Spelling suggestions: "subject:"metaanalysis"" "subject:"metaanalysis""
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Assessing efficacy of stuttering treatments using single-subject design research : a systematic reviewTimson, Melissa J. 01 January 2010 (has links)
In the ongoing discussion of treatment efficacy, some researchers have argued for the use of evidence from randomized controlled trials while others have argued the case for the use of non-randomized designs (Ingham 2003) in the study of the treatment of stuttering. Few attempts have been made to integrate findings from the research on stuttering intervention {Andrews, et al.1980; Howard, Nye, & Vanryckegbem, 2005; Herder, Howard, Nye & Vanryckeghem 2006; Thomas and Howell, 2001). Since the usual approach to the study of treatment efficacy uses experimental and quasi-experimental sources, a summary of the data available from single subject design {SSD) studies would seem warranted. The purpose of this project was to conduct a systematic review and meta-analysis of the effectiveness of stuttering treatment for children and adults by summarizing studies and determining an overall effect by calculating the percentage of non-overlapping data points (PND). The resulting review provides a summary of the effects of stuttering treatment, the nature of the treatment program characteristics and their associated effectiveness, and a general mapping of the research landscape in stuttering treatment terms of its' strengths and weaknesses and areas of need for future research.
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When is refraction stable following routine cataract surgery? A systematic review and meta-analysisCharlesworth, Emily, Alderson, Alison J., de Juan, V., Elliott, David 21 December 2020 (has links)
Yes / Purpose: We systematically reviewed the literature to investigate when refraction is stable following routine cataract surgery implanting monofocal intraocular lenses. Current advice recommends obtaining new spectacles 4–6 weeks following surgery. Due to advancements in surgical techniques, we hypothesised that refractive stability would be achieved earlier, which could have major short-term improvements in quality of life for patients. Methods: Medline, CINAHL, AMED, Embase, Web of Science and the Cochrane Library were searched with key words chosen to find articles, which assessed refraction following uncomplicated cataract surgery. Citation chains and the reference lists of all included papers were searched. Unpublished literature was identified using OpenGrey (www.opengrey.eu). The review considered studies that measured refraction at regular intervals following surgery until stability was achieved. Results: The search identified 6,680 papers. Two reviewers independently screened the abstracts and nine papers were found to fit the criteria, of which five were included in the meta-analysis. The quality of the papers was evaluated using the Methodological Index for Non-Randomised Studies (MINORS) instrument. Meta-analysis of 301 patients’ data of spherical, cylindrical and spherical equivalent correction were performed using Review Manager 5 (RevMan 5.3) (https://revman.cochrane.org/). Refraction at 1-week versus the gold standard of 4-weeks showed no significant difference for sphere data (effect size and 95% confidence interval of; ES = 0.00, 95% CI: −0.17, 0.17; p = 1.00), cylindrical data (ES = +0.06; 95% CI: −0.05, 0.17; p = 0.31), and spherical equivalent (ES = −0.01; 95% CI: −0.12, 0.10; p = 0.90). Heterogeneity was non-significant (I2
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Fatores preditores de abandono de tratamento de tuberculose: uma metanálise / Predictors of treatment dropout factors for tuberculosis: a meta-analysisPedro Emmanuel Alvarenga Americano do Brasil 13 March 2006 (has links)
A tuberculose (TB) é uma doença que foi declarada pela Organização Mundial de Saúde como emergência mundial em 1993. As ferramentas disponíveis hoje para controle da TB são: o diagnóstico precoce e o tratamento eficiente. Porém, o abandono do tratamento de TB é um problema enfrentado mundialmente em proporções que podem variar entre 3% a
80%. Por isso, a identificação dos fatores que são preditores do abandono do tratamento de TB pode ajudar a desenvolver melhores estratégias para o seu controle. O objetivo deste
