905 research outputs found
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Comparison of Bayesian and frequentist group-sequential clinical trial designs
Background: There is a growing interest in the use of Bayesian adaptive designs in late-phase clinical trials. This
includes the use of stopping rules based on Bayesian analyses in which the frequentist type I error rate is controlled as
in frequentist group-sequential designs.
Methods: This paper presents a practical comparison of Bayesian and frequentist group-sequential tests. Focussing
on the setting in which data can be summarised by normally distributed test statistics, we evaluate and compare
boundary values and operating characteristics.
Results: Although Bayesian and frequentist group-sequential approaches are based on fundamentally different
paradigms, in a single arm trial or two-arm comparative trial with a prior distribution specified for the treatment
difference, Bayesian and frequentist group-sequential tests can have identical stopping rules if particular critical values
with which the posterior probability is compared or particular spending function values are chosen. If the Bayesian
critical values at different looks are restricted to be equal, OâBrien and Flemingâs design corresponds to a Bayesian
design with an exceptionally informative negative prior, Pocockâs design to a Bayesian design with a non-informative
prior and frequentist designs with a linear alpha spending function are very similar to Bayesian designs with slightly
informative priors.
This contrasts with the setting of a comparative trial with independent prior distributions specified for treatment
effects in different groups. In this case Bayesian and frequentist group-sequential tests cannot have the same
stopping rule as the Bayesian stopping rule depends on the observed means in the two groups and not just on their
difference. In this setting the Bayesian test can only be guaranteed to control the type I error for a specified range of
values of the control group treatment effect.
Conclusions: Comparison of frequentist and Bayesian designs can encourage careful thought about design
parameters and help to ensure appropriate design choices are made
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Assessment of the information theory approach to evaluating time-to-event surrogate and true endpoints in a meta-analytic setting
In many disease areas, commonly used longâterm clinical endpoints are becoming increasingly difficult to implement due to long followâup times and/or increased costs. Shorterâterm surrogate endpoints are urgently needed to expedite drug development, the evaluation of which requires robust and reliable statistical methodology to drive meaningful clinical conclusions about the strength of relationship with the true longâterm endpoint. This paper uses a simulation study to explore one such previously proposed method, based on information theory, for evaluation of time to event surrogate and longâterm endpoints, including the first examination within a metaâanalytic setting of multiple clinical trials with such endpoints. The performance of the information theory method is examined for various scenarios including different dependence structures, surrogate endpoints, censoring mechanisms, treatment effects, trial and sample sizes, and for surrogate and true endpoints with a natural timeâordering. Results allow us to conclude that, contrary to some findings in the literature, the approach provides estimates of surrogacy that may be substantially lower than the true relationship between surrogate and true endpoints, and rarely reach a level that would enable confidence in the strength of a given surrogate endpoint. As a result, care is needed in the assessment of time to event surrogate and true endpoints based only on this methodology
ASTRO Journals' Data Sharing Policy and Recommended Best Practices.
Transparency, openness, and reproducibility are important characteristics in scientific publishing. Although many researchers embrace these characteristics, data sharing has yet to become common practice. Nevertheless, data sharing is becoming an increasingly important topic among societies, publishers, researchers, patient advocates, and funders, especially as it pertains to data from clinical trials. In response, ASTRO developed a data policy and guide to best practices for authors submitting to its journals. ASTRO's data sharing policy is that authors should indicate, in data availability statements, if the data are being shared and if so, how the data may be accessed
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Reformulation initiative for partial replacement of saturated with unsaturated fats in dairy foods attenuates the increase in LDL cholesterol and improves flow-mediated dilatation compared with conventional dairy: the randomized, controlled REplacement of SaturatEd fat in dairy on Total cholesterol (RESET) study
Background
Modifying dairy fat composition by increasing the MUFA content is a potential strategy to reduce dietary SFA intake for cardiovascular disease (CVD) prevention in the population.
Objectives
To determine the effects of consuming SFA-reduced, MUFA-enriched (modified) dairy products, compared with conventional dairy products (control), on the fasting cholesterol profile (primary outcome), endothelial function assessed by flow-mediated dilatation (FMD; key secondary outcome), and other cardiometabolic risk markers.
Methods
A double-blind, randomized, controlled crossover 12-wk intervention was conducted. Participants with a 1.5-fold higher (moderate) CVD risk than the population mean replaced habitual dairy products with study products (milk, cheese, and butter) to achieve a high-fat, high-dairy isoenergetic daily dietary exchange [38% of total energy intake (%TE) from fat: control (dietary target: 19%TE SFA; 11%TE MUFA) and modified (16%TE SFA; 14%TE MUFA) diet].
