Evidence mapping: methodologic foundations and application to intervention and observational research on sugar-sweetened beverages and health outcomes

Diet-Related and Gut-Derived Metabolites and Health Outcomes: A Scoping Review

We conducted a scoping review to map available evidence about the health impact of gut microbiota-derived metabolites. We searched PubMed and Embase for studies that assessed the health impact of ten metabolites on any health condition: deoxycholate or deoxycholic acid (DCA), lithocholate or lithocholic acid (LCA), glycolithocholate or glycolithocholic acid, glycodeoxycholate or glycodeoxycholic acid, tryptamine, putrescine, d-alanine, urolithins, N-acetylmannosamine, and phenylacetylglutamine. We identified 352 eligible studies with 168,072 participants. Most (326, 92.6%) were case-control studies, followed by cohort studies (14, 4.0%), clinical trials (8, 2.3%), and cross-sectional studies (6, 1.7%). Most studies assessed the following associations: DCA on hepatobiliary disorders (64 studies, 7976 participants), colorectal cancer (19 studies, 7461 participants), and other digestive disorders (27 studies, 2463 participants); LCA on hepatobiliary disorders (34 studies, 4297 participants), colorectal cancers (14 studies, 4955 participants), and other digestive disorders (26 studies, 2117 participants); putrescine on colorectal cancers (16 studies, 94,399 participants) and cancers excluding colorectal and hepatobiliary cancers (42 studies, 4250 participants). There is a need to conduct more prospective studies, including clinical trials. Moreover, we identified metabolites and conditions for which systemic reviews are warranted to characterize the direction and magnitude of metabolite-disease associations.

Effectiveness of reminiscence therapy interventions for older people: Evidence mapping and qualitative evaluation

WHAT IS KNOWN ON THE SUBJECT?: Reminiscence therapy is a common psychosocial intervention in mental health nursing. Numerous secondary studies have explored the effects of reminiscence therapy interventions in older adults, and while the effects are significant, conflicting results remain. WHAT THIS PAPER ADDS TO EXISTING KNOWLEDGE?: To date, research on reminiscence therapy has examined different disorders in isolation from one another. By illustrating the evidence gaps between studies, this paper highlights the need for a new evidence-based summary overview of reminiscence therapy research. The results suggest that reminiscence therapy can be beneficial to the improvement of mental health and quality of life for older people. However, we found that the secondary studies were not of high quality and that further high-quality literature supporting the evidence is still needed. WHAT ARE THE IMPLICATION FOR PRACTICE?: Reminiscence therapy may be considered a useful non-pharmacological intervention for older people with mental and psychological problems. However, there is a lack of normative guidelines for reminiscence therapy in terms of intervention time, frequency, and form. The development of a global standard protocol for the application of reminiscence therapy may be necessary for future randomized controlled trials (RCTs).

ABSTRACT

INTRODUCTION: Reminiscence therapy is an alternative to pharmaceutical intervention provided during long-term care, especially for older people with mental and psychological problems. However, the effects of reminiscence therapy remain inconclusive.

AIM

The present study aimed to systematically identify, synthesize and describe the research evidence and quality of systematic reviews (SRs) related to reminiscence interventions for older people through an evidence-mapping approach.

METHODS

Commonly used English and Chinese databases, including PubMed, EMBASE, The Cochrane Library, Web of Science, CNKI, WANFANG, VIP and SinoMed, were searched from inception till 31 March 2022. The study type was restricted to SRs with or without meta-analysis. The methodological quality of the included SRs was assessed by A Measurement Tool to Assess Systematic Reviews (AMSTAR-2). The Microsoft Excel 2019 tool was used for data extraction and coding, and bubble charts were used to synthesize information on the study population, intervention category, original study sample size and classification of findings.

RESULTS

A total of 28 SRs were enrolled, including 514 original studies, 91.4% of which were randomized controlled trials. The main participants of the study were depressed older people (7 publications), older people with dementia (10 publications) and ordinary older people (8 publications). The findings of 26 (92.8%) publications were categorized as either "beneficial" or "potentially beneficial." The primary outcome indicators of the effectiveness of the reminiscence intervention for older people are mental and psychological problems (especially depressive symptoms and cognitive functioning), quality of life and categories of positive psychology (e.g., life satisfaction, happiness and self-esteem). The main factors influencing the intervention effect were the intervention period, residential setting, intervention format (group/individual) and intervention intensity. The intervention settings/contexts were mainly community and long-term care facilities. However, the methodological quality of 27 (96.4%) of the SRs was scored as either "Low" or "Critically Low."

DISCUSSION

Reminiscence therapy has been used to study the mental health and quality of life of older people in various conditions, with significant results. However, due to the limited evidence included in the studies and the low methodological quality, there is still a need to focus on the issue of effectiveness and evidence gaps for different interventions in the field of recall in the future, in addition to efforts to improve the methodological quality and standardize the reporting process for the evaluation of reminiscence intervention systems.

IMPLICATIONS FOR PRACTICE

Reminiscence therapy may be considered a useful non-pharmacological intervention for older people with mental and psychological problems. A standard protocol for reminiscence therapy may be necessary for future studies.