trabalho é, através de uma metanálise, fazer uma estimativa sumária da medida de associação entre cada um dos fatores (a) relacionados ao serviço de saúde, (b) relacionado ao quadro clínico e à terapia da TB e (c) relacionados aos indivíduos e o abandono do tratamento de TB. A estratégia de busca eletrônica remota para a recuperação de publicações relevantes foi desenvolvida de forma específica para as diferentes bases consideradas relevantes (MEDLINE [Pubmed] e LILCS). Buscas por referências cruzadas, além da consulta à base de revisões sistemáticas COCHRANE, também foram realizadas. Investigações foram incluídas se fossem trabalhos observacionais ou experimentais que estudem fatores de risco ou preditores do desfecho de interesse (abandono do tratamento de tuberculose) através de comparações de dois ou mais grupos e se seus dados pudessem ser extraídos. Dois revisores classificaram os trabalhos e extraíram dados de forma mascarada e as discordâncias resolvidas. Mais de 190 textos completos foram aptos à combinação de dados. Destes, foi
possível extrair dados para combinação de 40 exposições. Destas, 19 foram demonstradas nesta investigação. Das 19 demonstradas, 13 exposições estudadas apresentaram associação e poderiam ser considerados preditores (sexo masculino, alcoolismo, infecção pelo HIV/SIDA, uso de drogas ilícitas, nacionalidade estrangeira, analfabetismo, retratamento, baciloscopia positiva, abandono prévio, tratamento de curta duração, acesso fácil à unidade de
saúde, treinamento para adesão, tuberculose extrapulmonar) e seis não apresentaram associação (desemprego, efeitos adversos, tuberculose resistente, necessidade de hospitalização, demora para o início do tratamento, espera longa para a consulta). Porém, essas associações devem ser consideradas de forma conservadora devido à elevada
heterogeneidade encontrada em todas as exposições. Apenas cinco exposições apresentaram explicação parcial e uma apresentou explicação total para a heterogeneidade. O viés de
publicação foi detectado em apenas duas das 19 exposições. / Tuberculosis (TB) has been as a world emergency by World Health Organization in 1993. Nowadays, the tools available for TB control are early diagnosis and efficient treatment. However, TB treatment default is a concerning problem in the world and may vary between 3% and 80%, So, the identification of factors that may predict TB treatment default
may help to develop better strategies to control TB. The objective of this work is, through a meta-analysis, to pool a summary estimate of associations of each factor (a) related to the health services, (b) to clinical condition and therapy and (c) to the individuals and TB treatment default. The remote electronic search strategy to find relevant publications was
specifically developed for the different databases considered important, wich are: LILACS and MedLine (Pubmed). Searches for cross reference and search at COCHRANE systematic
reviews database were also made. Investigations were included if they were observations or experimental that studied risk factors or predictive factors of the outcomes of interest (TB treatment default) through comparing two or more groups and the data could be extracted. Two independent reviewers classified and extracted the data and the discordances were solved in later meetings. More than 190 full texts were apt to be combines. From these texts, 40 exposures were extracted and combined. From these, 19 were shown in this investigation. 13 of 19 shown exposures demonstrated associations and could be considered as predictors (
male gender, alcoholism, HIV infection/AIDS, illicit drug use, foreign nationality, illiteracy, retreatment, positive sputum smear, previous default, short course therapy, easy access to
health unit and adherence training extrapulmonary TB) and six did not show associations (unemployment , adverse effects, drug resistance, need for hospitalization, delay in start
treatment, long wait for attendance). However these associations must considered very in a conservative way due to high level heterogeneity found in all exposures. Only five exposures have partially explanation and one have total explanation to the heterogeneity. Publication bias was detected in only two of the 19 exposures studied.
