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Research Synthesis Methods

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https://www.readbyqxmd.com/read/28732142/network-meta-analysis-including-treatment-by-covariate-interactions-consistency-can-vary-across-covariate-values
#1
Sarah Donegan, Nicky J Welton, Catrin Tudur Smith, Umberto D'Alessandro, Sofia Dias
BACKGROUND: Many reviews aim to compare numerous treatments and report results stratified by subgroups (e.g. by disease severity). In such cases, a network meta-analysis model including treatment by covariate interactions can estimate the relative effects of all treatment pairings for each subgroup of patients. Two key assumptions underlie such models, consistency of treatment effects and consistency of the regression coefficients for the interactions. Consistency may differ depending on the covariate value at which consistency is assessed...
July 21, 2017: Research Synthesis Methods
https://www.readbyqxmd.com/read/28719074/influence-diagnostics-in-meta-regression-model
#2
Lei Shi, ShanShan Zuo, Dalei Yu, Xiaohua Zhou
This paper studies the influence diagnostics in meta-regression model including case deletion diagnostic and local influence analysis. We derive the subset deletion formulae for the estimation of regression coefficient and heterogeneity variance and obtain the corresponding influence measures. The DerSimonian and Laird estimation and maximum likelihood estimation methods in meta-regression are considered, respectively, to derive the results. Internal and external residual and leverage measure are defined. The local influence analysis based on case-weights perturbation scheme, responses perturbation scheme, covariate perturbation scheme, and within-variance perturbation scheme are explored...
July 18, 2017: Research Synthesis Methods
https://www.readbyqxmd.com/read/28683516/diagnostics-for-generalized-linear-hierarchical-models-in-network-meta-analysis
#3
Hong Zhao, James S Hodges, Bradley P Carlin
Network meta-analysis (NMA) combines direct and indirect evidence comparing more than 2 treatments. Inconsistency arises when these 2 information sources differ. Previous work focuses on inconsistency detection, but little has been done on how to proceed after identifying inconsistency. The key issue is whether inconsistency changes an NMA's substantive conclusions. In this paper, we examine such discrepancies from a diagnostic point of view. Our methods seek to detect influential and outlying observations in NMA at a trial-by-arm level...
July 6, 2017: Research Synthesis Methods
https://www.readbyqxmd.com/read/28677339/towards-a-taxonomy-of-logic-models-in-systematic-reviews-and-health-technology-assessments-a-priori-staged-and-iterative-approaches
#4
Eva A Rehfuess, Andrew Booth, Louise Brereton, Jacob Burns, Ansgar Gerhardus, Kati Mozygemba, Wija Oortwijn, Lisa M Pfadenhauer, Marcia Tummers, Gert-Jan van der Wilt, Anke Rohwer
The complexity associated with how interventions result - or fail to result - in outcomes, and how context matters is increasingly recognised. Logic models provide an important tool for handling complexity, with contrasting uses in programme evaluation and evidence synthesis. To reconcile these, we developed an approach that combines the strengths of both traditions, propose a taxonomy of logic models, and provide guidance on how to choose between approaches and types of logic models in systematic reviews and health technology assessments (HTA)...
July 5, 2017: Research Synthesis Methods
https://www.readbyqxmd.com/read/28677322/an-exploration-of-crowdsourcing-citation-screening-for-systematic-reviews
#5
Michael L Mortensen, Gaelen P Adam, Thomas A Trikalinos, Tim Kraska, Byron C Wallace
Systematic reviews are increasingly used to inform health care decisions, but are expensive to produce. We explore the use of crowdsourcing (distributing tasks to untrained workers via the web) to reduce the cost of screening citations. We used Amazon Mechanical Turk as our platform and 4 previously conducted systematic reviews as examples. For each citation, workers answered 4 or 5 questions that were equivalent to the eligibility criteria. We aggregated responses from multiple workers into an overall decision to include or exclude the citation using 1 of 9 algorithms and compared the performance of these algorithms to the corresponding decisions of trained experts...
July 4, 2017: Research Synthesis Methods
https://www.readbyqxmd.com/read/28660680/text-mining-for-search-term-development-in-systematic-reviewing-a-discussion-of-some-methods-and-challenges
#6
Claire Stansfield, Alison O'Mara-Eves, James Thomas
Using text mining to aid the development of database search strings for topics described by diverse terminology has potential benefits for systematic reviews; however, methods and tools for accomplishing this are poorly covered in the research methods literature. We briefly review the literature on applications of text mining for search term development for systematic reviewing. We found that the tools can be used in 5 overarching ways: improving the precision of searches; identifying search terms to improve search sensitivity; aiding the translation of search strategies across databases; searching and screening within an integrated system; and developing objectively derived search strategies...