Overview of Cochrane Systematic Reviews of Rehabilitation Interventions for Persons with Traumatic Brain Injury: A Mapping Synthesis

Background: The World Health Organization has identified an unmet global need for rehabilitation interventions concerning 20 non-communicable diseases, traumatic brain injury included. This overview compiles and synthesizes the quality and quantity of available evidence on the effectiveness of rehabilitation interventions for traumatic brain injury from Cochrane systematic reviews (CSRs). The results will be used to develop the Package of Interventions for Rehabilitation. Methods: All CSRs on TBI tagged in the Cochrane Rehabilitation database published between August 2009 and September 2021 were included. Evidence mapping was implemented to extract study characteristics and evidence from the CSRs. Results: Six CSRs (42 studies; n = 3983) examined the effectiveness of either non-pharmacological or pharmacological interventions after TBI. Among 19 comparisons, 3% were rated as high in quality of evidence, 9% moderate, 54% low, and 34% very low. Non-pharmacological interventions with moderate quality, hospital-based cognitive rehabilitation and cognitive didactic therapy, likely produced minimal to no changes in the return-to-work rate. Anti-epileptic drugs and neuroprotective agents resulted in a minimal difference to the frequency of late seizure episodes in post-traumatic epilepsy. Conclusions: No prominent advances in treatment options were reported in any of the CSRs. The high rate of low and very low quality of evidence makes it difficult to ascertain the effectiveness of several recommended non-pharmacological interventions.

Impact of cardiovascular evaluations and interventions on fall risk in older adults: a protocol for a scoping review and evidence map

INTRODUCTION

Cardiovascular disorders are increasingly recognised as important fall risk factors in older adults. Falls are a major public health problem in older adults, and therefore, effective interventions for reducing falls are essential for this population. Cardiovascular disease is a clinically relevant (but often overlooked) and potentially modifiable risk factor for falls. Literature describing the effects of cardiovascular assessments and treatments on fall prevention has generally focused on only one specific test or treatment. A comprehensive, comparative overview surrounding the effectiveness of available assessments and treatments on cardiovascular related fall risk is currently lacking.

METHODS AND ANALYSIS

A scoping review and evidence map will be conducted to summarise the available evidence regarding the (comparative) effectiveness of cardiovascular assessments and therapeutic interventions on reducing fall risk in older individuals. A systematic and comprehensive literature search will be performed in MEDLINE and Embase using the key components 'older adults', 'cardiovascular evaluation', 'cardiovascular intervention' and 'falls'. Furthermore, we will create an evidence map to summarise the quantity and quality of currently available evidence identified in the scoping review. The evidence map will consider, but will not be limited to, observational studies, randomised controlled trials and reviews evaluating cardiovascular tests and treatments (vs controls) on fall risk in older adults.

ETHICS AND DISSEMINATION

The scoping review and evidence map will only include data that are publicly available and, therefore, ethical approval is not required. The results will be submitted for publication in a peer-reviewed journal and presented at scientific conferences.

Impact of Measures Aiming to Reduce Sugars Intake in the General Population and Their Implementation in Europe: A Scoping Review

Objectives: Implementing public health measures is necessary to decrease sugars intake, which is associated with increased risk of noncommunicable diseases. Our scoping review aimed to identify the types of measures implemented and evaluated to decrease sugars intake in the population and to assess their impact.

Methods: Following a review of systematic reviews (SRs) published in 2018, we systematically searched new SR (May 2017–October 2020) in electronic databases. We also searched the measures implemented in Europe in the NOURISHING database. Two researchers selected the reviews, extracted and analysed the data.

Results: We included 15 SRs assessing economic tools (n = 5), product reformulation and labels/claims (n = 5), and educational/environmental interventions (n = 7). Economic tools, product reformulation and environmental measures were effective to reduce sugar intake or weight outcomes, while labels, education and interventions combining educational and environmental measures found mixed effects. The most frequently implemented measures in Europe were public awareness, nutritional education, and labels.

Conclusion: Among measures to reduce sugar intake in the population, economic tools, product reformulation, and environmental interventions were the most effective, but not the more frequently implemented in Europe.

Dose-response association between sugar- and artificially sweetened beverage consumption and the risk of metabolic syndrome: a meta-analysis of population-based epidemiological studies

OBJECTIVE

The associations between sugar-sweetened beverage (SSB) and artificially sweetened beverage (ASB) consumption and the risk of metabolic syndrome (MetS) remain controversial. A quantitative assessment of dose-response associations has not been reported. This study aims to assess the associations between the risk of MetS and SSB, ASB, and total sweetened beverage (TSB, the combination of SSB and ASB) consumption by reviewing population-based epidemiological studies.

DESIGN

Meta-analysis.

SETTING

We searched PubMed, Embase and Web of Science databases prior to 4 November 2019, for relevant studies investigating the SSB-MetS and ASB-MetS associations. A random effects model was used to estimate pooled relative risks (RR) and 95 % CI. Dose-response association was assessed using a restricted cubic splines model.

PARTICIPANTS

We identified seventeen articles (twenty-four studies, including 93 095 participants and 20 749 MetS patients).

RESULTS

The pooled RR for the risk of MetS were 1·51 (95 % CI 1·34, 1·69), 1·56 (1·32, 1·83) and 1·44 (1·19, 1·75) in high consumption group of TSB, SSB and ASB, respectively; and 1·20 (1·13, 1·28), 1·19 (1·11, 1·28) and 1·31 (1·05, 1·65) per 250 ml/d increase in TSB, SSB and ASB consumption, respectively. Additionally, we found evidence of non-linear, TSB-MetS and SSB-MetS dose-response associations and a linear ASB-MetS dose-response association.

CONCLUSIONS

TSB, SSB and ASB consumption was associated with the risk of MetS. The present findings provide evidence that supports reducing intake of these beverages to lower the TSB-, SSB- and ASB-related risk of MetS.

Digital tools for the recruitment and retention of participants in randomised controlled trials: a systematic map

BACKGROUND

Recruiting and retaining participants in randomised controlled trials (RCTs) is challenging. Digital tools, such as social media, data mining, email or text-messaging, could improve recruitment or retention, but an overview of this research area is lacking. We aimed to systematically map the characteristics of digital recruitment and retention tools for RCTs, and the features of the comparative studies that have evaluated the effectiveness of these tools during the past 10 years.

