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Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) 2015 statement
Abstract
Systematic reviews should build on a protocol that describes the rationale, hypothesis, and planned methods of the review; few reviews report whether a protocol exists. Detailed, well-described protocols can facilitate the understanding and appraisal of the review methods, as well as the detection of modifications to methods and selective reporting in completed reviews. We describe the development of a reporting guideline, the Preferred Reporting Items for Systematic reviews and Meta-Analyses for Protocols 2015 (PRISMA-P 2015). PRISMA-P consists of a 17-item checklist intended to facilitate the preparation and reporting of a robust protocol for the systematic review. Funders and those commissioning reviews might consider mandating the use of the checklist to facilitate the submission of relevant protocol information in funding applications. Similarly, peer reviewers and editors can use the guidance to gauge the completeness and transparency of a systematic review protocol submitted for publication in a journal or other medium.
... The first author, K.C.S., worked with university librarians to develop the search strategy to compile data to inform RQ1. The Preferred Reporting Items for Systematic Review and Meta-Analysis Protocol (PRISMA-P) [52] and the PRISMA Extension for Scoping Reviews (PRISMA-ScR) [53] checklists were used for the search strategy. Risk of bias and study quality were not assessed since the research questions were exploratory in nature. ...
The United States (U.S.) Department of Agriculture (USDA)-administered Supplemental Nutrition Assistance Program (SNAP) made substantial changes in response to the coronavirus disease 2019 (COVID-19) pandemic. These changes highlight the need to identify the digital literacy skills and capacities of SNAP adults to purchase healthy groceries online. We conducted a scoping review of four electronic databases, Google and Google Scholar to identify studies that measured food and nutrition literacy outcomes for U.S. adults. We applied a multi-dimensional digital food and nutrition literacy (MDFNL) model to assess six literacy levels and components. Of 18 studies published from 2006–2021, all measured functional and interactive literacy but no study measured communicative, critical, translational, or digital literacy. Six studies examined SNAP or SNAP-Education outcomes. Adults with higher food or nutrition literacy scores had better cognitive, behavioral, food security and health outcomes. We suggest how these findings may inform research, policies, and actions to strengthen the multi-dimensional literacy skills of SNAP participants and SNAP-eligible adults to support healthy purchases in the online food retail ecosystem.
... The protocol of this study was developed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P) and was registered in the International Prospective Register of Systematic Reviews (PROSPERO). 20 The systematic review will be carried out according to the most up-to-date COSMIN methodology. 19 In this context, the COSMIN initiative aims to improve the selection of health measurement instruments in research and clinical practice by developing tools and guidelines to select the most appropriate instrument for a given purpose. ...
Introduction
Health professionals are often involved in the process of breaking bad news (BBN), which remains a difficult challenge, as it requires not only theoretical knowledge, but also the development of humanistic, emotional and communication skills. Therefore, optimal BBN assessment is essential. In this regard, sound measurement instruments are needed to evaluate BBN properly in research, teaching and clinical settings. Several instruments have been designed and validated to assess BBN. In this context, choosing the most appropriate instrument for assessing health professionals’ skills in BBN is essential. The aims of this systematic review are to: (1) identify all the instruments used for assessing health professionals’ skills in BBN; and (2) critically appraise their measurement properties.
Methods
A systematic review will be undertaken according to the most up-to-date COnsensus-based Standards for the selection of health status Measurement INstruments’ (COSMIN) methodology. The protocol of this systematic review was developed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The search strategy will be performed following the Peer Review of Electronic Search Strategies. The search strategy will be conducted in CINAHL, MEDLINE, Embase, PsycINFO, SciELO and Open Grey. Two review authors will independently appraise the full-text articles according to the COSMIN Risk of Bias checklist. Quality ratings and evidence synthesis will be performed using a modified Grading of Recommendations Assessment, Development and Evaluation approach.
Ethics and dissemination
Ethical approval is not necessary for systematic review protocols. The results will be disseminated by publication in a peer-reviewed journal and presented at a relevant conference.
PROSPERO registration number
CRD42020207586.
... A meta-analysis of the literature on alterations in the white matter of T2DM was performed according to PRISMA guidelines (Moher et al., 2015). All the articles published before October 30, 2020, were retrieved from PubMed, Web of Science, Embase, CNKI, and Wan Fang database. ...
