1,721,002 research outputs found
Use of prior manufacturer specifications with Bayesian logic eludes preliminary phase issues in quality control: An example in a hemostasis laboratory
No full textThe present study seeks to demonstrate the feasibility of avoiding the preliminary phase, which is mandatory in all conventional approaches for internal quality control (IQC) management. Apart from savings on the resources consumed by the preliminary phase, the alternative approach described here is able to detect any analytic problems during the startup and provide a foundation for subsequent conventional assessment. A new dynamically updated predictive control chart (PCC) is used. Being Bayesian in concept, it utilizes available prior information. The manufacturer's prior quality control target value, the manufacturer's maximum acceptable interassay coefficient of variation value and the interassay standard deviation value defined during method validation in each laboratory, allow online IQC management. An Excel template, downloadable from journal website, allows easy implementation of this alternative approach in any laboratory. In the practical case of prothrombin percentage measurement, PCC gave no false alarms with respect to the 1(ks) rule (with same 5% false-alarm probability on a single control sample) during an overlap phase between two IQC batches. Moreover, PCCs were as effective as the 1(ks) rule in detecting increases in both random and systematic error after the minimal preliminary phase required by medical biology guidelines. PCCs can improve efficiency in medical biology laboratories
A comparison of the 12s rule and Bayesian approach for quality control: Application to one-stage clotting factor VIII assay
No full textAn ideal medical biology internal quality control (IQC) plan should both monitor the laboratory methods efficiently and implement the relevant clinical-biological specifications. However, many laboratories continue to use the 1(2s) quality control rule without considering the high risk of false rejection and without considering the relationship of analytical performance to quality requirements. Alternatively, one can move to the Bayesian arena, enabling probabilistic quantification of the information coming in, on a daily basis from the laboratory's IQC tests, and taking into account the laboratory's medical and economic contexts. Using the example of one-stage clotting factor VIII assay, the present study compares frequentist (1(2s) quality control rule) and Bayesian IQC management with respect to prescriber requirements, process start-up phase issues, and abnormal scenarios in IQC results. To achieve comparable confidence, the traditional 1(2s) quality control rule requires more data than the Bayesian approach in order to detect an increase in the random or systematic error of the method. Moreover, the Bayesian IQC management approach explicitly implements respect of prescriber requirements in terms of calculating the probability that the variable in question lies in a given predefined interval: for example, the factor VIII concentration required after knee surgery in a hemophilia patient. (C) 2014 Wolters Kluwer Health I Lippincott Williams & Wilkins
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
Bayesian logic in statistical test control: Application to coagulation factor VIII assay
No full textCoagulation factor VIII was assayed around the critical concentration of 80 U/dl, which is optimal for postoperative haemostasis in haemophiliac patients, in order to assess the use of Bayesian logic in interpreting internal quality control results during a change of reagent or control batch. A mathematical model based on Bayesian inference, requiring no preliminary control-plan phase, was compared with a classical approach, which necessarily involves performing a preliminary phase. Tsiamyrtzis and Hawkins' Bayesian model proved applicable to rapid statistical control of factor VIII assay, detecting shift at least as efficiently as classical approaches, which depend on running the kind of costly and controversial preliminary control phase recommended by Shewhart. Blood Coagul Fibrinolysis 21:289-295 (C) 2010 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins
SAFETY AND EFFECTIVENESS OF ACTIVATED PROTHROMBIN COMPLEX CONCENTRATE (APCC) MONOTHERAPY IN PATIENTS WITH HEMOPHILIA AND INHIBITORS (PWHI) UNDERGOING SURGERY: A SYSTEMATIC REVIEW AND META-ANALYSIS
No full textIntroduction: Control of hemostasis during and after surgical procedures in PwHI is challenging. aPCC (Feiba®, Baxalta Inc, a Takeda company, Lexington, MA, USA), a bypassing agent, is indicated for patients with congenital hemophilia A or B with inhibitors for on-demand, prophylaxis and perioperative management, and for acquired hemophilia patients. We present a systematic literature review of studies reporting aPCC safety and a meta-analysis of the hemostatic effectiveness of aPCC monotherapy during major and minor surgical procedures in PwHI.
Methods: This systematic review and meta-analysis was carried out in MedLine through Pubmed from January 1, 1980 (aPCC inception) to June 30, 2018. Prospective, retrospective, randomized and non-randomized studies that reported the safety and hemostatic effectiveness of aPCC monotherapy in PwHI during surgery were eligible. Studies investigating concomitant/sequential infusion of aPCC with rFVIIa, tranexamic acid or emicizumab were excluded. Safety outcomes included serious adverse events (SAEs), including thromboembolic event (TEE), thrombotic microangiopathy (TMA), and other AEs associated with aPCC monotherapy. The hemostatic effectiveness was assessed intraoperatively by the surgeon and late postoperatively by the hematologist and rated as “excellent, good, fair or poor”.
Results: Of 645 publications describing aPCC as monotherapy in PwHI, 14 publications (including 158 patients) reported aPCC monotherapy in a surgical setting (100 major and 162 minor surgeries). TEE occurrence was reported in 4 major surgeries in 4 patients. One SAE of a clot in an arteriovenous fistula (possibly-related to aPCC) was reported. No reports of TMAs were identified in publications of studies that used aPCC as monotherapy. The proportion (95% confidence interval, CI) of major procedures in which hemostatic effectiveness was rated as excellent/good was 0.91 [(0.83-0.99); p=0.04 for heterogeneity] and for minor procedures this was 0.98 [(0.95-1.00); p=0.86 for heterogeneity].
Discussion/Conclusion: In this analysis of published studies involving patients treated with aPCC monotherapy in a surgical setting, a low rate of TEE occurrence and no TMAs were reported, while the hemostatic effectiveness of aPCC monotherapy was rated as excellent/good in >90% of both minor and major surgical procedures
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
- …