METHODS

We searched Medline, Embase, other databases, the Internet, and relevant web sites in July 2018 to identify comparative studies of digital tools for recruiting and/or retaining participants in health RCTs. Two reviewers independently screened references against protocol-specified eligibility criteria. Included studies were coded by one reviewer with 20% checked by a second reviewer, using pre-defined keywords to describe characteristics of the studies, populations and digital tools evaluated.

RESULTS

We identified 9163 potentially relevant references, of which 104 articles reporting 105 comparative studies were included in the systematic map. The number of published studies on digital tools has doubled in the past decade, but most studies evaluated digital tools for recruitment rather than retention. The key health areas investigated were health promotion, cancers, circulatory system diseases and mental health. Few studies focussed on minority or under-served populations, and most studies were observational. The most frequently-studied digital tools were social media, Internet sites, email and tv/radio for recruitment; and email and text-messaging for retention. One quarter of the studies measured efficiency (cost per recruited or retained participant) but few studies have evaluated people's attitudes towards the use of digital tools.

CONCLUSIONS

This systematic map highlights a number of evidence gaps and may help stakeholders to identify and prioritise further research needs. In particular, there is a need for rigorous research on the efficiency of the digital tools and their impact on RCT participants and investigators, perhaps as studies-within-a-trial (SWAT) research. There is also a need for research into how digital tools may improve participant retention in RCTs which is currently underrepresented relative to recruitment research.

REGISTRATION

Not registered; based on a pre-specified protocol, peer-reviewed by the project's Advisory Board.

Using Evidence Mapping to Examine Motivations for Following Plant-Based Diets

Motivations to adopt plant-based diets are of great public health interest. We used evidence mapping to identify methods that capture motivations to follow plant-based diets and summarize demographic trends in dietary motivations. We identified 56 publications that described 90 samples of plant-based diet followers and their dietary motivations. We categorized the samples by type of plant-based diet: vegan (19%), vegetarian (33%), semivegetarian (24%), and other, unspecified plant-based diet followers (23%). Of 90 studies examined, 31% administered multiple-choice questions to capture motivations, followed by rate items (23%), Food Choice Questionnaire (17%), free response (9%), and rank choices (10%). Commonly reported motivations were health, sensory/taste/disgust, animal welfare, environmental concern, and weight loss. The methodological variation highlights the importance of using a structured questionnaire to investigate dietary motivations in epidemiological studies. Motivations among plant-based diet followers appear distinct, but evidence on the association between age and motivations appears limited.

A scoping review describes methods used to identify, prioritize and display gaps in health research

BACKGROUND AND OBJECTIVES

Different methods to examine research gaps have been described, but there are still no standard methods for identifying, prioritizing, or reporting research gaps. This study aimed to describe the methods used to identify, prioritize, and display gaps in health research.

METHODS

A scoping review using the Arksey and O'Malley methodological framework was carried out. We included all study types describing or reporting on methods to identify, prioritize, and display gaps or priorities in health research. Data synthesis is both quantitative and qualitative.

RESULTS

Among 1,938 identified documents, 139 articles were selected for analysis; 90 (65%) aimed to identify gaps, 23 (17%) aimed to determine research priorities, and 26 (19%) had both aims. The most frequent methods in the review were aimed at gap identification and involved secondary research, which included knowledge synthesis (80/116 articles, 69%), specifically systematic reviews and scoping reviews (58/80, 73%). Among 49 studies aimed at research prioritization, the most frequent methods were both primary and secondary research, accounting for 24 (49%) reports. Finally, 52 (37%) articles described methods for displaying gaps and/or priorities in health research.

CONCLUSION

This study provides a mapping of different methods used to identify, prioritize, and display gaps or priorities in health research.

Evaluating Whole Grain Intervention Study Designs and Reporting Practices Using Evidence Mapping Methodology

Consumption of whole grains have been associated with reduced risk of chronic diseases in many observational studies; yet, results of intervention studies are mixed. We aimed to use evidence mapping to capture the methodological and reporting variability in whole grain intervention studies that may contribute to this inconsistency. We conducted a reproducible search in OVID Medline for whole grain human intervention studies (published 1946 to February 2018). After screening based on a priori criteria, we identified 202 publications describing a total of 213 unique trials. Over half (55%) were acute trials, lasting ≤1 day, 30% were moderate duration studies (up to 6 weeks) and 15% were of longer duration (more than 6 weeks). The majority of acute trials (75%) examined measures of glycaemia and/or insulinemia, while most of the longer trials included measures of cardiometabolic health (71%), appetite/satiety (57%) and weight/adiposity (56%). Among the moderate and long duration trials, there was a wide range of how whole grains were described but only 10 publications referenced an established definition. Only 55% of trials reported the actual amount of whole grains (in grams or servings), while 36% reported the amount of food/product and 9% did not report a dose at all. Of the interventions that provided a mixture of whole grains, less than half (46%) reported the distribution of the different grain types. Reporting of subject compliance also varied and only 22% used independent biomarkers of whole grain intake. This evidence map highlights the need to standardize both study protocols and reporting practices to support effective synthesis of study results and provide a stronger foundation to better inform nutrition scientists and public health policy.

Gaps in the Evidence on Population Interventions to Reduce Consumption of Sugars: A Review of Reviews

There is currently considerable attention directed to identifying promising interventions to reduce consumption of sugars among populations around the world. A review of systematic reviews was conducted to identify gaps in the evidence on such interventions. Medline, EMBASE CINAHL, and the Cochrane Database of Systematic Reviews were searched to identify systematic reviews published in English from January 2005 to May 2017 and considering research on interventions to reduce sugar intake. Twelve systematic reviews that considered price changes, interventions to alter the food available within specific environments, and health promotion and education programs were examined. Each of the identified reviews focused on sugar-sweetened beverages (SSBs). The existing literature provides some promising indications in terms of the potential of interventions to reduce SSB consumption among populations. However, a common thread is the limited scope of available evidence, combined with the heterogeneity of methods and measures used in existing studies, which limits conclusions that can be reached regarding the effectiveness of interventions. Reviewed studies typically had limited follow-up periods, making it difficult to assess the sustainability of effects. Further, there is a lack of studies that address the complex context within which interventions are implemented and evaluated, and little is known about the cost-effectiveness of interventions. Identified gaps speak to the need for a more holistic approach to sources of sugars beyond SSBs, consensus on measures and methods, attention to the implementation of interventions in relation to context, and careful monitoring to identify intended and unintended consequences.

