Gavin B. Stewart

Preferred Reporting Items for a Systematic Review and Meta-analysis of Individual Participant Data The PRISMA-IPD Statement

IMPORTANCE Systematic reviews and meta-analyses of individual participant data (IPD) aim to collect, check, and reanalyze individual-level data from all studies addressing a particular research question and are therefore considered a gold standard approach to evidence synthesis. They are likely to be used with increasing frequency as current initiatives to share clinical trial data gain momentum and may be particularly important in reviewing controversial therapeutic areas. OBJECTIVE To develop PRISMA-IPD as a stand-alone extension to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) Statement, tailored to the specific requirements of reporting systematic reviews and meta-analyses of IPD. Although developed primarily for reviews of randomized trials, many items will apply in other contexts, including reviews of diagnosis and prognosis. DESIGN Development of PRISMA-IPD followed the EQUATOR Network framework guidance and used the existing standard PRISMA Statement as a starting point to draft additional relevant material. A web-based survey informed discussion at an international workshop that included researchers, clinicians, methodologists experienced in conducting systematic reviews and meta-analyses of IPD, and journal editors. The statement was drafted and iterative refinements were made by the project, advisory, and development groups. The PRISMA-IPD Development Group reached agreement on the PRISMA-IPD checklist and flow diagram by consensus. FINDINGS Compared with standard PRISMA, the PRISMA-IPD checklist includes 3 new items that address (1) methods of checking the integrity of the IPD (such as pattern of randomization, data consistency, baseline imbalance, and missing data), (2) reporting any important issues that emerge, and (3) exploring variation (such as whether certain types of individual benefit more from the intervention than others). A further additional item was created by reorganization of standard PRISMA items relating to interpreting results. Wording was modified in 23 items to reflect the IPD approach. CONCLUSIONS AND RELEVANCE PRISMA-IPD provides guidelines for reporting systematic reviews and meta-analyses of IPD.

A checklist designed to aid consistency and reproducibility of GRADE assessments: development and pilot validation

BackgroundThe grading of recommendation, assessment, development and evaluation (GRADE) approach is widely implemented in health technology assessment and guideline development organisations throughout the world. GRADE provides a transparent approach to reaching judgements about the quality of evidence on the effects of a health care intervention, but is complex and therefore challenging to apply in a consistent manner.MethodsWe developed a checklist to guide the researcher to extract the data required to make a GRADE assessment. We applied the checklist to 29 meta-analyses of randomised controlled trials on the effectiveness of health care interventions. Two reviewers used the checklist for each paper and used these data to rate the quality of evidence for a particular outcome.ResultsFor most (70%) checklist items, there was good agreement between reviewers. The main problems were for items relating to indirectness where considerable judgement is required.ConclusionsThere was consistent agreement between reviewers on most items in the checklist. The use of this checklist may be an aid to improving the consistency and reproducibility of GRADE assessments, particularly for inexperienced users or in rapid reviews without the resources to conduct assessments by two researchers independently.

Meta-analysis in applied ecology

This overview examines research synthesis in applied ecology and conservation. Vote counting and pooling unweighted averages are widespread despite the superiority of syntheses based on weighted combination of effects. Such analyses allow exploration of methodological uncertainty in addition to consistency of effects across species, space and time, but exploring heterogeneity remains controversial. Meta-analyses are required to generalize in ecology, and to inform evidence-based decision-making, but the more sophisticated statistical techniques and registers of research used in other disciplines must be employed in ecology to fully realize their benefits.

Effectiveness of predator removal for enhancing bird populations.

Predation pressure on vulnerable bird species has made predator control an important issue for international nature conservation. Predator removal by culling or translocation is controversial, expensive, and time-consuming, and results are often temporary. Thus, it is important to assess its effectiveness from all available evidence. We used explicit systematic review methodology to determine the impact of predator removal on four measurable responses in birds: breeding performance (hatching success and fledging success) and population size (breeding and postbreeding). We used meta-analysis to summarize results from 83 predator removal studies from six continents. We also investigated whether characteristics of the prey, predator species, location, and study methodology explained heterogeneity in effect sizes. Removing predators increased hatching success, fledging success, and breeding populations. Removing all predator species achieved a significantly larger increase in breeding population than removing only a subset. Postbreeding population size was not improved on islands, or overall, but did increase on mainlands. Heterogeneity in effect sizes for the four population parameters was not explained by whether predators were native or introduced; prey were declining, migratory, or game species; or by the study methodology. Effect sizes for fledging success were smaller for ground-nesting birds than those that nest elsewhere, but the difference was not significant. We conclude that current evidence indicates that predator removal is an effective strategy for the conservation of vulnerable bird populations. Nevertheless, the ethical and practical problems associated with predator removal may lead managers to favor alternative, nonlethal solutions. Research is needed to provide and synthesize data to determine whether these are effective management practices for future policies on bird conservation.

