Abel Tilahun

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The drug development process involves identifying a compound and assessing its merit through rigorous pre-clinical and clinical trials. The pre-clinical stage is designed to assess the chemical properties of the new drug, as well as to determine the steps for synthesis and purification. In this stage of drug development, circumstances might dictate the use(More)
For a number of reasons, surrogate endpoints are considered instead of the so-called true endpoint in clinical studies, especially when such endpoints can be measured earlier, and/or with less burden for patient and experimenter. Surrogate endpoints may occur more frequently than their standard counterparts. For these reasons, it is not surprising that the(More)
One of the paradigms for surrogate marker evaluation in clinical trials is based on employing data from several clinical trials: the meta-analytic approach. It was originally developed for continuous outcomes by means of the linear mixed model, but other situations are of interest. One such situation is when both outcomes are binary. Although joint models(More)
BACKGROUND Surrogate endpoints potentially reduce the duration and/or increase the amount of information available in a study, thereby diminishing patient burden and cost. They may also increase the effectiveness and reliability of research, through beneficial impact on noncompliance and missingness. PURPOSE In this article, we review the meta-analytic(More)
The evaluation of surrogate endpoints is thought to be first studied by Prentice (1989), who presented a definition of a surrogate as well as a set of criteria. Freedman et al (2001) supplemented these criteria with the so-called proportion explained after notifying some drawbacks in Prentice’s approach. Buyse et al (2000) framed the evaluation exercise(More)
Over the last decades, the evaluation of potential surrogate endpoints in clinical trials has steadily been growing in importance, not only thanks to the availability of ever more potential markers and surrogate endpoints, also because more methodological development has become available. While early work has been devoted, to a large extent, to Gaussian,(More)
The number of potential surrogate markers for clinical-trial endpoints is increasing rapidly, not in the least owing to the availability of biomarkers. At the same time, considerable development has taken place regarding statistical evaluation paradigms for such markers. As a consequence, such endpoints are given more extensive consideration for practice(More)
In recent years, a lot of attention is placed on the selection and evaluation of biomarkers in microarray experiments. Two sets of biomarkers are of importance, namely therapeutic and prognostic. The therapeutic biomarkers would give us information on the response of the genes to treatment in relation to the response of the clinical outcome to the same(More)
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