Sensitivity Analysis For Publication Bias Research Articles

A likelihood-based sensitivity analysis for publication bias on the summary receiver operating characteristic in meta-analysis of diagnostic test accuracy.

In meta-analysis of diagnostic test accuracy, the summary receiver operating characteristic (SROC) curve is a recommended method to summarize the diagnostic capacity of a medical test in the presence of study-specific cutoff values. The SROC curve can be estimated by bivariate modeling of pairs of sensitivity and specificity across multiple diagnostic studies, and the area under the SROC curve (SAUC) gives the aggregate estimate of diagnostic test accuracy. However, publication bias is a major threat to the validity of the estimates. To make inference of the impact of publication bias on the SROC curve or the SAUC, we propose a sensitivity analysis method by extending the likelihood-based sensitivity analysis of Copas. In the proposed method, the SROC curve or the SAUC are estimated by maximizing the likelihood constrained by different values of the marginal probability of selective publication under different mechanisms of selective publication. A cutoff-dependent selection function is developed to model the selective publication mechanism via the -type statistics or -value of the linear combination of the logit-transformed sensitivity and specificity from the published studies. It allows us to model selective publication suggested by the funnel plots of sensitivity, specificity, or diagnostic odds ratio, which are often observed in practice. A real meta-analysis of diagnostic test accuracy is re-analyzed to illustrate the proposed method, and simulation studies are conducted to evaluate its performance.

The effect of regenerative therapy in functional outcome in the treatment of patellar and Achilles tendinopathy: A Meta-analysis of Randomized Controlled Clinical Trials

Background: Achilles and patellar tendinopathy are the most common musculoskeletal disorders in lower extremities, with numerous therapeutic modalities for treatment and management. Nowadays, cell-based therapies like stem cells (SC) and platelet-rich plasma (PRP) have satisfactory clinical outcomes. Aim: To perform a meta-analysis of randomized controlled clinical trials to determine the functional efficacy of cell therapy (SC or PRP) in patellar (PT) and Achilles tendinopathy (AT). Study Design: Meta-analysis. Methods: PubMed, Cochrane Library, Google Scholar, SciELO, International Clinical Trials Registry, Clinical Trials.gov, and Lilacs were searched from January 2010 to May 2021. Reference lists were manually checked. Randomized controlled trials (RCTs) using SC and PRP to treat tendinopathy using the Victorian Institute of Sport Assessment (VISA) for patellar (VISA-P) and Achilles (VISA-A) tendinopathy were included. Published RCTs using other treatment modalities, non-tendon condition, non-per-protocol analysis, and other studies designs were excluded. Study quality was assessed using the CONSORT 2010 checklist for reporting a randomized trial. The Cochrane Collaboration risk of bias tool for randomized trials was used, and two review authors assessed their quality. The effect size was reported as a standardized mean difference (SMD) in a random effect model. The sensitivity analysis for publication bias was evaluated. A funnel plot was used, and Egger´s regression test was performed for asymmetry evaluation. Results: A total of eight RCTs with cell therapy were considered. The studies included a total of 318 patients with PT and AT with a mean follow-up of 28.75 (+-11.82) weeks. There was no significant difference between the two groups in the random-effects model (SMD=0.43, 95%CI (-0.52, 1.37), t=1.07, p=0.32). No significant difference between subgroups analysis considered the type of regenerative therapy (Q=3.49, df=2, p=0.17), and injection site (Q=0.36, df=1, p=0.55) were detected. Conclusion: This meta-analysis does not provide enough evidence to support the use of cell therapy (SC and PRP) to manage PT and AT. Keywords: Achilles, Patellar, Platelet-rich plasma, Tendinopathy, VISA.

Sensitivity analysis for publication bias in meta-analyses.

SummaryWe propose sensitivity analyses for publication bias in meta‐analyses. We consider a publication process such that ‘statistically significant’ results are more likely to be published than negative or “non‐significant” results by an unknown ratio, η. Our proposed methods also accommodate some plausible forms of selection based on a study's standard error. Using inverse probability weighting and robust estimation that accommodates non‐normal population effects, small meta‐analyses, and clustering, we develop sensitivity analyses that enable statements such as ‘For publication bias to shift the observed point estimate to the null, “significant” results would need to be at least 30 fold more likely to be published than negative or “non‐significant” results’. Comparable statements can be made regarding shifting to a chosen non‐null value or shifting the confidence interval. To aid interpretation, we describe empirical benchmarks for plausible values of η across disciplines. We show that a worst‐case meta‐analytic point estimate for maximal publication bias under the selection model can be obtained simply by conducting a standard meta‐analysis of only the negative and ‘non‐significant’ studies; this method sometimes indicates that no amount of such publication bias could ‘explain away’ the results. We illustrate the proposed methods by using real meta‐analyses and provide an R package: PublicationBias.

