87 citations · 557 across the 33 of their papers we have counts for
15 papers · 1 filter
Communicating results in trials with multiple hypotheses or adaptive design features
Elina Asikanius, Marcel Wolbers, Mouna Akacha +8
Over time, clinical trials have increasingly incorporated complex design and analysis elements such as interim analyses, adaptations, multiple endpoints, and sophisticated multipli…
Exhausting the type I error level in event-driven group-sequential designs with a closed testing procedure for progression-free and overall survival
Moritz Fabian Danzer, Kaspar Rufibach, Jan Beyersmann +1
In oncological clinical trials, overall survival (OS) is the gold-standard endpoint, but long follow-up and treatment switching can delay or dilute detectable effects. Progression-…
"6 choose 4": A framework to understand and facilitate discussion of strategies for overall survival safety monitoring
Godwin Yung, Kaspar Rufibach, Marcel Wolbers +2
Advances in anticancer therapies have significantly contributed to declining death rates in certain disease and clinical settings. However, they have also made it difficult to powe…
Using shrinkage methods to estimate treatment effects in overlapping subgroups in randomized clinical trials with a time-to-event endpoint
Marcel Wolbers, Mar Vázquez Rabuñal, Ke Li +2
In randomized controlled trials, forest plots are frequently used to investigate the homogeneity of treatment effect estimates in subgroups. However, the interpretation of subgroup…
Balancing events, not patients, maximizes power of the logrank test: and other insights on unequal randomization in survival trials
Godwin Yung, Kaspar Rufibach, Marcel Wolbers +2
We revisit the question of what randomization ratio (RR) maximizes power of the logrank test in event-driven survival trials under proportional hazards (PH). By comparing three app…
Applying the Estimand and Target Trial frameworks to external control analyses using observational data: a case study in the solid tumor setting
Letizia Polito, Qixing Liang, Navdeep Pal +5
In causal inference, the correct formulation of the scientific question of interest is a crucial step. Here we apply the estimand framework to a comparison of the outcomes of patie…
Quantification of follow-up time in oncology clinical trials with a time-to-event endpoint: Asking the right questions
Kaspar Rufibach, Lynda Grinsted, Jiang Li +3
For the analysis of a time-to-event endpoint in a single-arm or randomized clinical trial it is generally perceived that interpretation of a given estimate of the survival function…
Joint modelling of progression-free and overall survival and computation of correlation measures
Matthias Meller, Jan Beyersmann, Kaspar Rufibach
In this paper, we derive the joint distribution of progression-free and overall survival as a function of transition probabilities in a multistate model. No assumptions on copulae…
Treatment Effect Quantification for Time-to-event Endpoints -- Estimands, Analysis Strategies, and beyond
Kaspar Rufibach
A draft addendum to ICH E9 has been released for public consultation in August 2017. The addendum focuses on two topics particularly relevant for randomized confirmatory clinical t…
Maximum-Likelihood Estimation of a Log-Concave Density based on Censored Data
Lutz Duembgen, Kaspar Rufibach, Dominic Schuhmacher
We consider nonparametric maximum-likelihood estimation of a log-concave density in case of interval-censored, right-censored and binned data. We allow for the possibility of a sub…
Asymptotics of the discrete log-concave maximum likelihood estimator and related applications
Fadoua Balabdaoui, Hanna Jankowski, Kaspar Rufibach +1
The assumption of log-concavity is a flexible and appealing nonparametric shape constraint in distribution modelling. In this work, we study the log-concave maximum likelihood esti…
Selection models with monotone weight functions in meta analysis
Kaspar Rufibach
Publication bias, the fact that studies identified for inclusion in a meta analysis do not represent all studies on the topic of interest, is commonly recognized as a threat to the…
Least Squares estimation of two ordered monotone regression curves
Fadoua Balabdaoui, Kaspar Rufibach, Filippo Santambrogio
In this paper, we consider the problem of finding the Least Squares estimators of two isotonic regression curves and under the additional constraint that th…
An Active Set Algorithm to Estimate Parameters in Generalized Linear Models with Ordered Predictors
Kaspar Rufibach
In biomedical studies, researchers are often interested in assessing the association between one or more ordinal explanatory variables and an outcome variable, at the same time adj…
Active Set and EM Algorithms for Log-Concave Densities Based on Complete and Censored Data
Lutz Duembgen, Andre Huesler, Kaspar Rufibach
We develop an active set algorithm for the maximum likelihood estimation of a log-concave density based on complete data. Building on this fast algorithm, we indidate an EM algorit…