1,720,964 research outputs found
Risk factors, antithrombotic treatment and outcome in retinal vein occlusion: an age-related prospective cohort study
Full text linkObjectives:
Antithrombotic treatment for retinal vein occlusion (RVO) is controversial, although RVO has
been surmised as a predictor of a subsequent vascular event. We aimed to evaluate risk factors, the effects
of antithrombotic therapy and the occurrence of subsequent vascular events in patients with a first episode
of RVO, according to age of RVO onset.
Methods:
In this prospective cohort study, patients with central
(CRVO) and branch RVO (BRVO) confirmed by fluorescein angiography were studied; they were divided
according to age. Cardiovascular risk factors and thrombophilia were evaluated. Anticoagulants or aspirin
were given for at least 3 months
.
Patients were followed every 6
–
12 months and vascular events were
recorded.
Results:
One hundred CRVO and 32 BRVO patients were enrolled. Five of 60 (8.3%) patients
<
50 yr and 4/72 (5.5%) over 50 yr had a hereditary thrombophilic defect. One or more cardiovascular risk
factors were found in 35 (58%) patients of the younger group, and in 66 (91%) of the older group (
P
<
0.001).
Antithrombotic treatment led to both a satisfactory recanalization of occluded veins and visual acuity
improvement especially in younger patients. Vascular events occurred in 19 (14%) cases after 4
3.3 yr
from RVO, more frequently in older than in younger patients (22% vs. 5%,
P
=
0.005).
Conclusions:
Distribution of cardiovascular, but not of thrombophilic risk factors seems to be influenced by age in RVO
patients. Patients with a first RVO, especially those
>
50 yr, are likely at risk of a subsequent vascular event
Optimal duration of anticoagulation: Provoked versus unprovoked VTE and role of adjunctive thrombophilia and imaging tests
No full textOnce anticoagulation is stopped, the risk of recurrent venous thromboembolism (VTE) over years after a first episode is consistently around 30%. This risk is higher in patients with unprovoked than in those with (transient) provoked VTE, and among the latter in patients with medical than in those with surgical risk factors. Baseline parameters that have been found to be related to the risk of recurrent VTE are the proximal location of deep-vein thrombosis, obesity, old age, male sex and non-0 blood group, whereas the role of inherited thrombophilia is controversial. The persistence of residual vein thrombosis at ultrasound assessment has consistently been shown to increase the risk, as do persistently high values of D-dimer and the early development of the post-thrombotic syndrome. Although the latest international guidelines suggest indefinite anticoagulation for most patients with the first episode of unprovoked VTE, strategies that incorporate the assessment of residual vein thrombosis and D-dimer have the potential to identify subjects in whom anticoagulation can be safely discontinued. Moreover, new opportunities are offered by a few emerging anti-Xa and anti-IIa oral compounds, which are likely to induce fewer haemorrhagic complications than vitamin K antagonists while preserving the same effectiveness; and by low-dose aspirin, which has the potential to prevent the occurrence of both venous and arterial thrombotic events
Incidence of arterial embolism in patients on treatment with old and new anticoagulants for venous thromboembolism
No full textThe separate nature of venous and arterial thrombotic disorders has recently been challenged. Patients with venous thromboembolism (VTE) have an increased risk of subsequent symptomatic arterial cardiovascular events, the risk being higher in those with unexplained episodes. Among the implications of this association, there is the potential for old and new antithrombotic drugs to impact on the development of both venous and arterial cardiovascular events. According to the results of recent studies, aspirin in low doses, when administered for the long-term management of patients with unprovoked VTE, reduces by approximately 35% the risk of recurrent VTE while offering a considerable protection against the development of arterial cardiovascular events. By contrast, there is no room to expect a reduction in the risk of subsequent arterial cardiovascular events in patients treated with vitamin K antagonists (VKA) in comparison to patients in whom VKAs are discontinued. According to the results from recent randomized clinical trials, the likelihood of arterial cardiovascular events in patients on the novel direct factor Xa inhibitors is unlikely to differ from that of patients receiving conventional anticoagulation. As dabigatran has been associated with a slight increase in the risk of myocardial infarction over warfarin, its use should be discouraged in patients with coronary heart disease. The long-term use of low-dose apixaban beyond the first months in patients with unprovoked VTE may decrease the long-term risk of arterial, as well as venous, thrombotic events
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
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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