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Research Synthesis Methods

Juan Víctor Ariel Franco, Virginia Laura Garrote, Camila Micaela Escobar Liquitay, Valeria Vietto
OBJECTIVE: Search strategies are essential for the adequate retrieval of studies in a systematic review (SR). Our objective was to identify problems in the design and reporting of search strategies in a sample of new Cochrane SRs first published in The Cochrane Library in 2015. STUDY DESIGN AND SETTING: We took a random sample of 70 new Cochrane SRs of interventions published in 2015. We evaluated their design and reporting of search strategies using the recommendations from the Cochrane Handbook for Systematic Reviews of Interventions, the Methodological Expectations of Cochrane Intervention Reviews (MECIR) and the Peer Review of Electronic Search Strategies (PRESS) evidence-based guideline...
May 15, 2018: Research Synthesis Methods
S C Freeman, D Fisher, J F Tierney, J R Carpenter
BACKGROUND: Stratified medicine seeks to identify patients most likely to respond to treatment. Individual participant data (IPD) network meta-analysis (NMA) models have greater power than individual trials to identify treatment-covariate interactions (TCI). TCI contain "within" and "across" trial interactions, where the across trial interaction is more susceptible to confounding and ecological bias. METHODS: We considered a network of IPD from 37 trials (5922 patients) for cervical cancer (2394 events), where previous research identified disease stage as a potential interaction covariate...
May 8, 2018: Research Synthesis Methods
Claire Watkins, Iain Bennett
In studies with time-to-event data, outcomes may be reported as hazard ratios (HR) or binomial counts/proportions at a specific time point. If the intent is to synthesise evidence by performing a meta-analysis or network meta-analysis (NMA) using the HR as the measure of treatment effect, studies that only report binomial data cannot be included in the network. Methods for converting binomial data to HRs were investigated, so that studies reporting binomial data only could be included in a network of HR data...
April 29, 2018: Research Synthesis Methods
Adam R Hafdahl
This eighth installment of 'Article Alerts' includes a print component with 200 methodological articles about research synthesis published in 2013. Since the preceding installment, more than 3400 articles, dissertations, book chapters, and other types of work in this methodological domain have been added to the archive component, all from 2009-2013. The online Supporting Information now includes over half of the parent compilation's more than 26000 records: 1000 from the print component and more than 13000 from the archive component...
March 25, 2018: Research Synthesis Methods
Tim Mathes, Oliver Kuss
Meta-analyses often include only a small number of studies (≤5). Estimating between study heterogeneity is difficult in this situation. An inaccurate estimation of heterogeneity can result in biased effect estimates and too narrow confidence intervals. The beta-binominal model has shown good statistical properties for meta-analysis of sparse data. We compare the beta-binominal model with different inverse variance random (e.g., DerSimonian-Laird, modified Hartung-Knapp, Paule-Mandel) and fixed effect methods (Mantel-Haenszel, Peto) in a simulation study...
March 23, 2018: Research Synthesis Methods
Nazila Alinaghi, W Robert Reed
This paper studies the performance of the FAT-PET-PEESE (FPP) procedure, a commonly employed approach for addressing publication bias in the economics and business meta-analysis literature. The FPP procedure is generally used for 3 purposes: (1) to test whether a sample of estimates suffers from publication bias, (2) to test whether the estimates indicate that the effect of interest is statistically different from zero, and (3) to obtain an estimate of the mean true effect. Our findings indicate that the FPP procedure performs well in the basic but unrealistic environment of fixed effects, where all estimates are assumed to derive from a single population value and sampling error is the only reason for why studies produce different estimates...
March 12, 2018: Research Synthesis Methods
Ralf Bender, Tim Friede, Armin Koch, Oliver Kuss, Peter Schlattmann, Guido Schwarzer, Guido Skipka
In systematic reviews, meta-analyses are routinely applied to summarize the results of the relevant studies for a specific research question. If one can assume that in all studies the same true effect is estimated, the application of a meta-analysis with common effect (commonly referred to as fixed-effect meta-analysis) is adequate. If between-study heterogeneity is expected to be present, the method of choice is a meta-analysis with random effects. The widely used DerSimonian and Laird method for meta-analyses with random effects has been criticized due to its unfavorable statistical properties, especially in the case of very few studies...
March 5, 2018: Research Synthesis Methods
J Burns, S Polus, L Brereton, J Chilcott, S E Ward, L M Pfadenhauer, E A Rehfuess
We describe a combination of methods for assessing the effectiveness of complex interventions, especially where substantial heterogeneity with regard to the population, intervention, comparison, outcomes, and study design of interest is expected. We applied these methods in a recent systematic review of the effectiveness of reinforced home-based palliative care (rHBPC) interventions, which included home-based care with an additional and explicit component of lay caregiver support. We first summarized the identified evidence, deemed inappropriate for statistical pooling, graphically by creating harvest plots...
March 2018: Research Synthesis Methods
Aogán Delaney, Peter A Tamás
Despite recognition that database search alone is inadequate even within the health sciences, it appears that reviewers in fields that have adopted systematic review are choosing to rely primarily, or only, on database search for information retrieval. This commentary reminds readers of factors that call into question the appropriateness of default reliance on database searches particularly as systematic review is adapted for use in new and lower consensus fields. It then discusses alternative methods for information retrieval that require development, formalisation, and evaluation...
