title: A practical comparison of blinded methods for sample size reviews in survival data clinical trials.
abstract: This paper presents practical approaches to the problem of sample size re-estimation in the case of clinical trials with survival data when proportional hazards can be assumed. When data are readily available at the time of the review, on a full range of survival experiences across the recruited patients, it is shown that, as expected, performing a blinded re-estimation procedure is straightforward and can help to maintain the trial's pre-specified error rates. Two alternative methods for dealing with the situation where limited survival experiences are available at the time of the sample size review are then presented and compared. In this instance, extrapolation is required in order to undertake the sample size re-estimation. Worked examples, together with results from a simulation study are described. It is concluded that, as in the standard case, use of either extrapolation approach successfully protects the trial error rates.
authors.affiliation: Department of Mathematics and Statistics, University of Reading, Philip Lyle Building, Reading RG6 6BX, UK. s.c.todd@reading.ac.uk
authors.forename: Susan
authors.initials: S
authors.lastname: Todd
authors.forename: Elsa
authors.initials: E
authors.lastname: Valdés-Márquez
authors.forename: Jodie
authors.initials: J
authors.lastname: West
mesh_terms: D002986:Clinical Trials as Topic / Q000379:methods*; D003198:Computer Simulation; D003627:Data Interpretation, Statistical; D006801:Humans; D016016:Proportional Hazards Models; D012107:Research Design; D018401:Sample Size; D016019:Survival Analysis