Augmenting the logrank test in the design of clinical trials in which non-proportional hazards of the treatment effect may be anticipated [PDF]
BMC Medical Research Methodology, 2016 Background Most randomized controlled trials with a time-to-event outcome are designed assuming proportional hazards (PH) of the treatment effect. The sample size calculation is based on a logrank test.
Patrick Royston, Mahesh K.B. Parmar
doaj +7 more sources
Survival analysis: coping with non proportional hazards in randomized trials [PDF]
Trials, 2011 Almost all trials with a censored time-to-event outcome are designed, powered and analysed with a target hazard ratio for comparing experimental and control treatments in mind. Differences in survival experience between trial arms are tested with a logrank test and usually illustrated using a Kaplan-Meier plot.
Royston Patrick, Parmar Mahesh KB
doaj +4 more sources
Quantifying treatment differences in confirmatory trials under non-proportional hazards. [PDF]
J Appl Stat, 2022 Proportional hazards are a common assumption when designing confirmatory clinical trials in oncology. With the emergence of immunotherapy and novel targeted therapies, departure from the proportional hazard assumption is not rare in nowadays clinical research.
Jiménez JL.
europepmc +5 more sources
A double-Cox model for non-proportional hazards survival analysis with frailty. [PDF]
Stat Med, 2023 The Cox regression, a semi‐parametric method of survival analysis, is extremely popular in biomedical applications. The proportional hazards assumption is a key requirement in the Cox model. To accommodate non‐proportional hazards, we propose to parameterize the shape parameter of the baseline hazard function using the additional, separate Cox ...
Begun A, Kulinskaya E, Ncube N.
europepmc +4 more sources
Interval-Censored Regression with Non-Proportional Hazards with Applications
Stats, 2023 Proportional hazards models and, in some situations, accelerated failure time models, are not suitable for analyzing data when the failure ratio between two individuals is not constant. We present a Weibull accelerated failure time model with covariables
Fábio Prataviera +4 more
doaj +2 more sources
Comparison of statistical methods for the analysis of recurrent adverse events in the presence of non-proportional hazards and unobserved heterogeneity: a simulation study [PDF]
BMC Medical Research Methodology, 2022 Background In preventive drug trials such as intermittent preventive treatment for malaria prevention during pregnancy (IPTp), where there is repeated treatment administration, recurrence of adverse events (AEs) is expected.
Noel Patson +6 more
doaj +2 more sources
An approach to trial design and analysis in the era of non-proportional hazards of the treatment effect. [PDF]
Trials, 2014 Background: Most randomized controlled trials with a time-to-event outcome are designed and analysed under the proportional hazards assumption, with a target hazard ratio for the treatment effect in mind. However, the hazards may be non-proportional.
Royston P, Parmar MK.
europepmc +4 more sources
Group sequential design for time-to-event outcome with non-proportional hazards using the concept of relative time utilizing two different Weibull distributions [PDF]
Contemporary Clinical Trials CommunicationsA group sequential design allows investigators to sequentially monitor efficacy and safety as part of interim testing in phase III trials. Literature is well developed in the case of continuous and binary outcomes, however, in case of trials with a time ...
Milind A. Phadnis +2 more
doaj +2 more sources
Adaptive Weight Selection for Time-To-Event Data Under Non-Proportional Hazards. [PDF]
Stat MedABSTRACTWhen planning a clinical trial for a time‐to‐event endpoint, we require an estimated effect size and need to consider the type of effect. Usually, an effect of proportional hazards is assumed with the hazard ratio as the corresponding effect measure.
Danzer MF, Dormuth I.
europepmc +4 more sources
On penalized likelihood estimation for a non-proportional hazards regression model. [PDF]
Stat Probab Lett, 2013 In this paper, a semi-parametric generalization of the Cox model that permits crossing hazard curves is described. A theoretical framework for estimation in this model is developed based on penalized likelihood methods. It is shown that the optimal solution to the baseline hazard, baseline cumulative hazard and their ratio are hyperbolic splines with ...
Devarajan K, Ebrahimi N.
europepmc +5 more sources