Dietary Fiber and the Human Gut Microbiota: Application of Evidence Mapping Methodology

Interest is rapidly growing around the role of the human gut microbiota in facilitating beneficial health effects associated with consumption of dietary fiber. An evidence map of current research activity in this area was created using a newly developed database of dietary fiber intervention studies in humans to identify studies with the following broad outcomes: (1) modulation of colonic microflora; and/or (2) colonic fermentation/short-chain fatty acid concentration. Study design characteristics, fiber exposures, and outcome categories were summarized. A sub-analysis described oligosaccharides and bacterial composition in greater detail. One hundred eighty-eight relevant studies were identified. The fiber categories represented by the most studies were oligosaccharides (20%), resistant starch (16%), and chemically synthesized fibers (15%). Short-chain fatty acid concentration (47%) and bacterial composition (88%) were the most frequently studied outcomes. Whole-diet interventions, measures of bacterial activity, and studies in metabolically at-risk subjects were identified as potential gaps in the evidence. This evidence map efficiently captured the variability in characteristics of expanding research on dietary fiber, gut microbiota, and physiological health benefits, and identified areas that may benefit from further research. We hope that this evidence map will provide a resource for researchers to direct new intervention studies and meta-analyses.

Trans fatty acids and cholesterol levels: An evidence map of the available science

High intakes of industrial trans fatty acids (iTFA) increase circulating low density lipoprotein cholesterol (LDL-C) levels, which has implicated iTFA in coronary heart disease (CHD) risk. Published data on iTFA and LDL-C, however, represent higher intake levels than the U.S. population currently consume. This study used state-of-the-art evidence mapping approaches to characterize the full body of literature on LDL-C and iTFA at low intake levels. A total of 32 independent clinical trials that included at least one intervention or control group with iTFA at ≤3%en were found. Findings indicated that a wide range of oils and interventions were used, limiting the ability to determine an isolated effect of iTFA intake. Few data points were found for iTFA at <3%en, with the majority of low-level exposures actually representing control group interventions containing non-partially hydrogenated (PHO) oils. Further, it appears that few dose-response data points are available to assess the relationship of low levels of iTFA, particularly from PHO exposure, and LDL-C. Therefore, limited evidence is available to determine the effect of iTFA at current consumption levels on CHD risk.

Development of a Publicly Available, Comprehensive Database of Fiber and Health Outcomes: Rationale and Methods

BACKGROUND

Dietary fiber is a broad category of compounds historically defined as partially or completely indigestible plant-based carbohydrates and lignin with, more recently, the additional criteria that fibers incorporated into foods as additives should demonstrate functional human health outcomes to receive a fiber classification. Thousands of research studies have been published examining fibers and health outcomes.

OBJECTIVES

(1) Develop a database listing studies testing fiber and physiological health outcomes identified by experts at the Ninth Vahouny Conference; (2) Use evidence mapping methodology to summarize this body of literature. This paper summarizes the rationale, methodology, and resulting database. The database will help both scientists and policy-makers to evaluate evidence linking specific fibers with physiological health outcomes, and identify missing information.

METHODS

To build this database, we conducted a systematic literature search for human intervention studies published in English from 1946 to May 2015. Our search strategy included a broad definition of fiber search terms, as well as search terms for nine physiological health outcomes identified at the Ninth Vahouny Fiber Symposium. Abstracts were screened using a priori defined eligibility criteria and a low threshold for inclusion to minimize the likelihood of rejecting articles of interest. Publications then were reviewed in full text, applying additional a priori defined exclusion criteria. The database was built and published on the Systematic Review Data Repository (SRDR™), a web-based, publicly available application.

CONCLUSIONS

A fiber database was created. This resource will reduce the unnecessary replication of effort in conducting systematic reviews by serving as both a central database archiving PICO (population, intervention, comparator, outcome) data on published studies and as a searchable tool through which this data can be extracted and updated.

An evidence map of yoga for low back pain

OBJECTIVE

Yoga is being increasingly studied as a treatment strategy for a variety of different clinical conditions, including low back pain (LBP). We set out to conduct an evidence map of yoga for the treatment, prevention and recurrence of acute or chronic low back pain (cLBP).

METHODS

We searched Medline, Cochrane Database of Systematic Reviews, EMBASE, Allied and Complementary Medicine Database and ClinicalTrials.gov for randomized controlled trials (RCT), systematic reviews or planned studies on the treatment or prevention of acute back pain or cLBP. Two independent reviewers screened papers for inclusion, extracted data and assessed the quality of included studies.

RESULTS

Three eligible systematic reviews were identified that included 10 RCTs (n=956) that evaluated yoga for non-specific cLBP. We did not identify additional RCTs beyond those included in the systematic reviews. Our search of ClinicalTrials.gov identified one small (n=10) unpublished trial and one large (n=320) planned clinical trial. The most recent good quality systematic review indicated significant effects for short- and long-term pain reduction (n=6 trials; standardized mean difference [SMD] -0.48; 95% CI, -0.65 to -0.31; I(2)=0% and n=5; SMD -0.33; 95% CI, -0.59 to -0.07; I(2)=48%, respectively). Long-term effects for back specific disability were also identified (n=5; SMD -0.35; 95% CI, -0.55 to -0.15; I(2)=20%). No studies were identified evaluating yoga for prevention or treatment of acute LBP.

