Why comparing survival curves between two subgroups may be misleading
This addresses a methodological issue for researchers validating prognostic tests in survival analysis, but it is incremental as it highlights a specific case rather than introducing a new method.
The paper identifies a problem where comparing survival curves between two subgroups can be misleading due to a relationship with predictive values in binary classification, particularly in validation of prognostic diagnostic tests with censored data.
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.