Dataset Information

A descriptive analysis of overviews of reviews published between 2000 and 2011.

ABSTRACT:

Background

Overviews of systematic reviews compile data from multiple systematic reviews (SRs) and are a new method of evidence synthesis.

Objectives

To describe the methodological approaches in overviews of interventions.

Design

Descriptive study.

Methods

We searched 4 databases from 2000 to July 2011; we handsearched Evidence-based Child Health: A Cochrane Review Journal. We defined an overview as a study that: stated a clear objective; examined an intervention; used explicit methods to identify SRs; collected and synthesized outcome data from the SRs; and intended to include only SRs. We did not restrict inclusion by population characteristics (e.g., adult or children only). Two researchers independently screened studies and applied eligibility criteria. One researcher extracted data with verification by a second. We conducted a descriptive analysis.

Results

From 2,245 citations, 75 overviews were included. The number of overviews increased from 1 in 2000 to 14 in 2010. The interventions were pharmacological (n?=?20, 26.7%), non-pharmacological (n?=?26, 34.7%), or both (n?=?29, 38.7%). Inclusion criteria were clearly stated in 65 overviews. Thirty-three (44%) overviews searched at least 2 databases. The majority reported the years and databases searched (n?=?46, 61%), and provided key words (n?=?58, 77%). Thirty-nine (52%) overviews included Cochrane SRs only. Two reviewers independently screened and completed full text review in 29 overviews (39%). Methods of data extraction were reported in 45 (60%). Information on quality of individual studies was extracted from the original SRs in 27 (36%) overviews. Quality assessment of the SRs was performed in 28 (37%) overviews; at least 9 different tools were used. Quality of the body of evidence was assessed in 13 (17%) overviews. Most overviews provided a narrative or descriptive analysis of the included SRs. One overview conducted indirect analyses and the other conducted mixed treatment comparisons. Publication bias was discussed in 18 (24%) overviews.

Conclusions

This study shows considerable variation in the methods used for overviews. There is a need for methodological rigor and consistency in overviews, as well as empirical evidence to support the methods employed.

SUBMITTER: Hartling L

PROVIDER: S-EPMC3499476 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

A descriptive analysis of overviews of reviews published between 2000 and 2011.

Hartling Lisa L Chisholm Annabritt A Thomson Denise D Dryden Donna M DM

PloS one 20121115 11

<h4>Background</h4>Overviews of systematic reviews compile data from multiple systematic reviews (SRs) and are a new method of evidence synthesis.<h4>Objectives</h4>To describe the methodological approaches in overviews of interventions.<h4>Design</h4>Descriptive study.<h4>Methods</h4>We searched 4 databases from 2000 to July 2011; we handsearched Evidence-based Child Health: A Cochrane Review Journal. We defined an overview as a study that: stated a clear objective; examined an intervention; us ...[more]

PMID: 23166744

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Project description:BACKGROUND:Consumers, clinicians, policymakers and researchers require high quality evidence to guide decision-making in child health. Though Cochrane systematic reviews (SRs) are a well-established source of evidence, little is known about the characteristics of non-Cochrane child-relevant SRs. To complement published descriptions of Cochrane SRs, we aimed to characterize the epidemiologic, methodological, and reporting qualities of non-Cochrane child-relevant SRs published in 2014. METHODS:English-language child-relevant SRs of quantitative primary research published outside the Cochrane Library in 2014 were eligible for this descriptive analysis. A research librarian searched MEDLINE, CINAHL, Web of Science, and PubMed in August 2015. A single reviewer screened articles for inclusion; a second verified the excluded studies. Reviewers extracted: general characteristics of the review; included study characteristics; methodological approaches. We performed univariate analyses and presented the findings narratively. RESULTS:We identified 1598 child-relevant SRs containing a median (IQR) 19 (11, 33) studies. These originated primarily from high-income countries (n?=?1247, 78.0%) and spanned 47 of the 53 Cochrane Review Groups. Most synthesized therapeutic (n?=?753, 47.1%) or epidemiologic (n?=?701, 43.8%) evidence. Though 39.3% (n?=?628) of SRs included evidence related to children only, few were published in pediatric-specific journals (n?=?283, 17.7%). Reporting quality seemed poor based on the items we assessed; few reviews mentioned an a-priori protocol (n?=?246, 15.4%) or registration (n?=?111, 6.9%), and only 23.4% (n?=?374) specified a primary outcome. Many SRs relied solely on evidence from non-RCTs (n?=?796, 49.8%). Less than two-thirds (n?=?953, 59.6%) appraised the quality of included studies and assessments of the certainty of the body of evidence were rare (n?=?102, 6.4%). CONCLUSIONS:Child-relevant Cochrane SRs are a known source of high quality evidence in pediatrics. There exists, however, an abundance of evidence from non-Cochrane SRs that may be complementary. Our findings show that high-quality non-Cochrane SRs may not be practical nor easy for knowledge users to find. Improvements are needed to ensure that evidence syntheses published outside of the Cochrane Library adhere to the high standard of conduct and reporting characteristic of Cochrane SRs.

