Publication bias in meta-analyses from the Cochrane Database of Systematic Reviews

2015 ◽  
Vol 34 (20) ◽  
pp. 2781-2793 ◽  
Author(s):  
Michal Kicinski ◽  
David A. Springate ◽  
Evangelos Kontopantelis
Keyword(s):  
Publication Bias ◽  
Systematic Reviews ◽  
Cochrane Database ◽  
Meta Analyses

scholarly journals Assessing treatment effects and publication bias across different specialties in medicine: a large empirical study of the Cochrane Database of Systematic Reviews

2020 ◽  
Author(s):  
Simon Schwab ◽  
Kreiliger Giuachin ◽  
Leonhard Held
Keyword(s):  
Publication Bias ◽  
Systematic Reviews ◽  
Treatment Effects ◽  
Evidence Based ◽  
Medical Specialties ◽  
Null Result ◽  
Cochrane Database ◽  
Funnel Plots ◽  
Meta Analyses ◽  
Based Medicine

Publication bias is a persisting problem in meta-analyses for evidence based medicine. As a consequence small studies with large treatment effects are more likely to be reported than studies with a null result which causes asymmetry. Here, we investigated treatment effects from 57,186 studies from 1922 to 2019, and overall 99,129 meta-analyses and 5,557 large meta-analyses from the Cochrane Database of Systematic Reviews. Altogether 19% (95%-CI from 18% to 20%) of the meta-analyses demonstrated evidence for asymmetry, but only 3.9% (95%-CI from 3.4% to 4.4%) showed evidence for publication bias after further assessment of funnel plots. Adjusting treatment effects resulted in overall less evidence for efficacy, and treatment effects in some medical specialties or published in prestigious journals were more likely to be statistically significant. These results suggest that asymmetry from exaggerated effects from small studies causes greater concern than publication bias.

An Analysis of “Publication Bias” in the Travel, Tourism, and Hospitality Research

2017 ◽  
Vol 6 (4) ◽  
pp. 19-37
Author(s):  
Atila Yüksel ◽  
Ekrem Tufan
Keyword(s):  
Publication Bias ◽  
Systematic Reviews ◽  
Research Articles ◽  
Null Results ◽  
Tourism And Hospitality ◽  
Meta Analyses

This article examines whether studies with favorable or statistically significant outcomes are more likely to be published than studies with null results. Should such a publication tendency be in the form of favoring significant findings exist, then the integrity of science, suggestions and conclusions becomes controversial. This also includes those particularly drawn from meta-analyses and systematic reviews. Drawing on a sample of research articles, an examination was undertaken to determine whether studies reporting significant findings were published more. Additional analyses were conducted to examine the validity of reject/support decisions in relation to null hypotheses tested in these studies. The share of the published articles, in which null hypotheses were rejected, was found to be much larger (81%). Interestingly however, calculated power levels and actual samples sizes of these studies were too small to confidently reject/support null hypotheses. Implications for research are discussed in the concluding section of the article.

The clinical outcome of the Metha short hip stem: a systematic scoping review

2020 ◽  
pp. 112070002090371 ◽  
Author(s):  
Michael-Alexander Malahias ◽  
Purnachandra Tejaswi ◽  
Dimitrios Chytas ◽  
Vikram Kadu ◽  
Dimitrios Karanikas ◽  
...  
Keyword(s):  
Clinical Outcome ◽  
Systematic Reviews ◽  
Scoping Review ◽  
Hip Resurfacing ◽  
Long Term Results ◽  
Middle Aged ◽  
Cochrane Database ◽  
Pubmed Database ◽  
Meta Analyses ◽  
Age Range

Introduction: Short femoral stems were designed to bridge the gap between conventional straight design stems and hip resurfacing prostheses in total hip arthroplasty (THA). A number of clinical trials have been recently conducted to assess the clinical and safety profile of the cementless, colarless, tapered Metha short hip stem in young or active middle-aged individuals. Methods: A systematic scoping review was conducted according to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. 4 reviewers independently conducted the search using the MEDLINE/PubMed database and the Cochrane Database of Systematic Reviews. These databases were queried with the terms “short” AND “hip” AND “stem”. Results: From the initial 773 studies we finally chose 12 studies after applying our inclusion-exclusion criteria. The number of operated hips that were included in these studies was 5048 (mean BMI range: 22.7–35.2, mean age range: 44.4–60.4 years, mean follow-up range: 2–9 years). The mean modified Coleman methodology score was 52.3/100, while it ranged from 31/100 to 63/100. All mean clinical outcome scores that were used in the studies illustrated significant postoperative improvement when compared with the respective initial values. The revision rate of the Metha stem for component-related reasons was 2.5%, while the rate of major complications not requiring revision of the Metha stem was 2.8%. Conclusions: The Metha stem performs well in young or active middle-aged THA patients. Further studies are required for the assessment of the long-term results.

