Sensitivity analyses comparing time-to-event outcomes only existing in a subset selected postrandomization and relaxing monotonicity.
In randomized studies researchers may be interested in the effect of treatment assignment on a time-to-event outcome that only exists in a subset selected after randomization. For example, in preventative HIV vaccine trials, it is of interest to determine whether randomization to vaccine affects the time from infection diagnosis until initiation of antiretroviral therapy. Earlier work assessed the effect of treatment on outcome among the principal stratum of individuals who would have been selected regardless of treatment assignment. These studies assumed monotonicity, that one of the principal strata was empty (e.g., every person infected in the vaccine arm would have been infected if randomized to placebo). Here, we present a sensitivity analysis approach for relaxing monotonicity with a time-to-event outcome. We also consider scenarios where selection is unknown for some subjects because of noninformative censoring (e.g., infection status k years after randomization is unknown for some because of staggered study entry). We illustrate our method using data from an HIV vaccine trial.
Department of Biostatistics, Vanderbilt University School of Medicine, 1161 21st Avenue South, Nashville, Tennessee 37232, USA. bryan.shepherd@vanderbilt.edu
Bryan E
BE
Shepherd
Peter B
PB
Gilbert
Charles T
CT
Dupont
D016915:AIDS Vaccines / Q000627:therapeutic use; D001699:Biometry / Q000379:methods; D015658:HIV Infections; D006801:Humans; D016032:Randomized Controlled Trials as Topic / Q000592:standards / Q000706:statistics & numerical data; D012107:Research Design / Q000592:standards / Q000706:statistics & numerical data; D012680:Sensitivity and Specificity; D013997:Time Factors
D016915:AIDS Vaccines