Suspected bias in selection criteria of target subpopulation and its validation

[...]there will appear to be a large difference in mortality rates between the intervention and control groups in a population that is likely to experience early mortality after observation. [...]the selection criteria for patients who are expected to have a large treatment effect could be influenced by this bias. [...]the results of the study could be affected by survivor treatment selection bias and these criteria may not capture patients who may benefit most from PMX-HA.