Aims: The study aimed to conduct a meta-analysis to determine the abnormalities of white matter in patients with type 2 diabetes mellitus (T2DM) by identifying the consistency of diffusion tensor imaging (DTI).
Method: The literature for DTI comparing patients with T2DM with controls published before October 30, 2020, were reviewed in PubMed, Web of Science, Embase, CNKI, and Wan Fang databases. The meta-analysis was performed using the activation likelihood estimation (ALE) method, including 12 reports and 381 patients with T2DM.
Results: The meta-analysis identified 10 white matter regions that showed a consistent reduction of fractional anisotropy (FA) in patients with T2DM, including genu of the corpus callosum, the body of corpus callosum, bilateral anterior corona radiata, bilateral superior corona radiata, bilateral cingulum, and bilateral superior fronto-occipital fasciculus.
Conclusion: This study revealed the abnormal characteristics of white matter in T2DM, which would be helpful to understand the underlying neuropathological and physiological mechanisms of T2DM and provide evidence for clinical diagnosis and treatment.
... Following PRISMA guidelines (Moher et al., 2015), a literature search was conducted with the scientific search engines Cochrane, PsycINFO, Pubmed, PubPsych, Scopus, and Web of Science using the search terms: (i) neuroimaging, brain imaging, fMRI, MRI, magnetic resonance imaging, BOLD, blood oxygen level dependent, VBM, voxel-based morphometry, voxelwise, voxelwise, DTI, diffusion tensor imaging, white matter, cortical thickness, grey matter which were fully crossed with the search terms (ii) therapy, psychotherapy, therapeutics, therapeutic, treatment, intervention and again fully crossed with the terms (iii) posttraumatic stress disorder, posttraumatic stress syndrome, PTSD, PTSS, posttraumatic stress, traumatic stress, psychological trauma without searching for the following terms animals, nonhuman, rodent, mice, SPECT, single photon emission computerized tomography, PET, positron emission tomography, CT, and computer tomography. Peer-reviewed original articles published in English, German, and French from January 2005 up to the end of October 2019 were selected from the search results. ...
Background
Meta-analytic results indicate that posttraumatic stress disorder (PTSD) is associated with hypoactivation of the medial prefrontal cortex (mPFC), hyperactivation of the amygdala, and volume reductions of the hippocampus. Effective psychotherapeutic treatments were hypothesized to normalize these neural patterns via upregulation of prefrontal structures, which in turn downregulate limbic regions.
Objective
To gain a sound understanding of the effects of successful psychotherapy on the brain, neural changes from pre- to post-treatment in PTSD patients will be aggregated.
Method
A systematic literature search identified 24 original studies employing structural or functional MRI measurements both before and after treatment of patients diagnosed with PTSD.
Results
In conjunction, the review returned little evidence of an activation increase in the mPFC/rostral anterior cingulate cortex (rACC) following successful treatment. Five out of 12 studies observed such an increase (especially during emotion processing tasks), albeit in partially non-overlapping brain regions. Conversely, neither the putative related activation decrease in the amygdala nor volumetric changes or altered activation during the resting state could be convincingly established.
Conclusion
Successful psychological treatments might potentially work via upregulation of the mPFC, which thus may be involved in symptom reduction. However, the role of the amygdala in recovery from PTSD remains unclear. There is currently no indication that the various PTSD treatment approaches employed by the reviewed studies differ regarding their action mechanisms, but further research on this topic is needed.
... The protocol of this systematic review and network meta-analysis will be reported in accordance with the Preferred Reporting Item for Systematic Review and Meta-analysis Protocols (PRISMA-P) [33]. The completed study will be compliant with the PRISMA 2020 [30] and PRISMA-NMA [29]. ...
Introduction
2021 Global Initiative for Chronic Obstructive Lung Disease (GOLD) Reports recommends that patients with clinically significant symptoms and exacerbations of chronic obstructive pulmonary disease (COPD) should escalate to triple therapy, a combined use of inhaled corticosteroids (ICS), long-acting muscarinic antagonists (LAMA) and long-acting b2-agonists (LABA)(ICS/LAMA/LABA). Triple therapy in fixed-dose combinations (FDCs), i.e., combining ICS, LABA with LAMA and administrating by a single inhalation device, has appeared in recent years. This study aims to compare the efficacy of triple therapy in FDCs in treating patients with moderate to severe COPD.