March 2018: Research Synthesis Methods
Simon Briscoe
The literature searches that are used to identify studies for inclusion in a systematic review should be comprehensively reported. This ensures that the literature searches are transparent and reproducible, which is important for assessing the strengths and weaknesses of a systematic review and re-running the literature searches when conducting an update review. Web searching using search engines and the websites of topically relevant organisations is sometimes used as a supplementary literature search method...
March 2018: Research Synthesis Methods
Evan Mayo-Wilson, Tianjing Li, Nicole Fusco, Kay Dickersin
Data for individual trials included in systematic reviews may be available in multiple sources. For example, a single trial might be reported in 2 journal articles and 3 conference abstracts. Because of differences across sources, source selection can influence the results of systematic reviews. We used our experience in the Multiple Data Sources in Systematic Reviews (MUDS) study, and evidence from previous studies, to develop practical guidance for using multiple data sources in systematic reviews. We recommend the following: (1) Specify which sources you will use...
March 2018: Research Synthesis Methods
Chuan Hong, Richard D Riley, Yong Chen
Multivariate meta-analysis, which jointly analyzes multiple and possibly correlated outcomes in a single analysis, is becoming increasingly popular in recent years. An attractive feature of the multivariate meta-analysis is its ability to account for the dependence between multiple estimates from the same study. However, standard inference procedures for multivariate meta-analysis require the knowledge of within-study correlations, which are usually unavailable. This limits standard inference approaches in practice...
March 2018: Research Synthesis Methods
Annika Hoyer, Stefan Hirt, Oliver Kuss
Systematic reviews and meta-analyses are the cornerstones of evidence-based medicine and inform treatment, diagnosis, or prevention of individual patients as well as policy decisions in health care. Statistical methods for the meta-analysis of intervention studies are well established today. Meta-analysis for diagnostic accuracy trials has also been a vivid research area in recent years, which is especially due to the increased complexity of their bivariate outcome of sensitivity and specificity. The situation is even more challenging when single studies report a full ROC curve with several pairs of sensitivity and specificity, each pair for a different threshold...
March 2018: Research Synthesis Methods
J Ensor, J J Deeks, E C Martin, R D Riley
INTRODUCTION: For tests reporting continuous results, primary studies usually provide test performance at multiple but often different thresholds. This creates missing data when performing a meta-analysis at each threshold. A standard meta-analysis (no imputation [NI]) ignores such missing data. A single imputation (SI) approach was recently proposed to recover missing threshold results. Here, we propose a new method that performs multiple imputation of the missing threshold results using discrete combinations (MIDC)...
March 2018: Research Synthesis Methods
Annette Schultz, Leah Goertzen, Janet Rothney, Pamela Wener, Jennifer Enns, Gayle Halas, Alan Katz
Knowledge translation is a central focus of the health research community, which includes strategies to synthesize published research to support uptake within health care practice and policy arenas. Within the literature concerning review methodologies, a new discussion has emerged concerning methods that review and synthesize published review articles. In this paper, our multidisciplinary team from family medicine, nursing, dental hygiene, kinesiology, occupational therapy, physiology, population health, clinical psychology, and library sciences contributes to this discussion by sharing our experiences in conducting 3 scoping reviews of published review studies...
March 2018: Research Synthesis Methods
George Karabatsos
There is a growing concern that much of the published research literature is distorted by the pursuit of statistically significant results. In a seminal article, Ioannidis and Trikalinos (2007, Clinical Trials) proposed an omnibus (I&T) test for significance chasing (SC) biases. This test compares the observed number of studies that report statistically significant results, against their expected number based on study power, assuming a common effect size across studies. The current article extends this approach by developing a Bayesian nonparametric (BNP) meta-regression model and test of SC bias, which can diagnose bias at the individual study level...
March 2018: Research Synthesis Methods
Thomas P A Debray, Karel G M Moons, Richard D Riley
Small-study effects are a common threat in systematic reviews and may indicate publication bias. Their existence is often verified by visual inspection of the funnel plot. Formal tests to assess the presence of funnel plot asymmetry typically estimate the association between the reported effect size and their standard error, the total sample size, or the inverse of the total sample size. In this paper, we demonstrate that the application of these tests may be less appropriate in meta-analysis of survival data, where censoring influences statistical significance of the hazard ratio...
March 2018: Research Synthesis Methods
Lisa Chan, Mary Ellen Macdonald, Franco A Carnevale, Russell J Steele, Ian Shrier
While the systematic review process is intended to maximize objectivity and limit researchers' biases, examples remain of discordant recommendations from meta-analyses. Current guidelines to explore discrepancies assume the variation is produced by methodological differences and thus focus only on the study process. Because heterogeneity of interpretation also occurs when experts examine the same data, our purpose was to examine if there are reasoning differences, ie, in how information is processed and valued...
March 2018: Research Synthesis Methods
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)...
March 2018: Research Synthesis Methods
O O Babatunde, V Tan, J L Jordan, K Dziedzic, C A Chew-Graham, C Jinks, J Protheroe, D A van der Windt
BACKGROUND & AIMS: Barriers to dissemination and engagement with evidence pose a threat to implementing evidence-based medicine. Understanding, retention, and recall can be enhanced by visual presentation of information. The aim of this exploratory research was to develop and evaluate the accessibility and acceptability of visual summaries for presenting evidence syntheses with multiple exposures or outcomes to professional and lay audiences. METHODS: "Evidence flowers" were developed as a visual method of presenting data from 4 case scenarios: 2 complex evidence syntheses with multiple outcomes, Cochrane reviews, and clinical guidelines...
February 13, 2018: Research Synthesis Methods
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