Effectiveness of engineered in‐stream structure mitigation measures to increase salmonid abundance: a systematic review

Engineered in-stream structures are often installed to increase salmonid abundance, either for commercial gain in fisheries or for conservation purposes in degraded habitats. Having been in widespread use for the last 80 years, at an estimated cost of hundreds of millions of U.S. dollars each year, the effectiveness of these structures is still widely debated in the literature. Many studies of varying quality have been undertaken that attempt to address this issue, but it has proved difficult for practitioners to develop a consensus regarding the utility of these structures, despite their continued use. Systematic review methodology was used to formally synthesize empirical evidence regarding the effectiveness of engineered in-stream structures as a management tool to increase salmonid abundance. Meta-analysis shows that evidence regarding the effectiveness of in-stream devices is equivocal. Heterogeneity is significant both for population size and local habitat preference. This heterogeneity is related to stream width, with in-stream devices being less effective in larger streams. Consequently, widespread use of in-stream structures for restoration, particularly in larger streams, is not supported by the current scientific evidence base.

Statistical Analysis of Individual Participant Data Meta-Analyses: A Comparison of Methods and Recommendations for Practice

Background Individual participant data (IPD) meta-analyses that obtain “raw” data from studies rather than summary data typically adopt a “two-stage” approach to analysis whereby IPD within trials generate summary measures, which are combined using standard meta-analytical methods. Recently, a range of “one-stage” approaches which combine all individual participant data in a single meta-analysis have been suggested as providing a more powerful and flexible approach. However, they are more complex to implement and require statistical support. This study uses a dataset to compare “two-stage” and “one-stage” models of varying complexity, to ascertain whether results obtained from the approaches differ in a clinically meaningful way. Methods and Findings We included data from 24 randomised controlled trials, evaluating antiplatelet agents, for the prevention of pre-eclampsia in pregnancy. We performed two-stage and one-stage IPD meta-analyses to estimate overall treatment effect and to explore potential treatment interactions whereby particular types of women and their babies might benefit differentially from receiving antiplatelets. Two-stage and one-stage approaches gave similar results, showing a benefit of using anti-platelets (Relative risk 0.90, 95% CI 0.84 to 0.97). Neither approach suggested that any particular type of women benefited more or less from antiplatelets. There were no material differences in results between different types of one-stage model. Conclusions For these data, two-stage and one-stage approaches to analysis produce similar results. Although one-stage models offer a flexible environment for exploring model structure and are useful where across study patterns relating to types of participant, intervention and outcome mask similar relationships within trials, the additional insights provided by their usage may not outweigh the costs of statistical support for routine application in syntheses of randomised controlled trials. Researchers considering undertaking an IPD meta-analysis should not necessarily be deterred by a perceived need for sophisticated statistical methods when combining information from large randomised trials.

A meta-analysis on the impact of different matrix structures on species movement rates

Many biodiversity conservation strategies aim to increase species movement by changing the landscape between suitable areas of habitat. We applied systematic review and meta-analytical methods to robustly assess evidence on the impact of matrix structure on movement rates, with the hypothesis that movement will be greater through matrix of a more similar structure (vegetation height and cover) to the home habitat. Twenty studies of movement through two or more different matrix types provided 107 effect sizes, expressing the difference between the relative movement rates in different matrix types. The studies were all on animals, including relatively mobile taxa such as birds and butterflies but also rodents and amphibians. We were able to detect that on average, movement was greater through matrix of a more similar structure to the species’ habitat despite the variation in studies in terms of matrix types, species and methods. The effect size was larger when there was a greater difference in the structure of the two matrix types being compared (e.g. comparing grassland to forest rather than short grass to long grass). However, there was a high degree of covariation between matrix contrast and studies and other significant subgroupings such as taxonomic group and matrix openness. The biological significance of the increase in movement is not clear; however, ecological theory predicts dispersing individuals are important for population dynamics. Changes to the structure of landscapes intended to improve permeability to movement are supported by the findings of this study, particularly for relatively mobile species. However, research over longer timescales, greater distances and range of taxonomic groups is necessary.