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Fatores preditores de abandono de tratamento de tuberculose: uma metanálise / Predictors of treatment dropout factors for tuberculosis: a meta-analysisPedro Emmanuel Alvarenga Americano do Brasil 13 March 2006 (has links)
A tuberculose (TB) é uma doença que foi declarada pela Organização Mundial de Saúde como emergência mundial em 1993. As ferramentas disponíveis hoje para controle da TB são: o diagnóstico precoce e o tratamento eficiente. Porém, o abandono do tratamento de TB é um problema enfrentado mundialmente em proporções que podem variar entre 3% a
80%. Por isso, a identificação dos fatores que são preditores do abandono do tratamento de TB pode ajudar a desenvolver melhores estratégias para o seu controle. O objetivo deste
trabalho é, através de uma metanálise, fazer uma estimativa sumária da medida de associação entre cada um dos fatores (a) relacionados ao serviço de saúde, (b) relacionado ao quadro clínico e à terapia da TB e (c) relacionados aos indivíduos e o abandono do tratamento de TB. A estratégia de busca eletrônica remota para a recuperação de publicações relevantes foi desenvolvida de forma específica para as diferentes bases consideradas relevantes (MEDLINE [Pubmed] e LILCS). Buscas por referências cruzadas, além da consulta à base de revisões sistemáticas COCHRANE, também foram realizadas. Investigações foram incluídas se fossem trabalhos observacionais ou experimentais que estudem fatores de risco ou preditores do desfecho de interesse (abandono do tratamento de tuberculose) através de comparações de dois ou mais grupos e se seus dados pudessem ser extraídos. Dois revisores classificaram os trabalhos e extraíram dados de forma mascarada e as discordâncias resolvidas. Mais de 190 textos completos foram aptos à combinação de dados. Destes, foi
possível extrair dados para combinação de 40 exposições. Destas, 19 foram demonstradas nesta investigação. Das 19 demonstradas, 13 exposições estudadas apresentaram associação e poderiam ser considerados preditores (sexo masculino, alcoolismo, infecção pelo HIV/SIDA, uso de drogas ilícitas, nacionalidade estrangeira, analfabetismo, retratamento, baciloscopia positiva, abandono prévio, tratamento de curta duração, acesso fácil à unidade de
saúde, treinamento para adesão, tuberculose extrapulmonar) e seis não apresentaram associação (desemprego, efeitos adversos, tuberculose resistente, necessidade de hospitalização, demora para o início do tratamento, espera longa para a consulta). Porém, essas associações devem ser consideradas de forma conservadora devido à elevada
heterogeneidade encontrada em todas as exposições. Apenas cinco exposições apresentaram explicação parcial e uma apresentou explicação total para a heterogeneidade. O viés de
publicação foi detectado em apenas duas das 19 exposições. / Tuberculosis (TB) has been as a world emergency by World Health Organization in 1993. Nowadays, the tools available for TB control are early diagnosis and efficient treatment. However, TB treatment default is a concerning problem in the world and may vary between 3% and 80%, So, the identification of factors that may predict TB treatment default
may help to develop better strategies to control TB. The objective of this work is, through a meta-analysis, to pool a summary estimate of associations of each factor (a) related to the health services, (b) to clinical condition and therapy and (c) to the individuals and TB treatment default. The remote electronic search strategy to find relevant publications was
specifically developed for the different databases considered important, wich are: LILACS and MedLine (Pubmed). Searches for cross reference and search at COCHRANE systematic
reviews database were also made. Investigations were included if they were observations or experimental that studied risk factors or predictive factors of the outcomes of interest (TB treatment default) through comparing two or more groups and the data could be extracted. Two independent reviewers classified and extracted the data and the discordances were solved in later meetings. More than 190 full texts were apt to be combines. From these texts, 40 exposures were extracted and combined. From these, 19 were shown in this investigation. 13 of 19 shown exposures demonstrated associations and could be considered as predictors (
male gender, alcoholism, HIV infection/AIDS, illicit drug use, foreign nationality, illiteracy, retreatment, positive sputum smear, previous default, short course therapy, easy access to
health unit and adherence training extrapulmonary TB) and six did not show associations (unemployment , adverse effects, drug resistance, need for hospitalization, delay in start
treatment, long wait for attendance). However these associations must considered very in a conservative way due to high level heterogeneity found in all exposures. Only five exposures have partially explanation and one have total explanation to the heterogeneity. Publication bias was detected in only two of the 19 exposures studied.
