Immortal Time Bias: A Frequently Unrecognized Threat to Validity in the Evaluation of Postoperative Radiotherapy
Park HS, Gross CP, Makarov DV, Yu JB. Immortal Time Bias: A Frequently Unrecognized Threat to Validity in the Evaluation of Postoperative Radiotherapy. International Journal Of Radiation Oncology • Biology • Physics 2012, 83: 1365-1373. PMID: 22342097, DOI: 10.1016/j.ijrobp.2011.10.025.Peer-Reviewed Original ResearchConceptsSequential landmark analysesPostoperative radiotherapyImmortal time biasLandmark analysisTumor typesEnd Results (SEER) databaseObservational cohort studyTime biasObservation cohortCohort studyHazard ratioProspective trialImproved survivalResults databaseConditional survivalRoutine useSurvivalApparent benefitRadiotherapyCohort