Bias and dispersal in the animal reintroduction literature

We examined the literature on animal reintroductions to assess the challenges facing individual conservation practitioners who wish to access, synthesize and interpret available evidence to inform their decision making. We undertook an extensive search in eight electronic literature databases, using seven different keyword combinations, and added the content of four bibliographies on reintroductions. We found 3,826 potentially relevant publications totalling at least 29,290 pages of text. Taxonomic bias is apparent in the distribution of general and conservation scientific literature and in reintroduction programmes. We examined whether the literature on reintroductions is biased in a similar way. Comparing the distribution of reintroduction publications to numbers of species, reintroduction programmes and the general conservation literature, there is a marked taxonomic bias favouring vertebrates, especially birds and mammals. The bias in relation to reintroduction programmes is surprising and indicates that managers working with invertebrates and amphibians are less willing and/or less able to publish their results than those working with mammals and birds. The reasons for this are unclear. The growth of the cumulative body of literature can be depicted by a sigmoid curve. Almost 40% of the items were scientific journal articles distributed across 335 journals. The large, ever-growing and dispersed evidence base results in an increased need for reviews, which must be systematic to minimize bias.

Higher antioxidant and lower cadmium concentrations and lower incidence of pesticide residues in organically grown crops: a systematic literature review and meta-analyses

Introduction: In the last years and decades more and more new plants came to the market as food or old crops have been rediscovered. Based on the presence of secondary plant metabolites specific effects are often attributed to these plants and/or derived preparations. Depending on the amount and the accompanying substances in extracts and preparations these substances can also be toxic. In many cases, plants and plant preparations are not adequately tested for their safety before marketing. In the European Union, authorization procedures and health assessments are only required for foods that are considered novel foods or produced from genetically modified organisms. A working group of federal and state governments, the BfR has worked with, has drawn up a list of nearly 600 plants and plant parts, which should facilitate the assessment of these plants (or plant parts) and derived preparations by food inspection bodies and food industry. Objectives: 18 plants or parts of plants were selected for an evaluation because of their known pharmacological or psychotropic effects or due to possible health risks. Method / Design: The risk assessments of these plants or parts of plants, including for example goji berries and yohimbe bark, were performed using the “Guidance on Safety assessment of botanicals and botanical preparations intended for use as ingredients in food supplements” of the European Food Safety Authority (EFSA). Results: Nine of the 18 plants or parts of plants pose a risk to consumers and should not be used in food. Five plants or parts of plants might pose risks when used in food. For four plants or plant parts, no risks were seen. Conclusions: The health assessments are intended to be a first step in the process of harmonization at European level. The opinions are published in a booklet and accessible on the web(04/08/2019) Organic food for sustainable and healthy diets lessons from the nordic diet? Introduction: The New Nordic Diet (NND) was developed in 2004 by chefs and food professionals from the five Nordic countries. The goal for the NND was that it should be based on traditional regional food products but healthier than the traditional eating habits. The NND builds on four key principles: Nordic identity, health, gastronomic potential and sustainability.Objectives: Can the NND be used as a model for a sustainable diet in other geographical regions?Methods/design: The NND can be described by a few overall guidelines: 1) more calories from plant foods and fewer from meat; 2) more foods from the wild countryside and 3) more foods from sea and lakes. In many ways, the New NND is very similar to a Mediterranean diet but relies on rapeseed (canola) oil instead of olive oil and ramson instead of garlic. The diets differ in their types of produce due to regional differences in climate, soil and water.Results: The health effects and sustainability of the NND has been tested in a number of scientific studies, including the OPUS project (Optimal Well-Being, Development and Health for Danish Children through a Healthy New Nordic Diet) supported by the Nordea foundation (http://foodoflife.ku.dk/opus/english/nyheder/publikationer/) in which the NND was compared to the Average Danish Diet (ADD). The use of mostly local products and reduction of the meat intake were of both socioeconomic and environmental advantage. Including organic produce increased environmental impact of the NND.Conclusion: In line with the Mediterranean diet the NND is a predominantly plant-based diet, and although the two have not been directly compared, it would be fairly safe to assume that they are equally healthy. Overall, the NND is just a regional interpretation of the tenets of healthy eating. Basically the principles of the NND could be incorporated into any regional diet.Who are we eating with? There are always companions to relate to in a meal, both to those who are present and they who are on another place or even in a past history. The choice of food and beverag ...Objectives : The aim of the present work was to compare the effect of ALA, EPA and DHA on the development of adipose tissue and its metabolism during a high fat-high sucrose (HFHS) challenge.Ann Nutr Metab 2015; 67(suppl 1) 435 BMD (BL: -2.4±0.7, PI: -0.9±0.44), serum calcium (BL: 9.5±0.6, PI: 10.5±0.52) and vitamin D (BL: 17.63±4.9, PI: 42.72±8.9) was observed. Locomotor problems were reduced among 44.06% subjects in group B compared to 11.11% in group A. Post interventional BMD (t: -2.16, P≤0.05), serum calcium (t: -4.05, P≤0.001) and vitamin D (t: -4.20, P≤0.001) of group B was significantly higher compared to group A.Affiliation: (1) PhD Student in Food Science. Human Nutrition Unit. Department of Food Science. University of Parma. Italy; (2) Associate Professor. Department of Food Science. University of Parma. Parma. Italy; (3) Full Professor. Department of Food Science, University of Parma. Parma. Italy; (4) Post-Doc Research Assistant. Department of Agricultural, Forest and Food Science, University of Turin. Torino. Italy; (5) Assistant Professor. Department of Soil, Plant and Food Science. University of Bari Aldo Moro. Bari. Italy; (6) Post-Doc Research Assistant. Department of Pharmacy and Biotechnology, Alma Mater Studiorum University of Bologna. Bologna. Italy; (7) Full Professor. Department of Soil, Plant and Food Science. University of Bari Aldo Moro. Bari. Italy; (8) Nutritionist. Department of Food Science. University of Parma. Parma Italy.Effect on attention of a vegetable smoothie, rich in berries, fruitsand vegetables, served at the school mid-morning brake. ViktoriaOhlsson. Kristianstad UniversityPurpose:The purpose of this pilot ...Introduction: Since appetite control works differently in fluid and solid intake we wanted to analyse the energy contribution from those two types of energy sources.Objectives: The objective of thi ...Introduction: Infrequent fruit and vegetable (FV) intake is especially common among children with low parental educational level (PEL) and among boys.Objectives: Our aim was to examine whether a school-based intervention was efficient in increasing children’s FV intake especially among those whose FV intake is the lowest and which factors could explain the the group differences in the associations.Method / Design: In Finland 11-year-old (at baseline) children participated in the PRO GREENS intervention in winter 2009. In control schools were 424 and in intervention schools 386 children (response rate 77%). Children filled in validated food frequency questionnaire assessing FV intake (times/day) and a validated questionnaire about factors influencing FV intake (availability of FV, liking for FV, preferences, self-efficacy to eat FV, attitudes towards FV and knowledge of the recommendations) both at baseline May 2009 and follow-up May 2010. Parental educational level (low, middle, high) was reported by the parents. Associations were examined with linear regression and mediation analyses.Results: The intervention increased fruit intake among girls but not among boys. Intervention increased also children’s knowledge of the recommendations. Since knowledge had no impact on boys’ fruit intake, the increase in knowledge mediated only intervention’s effect on girls’ fruit intake. Intervention increased children’s fruit intake similarly in all PEL groups.Intervention increased vegetable intake only in the middle PEL group but no intervention effect was noted among children with low or high PEL. Knowledge, the only factor which mediated the intervention’s effect on children’s vegetable intake, could not explain PEL differences in the effectivity of the intervention.Conclusions: Increase in knowledge was not a sufficient prerequisite to increase FV intake among boys or the lowest PEL group. More in depth analyses are needed to find out which factors to target in interventions to reach an effect in the target groups.