Reducing meat consumption by appealing to animal welfare: protocol for a meta-analysis and theoretical review

BackgroundReducing meat consumption may improve human health, curb environmental damage and greenhouse gas emissions, and limit the large-scale suffering of animals raised in factory farms. Previous work has begun to develop interventions to reduce individual meat consumption, often by appealing directly to individual health motivations. However, research on nutritional behavior change suggests that interventions additionally linking behavior to ethical values, identity formation, and existing social movements may be particularly effective and longer-lasting. Regarding meat consumption, preliminary evidence and psychological theory suggest that appeals related to animal welfare may have considerable potential to effectively leverage these elements of human psychology. We aim to conduct a systematic review and quantitative meta-analysis evaluating the effectiveness of animal welfare-related appeals on actual or intended meat consumption or purchasing. Our investigation will critically synthesize the current state of knowledge regarding psychological mechanisms of intervening on individual meat consumption and empirically identify the psychological characteristics underlying the most effective animal welfare-based interventions.MethodsWe will systematically search eight academic databases and extensively search unpublished grey literature. We will include studies that assess interventions intended to reduce meat consumption or purchase through the mention or portrayal of animal welfare, that measure outcomes related to meat consumption or purchase, and that have a control condition. Eligible studies may recruit from any human population, be written in any language, and be published or released any time. We will meta-analyze the studies, reporting the pooled point estimate and additional metrics that describe the distribution of potentially heterogeneous effects. We will assess studies’ risk of bias and conduct sensitivity analyses for publication bias. We describe possible follow-up analyses to investigate hypothesized moderators of intervention effectiveness.DiscussionThe findings of the proposed systematic review and meta-analysis, including any identified methodological limitations of the existing literature, could inform the design of successful evidence-based interventions with broad potential to improve human, animal, and environmental well-being.Systematic review registrationThe protocol was preregistered via the Open Science Framework (https://osf.io/d3y56/registrations).

Reducing Meat Consumption by Appealing to Animal Welfare: Protocol for a Meta-Analysis and Theoretical Review

Background: Reducing meat consumption may improve human health, curb environmental damage and greenhouse gas emissions, and limit the large-scale suffering of animals raised in factory farms. Previous work has begun to develop interventions to reduce individual meat consumption, often by appealing directly to individual health motivations. However, research on nutritional behavior change suggests that interventions additionally linking behavior to ethical values, identity formation, and existing social movements may be particularly effective and longer-lasting. Regarding meat consumption, preliminary evidence and psychological theory suggest that appeals related to animal welfare may have considerable potential to effectively leverage these elements of human psychology. We aim to conduct a systematic review and quantitative meta-analysis evaluating the effectiveness of animal welfare-related appeals on actual or intended meat consumption or purchasing. Our investigation will critically synthesize the current state of knowledge regarding psychological mechanisms of intervening on individual meat consumption and empirically identify the psychological characteristics underlying the most effective animal welfare-based interventions. Methods: We will systematically search eight academic databases and extensively search unpublished grey literature. We will include studies that assess interventions intended to reduce meat consumption or purchase through the mention or portrayal of animal welfare that measure outcomes related to meat consumption or purchase, and that have a control condition. Eligible studies may recruit from any human population, be written in any language, and be published or released any time. We will meta-analyze the studies, reporting the pooled point estimate and additional metrics that describe the distribution of potentially heterogeneous effects. We will assess studies’ risk of bias and conduct sensitivity analyses for publication bias. We describe possible follow-up analyses to investigate hypothesized moderators of intervention effectiveness. Discussion: The findings of the proposed systematic review and meta-analysis, including any identified methodological limitations of the existing literature, could inform the design of successful evidence-based interventions with broad potential to improve human, animal, and environmental well-being. Systematic review registration: The protocol was preregistered via the Open Science Framework.