CONCLUSION

Evidence suggests benefit of yoga in midlife adults with non-specific cLBP for short- and long-term pain and back-specific disability, but the effects of yoga for health-related quality of life, well- being and acute LBP are uncertain. Without additional studies, further systematic reviews are unlikely to be informative.

What is an evidence map? A systematic review of published evidence maps and their definitions, methods, and products

BACKGROUND

The need for systematic methods for reviewing evidence is continuously increasing. Evidence mapping is one emerging method. There are no authoritative recommendations for what constitutes an evidence map or what methods should be used, and anecdotal evidence suggests heterogeneity in both. Our objectives are to identify published evidence maps and to compare and contrast the presented definitions of evidence mapping, the domains used to classify data in evidence maps, and the form the evidence map takes.

METHODS

We conducted a systematic review of publications that presented results with a process termed "evidence mapping" or included a figure called an "evidence map." We identified publications from searches of ten databases through 8/21/2015, reference mining, and consulting topic experts. We abstracted the research question, the unit of analysis, the search methods and search period covered, and the country of origin. Data were narratively synthesized.

RESULTS

Thirty-nine publications met inclusion criteria. Published evidence maps varied in their definition and the form of the evidence map. Of the 31 definitions provided, 67 % described the purpose as identification of gaps and 58 % referenced a stakeholder engagement process or user-friendly product. All evidence maps explicitly used a systematic approach to evidence synthesis. Twenty-six publications referred to a figure or table explicitly called an "evidence map," eight referred to an online database as the evidence map, and five stated they used a mapping methodology but did not present a visual depiction of the evidence.

CONCLUSIONS

The principal conclusion of our evaluation of studies that call themselves "evidence maps" is that the implied definition of what constitutes an evidence map is a systematic search of a broad field to identify gaps in knowledge and/or future research needs that presents results in a user-friendly format, often a visual figure or graph, or a searchable database. Foundational work is needed to better standardize the methods and products of an evidence map so that researchers and policymakers will know what to expect of this new type of evidence review.

SYSTEMATIC REVIEW REGISTRATION

Although an a priori protocol was developed, no registration was completed; this review did not fit the PROSPERO format.

Evidence map of studies evaluating methods for conducting, interpreting and reporting overviews of systematic reviews of interventions: rationale and design

BACKGROUND

Overviews of systematic reviews attempt to systematically retrieve and summarise the results of multiple systematic reviews into a single document. Methods for conducting, interpreting and reporting overviews of reviews are in their infancy. To date, there has been no systematic review or evidence map examining the range of methods for overviews nor of the evidence for using these methods. The objectives of the study are to develop and populate a framework of methods that have or may be used in conducting, interpreting and reporting overviews of systematic reviews of interventions (stage I); create an evidence map of studies that have evaluated these methods (stage II); and identify and describe unique methodological challenges of overviews.

METHODS

The research will be undertaken in two stages. For both stages, we plan to search methods collections (e.g. Cochrane Methodology Register, Meth4ReSyn library, AHRQ Effective Health Care Program) to identify eligible studies. These searches will be supplemented by searching reference lists and citation searching. Stage I: Methods used in overviews will be identified from articles describing methods for overviews, methods studies examining a cross section/cohort of overviews, guidance documents and commentaries. The identified methods will populate a framework of available methods for conducting an overview. Two reviewers will independently code included studies to develop the framework. Thematic analysis of the coded data will be used to categorise and describe methods. Stage II: Evaluations of the performance of methods will be identified from systematic reviews of methods studies and methods studies. Evaluations will be described and mapped to the framework of methods identified in stage I.

DISCUSSION

The results of this process will be useful for mapping of methods for overviews of systematic reviews, informing guidance and identifying and prioritising method research in this field.

Creating a literature database of low-calorie sweeteners and health studies: evidence mapping

BACKGROUND

Evidence mapping is an emerging tool used to systematically identify, organize and summarize the quantity and focus of scientific evidence on a broad topic, but there are currently no methodological standards. Using the topic of low-calorie sweeteners (LCS) and selected health outcomes, we describe the process of creating an evidence-map database and demonstrate several example descriptive analyses using this database.

METHODS

The process of creating an evidence-map database is described in detail. The steps include: developing a comprehensive literature search strategy, establishing study eligibility criteria and a systematic study selection process, extracting data, developing outcome groups with input from expert stakeholders and tabulating data using descriptive analyses. The database was uploaded onto SRDR™ (Systematic Review Data Repository), an open public data repository.

RESULTS

Our final LCS evidence-map database included 225 studies, of which 208 were interventional studies and 17 were cohort studies. An example bubble plot was produced to display the evidence-map data and visualize research gaps according to four parameters: comparison types, population baseline health status, outcome groups, and study sample size. This plot indicated a lack of studies assessing appetite and dietary intake related outcomes using LCS with a sugar intake comparison in people with diabetes.

CONCLUSION

Evidence mapping is an important tool for the contextualization of in-depth systematic reviews within broader literature and identifies gaps in the evidence base, which can be used to inform future research. An open evidence-map database has the potential to promote knowledge translation from nutrition science to policy.

Sugar-Sweetened Beverages and Obesity among Children and Adolescents: A Review of Systematic Literature Reviews

BACKGROUND

The prevalence of overweight and obesity among children and adolescents has increased worldwide and has reached alarming proportions. Currently, sugar-sweetened beverages (SSBs) are the primary source of added sugar in the diet of children and adolescents. Contradictive findings from studies and reviews have fueled an endless debate on the role of SSBs in the development of childhood obesity.