Methods and analyses
Literature search will be conducted on PubMed, Embase and Web of science, according to pre-specified and corresponding search strategies, for relevant reports published since the inception dates of the databases. Randomised controlled trials (RCT) which compared the triple therapy in FDCs with other pharmacological therapies will be included. The Cochrane risk of bias assessment tool (RoB 2) will be used to assess the RCT quality. The outcomes will be analyzed as rate ratios and mean differences under a random-effects model in a frequentist network meta-analysis (NMA). Additional statistical analyses including subgroup analysis, sensitivity analysis, and publication bias analysis will be performed to assess the evidential heterogeneity and robustness. The strength of evidence from the NMA will be evaluated with the Grading of Recommendation, Assessment, Development and Evaluation (GRADE) methods.
Ethics and dissemination
No ethics approval is required as this systematic review and network meta-analysis do not collect confidential personal data and do not carry out interventions in treating patients.
Protocol registration number
CRD42021240823 .
... This was designed by the authors SS and WR and performed in adherence to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA). 9 Methods are described in more detail in the following sections. ...
Introduction
Noma is a significant yet neglected disease which affects some of the least developed countries in the world. The long-term benefit and safety of Noma surgical reconstructive missions have recently been under scrutiny due to a perceived lack of measurable outcomes and appropriate follow-up. This study analyses and reports on classifications, outcome measurement tools and follow-up for reconstructive surgery after Noma disease.
Methods
This systematic review was undertaken following Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. The three medical databases Medline, EMBASE and Web of Sciences were searched, articles published between 1 January 1983 and 15 April 2020 were included. All primary evidence on reconstructive surgery following Noma disease, reporting data on outcome after surgery, follow-up time and complications were included. Extracted data were aggregated to generate overall and population corrected mean outcomes and complication rates.
Results
Out of 1393 identified records, 31 studies including 1110 Noma patients were analysed. NOITULP and Montandon/WHO were the most commonly used classification systems. Mouth opening (MO) and complication rates were the two most often reported outcomes. Overall mean complication rate was 44%, reported by 24 studies. Postoperative MO was reported by eight publications, of which, five reported long-term outcomes (>12 months). Mean MO improved by 20 mm when compared with mean population weighted preoperative MO (7 mm). At long-term follow-up, MO decreased to 20 mm.
Conclusions
Studies reporting on neglected diseases in developing countries often lack methodological rigour. Surgeons should be mindful during patient examination by using a classification system that allows to compare preoperative versus postoperative state of disease. Short-term mission surgery is a vital part of healthcare delivery to underdeveloped and poor regions. Future missions should aim at sustainable partnerships with local healthcare providers to ensure postoperative care and long-term patient-oriented follow-up. A shift towards a diagonal treatment delivery approach, whereby local surgeons and healthcare staff are educated and empowered, should be actively promoted.
PROSPERO registration number
CRD42020181931.
Background
Intensive care unit diaries are often used to support patients during their psychological recovery. The intensive care unit stay can be upsetting, disturbing and traumatic for both patients and their families especially when the patient does not survive.
Aim
To investigate the connection between intensive care unit diaries and the grieving process experienced by family members of adult patients deceased in the intensive care unit.
Methods
Systematic literature review according to PRISMA guidelines: PubMed, CINAHL and Cochrane Library were consulted. The Caldwell’s framework was used for the quality appraisal.
Results
Only six studies examine this topic. The potential benefits of intensive care unit diaries in family members’ bereavement process may be an aid to realise how extremely ill their loved one was, may provide comfort and may help relatives to cope with their loss.
Conclusion
The use of intensive care unit diaries to help family members’ bereavement process may be a useful tool but further research is necessary to better understand their role and benefits.
