The importance of considering competing treatment affecting prognosis in the evaluation of therapy in trials: the example of renal transplantation in hemodialysis trials. by Hazelbag, C, Peters, S, Blankestijn, P, Bots, M, Canaud, B, Davenport, A, Grooteman, M, Kircelli, F, Locatelli, F, Maduell, F, Morena, M, Nubé, M, Ok, E, Torres, F, Hoes, A, Groenwold, R, HDF Pooling Project investigators