Alex Dmitrienko

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In this paper we describe methods for addressing multiplicity issues arising in the analysis of clinical trials with multiple endpoints and/or multiple dose levels. Efficient 'gatekeeping strategies' for multiplicity problems of this kind are developed. One family of hypotheses (comprising the primary objectives) is treated as a 'gatekeeper', and the other(More)
OBJECTIVE Neutrophil elastase is believed to be an important mediator of acute lung injury. Sivelestat (ONO-5046, Elaspol) is a small molecular weight inhibitor of neutrophil elastase. The primary objectives of this study were to determine whether sivelestat would reduce 28-day all-cause mortality or increase the number of ventilator-free days (days alive(More)
Inadequate selection of the dose to bring forward in confirmatory trials has been identified as one of the key drivers of the decreasing success rates observed in drug development programs across the pharmaceutical industry. In recognition of this problem, the Pharmaceutical Research and Manufacturers of America (PhRMA), formed a working group to evaluate(More)
In testing multiple hypotheses, control of the familywise error rate is often considered. We develop a procedure called the "fallback procedure" to control the familywise error rate when multiple primary hypotheses are tested. With the fallback procedure, the Type I error rate (alpha) is partitioned among the various hypotheses of interest. Unlike the(More)
We propose a novel recursive partitioning method for identifying subgroups of subjects with enhanced treatment effects based on a differential effect search algorithm. The idea is to build a collection of subgroups by recursively partitioning a database into two subgroups at each parent group, such that the treatment effect within one of the two subgroups(More)
This paper discusses multiple testing procedures in dose-response clinical trials with primary and secondary endpoints. A general gatekeeping framework for constructing multiple tests is proposed, which extends the Dunnett test [Journal of the American Statistical Association 1955; 50: 1096-1121] and Bonferroni-based gatekeeping tests developed by(More)
Several approaches to identification of predictive biomarkers and subgroups of patients with enhanced treatment effect have been proposed in the literature. The SIDES method introduced in Lipkovich et al. (2011) adopts a recursive partitioning algorithm for screening treatment-by-biomarker interactions. This article introduces an improved biomarker(More)
A general multistage (stepwise) procedure is proposed for dealing with arbitrary gatekeeping problems including parallel and serial gatekeeping. The procedure is very simple to implement since it does not require the application of the closed testing principle and the consequent need to test all nonempty intersections of hypotheses. It is based on the idea(More)
BACKGROUND The presence of comorbidities often influences clinical decision-making, although many studies exclude patients with comorbid disease for the sake of analysis. OBJECTIVES The purpose of this study was to develop a Comprehensive Prognostic Index (CPI), designed specifically for breast cancer patients. RESEARCH DESIGN This study linked Medicare(More)
BACKGROUND LY517717 is an oral direct inhibitor of activated factor X that is currently under clinical development. OBJECTIVES The aims of this proof-of-concept study in patients undergoing total knee replacement (TKR) or total hip replacement (THR) were to determine whether LY517717 can safely reduce the risk of venous thromboembolism (VTE) and to(More)