Altered pain processing in people with type I and II diabetes: a protocol for a systematic review and meta-analysis of pain threshold and pain modulation mechanisms

BackgroundPeripheral neuropathies are a common complication in patients with diabetes. Changes in nerve function and central pain processing can be quantified by assessing pain thresholds and pain modulation mechanisms.AimTo summarise the literature which compares pain thresholds and pain modulation mechanisms in people with diabetes without neuropathies, with non-painful diabetic neuropathies and with painful diabetic neuropathies, and in people without diabetes.MethodsA systematic review and meta-analysis will be conducted. Terms related to diabetes, pain thresholds and pain modulation mechanisms will be combined in a structured search in MEDLINE, CINAHL, EMBASE, the Cochrane Library, SPORTDiscus, Web of Science and PEDro. Publications on adults (18 years and older) with diabetes and at least one pain threshold measure following thermal, mechanical or electrical stimuli and/or at least one pain modulation mechanisms (temporal summation or conditioned pain modulation) with a comparison group will be considered. There will be no restriction regarding language or year of publication. One investigator will screen records based on title and abstract (ESS). Two independent investigators (ESS and MC) will select full-text papers and assess risk of bias using a modified Downs and Black checklist. Potential disagreements will be resolved with a third investigator (LB). One investigator (ESS) will extract all data and a second investigator (MS) will extract data for 20% of the papers to verify accuracy of the process. A sensitivity analysis for publication bias will be conducted.DiscussionThis systematic review and meta-analysis will summarise the evidence on pain threshold profiles and pain modulation mechanisms in people with diabetes without and with neuropathies (both painful and non-painful). This will provide more insight in the clinical presentation and progression of diabetic neuropathies.Systematic review registrationPROSPERO CRD42018088173

Mate Choice Copying in Humans: a Systematic Review and Meta-Analysis

Mate choice copying (MCC) is a type of non-independent mate choice where the ‘probability of acceptance’ of a potential mate increases if they are observed to be chosen by others first. The phenomenon was first demonstrated in several non-human taxa, with studies on humans conducted shortly after. The effect has been consistently documented among women choosing men (female choice), with mixed results among men choosing women (male choice). To understand and test the overall level of support for MCC in humans, we conducted a systematic review and meta-analysis, including a sensitivity analysis for publication bias. We found that the two most commonly used methods of studying MCC in humans involved either the ‘addition’ of a cue (opposite sex other) or the ‘augmentation’ of cues (manipulating ‘mate quality’ of opposite sex other). We performed separate meta-analyses for these two approaches, splitting each into male choice and female choice. Women were more likely to rate male targets as more desirable when presented alongside a female while no obvious effects were detected with male choice. These sex differences disappeared in studies that ‘augment’ cues, as both sexes rated targets as more attractive when in the presence of more desirable others. We also detected high levels of heterogeneity in effect sizes and a moderate publication bias in favor of positive reports of MCC. Our results provide clarification for documented sex differences (or lack thereof) in human MCC. We also discuss the importance of method consistency in studies that transfer ideas from non-human to human behavioral studies, highlighting replication issues in the light of the publication crisis in psychological science.

Sensitivity analysis for publication bias in meta-analysis of diagnostic studies for a continuous biomarker.

Publication bias is one of the most important issues in meta-analysis. For standard meta-analyses to examine intervention effects, the funnel plot and the trim-and-fill method are simple and widely used techniques for assessing and adjusting for the influence of publication bias, respectively. However, their use may be subjective and can then produce misleading insights. To make a more objective inference for publication bias, various sensitivity analysis methods have been proposed, including the Copas selection model. For meta-analysis of diagnostic studies evaluating a continuous biomarker, the summary receiver operating characteristic (sROC) curve is a very useful method in the presence of heterogeneous cutoff values. To our best knowledge, no methods are available for evaluation of influence of publication bias on estimation of the sROC curve. In this paper, we introduce a Copas-type selection model for meta-analysis of diagnostic studies and propose a sensitivity analysis method for publication bias. Our method enables us to assess the influence of publication bias on the estimation of the sROC curve and then judge whether the result of the meta-analysis is sufficiently confident or should be interpreted with much caution. We illustrate our proposed method with real data.

Inflammatory Markers and the Risk of Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis.