scholarly journals Systematic Reviews and Meta-Analysis in Spine Surgery—How Good Are They in Methodological Quality? A Systematic Review

2020 ◽  
pp. 219256822090681 ◽  
Author(s):  
Muthu Sathish ◽  
Ramakrishnan Eswar
Keyword(s):  
Systematic Review ◽  
Spine Surgery ◽  
Systematic Reviews ◽  
Methodological Quality ◽  
Meta Analysis ◽  
Eligibility Criteria ◽  
Cochrane Database ◽  
Critical Flaw ◽  
Meta Analyses

Study Design: Systematic review. Objectives: To assess the methodological quality of systematic reviews and meta-analyses in spine surgery over the past 2 decades. Materials and Methods: We conducted independent and in duplicate systematic review of the published systematic reviews and meta-analyses between 2000 and 2019 from PubMed Central and Cochrane Database pertaining to spine surgery involving surgical intervention. We searched bibliographies to identify additional relevant studies. Methodological quality was evaluated with AMSTAR score and graded with AMSTAR 2 criteria. Results: A total of 96 reviews met the eligibility criteria, with mean AMSTAR score of 7.51 (SD = 1.98). Based on AMSTAR 2 criteria, 13.5% (n = 13) and 18.7% (n = 18) of the studies had high and moderate level of confidence of results, respectively, without any critical flaws. A total of 29.1% (n = 28) of the studies had at least 1 critical flaw and 38.5% (n = 37) of the studies had more than 1 critical flaw, so that their results have low and critically low confidence, respectively. Failure to analyze the conflict of interest of authors of primary studies included in review and lack of list of excluded studies with justification were the most common critical flaw. Regression analysis demonstrated that studies with funding and studies published in recent years were significantly associated with higher methodological quality. Conclusion: Despite improvement in methodological quality of systematic reviews and meta-analyses in spine surgery in current decade, a substantial proportion continue to show critical flaws. With increasing number of review articles in spine surgery, stringent measures must be taken to adhere to methodological quality by following PRISMA and AMSTAR guidelines to attain higher standards of evidence in published literature.

Is grey literature essential for a better control of publication bias in psychiatry? An example from three meta-analyses of schizophrenia

2005 ◽  
Vol 20 (8) ◽  
pp. 550-553 ◽  
Author(s):  
José Luis R. Martin ◽  
Víctor Pérez ◽  
Montse Sacristán ◽  
Enric Álvarez
Keyword(s):  
Publication Bias ◽  
Systematic Reviews ◽  
Meta Analysis ◽  
Grey Literature ◽  
Risk Of Bias ◽  
Medical Databases ◽  
Study Results ◽  
Heterogeneous Nature ◽  
Meta Analyses ◽  
Literature Material

AbstractSystematic reviews in mental health have become useful tools for health professionals in view of the massive amount and heterogeneous nature of biomedical information available today. In order to determine the risk of bias in the studies evaluated and to avoid bias in generalizing conclusions from the reviews it is therefore important to use a very strict methodology in systematic reviews. One bias which may affect the generalization of results is publication bias, which is determined by the nature and direction of the study results. To control or minimize this type of bias, the authors of systematic reviews undertake comprehensive searches of medical databases and expand on the findings, often undertaking searches of grey literature (material which is not formally published). This paper attempts to show the consequences (and risk) of generalizing the implications of grey literature in the control of publication bias, as was proposed in a recent systematic work. By repeating the analyses for the same outcome from three different systematic reviews that included both published and grey literature our results showed that confusion between grey literature and publication bias may affect the results of a concrete meta-analysis.

scholarly journals Search for unpublished data by systematic reviewers: an audit

BMJ Open ◽  
2017 ◽  
Vol 7 (10) ◽  
pp. e017737 ◽  
Author(s):  
Hedyeh Ziai ◽  
Rujun Zhang ◽  
An-Wen Chan ◽  
Nav Persaud
Keyword(s):  
Publication Bias ◽  
Systematic Reviews ◽  
Data Extraction ◽  
Grey Literature ◽  
Cochrane Library ◽  
Eligibility Criteria ◽  
Ovid Medline ◽  
Cochrane Reviews ◽  
Unpublished Studies ◽  
Cochrane Database

