1,721,495 research outputs found
Coronary stenting versus balloon angioplasty for acute myocardial infarction: A meta-regression analysis of randomized trials
No full textIntroduction: Although stenting has been shown to reduce the need for target vessel revascularization (TVR) in acute myocardial infarction (AMI), the benefits in terms of mortality and reinfarction are still unclear. Previous meta-analyses have failed to include all currently available randomized trials. The aim of the current study was to perform an updated meta-analysis to evaluate the benefits of coronary stenting for AMI in terms of mortality, reinfarction, and TVR, and whether these benefits correlated with the patient's risk profile. Methods: The literature was scanned by formal searches of electronic databases (MEDLINE and CENTRAL) from January 1990 to September 2006. We examined all completed, published, randomized trials of coronary stenting for AMI. The following key words were used for study selection: randomized trial, myocardial infarction, reperfusion, primary angioplasty, rescue angioplasty, stenting, and balloon angioplasty. Information on study design, type of stent, inclusion and exclusion criteria, primary endpoint, number of patients, angiographic and clinical outcome, were extracted by two investigators. Disagreements were resolved by consensus. Results: A total of 13 randomized trials were identified and analyzed involving 6922 patients (3460 or 50% randomized to stent and 3462 or 50% to balloon). Stenting was not associated with a significant reduction in 30-day (2.9% versus 3.0%, p = 0.81) and 1-year mortality (5.1% versus 5.2%, p = 0.81), as compared to balloon angioplasty. However, a significant relationship was observed between patient's risk profile and mortality benefits from coronary stenting at 30-day (beta - 0.63 [- 25.4; - 2.45], p = 0.022) and 1-year follow-up (beta - 0.61 [- 15.9; - 0.76], p = 0.034). Stenting was associated with benefits in terms of TVR at both 30-day (3.1% versus 5.1%, p < 0.0001) and 6 to 12 months (11.3% versus 18.4%, p < 0.0001) follow-up, without any difference in terms of reinfarction. Conclusions: Among AMI patients undergoing primary angioplasty, coronary stent implantation, when anatomically and technically feasible, may be considered, in addition to benefits in terms of TVR, to reduce mortality in high-risk patients, who may be identified by the use of validated risk scores. © 2007 Elsevier Ireland Ltd. All rights reserved
Routine upstream versus selective downstream administration of glycoprotein IIb/IIIa inhibitors in patients with non-ST-elevation acute coronary syndromes: A meta-analysis of randomized trials
No full textBackground: Glycoprotein (GP) IIb/IIIa inhibitors reduce ischemic complications in patients with non-ST-elevation acute coronary syndromes (NSTEACS) who undergo invasive procedures. However the optimal timing of therapy (upstream - at hospital admission in all patients prior to coronary catheterization, or downstream - after coronary angiography selectively in patients prior to percutaneous coronary intervention) is still debated. The aim of this meta-analysis was to compare the outcome of NSTEACS patients randomized to routine upstream versus deferred selective downstream GP IIb/IIIa inhibitors. Methods: We scanned the literature from January 1990 to May 2009 to identify all randomized trials comparing upstream administration of GP IIb/IIIa inhibitors versus its downstream use in invasively managed NSTEACS. Results: In 5 randomized trials a total of 9753 patients were randomized to upstream GP IIb/IIIa inhibitors therapy versus 9716 patients randomized to deferred selective downstream therapy. Upstream therapy was associated with reduced in-hospital or 30-day major adverse ischemic cardiac events (odds ratio= 0.90 [95% confidence interval 0.82-0.98], p=0.02). However the risk of major bleeding was significantly higher with upstream therapy (odds ratio=1.35 [1.11-1.63], p=0.002). Combining ischemic and hemorrhagic events in a net clinical end-point showed no significant differences between the two approaches (odds ratio=1.01 [0.92-1.10], p=0.88). Conclusions: In conclusion early administration of GP IIb/IIIa inhibitors in NSTEACS is associated with significant reduction in ischemic events compared to a selective deferred therapy after coronary angiography. However upstream therapy is also associated with increased bleeding complications. This approach should therefore be reserved for patients at high ischemic and/or low hemorrhagic risk. (C) 2010 Elsevier Ireland Ltd. All rights reserved
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Risk of Stroke With Coronary Artery Bypass Graft Surgery Compared With Percutaneous Coronary Intervention
No full textObjectives This study sought to determine whether coronary artery bypass graft (CABG) surgery is associated with an increased risk of stroke compared with percutaneous coronary intervention (PCI). Background Some, but not all, randomized trials have reported increased rates of stroke with CABG compared with PCI. However, all these studies were powered insufficiently to examine differences in the risk of stroke reliably. Methods We performed a meta-analysis of 19 trials in which 10,944 patients were randomized to CABG versus PCI. The primary end point was the 30-day rate of stroke. We also determined the rate of stroke at the midterm follow-up and investigated whether there was an interaction between revascularization type and the extent of coronary artery disease on the relative risk of stroke. Results The 30-day rate of stroke was 1.20% after CABG compared with 0.34% after PCI (odds ratio: 2.94, 95% confidence interval: 1.69 to 5.09, p < 0.0001). Similar results were observed after a median follow-up of 12.1 months (1.83% vs. 0.99%, odds ratio: 1.67, 95% confidence interval: 1.09 to 2.56, p = 0.02). The extent of coronary artery disease (single vessel vs. multivessel vs. left main) did not affect the relative increase in the risk of stroke observed with CABG compared with PCI at either 30 days (p = 0.57 for interaction) or midterm follow-up (p = 0.08 for interaction). Similar results were observed when the outcomes in 33,980 patients from 27 observational studies were analyzed. Conclusions Coronary revascularization by CABG compared with PCI is associated with an increased risk of stroke at 30 days and at the mid-term follow-up. (J Am Coll Cardiol 2012;60:798-805) (c) 2012 by the American College of Cardiology Foundatio
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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