Results
Fifty-four participants (57.4% men; mean ± SEM age: 52 ± 3 y; BMI: 25.8 ± 0.5 kg/m2) completed the study. The modified diet attenuated the rise in fasting LDL cholesterol observed with the control diet (0.03 ± 0.06 mmol/L and 0.19 ± 0.05 mmol/L, respectively; P = 0.03). Relative to baseline, the %FMD response increased after the modified diet (0.35% ± 0.15%), whereas a decrease was observed after the control diet (â0.51% ± 0.15%; P< 0.0001). In addition, fasting plasma nitrite concentrations increased after the modified diet, yet decreased after the control diet (0.02 ± 0.01 ÎŒmol/L and â0.03 ± 0.02 ÎŒmol/L, respectively; P = 0.01).
Conclusions
In adults at moderate CVD risk, consumption of a high-fat diet containing SFA-reduced, MUFA-enriched dairy products for 12 wk showed beneficial effects on fasting LDL cholesterol and endothelial function compared with conventional dairy products. Our findings indicate that fatty acid modification of dairy products may have potential as a public health strategy aimed at CVD risk reduction. This trial was registered at clinicaltrials.gov as NCT02089035
Bridging the Gap: Selected Works and TopScholar Galleries
Higher educationâs scholars utilize online catalogs and library finding aids with ease. However, for the larger community, accessing scholarsâ Selected Works and online galleries with topical themes is a helpful intermediary step. Non-scholars often explore and produce scholarship, seek out obscure online sources and gladly volunteer to document cultural resources.Every day historically valuable ephemera is thrown away due to an ignorance of its value to research. Special Collections Librarians partnering with Scholarly Communication Specialists utilize social media to create a gateway and make certain that taxpaying interested parties do not miss the wealth of primary sources compiled over centuries by librarians and archivists. We hope this ease of access to information will encourage casual researchers to support our academic efforts. It may also result in donations of unique letters, photographs, diaries, ephemera and inaccessible publications. The Special Collections galleries allow exhibits of unique photographs, ephemera, oral histories and manuscripts. Scholars create personal selected works sites to showcase individual research projects and collections. University faculty, teachers, adults, and amateur historians can use these accessible resources to gather information and create items to motivate, entertain or educate others. Technology created the door to Libraries via KenCat and TopScholar. Now the galleries and Selected Works throw open wide resources for all
Shared perspectives: how do we facilitate 'participation in recreational activities' for children with disabilities?
This presentation will introduce the âWheel of Participationâ from a pilot study which measured the effects of adapted cycling for 35 children and young people with Cerebral Palsy. Whilst the initial research aims were to explore the effects of cycling, findings showed an increase in muscle strength and some outstanding personal achievements and ambitions for cycling in the future. Additionally, children reported a variety of other physical activities they were able to participate in such as steel drumming, dancing, wheelchair basketball, ball games and computer games.
Imogen Hurrellâs (now aged 8 years) current cycling experiences will be presented via the use of a photographic diary and parental reporting. This sharing of perspectives from children and parents is building our understanding of the different contexts where adapted cycling participation can take place. This research has led to the development of some after school cycling clubs and the exploration of a competitive sport-Race running bikes.
Barriers to wider participation in recreational activities will be described such as enabling the children to make friends, manual handling issues and the impact of surgical interventions which can change physical capabilities
Human Cardiomyocytes Prior to Birth by IntegrationĂą Free Reprogramming of Amniotic Fluid Cells
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135525/1/Supplemental_Information.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/135525/2/sct320165121595.pd
Scientific mindfulness: a foundation for future themes in international business
We conceptualize new ways to qualify what themes should dominate the future IB
research agenda by examining three questions: Whom should we ask? What should we ask and which selection criteria should we apply? What are the contextual forces? We propose scientific mindfulness as the way forward for generating themes in IB research
University-Business Cooperation and Entrepreneurship at Universities â An Empirical Based Comparison of Poland and Germany
The EUâs growth strategy for the coming decade (recorded and defined by Horizon2020) and the higher education modernisation agenda force all European countries to establish a more connected and better functioning relationship between the three most important players government, business and higher education institutions (HEIâs) in order to increase employment, productivity and social cohesion.
This article explores the development of University-Business Cooperation (UBC) both in Poland and in Germany, shining a spotlight on the various factors influencing UBC, as well as providing a comparison of the two countries. The focus lays on a Polish-German comparison i.e. the compared analyses of the state of UBC in Germany and Poland from the perspective of HEI managers and researchers.
Applying a UBC-ecosystem of different factors and action levels (http://ub-cooperation.eu/pdf/ UBCECO.pdf) the major differences of both countries are identified, addressed and commented to offer opportunities for improvements.
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