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Should I Bridge or Should I Bond? Social Capital Strategies and Contingencies / Capital social : Stratégies et éventualitésAtanassova, Evelina 20 December 2016 (has links)
La thèse se compose de trois essais, abordant chacun la dichotomie entre la liaison et l'adhérence à partir d'un angle théorique différent. Dans le premier essai, je pose la question Comment Lier et Comment Adhérer et je propose un nouveau cadre théorique pour analyser le capital social, qui déconstruit sa principale fonction au-delà de la liaison ou de l'adhérence dans sa substance comme les relations sociales par rapport à la position dans la structure du réseau. Compte tenu de ces deux dimensions de l'analyse des réseaux sociaux, je propose quatre sources distinctes du capital social qui ont une valeur prédictive différente pour les réalisations individuelles - le réseau de liaison, les relations de liaison, le réseau d'adhérence et les relations d'adhérence - et j'examine leur valeur à la performance individuelle. La question du plomb dans le deuxième essai de ma thèse est Quand faut-il lier et Quand faut-il adhérer? Rejoignant la recherche sur la valeur éventuelle du capital social, je cherche comment l'organisation et les facteurs liés à l'emploi modèrent la relation entre chaque source de capital social à la performance et théorisent sur les stratégies que les individus devraient poursuivre afin d'obtenir de meilleures performances. Dans le troisième essai, je pose la question Sur Quelle Source devrais-je me fonder ? J'examine la puissance individuelle de chaque source de capital social et de la complémentarité entre les quatre d'entre eux. Je démontre que, bien que toutes les sources de capital social doivent avoir un impact positif sur la performance, certains d'entre eux pourraient supprimer le déploiement des autres formes. / My dissertation expands the line of inquiry of the contingent value of social capital to individual performance by raising three novel questions. In the first essay of my dissertation I focus on “How to bridge and how to bond” and propose a new theoretical framework for analyzing social capital, which deconstructs its major function beyond bridging or bonding into its substance as social relations versus position in network structure. Considering these two dimensions of social network analysis I propose four distinct sources of social capital that have different predictive value for individual achievements: bridging network, bridging relations, bonding network and bonding relations. The lead question in the second chapter of my dissertation is “When to bridge and when to bond”. Joining the research on the contingent value of social capital, I look at organization and individual level factors to predict the value of each social capital source to performance and theorize about the strategies individuals should pursue in order to achieve better performance. In the third essay I ask “Should one start with bridging or with bonding?” Building on the categorization proposed in the first chapter I investigate the most successful social capital path to on-the-job performance.
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Bivariate meta-analysis of sensitivity and specificity of radiographers' plain radiograph reporting in clinical practice.Brealey, S., Hewitt, C., Scally, Andy J., Hahn, S., Godfrey, C., Thomas, N. January 2009 (has links)
Studies of diagnostic accuracy often report paired tests for sensitivity and specificity that can be pooled separately to produce summary estimates in a meta-analysis. This was done recently for a systematic review of radiographers' reporting accuracy of plain radiographs. The problem with pooling sensitivities and specificities separately is that it does not acknowledge any possible (negative) correlation between these two measures. A possible cause of this negative correlation is that different thresholds are used in studies to define abnormal and normal radiographs because of implicit variations in thresholds that occur when radiographers' report plain radiographs. A method that allows for the correlation that can exist between pairs of sensitivity and specificity within a study using a random effects approach is the bivariate model. When estimates of accuracy as a fixed-effects model were pooled separately, radiographers' reported plain radiographs in clinical practice at 93% (95% confidence interval (CI) 92-93%) sensitivity and 98% (95% CI 98-98%) specificity. The bivariate model produced the same summary estimates of sensitivity and specificity but with wider confidence intervals (93% (95% CI 91-95%) and 98% (95% CI 96-98%), respectively) that take into account the heterogeneity beyond chance between studies. This method also allowed us to calculate a 95% confidence ellipse around the mean values of sensitivity and specificity and a 95% prediction ellipse for individual values of sensitivity and specificity. The bivariate model is an improvement on pooling sensitivity and specificity separately when there is a threshold effect, and it is the preferred method of choice.
