1,721,056 research outputs found
A Comparison of Intraarticular Lumbar Facet Joint Steroid Injections and Lumbar Facet Joint Radiofrequency Denervation in the Treatment of Low Back Pain: A Randomized, Controlled, Double-Blind Trial
No full textBACKGROUND: Lumbar facet joint degeneration is a source of chronic low back pain, with an incidence of 15% to 45% among patients with low back pain. Various therapeutic techniques in the treatment of facet-related pain have been described in the literature, including intraarticular lumbar facet joint steroid injections and radiofrequency denervation. In this study, we compared the effectiveness of intraarticular facet joint steroid injections and radiofrequency denervation. METHODS: Our randomized, double-blind, controlled study included patients who received intraarticular steroid infiltrations in the lumbar facet joints (L3/L4-L5/S1) and patients who underwent radiofrequency denervation of L3/L4-L5/S1 segments. The inclusion criteria were based first on magnetic resonance imaging findings showing hypertrophy of the facet joints L3/L4-L5/S1 and a positive response to an intraarticular test infiltration of the facet joints L3/L4-L5/S1 with local anesthetics. The primary end point was the Roland-Morris Questionnaire. Secondary end points were the visual analog scale and the Oswestry Disability Index. All outcome assessments were performed at baseline and at 6 months. RESULTS: Fifty-six patients were randomized; 24 of 29 patients in the steroid injection group and 26 of 27 patients in the denervation group completed the 6-month follow-up. Pain relief and functional improvement were observed in both groups. There were no significant differences between the 2 groups for the primary end point (95% confidence interval [CI], -3 to 4) and for both secondary end points (95% CI for visual analog scale, -2 to 1; 95% CI for Oswestry Disability Index, -18 to 0). CONCLUSIONS: Intraarticular steroid infiltration or radiofrequency denervation appear to be a managing option for chronic function-limiting low back pain of facet origin with favorable short- and midterm results in terms of pain relief and function improvement, but improvements were similar in both groups
Test-Retest Reliability of 3D Ultrasound Measurements of the Thoracic Spine
No full textObjective: To explore the reliability of the Zebris CMS 20 ultrasound analysis system with pointer application for measuring end-range flexion, end-range extension, and neutral kyphosis angle of the thoracic spine. Setting: The study was performed within the School of Physiotherapy in cooperation with the Orthopedic Department at a University Hospital. Participants: The thoracic spines of 28 healthy subjects were measured. Methods: Measurements for neutral kyphosis angle, end-range flexion, and end-range extension were taken once at each time point. The bone landmarks were palpated by one examiner and marked with a pointer containing 2 transmitters using a frequency of 40 kHz. A third transmitter was fixed to the pelvis, and 3 microphones were used as receiver. The real angle was calculated by the software. Bland-Altman plots with 95% limits of agreement, intraclass correlations (ICC), standard deviations of mean measurements, and standard error of measurements were used for statistical analyses. The test-retest reliability in this study was measured within a 24-hour interval. Main Outcome Measurements: Statistical parameters were used to judge reliability. Results: The mean kyphosis angle was 44.8 degrees with a standard deviation of 17.3 degrees at the first measurement and a mean of 45.8 degrees with a standard deviation of 16.2 degrees the following day. The ICC was high at 0.95 for the neutral kyphosis angle, and the Bland-Altman 95% limits of agreement were within clinical acceptable margins. The ICC was 0.71 for end-range flexion and 0.34 for end-range extension, whereas the Bland-Altman 95% limits of agreement were wider than with the static measurement of kyphosis. Compared with static measurements, the analysis of motion with 3-dimensional ultrasound showed an increased standard deviation for test-retest measurements. Conclusions: The test-retest reliability of ultrasound measuring of the neutral kyphosis angle of the thoracic spine was demonstrated within 24 hours. Bland-Altman 95% limits of agreement and the standard deviation of differences did not appear to be clinically acceptable for measuring flexion and extension. PM R 2012;4:335-34
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Flexible designs for clinical trials in the presence of nuisance paramters
No full textKontrollierte klinische Studien sind eine experimentelle Methode der klinisch-epidemiologischen Forschung, mit deren Hilfe der kausale Nachweis therapeutischer Wirksamkeit erbracht und somit der Therapiefortschritt abgesichert wird. Im Laufe einer solchen Studie stellte sich nicht selten heraus, dass die Annahmen, die der Studienplanung zugrundeliegen, einer Korrektur bedürfen. Der zu erwartende Therapieunterschied oder die Varianz der Messgröße kann sich als kleiner oder größer herausstellen als ursprünglich angenommen.
Mit konventionellen statistischen Verfahren, war es nur bedingt möglich eine einmal geplante Studie nachträglich zu ändern, da nach datenabhängige Änderungen die statistische Fehlerkontrolle nicht mehr gesichert ist. Dies führte dazu, dass viele Studien aufgrund falscher Planungsannahmen nicht zufriedenstellend beendet werden konnten oder die statistische Fehlerkontrolle nicht mehr in der gebotenen Strenge beachtet wurde.