Project description:OBJECTIVES: To identify all systematic reviews (SRs) published in the domain of oral health research and describe them in terms of their epidemiological and descriptive characteristics. DESIGN: Cross sectional, descriptive study. METHODS: An electronic search of seven databases was performed from inception through May 2012; bibliographies of relevant publications were also reviewed. Studies were considered for inclusion if they were oral health SRs defined as therapeutic or non-therapeutic investigations that studied a topic or an intervention related to dental, oral or craniofacial diseases/disorders. Data were extracted from all the SRs based on a number of epidemiological and descriptive characteristics. Data were analysed descriptively for all the SRs, within each of the nine dental specialities, and for Cochrane and non-Cochrane SRs separately. RESULTS: 1,188 oral health (126 Cochrane and 1062 non-Cochrane) SRs published from 1991 through May 2012 were identified, encompassing the nine dental specialties. Over half (n?=?676; 56.9%) of the SRs were published in specialty oral health journals, with almost all (n?=?1,178; 99.2%) of the SRs published in English and almost none of the non-Cochrane SRs (n?=?11; 0.9%) consisting of updates of previously published SRs. 75.3% of the SRs were categorized as therapeutic, with 64.5% examining non-drug interventions, while approximately half (n?=?150/294; 51%) of the non-therapeutic SRs were classified as epidemiological SRs. The SRs included a median of 15 studies, with a meta-analysis conducted in 43.6%, in which a median of 9 studies/1 randomized trial were included in the largest meta-analysis conducted. Funding was received for 25.1% of the SRs, including nearly three-quarters (n?=?96; 76.2%) of the Cochrane SRs. CONCLUSION: Epidemiological and descriptive characteristics of the 1,188 oral health SRs varied across the nine dental specialties and by SR category (Cochrane vs. non-Cochrane). There is a clear need for more updates of SRs in all the dental specialties.

Project description:Previous research shows that many authors of Cochrane overviews were also involved in some of the included systematic reviews (SRs). This type of dual (co-)authorship (DCA) may be a conflict of interest and a potential source of bias. Our objectives were to (1) additionally investigate DCA in non-Cochrane overviews; (2) investigate whether there is an association between DCA and quality assessments of SRs in Cochrane and non-Cochrane overviews.We selected a sample of Cochrane (n =?20) and non-Cochrane (n =?78) overviews for analysis. We extracted data on the number of reviews affected by DCA and whether quality assessment of included reviews was conducted independently. Differences in mean quality scores between SRs with and without DCA were calculated in each overview. These differences were standardized (using the standardized mean difference (SMD)) and meta-analyzed using a random effects model.Forty out of 78 non-Cochrane overviews (51%) and 18 out of 20 Cochrane overviews (90%) had included at least one SR with DCA. For Cochrane overviews, a median of 5 [interquartile range (IQR) 2.5 to 7] SRs were affected by DCA (median of included reviews 10). For non-Cochrane overviews a median of 1 [IQR 0 to 2] of the included SRs were affected (median of included reviews 14). The meta-analysis showed a SMD of 0.58 (95% confidence interval (CI) 0.27 to 0.90) indicating higher quality scores in reviews with overlapping authors. The test for subgroup differences shows no evidence of a difference between Cochrane (SMD 0.44; 95% CI 0.07 to 0.81) and non-Cochrane overviews (SMD 0.62; 95% CI 0.06 to 1.17).Many authors of overviews also often have an authorship on one or more of the underlying reviews. Our analysis shows that, on average, authors of overviews give higher quality ratings to SRs in which they were involved themselves than to other SRs. Conflict of interest is one explanation, but there are several others such as reviewer expertise. Independent and blinded reassessments of the reviews would provide more robust evidence on potential bias arising from DCA.