Composition differences between organic and conventional meat: a systematic literature review and meta-analysis

Demand for organic meat is partially driven by consumer perceptions that organic foods are more nutritious than non-organic foods. However, there have been no systematic reviews comparing specifically the nutrient content of organic and conventionally produced meat. In this study, we report results of a meta-analysis based on sixty-seven published studies comparing the composition of organic and non-organic meat products. For many nutritionally relevant compounds (e.g. minerals, antioxidants and most individual fatty acids (FA)), the evidence base was too weak for meaningful meta-analyses. However, significant differences in FA profiles were detected when data from all livestock species were pooled. Concentrations of SFA and MUFA were similar or slightly lower, respectively, in organic compared with conventional meat. Larger differences were detected for total PUFA and n-3 PUFA, which were an estimated 23 (95 % CI 11, 35) % and 47 (95 % CI 10, 84) % higher in organic meat, respectively. However, for these and many other composition parameters, for which meta-analyses found significant differences, heterogeneity was high, and this could be explained by differences between animal species/meat types. Evidence from controlled experimental studies indicates that the high grazing/forage-based diets prescribed under organic farming standards may be the main reason for differences in FA profiles. Further studies are required to enable meta-analyses for a wider range of parameters (e.g. antioxidant, vitamin and mineral concentrations) and to improve both precision and consistency of results for FA profiles for all species. Potential impacts of composition differences on human health are discussed.