In den letzten Jahren wurden verschiedene Methoden entwickelt, die Änderungen in laufenden Studien ermöglichen, ohne die Integrität der Studien zu verletzen. Dies sind unter anderem die adaptiven Designs, welche erstmals von Bauer (1989) vorgeschlagen wurden. Später wurden diese Verfahren in flexible Designs umbenannt, um einen Namenskonflikt zu vermeiden. Flexible Designs ermöglichen es, an vorgegebenen Zeitpunkten im Verlaufe der Studie Designänderungen vorzunehmen und dabei das Fehlerniveau 1. Art einzuhalten. Ein weiterer Ansatz wurde von Müller und Schäfer (2004) vorgeschlagen, das sogenannte CRP-Prinzip. Im Gegensatz zu den flexiblen Designs müssen hierbei die Zeitpunkte, an denen Designänderungen möglich sind, nicht vorher (zum Zeitpunkt der Studienplanung) festgelegt werden. Dennoch ist die Kontrolle des Fehlerniveaus 1. Art sichergestellt. Damit ist es möglich, noch zeitnaher Korrekturen des Studiendesigns vorzunehmen, wenn sich Planungsannahmen als falsch herausstellen.
Obwohl die Idee des CRP-Prinzip sehr allgemein formuliert ist, war eine exakte Anwendungen bisher nur in Verteilungssituationen mit nur einem unbekannten Parameter möglich, wie im Falle der Normalverteilung mit unbekanntem Erwartungswert und bekannter Varianz. War die Varianz ebenfalls unbekannt (t-Test), so konnte dieses Verfahren nur noch approximativ angewendet werden. Insbesondere für kleine Fallzahlen ist daher die Kontrolle des Fehlerniveaus 1. Art nicht mehr sichergestellt.
Ziel dieser Arbeit ist eine Weiterentwicklung des von Müller und Schäfer vorgeschlagenen Verfahrens, so dass es auch in Verteilungssituationen mit mehreren unbekannten Parametern, wie dem t-Test, exakt angewandt werden kann.
Im Kapitel 2 geben wir zunächst eine Einführung in die besondere Problematik klinischer Studien. Kapitel 3 enthält einen Literaturüberblick über die bisherigen Gruppensequentiellen und flexiblen Designs. Im Kapitel 4 wird ein allgemeines mathematisches Konzept zur formalen Beschreibung und Definition entwickelt, welches sowohl die flexiblen Designs als auch das CRP-Prinzip beinhaltet. Dieses Konzept stellt eine Erweiterung des bekannten Begriffs der statistischen Entscheidungsfunktion dar. Auf dieser Basis werden im Kapitel 5 die Hauptergebnisse dieser Arbeit entwickelt. Damit gelingt es, das CRP-Prinzip auf beliebige k-parametrige Exponentialfamilien zu verallgemeinern . Diese Verallgemeinerung wenden wir am Ende dieses Kapitels auf die Testung des Lageparameters einer Normalverteilung bei unbekannter Varianz (t-Test) und auf den Vergleich zweier unbekannter Binomialparameter (Fishers exakter Test) an.Controlled clinical trials are an experimental method of clinical research. They are used to demonstrate the efficacy of a therapy and hence to ensure therapeutic improvement. During such trials there are often reasons to change the design of the trial when the assumptions made at the planning stage turn out to be wrong. For example, the expected effect size or the estimated variance might be smaller or greater than assumed at the beginning. Conventional statistical methods do not allow for data dependent changes to the design during the course of the trial while still controlling the error rates. For this reason many clinical trials fail to show efficacy, or the strict control of the error rates, especially the type I error rate, is abandoned.
In the last years, new methods have been developed which allow for design modification during the course of a trial without violating the integrity of the trial. Among these methods are the so-called adaptive designs, first proposed by Bauer (1989), which make it possible to change the design at preplanned interim analyses without inflating the type I error rate. Adaptive designs are later renamed flexible designs because the name adaptive designs was already in use. More recently, Müller and Schäfer (2004) proposed the so-called CRP-principle. Unlike the flexible designs, here the design can be changed at any time during the course of the trial, which means that the possibility of design modifications and the suitable time points do not have to be specified at the planning stage. Nevertheless, the type I error rate is still controlled. This approach thus allows for corrections of the study design at the moment when misspecfications become apparent.
Although the CRP-principle is a general principle, its exact application was restricted to problems where only one parameter of the underlying distribution is unknown. For example, this is the case, when the data are normally distributed with unknown expectation but known variance. Until now, if the variance is also unknown (t-test), the CRP-principle could only be applied approximately. Particularly for small sample sizes, this does not control the type I error rate adequately.
The aim of this thesis is the development of a method on the basis of the CRP-principle, which is applicable for exact design modifications in situations with more than one unknown parameter such as the t-test.
In chapter 2 an introduction to the special problems of clinical trials is given. Chapter 3 gives an overview of the literature of group-sequential and flexible designs. In chapter 4 a general mathematical theory is developed, which includes the flexible designs and the CRP-principle. This theory is an extension of the well-known concept of decision functions. The main findings will be represented in chapter 5, and it is then possible to make exact design modifications in problems where the underlying distribution forms a k-parametric exponential family. At the end of this chapter the application to a normal distribution with unknown variance (t-test) and to the comparison of two binomial probabilities (Fishers exact test) is shown
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