Project description:BackgroundOverviews often identify and synthesise a large number of systematic reviews on the same topic, which is likely to lead to overlap (i.e. duplication) in primary studies across the reviews. Using a primary study result multiple times in the same analysis overstates its sample size and number of events, falsely leading to greater precision in the analysis. This paper aims to: (a) describe types of overlapping data that arise from the same primary studies reported across multiple reviews, (b) describe methods to identify and explain overlap of primary study data, and (c) present six case studies illustrating different approaches to manage overlap.MethodsWe first updated the search in PubMed for methods from the MOoR framework relating to overlap of primary studies. One author screened the studies titles and abstracts, and any full-text articles retrieved, extracted methods data relating to overlap of primary studies and mapped it to the overlap methods from the MOoR framework. We also describe six case studies as examples of overviews that use specific overlap methods across the steps in the conduct of an overview. For each case study, we discuss potential methodological implications in terms of limitations, efficiency, usability, and resource use.ResultsNine methods studies were found and mapped to the methods identified by the MOoR framework to address overlap. Overlap methods were mapped across four steps in the conduct of an overview - the eligibility criteria step, the data extraction step, the assessment of risk of bias step, and the synthesis step. Our overview case studies used multiple methods to reduce overlap at different steps in the conduct of an overview.ConclusionsOur study underlines that there is currently no standard methodological approach to deal with overlap in primary studies across reviews. The level of complexity when dealing with overlap can vary depending on the yield, trends and patterns of the included literature and the scope of the overview question. Choosing a method might be dependent on the number of included reviews and their primary studies. Gaps in evaluation of methods to address overlap were found and further investigation in this area is needed.

Project description:BackgroundSystematic reviews support health systems and clinical decision-making by identifying and summarizing all existing studies on a particular topic. In 2009, a comprehensive description of child-relevant systematic reviews published in the Cochrane Database of Systematic Reviews was compiled. This study aims to provide an update, and to describe these systematic reviews according to their content and methodological approaches.MethodsAll child-relevant systematic reviews published by the Cochrane Collaboration in the Cochrane Database of Systematic Reviews (CDSR) as of March, 2013 were identified and described in relation to their content and methodological approaches. This step equated to an update of the Child Health Field Review Register (CHFRR). The content of the updated CHFRR was compared to the published 2009 CHFRR description regarding clinical and methodological characteristics, using bivariate analyses. As the Cochrane Collaboration has recognized that disease burden should guide research prioritization, we extracted data from the Global and National Burden of Diseases and Injuries Among Children and Adolescents Between 1990 and 2013 study in order to map the distribution of the burden of disease in child health to the distribution of evidence across Review Groups in the CHFRR.ResultsOf the 5,520 potential Cochrane systematic reviews identified, 1,293 (23.4%) were child-relevant (an increase of 24% since 2009). Overall, these reviews included 16,738 primary studies. The most commonly represented Review Groups were Airways (11.5%), Cystic Fibrosis and Genetic Diseases (7.9%), Acute Respiratory Infections (7.8%), Developmental, Psychological and Learning Problems (6.7%), and Infectious Diseases (6.2%). Corresponding authors were most often from Europe (51%), North America (15%), and Australia (15%). The majority of systematic reviews examined pharmacological interventions alone (52% compared to 59% in 2009). Out of 611 reviews that were assessed as up-to-date, GRADE was used in 204 (35%) reviews to assess the overall quality of the evidence, which was often moderate (35.6%) or low (37.8%) for primary outcomes. Ninety percent of reviews that were assessed as up to date used the Cochrane Risk of Bias tool, or a modified version, to assess methodological quality. Most reviews conducted one or more meta-analyses (73%). Among the 25 leading causes of death globally, the Review Groups associated with the largest number of causes were: 1) Infectious Diseases, 2) Anaesthesia, Critical, and Emergency Care, 3) Injuries, 4) Pregnancy and Childbirth (PC), and 5) Neonatal. There were large discrepancies between the number of causes of mortality that each Review Group was associated with and the total amount of evidence each Review Group contributed to the CHFRR. Ninety-eight percent of the causes of mortality in 2013 were from developing nations, but only 224 (17.3%) reviews had corresponding authors from developing countries.ConclusionThe content and methodological characteristics of child-relevant systematic reviews in the Cochrane CHFRR have been described in detail. There were modest advances in methods between 2009 and 2013. Systematic reviews contained in the CDSR offer an important resource for researcher's, clinicians and policy makers by synthesizing an extensive body of primary research. Further content analysis will allow the identification of clinical topics of greatest priority for future systematic reviews in child health.

Dataset Information

A descriptive analysis of overviews of reviews published between 2000 and 2011.

Background

Objectives

Design

Methods

Results

Conclusions

Publications

A descriptive analysis of overviews of reviews published between 2000 and 2011.

Similar Datasets

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