title: Sample size estimation for non-inferiority trials of time-to-event data.
abstract: We consider the problem of sample size calculation for non-inferiority based on the hazard ratio in time-to-event trials where overall study duration is fixed and subject enrollment is staggered with variable follow-up. An adaptation of previously developed formulae for the superiority framework is presented that specifically allows for effect reversal under the non-inferiority setting, and its consequent effect on variance. Empirical performance is assessed through a small simulation study, and an example based on an ongoing trial is presented. The formulae are straightforward to program and may prove a useful tool in planning trials of this type.
authors.affiliation: GlaxoSmithKline R&D, Middlesex, UB6 0HE, UK. adam.x.crisp@gsk.com
authors.forename: Adam
authors.initials: A
authors.lastname: Crisp
authors.forename: Paula
authors.initials: P
authors.lastname: Curtis
mesh_terms: D002986:Clinical Trials as Topic / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data*; D005500:Follow-Up Studies; D006801:Humans; D012107:Research Design / Q000592:standards; D018401:Sample Size; D013997:Time Factors