Systemic inflammatory factors are inconsistently associated with the pathogenesis of chronic obstructive pulmonary disease (COPD). We conducted a systematic review and meta-analysis to summarize the evidence supporting the association between systemic inflammation and the risk of COPD. Pertinent studies were retrieved from PubMed, EmBase, and the Cochrane Library until April 2015. A random-effects model was used to process the data, and the analysis was further stratified by factors affecting these associations. Sensitivity analyses for publication bias were performed. We included 24 observational studies reporting data on 10,677 COPD patients and 28,660 controls. Overall, we noted that COPD was associated with elevated serum CRP (SMD: 1.21; 95%CI: 0.92–1.50; P < 0.001), leukocytes (SMD: 1.07; 95%: 0.25–1.88; P = 0.010), IL-6 (SMD: 0.90; 95%CI: 0.48–1.31; P < 0.001), IL-8 (SMD: 2.34; 95%CI: 0.69–4.00; P = 0.006), and fibrinogen levels (SMD: 0.87; 95%CI: 0.44–1.31; P < 0.001) when compared with control. However, COPD was not significantly associated with TNF-α levels when compared with control (SMD: 0.60; 95%CI: -0.46 to 1.67; P = 0.266). Our findings suggested that COPD was associated with elevated serum CRP, leukocytes, IL-6, IL-8, and fibrinogen, without any significant relationship with TNF-α.

PWE-072 Effect Of Chromoendoscopy on Adenoma Detection in the Colon: A Meta-Analysis

IntroductionEarly adenoma detection is shown to reduce mortality from colorectal cancers. Advances in endoscopy are aimed at improving adenoma detection. Contrast enhancement using dye spray is reported to improve the...

A Likelihood-Based Sensitivity Analysis for Publication Bias in Meta-Analysis

Summary A common conjecture in the study of publication bias is that studies reporting a significant result are more likely to be selected for review than studies whose results are inconclusive. We envisage a population of studies following the standard random-effects model of meta-analysis, and a selection probability given by a function of the study's ‘t-statistic’. In practice it is difficult to estimate this function, and hence difficult to estimate its associated bias correction. The paper suggests the more modest aim of a sensitivity analysis in which the treatment effect is estimated by maximum likelihood constrained by given values of the marginal probability of selection. This gives a graphical summary of how the inference from a meta-analysis changes as we allow for increasing selection (as the marginal selection probability decreases from 1), with an associated diagnostic plot comparing the observed treatment effects with their fitted values implied by the corresponding selection model. The approach is motivated by a medical example in which the highly significant result of a published meta-analysis was subsequently overturned by the results of a large-scale clinical trial.

Confidence Intervals and P‐Values for Meta‐Analysis with Publication Bias

We study publication bias in meta-analysis by supposing there is a population (y, sigma) of studies which give treatment effect estimates y approximately N(theta, sigma(2)). A selection function describes the probability that each study is selected for review. The overall estimate of theta depends on the studies selected, and hence on the (unknown) selection function. Our previous paper, Copas and Jackson (2004, Biometrics 60, 146-153), studied the maximum bias over all possible selection functions which satisfy the weak condition that large studies (small sigma) are as likely, or more likely, to be selected than small studies (large sigma). This led to a worst-case sensitivity analysis, controlling for the overall fraction of studies selected. However, no account was taken of the effect of selection on the uncertainty in estimation. This article extends the previous work by finding corresponding confidence intervals and P-values, and hence a new sensitivity analysis for publication bias. Two examples are discussed.

A bound for publication bias based on the fraction of unpublished studies.

Publication bias in meta-analysis is usually modeled in terms of an accept/reject selection procedure in which the selected studies are the "published" studies and the rejected studies are the "unpublished" studies. One possible selection mechanism is to suppose that only studies that report an estimated treatment effect exceeding (or falling short of) some threshold are accepted. We show that, with appropriate choice of thresholds, this attains the maximum bias among all selection mechanisms in which the probability of selection increases with study size. It is impossible to estimate the selection mechanism from the observed studies alone: this result leads to a "worst-case" sensitivity analysis for publication bias, which is remarkably easy to implement in practice. The method is illustrated using data on the effectiveness of prophylactic corticosteroids.

A sensitivity analysis for publication bias in systematic reviews.

There is no simple method of correcting for publication bias in systematic reviews. We suggest a sensitivity analysis in which different patterns of selection bias can be tested against the fit to the funnel plot. Publication bias leads to lower values, and greater uncertainty, in treatment effect estimates. Two examples are discussed. An appendix lists the S-plus code needed for carrying out the analysis.

A sensitivity analysis for publication bias in systematic reviews

A sensitivity analysis for publication bias in systematic reviews