title: On assessing the presence of evaluation-time bias in progression-free survival in randomized trials.
abstract: Evaluation (or assessment)-time bias can arise in oncology trials that study progression-free survival (PFS) when randomized groups have different patterns of timing of assessments. Modelling or computer simulation is sometimes used to explore the extent of such bias; valid results require building such simulations under realistic assumptions concerning the timing of assessments. This paper considers a trial that used a logrank test where computer simulations were based on unrealistic assumptions that severely overestimated the extent of potential bias. The paper shows that seemingly small differences in assumptions can lead to dramatic differences in the apparent operating characteristics of logrank tests.
authors.affiliation: RK Statistics Ltd, Great Longstone, UK. richard.kay@rkstatistics.com
authors.forename: Richard
authors.initials: R
authors.lastname: Kay
authors.forename: Jane
authors.initials: J
authors.lastname: Wu
authors.forename: Janet
authors.initials: J
authors.lastname: Wittes
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use; D018906:Antineoplastic Agents, Alkylating / Q000627:therapeutic use; D015982:Bias; D003198:Computer Simulation; D003606:Dacarbazine / Q000627:therapeutic use; D018572:Disease-Free Survival; D006801:Humans; D053208:Kaplan-Meier Estimate; D008545:Melanoma / Q000188:drug therapy / Q000453:epidemiology; D008962:Models, Theoretical; D010043:Outcome and Process Assessment, Health Care; D016032:Randomized Controlled Trials as Topic; D015203:Reproducibility of Results; D012107:Research Design; D013873:Thionucleotides / Q000627:therapeutic use; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States; D014486:United States Food and Drug Administration
chemical_list: D000970:Antineoplastic Agents; D018906:Antineoplastic Agents, Alkylating; D013873:Thionucleotides; D003606:Dacarbazine; C408162:oblimersen