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META-ANALYSIS OF GENE EXPRESSION STUDIESSiangphoe, Umaporn 01 January 2015 (has links)
Combining effect sizes from individual studies using random-effects models are commonly applied in high-dimensional gene expression data. However, unknown study heterogeneity can arise from inconsistency of sample qualities and experimental conditions. High heterogeneity of effect sizes can reduce statistical power of the models. We proposed two new methods for random effects estimation and measurements for model variation and strength of the study heterogeneity. We then developed a statistical technique to test for significance of random effects and identify heterogeneous genes. We also proposed another meta-analytic approach that incorporates informative weights in the random effects meta-analysis models. We compared the proposed methods with the standard and existing meta-analytic techniques in the classical and Bayesian frameworks. We demonstrate our results through a series of simulations and application in gene expression neurodegenerative diseases.
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VISUALIZAÇÃO HIERARQUICA APLICADA À METANÁLISE DA EFICIÊNCIA DO FUNGICIDA FLUQUINCONAZOL EM SEMENTES DE SOJA PARA O CONTROLE DA FERRUGEM ASIÁTICADelazeri, Bruna Rossetto 15 March 2015 (has links)
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Previous issue date: 2015-03-15 / Asian soybean rust caused by Phakopsora pachyrhizi, is one of the main phytosanitary problems of soybean in Brazil. Aiming to reduce the losses caused by the pathogen, the treatment of soybean seeds with fungicide fluquinconazole has motivated researchers to conduct studies and simulate their performance. The compilation of these various studies may be conducted by the meta-analysis, which is a probabilistic technique that produces a result which summarizes studies. In
agricultural context, meta-analysis is used to perform empirical estimates of technical efficiency for the development of productivity and economic research of agriculture, such as the use of the fungicide fluquinconazole. Meta-analysis can be applied through existing software such as R, run through commands, and WMA, which operates through a graphical user interface for data entry made by the user. The
results generated by both software are shown in graphical form without providing interactivity with the user, neither reproducing a friendly software and easy to
understand interface. This study applied meta-analysis using the WMA Software, which uses R to calculate the statistical results, to determine the efficiency of fungicide fluquinconazole in soybean seed, used to minimize the impact of the asian rust disease in the crop productivity. To provide a dynamic display of obtained results by meta-analysis, this study created a method to identify the best information visualization technique to represent hierarchical data. This method was applied to identify which better visualization technique represented the graphic forest plot, namely, bifocal tree. Changes were made at the WMA, such as: incorporation of a new effect measure, change in the help system and font files and the implementation bifocal tree technique using Gephi as a support tool. The implementation allowed to create a more interactive environment for analyzing the results of the R and provides two display options for the user: basic and advanced. The advantages of the visualization are that the user can explore more the data and results. In this study it was observed that when fluquinconazole was used to minimize the effects caused by
rust soybean productivity (yield) was improved. / A ferrugem asiática da soja, causada pelo fungo Phakopsora pachyrhizi, é um dos principais problemas fitossanitários da cultura da soja no Brasil. Visando diminuir os prejuízos causados pelo patógeno, o tratamento das sementes de soja com o fungicida fluquinconazol tem motivado pesquisadores a realizar estudos e simular seu desempenho. A compilação destes vários estudos pode ser realizada através da metanálise, que é uma técnica probabilística que produz um resultado que resume os estudos. No âmbito agrícola a metanálise é utilizada para realizar estimativas empíricas de eficiência para o desenvolvimento da produtividade e investigação
econômica da agricultura, como é o caso do uso do fungicida fluquinconazol. A metanálise pode ser aplicada por meio de software existentes como por exemplo o