June 29, 2017: Research Synthesis Methods
https://www.readbyqxmd.com/read/28631402/authors-response-to-letter-to-the-editor
#7
LETTER
Michael Borenstein, Julian P T Higgins, Larry V Hedges, Hannah R Rothstein
No abstract text is available yet for this article.
June 20, 2017: Research Synthesis Methods
https://www.readbyqxmd.com/read/28631294/practical-challenges-of-i-2-as-a-measure-of-heterogeneity
#8
LETTER
David C Hoaglin
No abstract text is available yet for this article.
June 20, 2017: Research Synthesis Methods
https://www.readbyqxmd.com/read/28585280/meta-analysis-combining-parallel-and-crossover-trials-using-generalised-estimating-equation-method
#9
François Curtin
Clinical trials have different designs: In late stage drug development, the parallel trial design is the most frequent one; however, the crossover design is not rare; different techniques are used to analyse their results. Although both designs measure the same treatment effect, combining parallel and crossover trials in a meta-analysis is not straightforward. We present here a meta-analysis method based on generalised estimating equation (GEE) regression to combine aggregated results of crossover and parallel trials using a marginal estimation approach...
June 5, 2017: Research Synthesis Methods
https://www.readbyqxmd.com/read/28585257/paule-mandel-estimators-for-network-meta-analysis-with-random-inconsistency-effects
#10
Dan Jackson, Areti Angeliki Veroniki, Martin Law, Andrea C Tricco, Rose Baker
Network meta-analysis is used to simultaneously compare multiple treatments in a single analysis. However, network meta-analyses may exhibit inconsistency, where direct and different forms of indirect evidence are not in agreement with each other, even after allowing for between-study heterogeneity. Models for network meta-analysis with random inconsistency effects have the dual aim of allowing for inconsistencies and estimating average treatment effects across the whole network. To date, two classical estimation methods for fitting this type of model have been developed: a method of moments that extends DerSimonian and Laird's univariate method and maximum likelihood estimation...
June 5, 2017: Research Synthesis Methods
https://www.readbyqxmd.com/read/28556477/assessing-meta-regression-methods-for-examining-moderator-relationships-with-dependent-effect-sizes-a-monte-carlo-simulation
#11
José Antonio López-López, Wim Van den Noortgate, Emily E Tanner-Smith, Sandra Jo Wilson, Mark W Lipsey
Dependent effect sizes are ubiquitous in meta-analysis. Using Monte Carlo simulation, we compared the performance of 2 methods for meta-regression with dependent effect sizes-robust variance estimation (RVE) and 3-level modeling-with the standard meta-analytic method for independent effect sizes. We further compared bias-reduced linearization and jackknife estimators as small-sample adjustments for RVE and Wald-type and likelihood ratio tests for 3-level models. The bias in the slope estimates, width of the confidence intervals around those estimates, and empirical type I error and statistical power rates of the hypothesis tests from these different methods were compared for mixed-effects meta-regression analysis with one moderator either at the study or at the effect size level...
May 28, 2017: Research Synthesis Methods
https://www.readbyqxmd.com/read/28544646/evaluating-the-accuracy-and-economic-value-of-a-new-test-in-the-absence-of-a-perfect-reference-test
#12
Xuanqian Xie, Alison Sinclair, Nandini Dendukuri
BACKGROUND: Streptococcus pneumoniae (SP) pneumonia is often treated empirically as diagnosis is challenging because of the lack of a perfect test. Using BinaxNOW-SP, a urinary antigen test, as an add-on to standard cultures may not only increase diagnostic yield but also increase costs. OBJECTIVE: To estimate the sensitivity and specificity of BinaxNOW-SP and subsequently estimate the cost-effectiveness of adding BinaxNOW-SP to the diagnostic work-up. DESIGN: We fit a Bayesian latent-class meta-analysis model to obtain estimates of BinaxNOW-SP accuracy that adjust for the imperfect accuracy of culture...
May 23, 2017: Research Synthesis Methods
https://www.readbyqxmd.com/read/28493383/a-large-scale-assessment-of-temporal-trends-in-meta-analyses-using-systematic-review-reports-from-the-cochrane-library
#13
Thomas R Fanshawe, Luke F Shaw, Graeme T Spence
INTRODUCTION: Previous studies suggest that many systematic reviews contain meta-analyses that display temporal trends, such as the first study's result being more extreme than later studies' or a drift in the pooled estimate. We assessed the extent and characteristics of temporal trends using all Cochrane intervention reports published 2008-2012. METHODS: We selected the largest meta-analysis within each report and analysed trends using methods including a Z-test (first versus subsequent estimates); generalised least squares; and cumulative sum charts...
