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Assessment of publication bias and outcome reporting bias in systematic reviews of health services and delivery research: A meta-epidemiological study.

ABSTRACT: Strategies to identify and mitigate publication bias and outcome reporting bias are frequently adopted in systematic reviews of clinical interventions but it is not clear how often these are applied in systematic reviews relating to quantitative health services and delivery research (HSDR). We examined whether these biases are mentioned and/or otherwise assessed in HSDR systematic reviews, and evaluated associating factors to inform future practice. We randomly selected 200 quantitative HSDR systematic reviews published in the English language from 2007-2017 from the Health Systems Evidence database (www.healthsystemsevidence.org). We extracted data on factors that may influence whether or not authors mention and/or assess publication bias or outcome reporting bias. We found that 43% (n = 85) of the reviews mentioned publication bias and 10% (n = 19) formally assessed it. Outcome reporting bias was mentioned and assessed in 17% (n = 34) of all the systematic reviews. Insufficient number of studies, heterogeneity and lack of pre-registered protocols were the most commonly reported impediments to assessing the biases. In multivariable logistic regression models, both mentioning and formal assessment of publication bias were associated with: inclusion of a meta-analysis; being a review of intervention rather than association studies; higher journal impact factor, and; reporting the use of systematic review guidelines. Assessment of outcome reporting bias was associated with: being an intervention review; authors reporting the use of Grading of Recommendations, Assessment, Development and Evaluations (GRADE), and; inclusion of only controlled trials. Publication bias and outcome reporting bias are infrequently assessed in HSDR systematic reviews. This may reflect the inherent heterogeneity of HSDR evidence and different methodological approaches to synthesising the evidence, lack of awareness of such biases, limits of current tools and lack of pre-registered study protocols for assessing such biases. Strategies to help raise awareness of the biases, and methods to minimise their occurrence and mitigate their impacts on HSDR systematic reviews, are needed.

SUBMITTER: Ayorinde AA

PROVIDER: S-EPMC6992172 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Assessment of publication bias and outcome reporting bias in systematic reviews of health services and delivery research: A meta-epidemiological study.

Ayorinde Abimbola A AA Williams Iestyn I Mannion Russell R Song Fujian F Skrybant Magdalena M Lilford Richard J RJ Chen Yen-Fu YF

PloS one 20200130 1

Strategies to identify and mitigate publication bias and outcome reporting bias are frequently adopted in systematic reviews of clinical interventions but it is not clear how often these are applied in systematic reviews relating to quantitative health services and delivery research (HSDR). We examined whether these biases are mentioned and/or otherwise assessed in HSDR systematic reviews, and evaluated associating factors to inform future practice. We randomly selected 200 quantitative HSDR sys ...[more]

PMID: 31999702

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Project description:BACKGROUND:The increased use of meta-analysis in systematic reviews of healthcare interventions has highlighted several types of bias that can arise during the completion of a randomised controlled trial. Study publication bias and outcome reporting bias have been recognised as a potential threat to the validity of meta-analysis and can make the readily available evidence unreliable for decision making. METHODOLOGY/PRINCIPAL FINDINGS:In this update, we review and summarise the evidence from cohort studies that have assessed study publication bias or outcome reporting bias in randomised controlled trials. Twenty studies were eligible of which four were newly identified in this update. Only two followed the cohort all the way through from protocol approval to information regarding publication of outcomes. Fifteen of the studies investigated study publication bias and five investigated outcome reporting bias. Three studies have found that statistically significant outcomes had a higher odds of being fully reported compared to non-significant outcomes (range of odds ratios: 2.2 to 4.7). In comparing trial publications to protocols, we found that 40-62% of studies had at least one primary outcome that was changed, introduced, or omitted. We decided not to undertake meta-analysis due to the differences between studies. CONCLUSIONS:This update does not change the conclusions of the review in which 16 studies were included. Direct empirical evidence for the existence of study publication bias and outcome reporting bias is shown. There is strong evidence of an association between significant results and publication; studies that report positive or significant results are more likely to be published and outcomes that are statistically significant have higher odds of being fully reported. Publications have been found to be inconsistent with their protocols. Researchers need to be aware of the problems of both types of bias and efforts should be concentrated on improving the reporting of trials.