OBJECTIVES

The primary aim of the present review of reviews was to assess how review- and study-level methodological factors explain conflicting results across reviews and meta-analyses by providing an up-to-date synthesis of recent evidence regarding the association between SSB consumption and weight gain, overweight, and obesity in a population of 6-month-old to 19-year-old children and adolescents. The secondary aim was to assess the quality of included reviews using the Assessment of Multiple SysTemAtic Reviews (AMSTAR) measurement tool.

METHODS

Systematic literature reviews and meta-analyses were included. The literature search was performed through the platforms Pubmed/Medline, Cinahl, and Web of Knowledge.

RESULTS

Thirteen reviews and meta-analyses were included. Nine reviews concluded that there was a direct association between SSBs and obesity in children and adolescents and four others did not. The quality of the included reviews was low to moderate, and the two reviews with the highest quality scores showed discrepant results.

CONCLUSIONS

The majority of reviews concluded that there was a direct association between SSB consumption and weight gain, overweight, and obesity in children and adolescents. However, recent evidence from well-conducted meta-analyses shows discrepant results regarding the association between SSB and weight gain, overweight, and obesity among children and adolescents. Improving methodological quality of studies and reviews as well as ensuring responsible conduct of research and scientific integrity is essential for the provision of objective results.

Consumption of sugar sweetened beverage is associated with incidence of metabolic syndrome in Tehranian children and adolescents

Background

Intakes of high sugar-sweetened beverages (SSBs) in adults can escalate risk of metabolic syndrome (MetS); however, data of longitudinal studies in children and adolescents are lacking. In this study we assessed consumption of SSBs in relation to incidence of MetS among children and adolescents during a 3.6 year follow-up.

Methods

This study was a population-based longitudinal study, in which 424 subjects, aged 6–18 years, from the Tehran Lipid and Glucose Study with complete data on dietary intake, blood pressure, anthropometry, and biochemical indices were followed for 3.6 years. Dietary intake was collected using a valid and reliable food frequency questionnaire. MetS was defined according to the Cook criteria. Sugar sweetened beverages included all kinds of sugar sweetened carbonated soft drinks (SSSDs) and fruit juice drinks.

Results

Average daily intakes of SSSD and fruit juice drinks were 38.5 ± 75.0 and 32.3 ± 60.1 g, respectively. After adjustment for confounders, compared to the first quartile, the odds ratio of incident MetS in the highest quartile of SSB and SSSD was 3.20 (95 % CI: 1.06–9.90) and 3.01 (95 % CI: 1.17–7.74), respectively. Regarding incidence of MetS components, compared with the lowest quartile, the highest quartile of SSSDs showed odds ratios of 2.49 (95 % CI: 1.00–6.53) for abdominal obesity and 2.79 (95 % CI: 1.02–7.64) for hypertension. No significant association was found between consumption of fruit juice drink and SSSD with other components of MetS.

Conclusions

Children and adolescents with high intakes of carbonated beverages could be at increased risk of MetS, abdominal obesity, and hypertension.

A Dual-Carbon-and-Nitrogen Stable Isotope Ratio Model Is Not Superior to a Single-Carbon Stable Isotope Ratio Model for Predicting Added Sugar Intake in Southwest Virginian Adults

BACKGROUND

An objective measure of added sugar (AS) and sugar-sweetened beverage (SSB) intake is needed. The δ(13)C value of finger-stick blood is a novel validated biomarker of AS/SSB intake; however, nonsweetener corn products and animal protein also carry a δ(13)C value similar to AS sources, which may affect blood δ(13)C values. The δ(15)N value of blood has been proposed as a "correction factor" for animal protein intake.

OBJECTIVES

The objectives were to 1) identify foods associated with δ(13)C and δ(15)N blood values, 2) determine the contribution of nonsweetener corn to the diet relative to AS intake, and 3) determine if the dual-isotope model (δ(13)C and δ(15)N) is a better predictor of AS/SSB intake than δ(13)C alone.

METHODS

A cross-sectional sample of southwest Virginian adults (n = 257; aged 42 ± 15 y; 74% overweight/obese) underwent dietary intake assessments and provided finger-stick blood samples, which were analyzed for δ(13)C and δ(15)N values by using natural abundance stable isotope mass spectrometry. Statistical analyses included ANOVAs, paired-samples t tests, and multiple linear regressions.

RESULTS

The mean ± SD daily AS intake was 88 ± 59 g and nonsweetener corn intake was 13 ± 13 g. The mean δ(13)C value was -19.1 ± 0.9‰, which was significantly correlated with AS and SSB intakes (r = 0.32 and 0.39, respectively; P ≤ 0.01). The δ(13)C value and nonsweetener corn intake and the δ(15)N value and animal protein intake were not correlated. AS intake was significantly greater than nonsweetener corn intake (mean difference = 76.2 ± 57.2 g; P ≤ 0.001). The δ(13)C value was predictive of AS/SSB intake (β range: 0.28-0.35; P ≤ 0.01); however, δ(15)N was not predictive and minimal increases in R(2) values were observed when the δ(15)N value was added to the model.

CONCLUSIONS

The data do not provide evidence that the dual-isotope method is superior for predicting AS/SSB intakes within a southwest Virginian population. Our results support the potential of the δ(13)C value of finger-stick blood to serve as an objective measure of AS/SSB intake. This trial was registered at clinicaltrials.gov as NCT02193009.

Evaluation of a novel biomarker of added sugar intake (δ 13C) compared with self-reported added sugar intake and the Healthy Eating Index-2010 in a community-based, rural U.S. sample

OBJECTIVE

The δ 13C value of human blood is an emerging novel biomarker of added sugar (AS) intake for adults. However, no free-living, community-based assessments of comparative validity of this biomarker have been conducted. The purpose of the present investigation was to determine if Healthy Eating Index-2010 (HEI-2010) score, SoFAAS score (HEI-2010 sub-component for solid fat, alcohol and AS), AS and sugar-sweetened beverage (SSB) intakes were associated with δ 13C value of fingerstick blood in a community-based sample of adults, while controlling for relevant demographics.