The wide interest in publishing and disseminating clinical practice guidelines (CPGs) reflects the need for better allocation and rational use of the scarce resources available. CPGs also has a contribution to the management and regulation of health systems, as its implementation is expected to promote better quality and equity in health care and could potentially improve patient outcomes by encouraging evidence-based decision making, influencing choices so that the most cost-effective interventions are applied in the day-to-day health systems and services. In this context, it is important to be aware of the likely facilitating factors and barriers during the CPG development. The process of CPG development can be summarized in several steps, involving different groups and professionals. This chapter will present each of the points, such as the theme and scope choice, guideline working group, conflict of interest, evidence, and recommendations as well as the quality, implementation, adaptation, and up-to-date of CPGs.
Aim
Maternal pregestational diabetes mellitus (PGDM), type 1 or type 2, has been established as a potential risk factor for congenital heart disease (CHD). At the same time, the correlation between gestational diabetes mellitus (GDM) and increased risk of CHD has not been yet fully elucidated. The objective of this systematic review and meta-analysis (PROSPERO number: CRD42020182390) was to analyze the existing evidence on PGDM and to attempt to fill, to the best of our ability, the remaining knowledge gap in the association of GDM with CHD.
Materials and methods
Two authors have independently searched the Pubmed/Medline, Scopus, Cochrane, Web of Science, and Theses Global databases with keywords and Boolean operators. The search yielded 9333 relevant articles, which were later screened for eligibility. Original peer-reviewed (case-control or cohort) studies were included if they were published in English between 1997 and 2020. Thirteen studies on mothers with PGDM and seven studies on mothers with GDM were finally included in our meta-analysis to investigate the association of maternal diabetes with the risk of delivering a child with CHD. The selected studies were all assessed for their methodological quality using the Newcastle–Ottawa scale. Associations with p < .05 were considered statistically significant.
Results
Our meta-analysis (I² > 75%, total population: n = 12,461,586) of 79,476 women with PGDM and 160,893 with GDM produced an odds ratio of 3.48 (2.36–4.61) and 1.55 (1.48–1.61), respectively. Additionally, we did not find any noticeable difference in the risk for CHD among diabetic women living in the USA and Europe. Nevertheless, it still needs to be clarified, whether or not the gestational diabetic population includes undiagnosed women with preexisting diabetes, which might account for the increased risk of delivering a child with CHD in women classified as suffering from GDM.
Conclusion
While both GDM and PGDM seem to significantly increase the risk of CHD in comparison with the general population, PDGM appears to have a greater association with CHD, being correlated with a 3.5-fold increase in the risk of malformation. Preconceptional and gestational diabetes care are, therefore, essential to mitigate the adverse effect of hyperglycemia on fetal heart formation during pregnancy.
Introduction: The lips and the mouth play an indispensable role in vocalization, mastication and face aesthetics. Various noxious factors may alter and destruct the original structure, and appearance of the lips and the anatomical area surrounding the mouth. The application of hyaluronic acid (HA) may serve as a safe method for lip regeneration. Although a number of studies exist for HA effectiveness and safety, its beneficial effect is not well-established. Aim: The present meta-analysis and systematic review was performed to investigate the effectiveness of HA on lip augmentation. We also investigated the types and nature of adverse effects (AEs) of HA application. Methods: We reported our meta-analysis in accordance with the PRISMA Statement. PROSPERO protocol registration: CRD42018102899. We performed the systematic literature search in CENTRAL, Embase, and MEDLINE. Randomized controlled trials, cohort studies, case series and case reports were included. The untransformed proportion (random-effects, DerSimonian-Laird method) of responder rate to HA injection was calculated. For treatment related AEs descriptive statistics were used. Results: The systematic literature search yielded 32 eligible records for descriptive statistics and 10 records for quantitative synthesis. The results indicated that the overall estimate of responders (percentage of subjects with increased lip fullness by one point or higher) was 91% (ES = 0.91, 95% CI:0.85−0.96) 2 months after injection. The rate of responders was 74% (ES = 0.74, 95% CI:0.66−0.82) and 46% (ES = 0.46, 95% CI:0.28−0.65) after 6 and 12 months, respectively. We included 1,496 participants for estimating the event rates of AEs. The most frequent treatment-related AEs were tenderness (88.8%), injection site swelling (74.3%) and bruising (39.5%). Rare AEs included foreign body granulomas (0.6%), herpes labialis (0.6%) and angioedema (0.3%). Conclusion: Our meta-analysis revealed that lip augmentation with injectable HA is an efficient method for increasing lip fullness for at least up to 6 months after augmentation. Moreover, we found that most AEs of HA treatment were mild or moderate, but a small number of serious adverse effects were also found. In conclusion, further well-designed RCTs are still needed to make the presently available evidence stronger.
