1,721,091 research outputs found
Are all children born the same?
No full textLet’s for one moment imagine you are taking a stroll on a lovely sunny day. You are wearing an expensive suit and a new pair of shoes. You are passing a lake and you see a small child who looks like he is drowning. What would you do? You know that jumping into the lake would ruin your expensive suit and new shoes. However, we are sure that this would not even cross your mind as you try to save the drowning boy because human instinct is to want to help
Risk of assessing mortality risk in elective cardiac operations. Age, creatinine, ejection fraction, and law of parsimony.
No full textBackground— Several mortality risk scores exist in cardiac surgery. All include a considerable number of independent risk factors. In elective cardiac surgery patients, the operative mortality is low, the number of events recorded per year is limited, and the risk model may be overfitted. The present study aims to develop and validate an operative mortality risk score for elective patients based on a limited number of factors.
Methods and Results— The development series included 4557 adult patients who had undergone an elective cardiac operation at our institution from 2001 to 2003; the validation series includes the 4091 patients who subsequently underwent an operation. Three independent factors were included in the mortality risk model: age, creatinine, and left ventricular ejection fraction (ACEF). The ACEF score was computed as follows: age (years)/ejection fraction (%)+1 (if serum creatinine value was >2 mg/dL). The ACEF score was compared with 5 other risk scores in the validation series. Discriminatory power (accuracy) was defined with a receiver-operating characteristics analysis. The best accuracy was achieved by the Cleveland Clinic score (0.812), with ACEF score just below it (0.808). In coronary operations, the 2 scores performed equally well (0.815 versus 0.813), and in isolated coronary operations, the best accuracy was achieved by ACEF (0.826), with the Cleveland Clinic score at 0.806.
Conclusion— A risk model limited to 3 independent predictors has similar or better accuracy and calibration compared with more complex risk scores if applied to elective cardiac operations
Accuracy, calibration and clinical performance of the EuroSCORE: can we reduce the number of variables?
No full textBACKGROUND:
The European system for cardiac operative risk evaluation (EuroSCORE) is currently used in many institutions and is considered a reference tool in many countries. We hypothesised that too many variables were included in the EuroSCORE using limited patient series. We tested different models using a limited number of variables.
METHODS:
A total of 11150 adult patients undergoing cardiac operations at our institution (2001-2007) were retrospectively analysed. The 17 risk factors composing the EuroSCORE were separately analysed and ranked for accuracy of prediction of hospital mortality. Seventeen models were created by progressively including one factor at a time. The models were compared for accuracy with a receiver operating characteristics (ROC) analysis and area under the curve (AUC) evaluation. Calibration was tested with Hosmer-Lemeshow statistics. Clinical performance was assessed by comparing the predicted with the observed mortality rates.
RESULTS:
The best accuracy (AUC 0.76) was obtained using a model including only age, left ventricular ejection fraction, serum creatinine, emergency operation and non-isolated coronary operation. The EuroSCORE AUC (0.75) was not significantly different. Calibration and clinical performance were better in the five-factor model than in the EuroSCORE. Only in high-risk patients were 12 factors needed to achieve a good performance.
CONCLUSIONS:
Including many factors in multivariable logistic models increases the risk for overfitting, multicollinearity and human error. A five-factor model offers the same level of accuracy but demonstrated better calibration and clinical performance. Models with a limited number of factors may work better than complex models when applied to a limited number of patients
Rhinocerebral zygomycosis: an unusual dramatic presentation in a paediatric cardiac patient without risk factors
No full textMucormycosis is an angioinvasive infection caused by ubiquitous filamentous fungi of the order Mucorales. We describe a case of rhinocerebral mucormycosis presented in a paediatric patient after cardiac surgery correction of a complete atrioventricular canal defect. The rhinocerebral form of mucormycosis in our patient presented as an important epistaxis that needed immediate intubation due to blood inhalation. Furthermore, due to the worsening of pulmonary function, the patient also needed mechanical support with veno-arterial extracorporeal membrane oxygenation. The patient died as a consequence of a disseminated form of fungal infection. We describe our experience of this rare opportunistic infection and we think that early recognition of the disease could help in proper management
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
Percutaneous coronary intervention or coronary artery bypass surgery for cardiogenic shock and multivessel coronary artery disease?
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