Project description:Previously, we reviewed 1052 randomized-controlled trial abstracts presented at the American Society of Anesthesiologists annual meetings from 2001-2004. We found significant positive publication bias in the period examined, with the odds ratio for abstracts with positive results proceeding to journal publication over those with null results being 2.01 [95% confidence interval: 1.52, 2.66; P < 0.001]. Mandatory trial registration was introduced in 2005 as a required standard for publication. We sought to examine whether mandatory trial registration has decreased publication bias in the anesthesia and perioperative medicine literature. We reviewed all abstracts from the 2010-2016 American Society of Anesthesiologists meetings that reported on randomized-controlled trials in humans. We scored the result of each abstract as positive or null according to a priori definitions. We systematically searched for any subsequent publication of the studies and calculated the odds ratio for journal publication, comparing positive vs null studies. We compared the odds ratio from the 2010-2016 abstracts (post-mandatory trial registration) with the odds ratio from the 2001-2004 abstracts (pre-mandatory trial registration) as a ratio of odds ratios. We defined a 33% decrease in the odds ratio as significant, corresponding to a new odds ratio of 1.33. We reviewed 9789 abstracts; 1049 met inclusion criteria as randomized-controlled trials, with 542 (51.7%) of the abstracts going on to publication. The odds ratio for abstracts with positive results proceeding to journal publication was 1.28 [95% CI: 0.97, 1.67; P = 0.076]. With adjustment for sample size and abstract quality, the difference in publication rate between positive and null abstracts was statistically significant (odds ratio 1.34; 95% CI: 1.02, 1.76; P = 0.037). The ratio of odds ratios, comparing the odds ratio from the 2010-2016 abstracts (post-mandatory trial registration) to the odds ratio from the 2001-2004 abstracts (pre-mandatory trial registration), was 0.63 (95% CI: 0.43, 0.93); P = 0.021). We present the first study in the anesthesia and perioperative medicine literature that examines and compares publication bias over two discrete periods of time, prior to and after the implementation of mandatory trial registration. Our results suggest that the amount of publication bias has decreased markedly following implementation of mandatory trial registration. However, some positive publication bias in the anesthesia and perioperative medicine literature remains.

Project description:BackgroundSystematic reviews and meta-analyses of pre-clinical studies, in vivo animal experiments in particular, can influence clinical care. Publication bias is one of the major threats of validity in systematic reviews and meta-analyses. Previous empirical studies suggested that systematic reviews and meta-analyses have become more prevalent until 2010 and found evidence for compromised methodological rigor with a trend towards improvement. We aim to comprehensively summarize and update the evidence base on systematic reviews and meta-analyses of animal studies, their methodological quality and assessment of publication bias in particular.Methods/designThe objectives of this systematic review are as follows: •To investigate the epidemiology of published systematic reviews of animal studies until present. •To examine methodological features of systematic reviews and meta-analyses of animal studies with special attention to the assessment of publication bias. •To investigate the influence of systematic reviews of animal studies on clinical research by examining citations of the systematic reviews by clinical studies. Eligible studies for this systematic review constitute systematic reviews and meta-analyses that summarize in vivo animal experiments with the purpose of reviewing animal evidence to inform human health. We will exclude genome-wide association studies and animal experiments with the main purpose to learn more about fundamental biology, physical functioning or behavior. In addition to the inclusion of systematic reviews and meta-analyses identified by other empirical studies, we will systematically search Ovid Medline, Embase, ToxNet, and ScienceDirect from 2009 to January 2013 for further eligible studies without language restrictions. Two reviewers working independently will assess titles, abstracts, and full texts for eligibility and extract relevant data from included studies. Data reporting will involve a descriptive summary of meta-analyses and systematic reviews.DiscussionResults are expected to be publicly available later in 2013 and may form the basis for recommendations to improve the quality of systematic reviews and meta-analyses of animal studies and their use with respect to clinical care.

Dataset Information

Assessment of publication bias and outcome reporting bias in systematic reviews of health services and delivery research: A meta-epidemiological study.

Publications

Assessment of publication bias and outcome reporting bias in systematic reviews of health services and delivery research: A meta-epidemiological study.

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