R, executado através de comandos, e o WMA (Wizard Metanálise), que opera através de um interface gráfica para entrada de dados feita pelo usuário. Os resultados gerados por ambos são exibidos em forma gráfica sem proporcionar interatividade com o usuário, tampouco reproduzem uma interface amigável e de fácil compreensão. Este trabalho aplicou a metanálise através do WMA, que utiliza o R para o cálculo dos resultados estatísticos, para determinar a eficiência do fungicida fluquinconazol na semente da soja utilizada para minimizar o impacto causado pela doença da ferrugem asiática na produtividade da cultura. Para proporcionar uma visualização dinâmica dos resultados obtidos pela metanálise este trabalho criou um método de identificação da melhor técnica de visualização de informação para representar dados hierárquicos. Este método foi aplicado para identificar qual técnica de visualização melhor representava o gráfico forest plot, a saber, bifocal tree. Mudanças foram realizadas no WMA tais como: incorporação de uma nova medida de efeito, mudança no sistema de ajuda e dos arquivos fontes e adição da técnica bifocal tree usando como ferramenta de apoio o Gephi. A implementação permitiu criar um ambiente mais interativo para análise dos resultados obtidos pelo R e fornece duas opções de exibição para o usuário: básica
e a avançada. As vantagens da visualização é que o usuário consegue explorar mais os dados e resultados. Neste trabalho observou-se que houve um ganho na
taxa de produtividade da soja com a utilização do fluquinconazol, para minimizar os efeitos causados pela ferrugem.
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Reassessment of the statistical power of published controlled clinical trials. / CUHK electronic theses & dissertations collectionJanuary 2005 (has links)
Background. The randomized controlled clinical trial is currently the most scientific method for evaluating the effect of medical interventions. The sample size of a trial is crucial for reliably estimating the effect. However, many clinical trials may not be sufficiently large in size to detect the effect of interventions assessed. Previous studies of the statistical power, a relative measure of the largeness of a study, were normally small, mainly examined trials with a statistically insignificant result and were flawed because of the biased or purely hypothetical estimate of the effect for the computation of the power. By using meta-analysis, we conducted this study with improved methods for estimating the power and included a larger number of trials. / Findings. A total of 2,923,912 patients from 2,872 clinical trials from 466 systematic reviews were included in the analyses of this thesis. Of the 466 systematic reviews, 24% (113) were identified from the five journals and the remaining 76% (353) were from the Cochrane Library. 1,000 trials and 1,583,204 patients were obtained from 113 systematic reviews identified in the journals, in which 13.7% (95% C.I.: 11.6%, 15.8%) of trials had a sufficient power and the overall power was 34.0% (95% C.I.: 33.7%, 34.3%). 1,872 trials and 1,340,708 patients were obtained from 353 systematic reviews identified in the Cochrane Library, in which 16.7% (95% C.I.: 15.0%, 18.4%) of trials had a sufficient power and the overall power was 37.8% (95% C.I.: 37.6%, 38.0%). (Abstract shortened by UMI.) / Methods. We identified trials from systematic reviews of clinical trials with binary outcomes published in five medical journals and the Cochrane Database of Systematic Reviews. We analyzed the power of trials with a significant result as well as those with an insignificant result. In estimating the power, we used the combined odds ratio of the meta-analysis as the estimate of the effect for trials from systematic reviews with a statistically significant result and a relative risk reduction of 25% for trials from systematic reviews with a statistically insignificant result. In addition to use of the conventional method to estimate the power, we also developed a new "counting method" that does not need any assumption about the effect. Furthermore, the power is also expressed as a relative and absolute difference between the number of subjects required for a power of 80% and that actually recruited by the trials. / Tsoi Kam Fai. / "July 2005." / Adviser: Jin Ling Tang. / Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0161. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 107-113). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.
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Bayesian generalized linear models for meta-analysis of diagnostic tests.Xing, Yan. Cormier, Janice N., Swint, John Michael, January 2008 (has links)
Thesis (Ph. D.)--University of Texas Health Science Center at Houston, School of Public Health, 2008. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 0769. Advisers: Claudia Pedroza; Asha S. Kapadia. Includes bibliographical references.
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