DESIGN

A cross-sectional analysis of data obtained from assessments of BMI, dietary intake using 24 h recalls and a fingerstick blood sample was completed. Statistical analyses included descriptive statistics, multiple linear regression and one-way ANOVA.

SETTING

Rural Southwest Virginia, U.S.A.

SUBJECTS

Adults (n 216) aged >18 years who consumed at least 837 kJ/d (200 kcal/d) from SSB.

RESULTS

This sample of adult participants with low socio-economic status demonstrated a mean HEI-2010 score of 43.4 (sd 12.2), mean SoFAAS score of 10.2 (sd 5.7), mean AS intake of 93 (sd 65) g/d and mean blood δ 13C value of -18.88 (sd 0.7) ‰. In four separate regression models, HEI-2010 (R 2=0.16), SoFAAS (R 2=0.19), AS (R 2=0.15) and SSB (R 2=0.14) predicted δ 13C value (all P≤0.001). Age was also predictive of δ 13C value, but not sex or race.

CONCLUSIONS

These findings suggest that fingerstick δ 13C value has the potential to be a minimally invasive method for assessing AS and SSB intake and overall dietary quality in community-based settings. Strengths, limitations and future areas of research for using an objective δ 13C biomarker in diet-related public health studies are discussed.

Impact of interventions to reduce sugar-sweetened beverage intake in children and adults: a protocol for a systematic review and meta-analysis

BACKGROUND

Sugar-sweetened beverages (SSBs) have been stressed as relevant targets of public health interventions considering the negative outcomes derived from their excessive intake. Though the evidence from published literature grows to support a cause-and-effect association of SSBs with obesity and other diseases, little is known on the effectiveness that strategies alone or as part of multi-component programmes have had to influence this particular dietary behaviour across all ages. Therefore, this review and meta-analysis aim to evaluate the effect that interventions have had to decrease their consumption or increase water intake in children and adults so as to guide the design of future programmes and inform policy making.

METHODS

Included studies in this review will be randomised controlled trials and quasi-experimental interventions (with a control group) that have reported baseline and post-intervention intakes of SSBs or water and that have been published from 1990 in any language. A thorough search will be performed in MEDLINE, EMBASE, Scopus, Web of Science, Cochrane's central register of controlled trials, and the Global Health Library. Two independent reviewers will conduct initial screening of potentially included articles and will later extract data to analyse domains of intervention design and delivery (with emphasis on behaviour change techniques used as rationale), as well as results in changes on consumption patterns and behavioural determinants. Internal and external validity of each study will also be appraised. A meta-analysis will be performed if a sufficient number of studies are available, and if not, a narrative review will be conducted instead.

DISCUSSION

The results from this review aim to strengthen public health initiatives tackling obesity through improvements in non-alcoholic drinking patterns. As a subject of growing attention globally, this review will help determine which strategies available are the most effective in different contexts. Knowledge gained from this work will also aid resource allocation in future research and government agendas.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO

CRD42014013436 .

Sugar-sweetened beverages, vascular risk factors and events: a systematic literature review

OBJECTIVE

A high intake of sugar-sweetened beverages (SSB) has been linked to weight gain, obesity and type 2 diabetes; however, the influence on CVD risk remains unclear. Therefore, our objective was to summarize current evidence for an association between SSB consumption and cardiovascular risk factors and events.

DESIGN

The article search was performed in August 2013. Two independent researchers performed the article search and selection, data extraction and quality assessment. Eligible studies reported the intake of SSB and one of the following outcomes: change in blood pressure, blood lipid or blood sugar, or CVD events such as stroke or myocardial infarction. Only intervention and longitudinal studies were included.

SUBJECTS

Only studies in adults (aged 18+ years old) were considered.

RESULTS

Two of four prospective studies found clear direct associations between SSB consumption and CHD, while two of three studies, including both men and women, found direct associations between SSB consumption and stroke; however, the association was significant among women only. All included studies examining vascular risk factors found direct associations between SSB consumption and change in blood pressure, blood lipid or blood sugar.

CONCLUSIONS

The reviewed studies generally showed that SSB intake was related to vascular risk factors, whereas associations with vascular events were less consistent. Due to a limited number of published papers, especially regarding vascular events, the strength of the evidence is still limited and hence more studies are needed before firm conclusions can be made.

Sugar-sweetened beverage consumption and central and total adiposity in older children: a prospective study accounting for dietary reporting errors

OBJECTIVE

To determine the prospective relationship between changes in sugar-sweetened beverage (SSB) intake and central adiposity in older children.

DESIGN

Dietary intakes of children were obtained by 3 d food records at ages 10 and 13 years. Waist circumference (WC) and weight and height to determine BMI were measured at 10 and 13 years and total body fat mass (TBFM) at 13 years by dual-energy X-ray absorptiometry. Analyses were conducted using multivariable linear regression. Reporting errors were measured and participants were categorized as under-, plausible and over-reporters of dietary intakes.

SETTING

Community-based British cohort of children participating in the Avon Longitudinal Study of Parents and Children.

RESULTS

Among 2455 older children, increased SSB consumption from ages 10 to 13 years was associated with higher WC (standardized β=0.020, P=0.19), BMI (β=0.028, P=0.03) and TBFM (β=0.017, P=0.20) at 13 years. Effects were strengthened among plausible dietary reporters (n 1059): WC (β=0.097, P<0.001), BMI (β=0.074, P<0.001) and TBFM (β=0.065, P=0.003). The association between change in SSB and WC was weakened, but remained statistically significant after accounting for BMI (β=0.042, P=0.02) and TBFM (β=0.048, P=0.01).