ObjectivesWe audited a selection of systematic reviews published in 2013 and reported on the proportion of reviews that researched for unpublished data, included unpublished data in analysis and assessed for publication bias.DesignAudit of systematic reviews.Data sourcesWe searched PubMed and Ovid MEDLINE In-Process & Other Non-Indexed Citations between 1 January 2013 and 31 December 2013 for the following journals:Journal of the American Medical Association,The British Medical Journal,Lancet,Annals of Internal Medicineand theCochrane Database of Systematic Reviews. We also searched the Cochrane Library and included 100 randomly selected Cochrane reviews.Eligibility criteriaSystematic reviews published in 2013 in the selected journals were included. Methodological reviews were excluded.Data extraction and synthesisTwo reviewers independently reviewed each included systematic review. The following data were extracted: whether the review searched for grey literature or unpublished data, the sources searched, whether unpublished data were included in analysis, whether publication bias was assessed and whether there was evidence of publication bias.Main findings203 reviews were included for analysis. 36% (73/203) of studies did not describe any attempt to obtain unpublished studies or to search grey literature. 89% (116/130) of studies that sought unpublished data found them. 33% (68/203) of studies included an assessment of publication bias, and 40% (27/68) of these found evidence of publication bias.ConclusionA significant fraction of systematic reviews included in our study did not search for unpublished data. Publication bias may be present in almost half the published systematic reviews that assessed for it. Exclusion of unpublished data may lead to biased estimates of efficacy or safety in systematic reviews.

scholarly journals Publication Bias in Meta-Analyses from Psychology and Medicine: A Meta-Meta-Analysis

2017 ◽  
Author(s):  
Robbie Cornelis Maria van Aert ◽  
Jelte M. Wicherts ◽  
Marcel A. L. M. van Assen
Keyword(s):  
Publication Bias ◽  
Systematic Reviews ◽  
Large Scale ◽  
Effect Sizes ◽  
Psychological Bulletin ◽  
Data Set ◽  
Monte Carlo Simulation Study ◽  
True Effect Size ◽  
Meta Analyses ◽  
Psychology And Medicine

Publication bias is a substantial problem for the credibility of research in general and of meta-analyses in particular, as it yields overestimated effects and may suggest the existence of non-existing effects. Although there is consensus that publication bias exists, how strongly it affects different scientific literatures is currently less well-known. We examined evidence of publication bias in a large-scale data set of primary studies that were included in 83 meta-analyses published in Psychological Bulletin (representing meta-analyses from psychology) and 499 systematic reviews from the Cochrane Database of Systematic Reviews (CDSR; representing meta-analyses from medicine). Publication bias was assessed on all homogeneous subsets (3.8% of all subsets of meta-analyses published in Psychological Bulletin) of primary studies included in meta-analyses, because publication bias methods do not have good statistical properties if the true effect size is heterogeneous. The Monte-Carlo simulation study revealed that the creation of homogeneous subsets resulted in challenging conditions for publication bias methods since the number of effect sizes in a subset was rather small (median number of effect sizes equaled 6). No evidence of bias was obtained using the publication bias tests. Overestimation was minimal but statistically significant, providing evidence of publication bias that appeared to be similar in both fields. These and other findings, in combination with the small percentages of statistically significant primary effect sizes (28.9% and 18.9% for subsets published in Psychological Bulletin and CDSR), led to the conclusion that evidence for publication bias in the studied homogeneous subsets is weak, but suggestive of mild publication bias in both psychology and medicine.

scholarly journals Nutritional Supplementation during Pulmonary Rehabilitation in COPD: A Systematic Review

2019 ◽  
Author(s):  
Abdulelah M Aldhahir ◽  
Ahmed M Al Rajah ◽  
Yousef S Aldabayan ◽  
Salifu Drammeh ◽  
Vanitha Subbu ◽  
...  
Keyword(s):  
Systematic Reviews ◽  
Pulmonary Rehabilitation ◽  
Nutritional Supplementation ◽  
Systematic Search ◽  
Current Evidence ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease ◽  
Cochrane Database ◽  
Registration Number ◽  
Meta Analyses

ABSTRACTBackgroundUptake of nutritional supplementation during pulmonary rehabilitation (PR) for people with chronic obstructive pulmonary disease (COPD) has been limited by an absence of rigorous evidence-based studies supporting use. Our objective were to report and summarise the current evidence supporting use of nutritional supplementation to improve outcomes during pulmonary rehabilitation in stable COPD patients.MethodsA systematic search was conducted up to May 7th, 2019 (registration number CRD42018089142). The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used. Six databases were included: Medical Literature Analysis and Retrieval System Online or MEDLARS Online (Medline), Allied and Complementary Medicine Database (AMED), the Cochrane Database of Systematic Reviews, Excerpta Medica dataBASE (Embase), Cumulative Index of Nursing and Allied Health Literature (CINAHL), and Web of Science.ResultsThis systematic search generated 580 initial matches, of which 24 studies (1035 COPD participants) met the pre-specified criteria and were included. Our analysis does not confirm an impact of nutritional supplementation during PR, but studies, supplements and PR programmes were heterogeneous in nature.ConclusionThere is currently insufficient evidence on the effect of nutritional supplementation on improving outcomes during PR in patients with COPD. Therefore, controversy remains and further research is needed.

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