May 11, 2017: Research Synthesis Methods
https://www.readbyqxmd.com/read/28453179/the-albatross-plot-a-novel-graphical-tool-for-presenting-results-of-diversely-reported-studies-in-a-systematic-review
#14
Sean Harrison, Hayley E Jones, Richard M Martin, Sarah J Lewis, Julian P T Higgins
Meta-analyses combine the results of multiple studies of a common question. Approaches based on effect size estimates from each study are generally regarded as the most informative. However, these methods can only be used if comparable effect sizes can be computed from each study, and this may not be the case due to variation in how the studies were done or limitations in how their results were reported. Other methods, such as vote counting, are then used to summarize the results of these studies, but most of these methods are limited in that they do not provide any indication of the magnitude of effect...
April 28, 2017: Research Synthesis Methods
https://www.readbyqxmd.com/read/27933728/sequential-change-detection-and-monitoring-of-temporal-trends-in-random-effects-meta-analysis
#15
Samson Henry Dogo, Allan Clark, Elena Kulinskaya
Temporal changes in magnitude of effect sizes reported in many areas of research are a threat to the credibility of the results and conclusions of meta-analysis. Numerous sequential methods for meta-analysis have been proposed to detect changes and monitor trends in effect sizes so that meta-analysis can be updated when necessary and interpreted based on the time it was conducted. The difficulties of sequential meta-analysis under the random-effects model are caused by dependencies in increments introduced by the estimation of the heterogeneity parameter τ(2) ...
June 2017: Research Synthesis Methods
https://www.readbyqxmd.com/read/27285532/random-effects-meta-analysis-for-systematic-reviews-of-phase-i-clinical-trials-rare-events-and-missing-data
#16
Mi-Ok Kim, Xia Wang, Chunyan Liu, Kathleen Dorris, Maryam Fouladi, Seongho Song
Phase I trials aim to establish appropriate clinical and statistical parameters to guide future clinical trials. With individual trials typically underpowered, systematic reviews and meta-analysis are desired to assess the totality of evidence. A high percentage of zero or missing outcomes often complicate such efforts. We use a systematic review of pediatric phase I oncology trials as an example and illustrate the utility of advanced Bayesian analysis. Standard random-effects methods rely on the exchangeability of individual trial effects, typically assuming that a common normal distribution sufficiently describes random variation among the trial level effects...
June 2017: Research Synthesis Methods
https://www.readbyqxmd.com/read/26679736/goodness-of-fit-tools-for-dose-response-meta-analysis-of-binary-outcomes
#17
Andrea Discacciati, Alessio Crippa, Nicola Orsini
Goodness of fit evaluation should be a natural step in assessing and reporting dose-response meta-analyses from aggregated data of binary outcomes. However, little attention has been given to this topic in the epidemiological literature, and goodness of fit is rarely, if ever, assessed in practice. We briefly review the two-stage and one-stage methods used to carry out dose-response meta-analyses. We then illustrate and discuss three tools specifically aimed at testing, quantifying, and graphically evaluating the goodness of fit of dose-response meta-analyses...
June 2017: Research Synthesis Methods
https://www.readbyqxmd.com/read/28429470/meta-analysis-combining-parallel-and-cross-over-trials-with-random-effects
#18
François Curtin
Meta-analysis can necessitate the combination of parallel and cross-over trial designs. Because of the differences in the trial designs and potential biases notably associated with the crossover trials, one often combines trials of the same designs only, which decreases the power of the meta-analysis. To combine results of clinical trials from parallel and cross-over designs, we extend the method proposed in an accompanying study to account for random effects. We propose here a hierarchical mixed model allowing the combination of the 2 types of trial designs and accounting for additional covariates where random effects can be introduced to account for heterogeneity in trial, treatment effect, and interactions...
April 21, 2017: Research Synthesis Methods
https://www.readbyqxmd.com/read/28429447/using-the-realist-perspective-to-link-theory-from-qualitative-evidence-synthesis-to-quantitative-studies-broadening-the-matrix-approach
#19
Leonie van Grootel, Floryt van Wesel, Alison O'Mara-Eves, James Thomas, Joop Hox, Hennie Boeije
BACKGROUND: This study describes an approach for the use of a specific type of qualitative evidence synthesis in the matrix approach, a mixed studies reviewing method. The matrix approach compares quantitative and qualitative data on the review level by juxtaposing concrete recommendations from the qualitative evidence synthesis against interventions in primary quantitative studies. However, types of qualitative evidence syntheses that are associated with theory building generate theoretical models instead of recommendations...
April 21, 2017: Research Synthesis Methods
https://www.readbyqxmd.com/read/28378395/power-analysis-for-random-effects-meta-analysis
#20
Dan Jackson, Rebecca Turner
One of the reasons for the popularity of meta-analysis is the notion that these analyses will possess more power to detect effects than individual studies. This is inevitably the case under a fixed-effect model. However, the inclusion of the between-study variance in the random-effects model, and the need to estimate this parameter, can have unfortunate implications for this power. We develop methods for assessing the power of random-effects meta-analyses, and the average power of the individual studies that contribute to meta-analyses, so that these powers can be compared...
April 4, 2017: Research Synthesis Methods
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