1,721,114 research outputs found
Perioperative atrial fibrillation and the long-term risk of ischemic stroke
No full textIMPORTANCE: Clinically apparent atrial fibrillation increases the risk of ischemic stroke. In contrast, perioperative atrial fibrillation may be viewed as a transient response to physiological stress, and the long-term risk of stroke after perioperative atrial fibrillation is unclear. OBJECTIVE: To examine the association between perioperative atrial fibrillation and the long-term risk of stroke. DESIGN, SETTING, AND PARTICIPANTS: Retrospective cohort study using administrative claims data on patients hospitalized for surgery (as defined by surgical diagnosis related group codes), and discharged alive and free of documented cerebrovascular disease or preexisting atrial fibrillation from nonfederal California acute care hospitals between 2007 and 2011. Patients undergoing cardiac vs other types of surgery were analyzed separately. MAIN OUTCOMES AND MEASURES: Previously validated diagnosis codeswere used to identify ischemic strokes after discharge from the index hospitalization for surgery. The primary predictor variable was atrial fibrillation newly diagnosed during the index hospitalization, as defined by previously validated present-on-admission codes. Patients were censored at postdischarge emergency department encounters or hospitalizations with a recorded diagnosis of atrial fibrillation. RESULTS: Of 1 729 360 eligible patients, 24 711 (1.43%; 95%CI, 1.41%-1.45%) had new-onset perioperative atrial fibrillation during the index hospitalization and 13 952 (0.81%; 95%CI, 0.79%-0.82%) experienced a stroke after discharge. In a Cox proportional hazards analysis accounting for potential confounders, perioperative atrial fibrillation was associated with subsequent stroke both after noncardiac and cardiac surgery. (Table Presented) The association with stroke was significantly stronger for perioperative atrial fibrillation after noncardiac vs cardiac surgery (P < .001 for interaction). CONCLUSIONS AND RELEVANCE: Among patients hospitalized for surgery, perioperative atrial fibrillation was associated with an increased long-term risk of ischemic stroke, especially following noncardiac surgery. Copyright 2014 American Medical Association. All rights reserved
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Early life risk factors for incident atrial fibrillation in the Helsinki Birth Cohort Study
No full textBackground: Early life risk factors are associated with cardiometabolic disease, but have not been fully studied in atrial fibrillation (AF). There are discordant results from existing studies of birth weight and AF, and the impact of maternal body size, gestational age, placental size, and birth length is unknown.
Methods and Results: The Helsinki Birth Cohort Study includes 13 345 people born as singletons in Helsinki in the years 1934–1944. Follow‐up was through national registries, and ended on December 31, 2013, with 907 incident cases. Cox regression analyses stratified on year of birth were constructed for perinatal variables and incident AF, adjusting for offspring sex, gestational age, and socioeconomic status at birth. There was a significant U‐shaped association between birth weight and AF (P for quadratic term=0.01). The lowest risk of AF was found among those with a birth weight of 3.4 kg (3.8 kg for women [85th percentile] and 3.0 kg for men [17th percentile]). High maternal body mass index (≥30 kg/m2) predicted offspring AF; hazard ratio 1.36 (95% CI 1.07–1.74, P=0.01) compared with normal body mass index (<25 kg/m2). Maternal height was associated with early‐onset AF (<65.3 years), hazard ratio 1.47 (95% CI 1.24–1.74, P<0.0001), but not with later onset AF. Results were independent of incident coronary artery disease, hypertension, or diabetes mellitus.
Conclusions: High maternal body mass index during pregnancy and maternal height are previously undescribed predictors of offspring AF. Efforts to prevent maternal obesity might reduce later AF in offspring. Birth weight has a U‐shaped relation to incident AF independent of other perinatal variables
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Management of atrial high-rate episodes detected by cardiac implanted electronic devices
No full textCardiac implanted electronic devices (CIEDs), including pacemakers and implantable defibrillators that perform atrial sensing typically using an atrial electrode, frequently detect subclinical atrial high-rate episodes (AHREs). When the intracardiac electrograms are carefully examined, the majority of AHREs are atrial fibrillation (AF) or other atrial tachyarrhythmias, which have been shown to be associated with both an increased risk of stroke, and subsequent development of clinical AF. However, the absolute risk of stroke among patients with AHREs is less than might be expected for clinically diagnosed paroxysmal AF. In addition, a close temporal relationship between AHREs and stroke is seen in only 15% of strokes in patients with a CIED: the majority have either no AHREs before the stroke, or AHREs very distant from incident stroke, suggesting that AHREs might be more of a risk marker than a risk factor for stroke. Management of AHREs should not be the same as for clinical AF, and a degree of uncertainty underpins the rationale for much-needed, ongoing, randomized trials of oral anticoagulation in patients with CIED-detected AHREs. We propose a management algorithm that takes into account both the stroke risk and the AHRE burden, but highlights the current uncertainty and evidence gaps for this condition.</p
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