Systematic reviews and meta-analyses are essential to summarize evidence relating to efficacy and safety of health care interventions accurately and reliably. The clarity and transparency of these reports, however, is not optimal. Poor reporting of systematic reviews diminishes their value to clinicians, policy makers, and other users.Since the development of the QUOROM (QUality Of Reporting Of Meta-analysis) Statement--a reporting guideline published in 1999--there have been several conceptual, methodological, and practical advances regarding the conduct and reporting of systematic reviews and meta-analyses. Also, reviews of published systematic reviews have found that key information about these studies is often poorly reported. Realizing these issues, an international group that included experienced authors and methodologists developed PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) as an evolution of the original QUOROM guideline for systematic reviews and meta-analyses of evaluations of health care interventions.The PRISMA Statement consists of a 27-item checklist and a four-phase flow diagram. The checklist includes items deemed essential for transparent reporting of a systematic review. In this Explanation and Elaboration document, we explain the meaning and rationale for each checklist item. For each item, we include an example of good reporting and, where possible, references to relevant empirical studies and methodological literature. The PRISMA Statement, this document, and the associated Web site (http://www.prisma-statement.org/) should be helpful resources to improve reporting of systematic reviews and meta-analyses.
Protocols of systematic reviews and meta-analyses allow for planning and documentation of review methods, act as a guard against arbitrary decision making during review conduct, enable readers to assess for the presence of selective reporting against completed reviews, and, when made publicly available, reduce duplication of efforts and potentially prompt collaboration. Evidence documenting the existence of selective reporting and excessive duplication of reviews on the same or similar topics is accumulating and many calls have been made in support of the documentation and public availability of review protocols. Several efforts have emerged in recent years to rectify these problems, including development of an international register for prospective reviews (PROSPERO) and launch of the first open access journal dedicated to the exclusive publication of systematic review products, including protocols (BioMed Central's Systematic Reviews). Furthering these efforts and building on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines, an international group of experts has created a guideline to improve the transparency, accuracy, completeness, and frequency of documented systematic review and meta-analysis protocols-PRISMA-P (for protocols) 2015. The PRISMA-P checklist contains 17 items considered to be essential and minimum components of a systematic review or meta-analysis protocol.This PRISMA-P 2015 Explanation and Elaboration paper provides readers with a full understanding of and evidence about the necessity of each item as well as a model example from an existing published protocol. This paper should be read together with the PRISMA-P 2015 statement. Systematic review authors and assessors are strongly encouraged to make use of PRISMA-P when drafting and appraising review protocols.
© BMJ Publishing Group Ltd 2014.
Objective To assess whether the completeness of reporting of health research is related to journals’ endorsement of reporting guidelines.
Design Systematic review.
Data sources Reporting guidelines from a published systematic review and the EQUATOR Network (October 2011). Studies assessing the completeness of reporting by using an included reporting guideline (termed “evaluations”) (1990 to October 2011; addendum searches in January 2012) from searches of either Medline, Embase, and the Cochrane Methodology Register or Scopus, depending on reporting guideline name.
Study selection English language reporting guidelines that provided explicit guidance for reporting, described the guidance development process, and indicated use of a consensus development process were included. The CONSORT statement was excluded, as evaluations of adherence to CONSORT had previously been reviewed. English or French language evaluations of included reporting guidelines were eligible if they assessed the completeness of reporting of studies as a primary intent and those included studies enabled the comparisons of interest (that is, after versus before journal endorsement and/or endorsing versus non-endorsing journals).
Data extraction Potentially eligible evaluations of included guidelines were screened initially by title and abstract and then as full text reports. If eligibility was unclear, authors of evaluations were contacted; journals’ websites were consulted for endorsement information where needed. The completeness of reporting of reporting guidelines was analyzed in relation to endorsement by item and, where consistent with the authors’ analysis, a mean summed score.