CONCLUSIONS

Higher consumption of SSB from ages 10 to 13 years was associated with a larger WC at age 13 years independent of differences in total adiposity. Accounting for dietary reporting errors strengthened associations. Our findings further support recommendations to limit intakes of SSB to reduce excess weight gain in children and suggest that SSB have an additional deleterious effect on central adiposity.

Evidence-based mapping of design heterogeneity prior to meta-analysis: a systematic review and evidence synthesis

BACKGROUND

Assessment of design heterogeneity conducted prior to meta-analysis is infrequently reported; it is often presented post hoc to explain statistical heterogeneity. However, design heterogeneity determines the mix of included studies and how they are analyzed in a meta-analysis, which in turn can importantly influence the results. The goal of this work is to introduce ways to improve the assessment and reporting of design heterogeneity prior to statistical summarization of epidemiologic studies.

METHODS

In this paper, we use an assessment of sugar-sweetened beverages (SSB) and type 2 diabetes (T2D) as an example to show how a technique called 'evidence mapping' can be used to organize studies and evaluate design heterogeneity prior to meta-analysis.. Employing a systematic and reproducible approach, we evaluated the following elements across 11 selected cohort studies: variation in definitions of SSB, T2D, and co-variables, design features and population characteristics associated with specific definitions of SSB, and diversity in modeling strategies.

RESULTS

Evidence mapping strategies effectively organized complex data and clearly depicted design heterogeneity. For example, across 11 studies of SSB and T2D, 7 measured diet only once (with 7 to 16 years of disease follow-up), 5 included primarily low SSB consumers, and 3 defined the study variable (SSB) as consumption of either sugar or artificially-sweetened beverages. This exercise also identified diversity in analysis strategies, such as adjustment for 11 to 17 co-variables and a large degree of fluctuation in SSB-T2D risk estimates depending on variables selected for multivariable models (2 to 95% change in the risk estimate from the age-adjusted model).

CONCLUSIONS

Meta-analysis seeks to understand heterogeneity in addition to computing a summary risk estimate. This strategy effectively documents design heterogeneity, thus improving the practice of meta-analysis by aiding in: 1) protocol and analysis planning, 2) transparent reporting of differences in study designs, and 3) interpretation of pooled estimates. We recommend expanding the practice of meta-analysis reporting to include a table that summarizes design heterogeneity. This would provide readers with more evidence to interpret the summary risk estimates.

Sugar sweetened beverages consumption and risk of coronary heart disease: a meta-analysis of prospective studies

OBJECTIVE

To summarize the evidence with respect to sugar sweetened beverages (SSBs) consumption and risk of coronary heart disease (CHD) and to recommend field standards for future analysis on this topic.

METHODS

We searched for articles published up to February 2013 through PubMed, EMbase, and Cochrane Library Database and reviewed reference list of the retrieved articles. Prospective studies with reported relative risks (RRs) with 95% confidence intervals (CIs) of CHD for different categories of SSBs consumption were included. Random-effects models were used to evaluate the associations by comparing the highest and lowest categories of SSBs consumption in relation to risk of CHD.

RESULTS

Four prospective studies with 7396 CHD cases among 173,753 participants were included in the meta-analysis. The pooled RR (95% CI) for CHD in the highest category of SSBs consumption in comparison with the lowest category of SSBs was 1.17 (1.07-1.28). Stratified analyses indicated a significant association for men but not for women, with pooled RRs (95%CI) of 1.17 (1.05-1.29) and 1.19 (0.94-1.50), respectively. For studies carried out in America, the pooled RR for CHD was 1.18 (1.07-1.30). Additionally, a one-severing per day increase in SSBs consumption was associated with a 16% increased risk of CHD (RR: 1.16, 95%CI: 1.10-1.23).

CONCLUSION

Our meta-analysis of four studies suggests that consumption of SSBs may increase risk of CHD, especially among men and American populations. However, this finding was based on limited studies; further studies are warranted to critically evaluate the relationship.

Financial conflicts of interest and reporting bias regarding the association between sugar-sweetened beverages and weight gain: a systematic review of systematic reviews

BACKGROUND

Industry sponsors' financial interests might bias the conclusions of scientific research. We examined whether financial industry funding or the disclosure of potential conflicts of interest influenced the results of published systematic reviews (SRs) conducted in the field of sugar-sweetened beverages (SSBs) and weight gain or obesity.

METHODS AND FINDINGS

We conducted a search of the PubMed, Cochrane Library, and Scopus databases to identify published SRs from the inception of the databases to August 31, 2013, on the association between SSB consumption and weight gain or obesity. SR conclusions were independently classified by two researchers into two groups: those that found a positive association and those that did not. These two reviewers were blinded with respect to the stated source of funding and the disclosure of conflicts of interest. We identified 17 SRs (with 18 conclusions). In six of the SRs a financial conflict of interest with some food industry was disclosed. Among those reviews without any reported conflict of interest, 83.3% of the conclusions (10/12) were that SSB consumption could be a potential risk factor for weight gain. In contrast, the same percentage of conclusions, 83.3% (5/6), of those SRs disclosing some financial conflict of interest with the food industry were that the scientific evidence was insufficient to support a positive association between SSB consumption and weight gain or obesity. Those reviews with conflicts of interest were five times more likely to present a conclusion of no positive association than those without them (relative risk: 5.0, 95% CI: 1.3-19.3). An important limitation of this study is the impossibility of ruling out the existence of publication bias among those studies not declaring any conflict of interest. However, the best large randomized trials also support a direct association between SSB consumption and weight gain or obesity.

CONCLUSIONS

Financial conflicts of interest may bias conclusions from SRs on SSB consumption and weight gain or obesity.