroups. We show that there is a direct relationship between estimates of subgroups' survival at a time point and positive and negative predictive values in the binary classification settings. Our findings present a case where current methods of comparing survival curves between subgroups may be misleading. We think that this ought to be taken into account during the validation of prognostic diagnostic tests that predict two prognostic subgroups for a given disease or treatment, when the validation data set consists of censored data.

翻译：在比较两个分组之间的生存曲线时,我们分析一个问题。我们发现,在一个时间点对分组生存的估计与二进制分类设置中的正和负预测值之间存在直接关系。我们的调查结果表明,目前比较分组之间生存曲线的方法可能会产生误导。我们认为,在验证预测性诊断测试时,应该考虑到这一点,该诊断测试预测特定疾病或治疗的两个预测性分组,当验证数据集由受审查的数据组成时。