Results 101 reporting guidelines were included. Of 15 249 records retrieved from the search for evaluations, 26 evaluations that assessed completeness of reporting in relation to endorsement for nine reporting guidelines were identified. Of those, 13 evaluations assessing seven reporting guidelines (BMJ economic checklist, CONSORT for harms, PRISMA, QUOROM, STARD, STRICTA, and STROBE) could be analyzed. Reporting guideline items were assessed by few evaluations.
Conclusions The completeness of reporting of only nine of 101 health research reporting guidelines (excluding CONSORT) has been evaluated in relation to journals’ endorsement. Items from seven reporting guidelines were quantitatively analyzed, by few evaluations each. Insufficient evidence exists to determine the relation between journals’ endorsement of reporting guidelines and the completeness of reporting of published health research reports. Journal editors and researchers should consider collaborative prospectively designed, controlled studies to provide more robust evidence.
Systematic review registration Not registered; no known register currently accepts protocols for methodology systematic reviews.
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.
High quality protocols facilitate proper conduct, reporting, and external review of clinical trials. However, the completeness of trial protocols is often inadequate. To help improve the content and quality of protocols, an international group of stakeholders developed the SPIRIT 2013 Statement (Standard Protocol Items: Recommendations for Interventional Trials). The SPIRIT Statement provides guidance in the form of a checklist of recommended items to include in a clinical trial protocol.
This SPIRIT 2013 Explanation and Elaboration paper provides important information to promote full understanding of the checklist recommendations. For each checklist item, we provide a rationale and detailed description; a model example from an actual protocol; and relevant references supporting its importance. We strongly recommend that this explanatory paper be used in conjunction with the SPIRIT Statement. A website of resources is also available (www.spirit-statement.org).
The SPIRIT 2013 Explanation and Elaboration paper, together with the Statement, should help with the drafting of trial protocols. Complete documentation of key trial elements can facilitate transparency and protocol review for the benefit of all stakeholders.
Objective.
—To examine the temporal relationship between accumulating data from randomized control trials of treatments for myocardial infarction and the recommendations of clinical experts writing review articles and textbook chapters.Data Sources.
—(1) MEDLINE search from 1966 to present; search terms used were myocardial infarction, clinical trials, multicenter studies, double-blind method, meta-analysis, and the text word "random:"; (2) references from pertinent articles and books; and (3) all editions of English-language general medical texts and manuals and review articles on treatment of myocardial infarction.Study Selection.
—Randomized control trials of therapies for reducing the risk of total mortality in myocardial infarction (acute and secondary prevention). Review articles and textbook chapters dealing with the general clinical management of patients with myocardial infarction.Data Extraction.
—Two authors read the material and recorded the results; disagreements were resolved by conference.Data Synthesis.
—We used the technique of cumulative meta-analysis (performing a new meta-analysis when the results of a new clinical trial are published) and compared the results with the recommendations of the experts for various treatments for myocardial infarction. Discrepancies were detected between the meta-analytic patterns of effectiveness in the randomized trials and the recommendations of reviewers. Review articles often failed to mention important advances or exhibited delays in recommending effective preventive measures. In some cases, treatments that have no effect on mortality or are potentially harmful continued to be recommended by several clinical experts.Conclusions.
—Finding and analyzing all therapeutic trials in a given field has become such a difficult and specialized task that the clinical experts called on to summarize the evidence in a timely fashion need access to better databases and new statistical techniques to assist them in this important task.(JAMA. 1992;268:240-248)
Background:
Systematic reviews may be compromised by selective inclusion and reporting of outcomes and analyses. Selective inclusion occurs when there are multiple effect estimates in a trial report that could be included in a particular meta-analysis (e.g. from multiple measurement scales and time points) and the choice of effect estimate to include in the meta-analysis is based on the results (e.g. statistical significance, magnitude or direction of effect). Selective reporting occurs when the reporting of a subset of outcomes and analyses in the systematic review is based on the results (e.g. a protocol-defined outcome is omitted from the published systematic review).
Objectives:
To summarise the characteristics and synthesise the results of empirical studies that have investigated the prevalence of selective inclusion or reporting in systematic reviews of randomised controlled trials (RCTs), investigated the factors (e.g. statistical significance or direction of effect) associated with the prevalence and quantified the bias.
Search methods:
We searched the Cochrane Methodology Register (to July 2012), Ovid MEDLINE, Ovid EMBASE, Ovid PsycINFO and ISI Web of Science (each up to May 2013), and the US Agency for Healthcare Research and Quality (AHRQ) Effective Healthcare Program's Scientific Resource Center (SRC) Methods Library (to June 2013). We also searched the abstract books of the 2011 and 2012 Cochrane Colloquia and the article alerts for methodological work in research synthesis published from 2009 to 2011 and compiled in Research Synthesis Methods.
Selection criteria:
We included both published and unpublished empirical studies that investigated the prevalence and factors associated with selective inclusion or reporting, or both, in systematic reviews of RCTs of healthcare interventions. We included empirical studies assessing any type of selective inclusion or reporting, such as investigations of how frequently RCT outcome data is selectively included in systematic reviews based on the results, outcomes and analyses are discrepant between protocol and published review or non-significant outcomes are partially reported in the full text or summary within systematic reviews.
Data collection and analysis:
Two review authors independently selected empirical studies for inclusion, extracted the data and performed a risk of bias assessment. A third review author resolved any disagreements about inclusion or exclusion of empirical studies, data extraction and risk of bias. We contacted authors of included studies for additional unpublished data. Primary outcomes included overall prevalence of selective inclusion or reporting, association between selective inclusion or reporting and the statistical significance of the effect estimate, and association between selective inclusion or reporting and the direction of the effect estimate. We combined prevalence estimates and risk ratios (RRs) using a random-effects meta-analysis model.
Main results:
Seven studies met the inclusion criteria. No studies had investigated selective inclusion of results in systematic reviews, or discrepancies in outcomes and analyses between systematic review registry entries and published systematic reviews. Based on a meta-analysis of four studies (including 485 Cochrane Reviews), 38% (95% confidence interval (CI) 23% to 54%) of systematic reviews added, omitted, upgraded or downgraded at least one outcome between the protocol and published systematic review. The association between statistical significance and discrepant outcome reporting between protocol and published systematic review was uncertain. The meta-analytic estimate suggested an increased risk of adding or upgrading (i.e. changing a secondary outcome to primary) when the outcome was statistically significant, although the 95% CI included no association and a decreased risk as plausible estimates (RR 1.43, 95% CI 0.71 to 2.85; two studies, n = 552 meta-analyses). Also, the meta-analytic estimate suggested an increased risk of downgrading (i.e. changing a primary outcome to secondary) when the outcome was statistically significant, although the 95% CI included no association and a decreased risk as plausible estimates (RR 1.26, 95% CI 0.60 to 2.62; two studies, n = 484 meta-analyses). None of the included studies had investigated whether the association between statistical significance and adding, upgrading or downgrading of outcomes was modified by the type of comparison, direction of effect or type of outcome; or whether there is an association between direction of the effect estimate and discrepant outcome reporting.Several secondary outcomes were reported in the included studies. Two studies found that reasons for discrepant outcome reporting were infrequently reported in published systematic reviews (6% in one study and 22% in the other). One study (including 62 Cochrane Reviews) found that 32% (95% CI 21% to 45%) of systematic reviews did not report all primary outcomes in the abstract. Another study (including 64 Cochrane and 118 non-Cochrane reviews) found that statistically significant primary outcomes were more likely to be completely reported in the systematic review abstract than non-significant primary outcomes (RR 2.66, 95% CI 1.81 to 3.90). None of the studies included systematic reviews published after 2009 when reporting standards for systematic reviews (Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) Statement, and Methodological Expectations of Cochrane Intervention Reviews (MECIR)) were disseminated, so the results might not be generalisable to more recent systematic reviews.
Authors' conclusions:
Discrepant outcome reporting between the protocol and published systematic review is fairly common, although the association between statistical significance and discrepant outcome reporting is uncertain. Complete reporting of outcomes in systematic review abstracts is associated with statistical significance of the results for those outcomes. Systematic review outcomes and analysis plans should be specified prior to seeing the results of included studies to minimise post-hoc decisions that may be based on the observed results. Modifications that occur once the review has commenced, along with their justification, should be clearly reported. Effect estimates and CIs should be reported for all systematic review outcomes regardless of the results. The lack of research on selective inclusion of results in systematic reviews needs to be addressed and studies that avoid the methodological weaknesses of existing research are also needed.
