Use of GRADE in evidence syntheses published in high-impact-factor nutrition journals: A methodological survey

Werner, Sarah S; Binder, Nadine; Toews, Ingrid; Meerpohl, Joerg J; Schwingshackl, Lukas

doi:10.1016/j.jclinepi.2021.02.010

Cited by 23 publications

(13 citation statements)

References 72 publications

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Section: Discussionmentioning

confidence: 99%

“…In this regard, we could show in a recent methodological survey that very low and high certainty of evidence ratings accounted for 61% and 1% of ratings in systematic reviews of observational studies, respectively, compared to 16% and 5% in systematic reviews of randomised controlled trials, respectively. 122 A recent cross sectional study has shown that very few Cochrane nutrition reviews include observational studies (2%), 123 which has been criticised. 124 BoE from cohort studies can strengthen or complement BoE from randomised controlled trials, and vice versa, so our meta-epidemiological study provides support for integration based on thorough assessment of PI/ECO similarities, and could be a starting point for future work.…”

Section: Potential Implicationsmentioning

confidence: 99%

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Evaluating agreement between bodies of evidence from randomised controlled trials and cohort studies in nutrition research: meta-epidemiological study

Schwingshackl

Balduzzi

Beyerbach

et al. 2021

BMJ

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Objective To evaluate the agreement between diet-disease effect estimates of bodies of evidence from randomised controlled trials and those from cohort studies in nutrition research, and to investigate potential factors for disagreement. Design Meta-epidemiological study. Data sources Cochrane Database of Systematic Reviews, and Medline. Review methods Population, intervention or exposure, comparator, outcome (PI/ECO) elements from a body of evidence from cohort studies (BoE(CS)) were matched with corresponding elements of a body of evidence from randomised controlled trials (BoE(RCT)). Pooled ratio of risk ratios or difference of mean differences across all diet-disease outcome pairs were calculated. Subgroup analyses were conducted to explore factors for disagreement. Heterogeneity was assessed through I 2 and τ 2 . Prediction intervals were calculated to assess the range of possible values for the difference in the results between evidence from randomised controlled trials and evidence from cohort studies in future comparisons. Results 97 diet-disease outcome pairs (that is, matched BoE(RCT) and BoE(CS)) were identified overall. For binary outcomes, the pooled ratio of risk ratios comparing estimates from BoE(RCT) with BoE(CS) was 1.09 (95% confidence interval 1.04 to 1.14; I 2 =68%; τ 2 =0.021; 95% prediction interval 0.81 to 1.46). The prediction interval indicated that the difference could be much more substantial, in either direction. We further explored heterogeneity and found that PI/ECO dissimilarities, especially for the comparisons of dietary supplements in randomised controlled trials and nutrient status in cohort studies, explained most of the differences. When the type of intake or exposure between both types of evidence was identical, the estimates were similar. For continuous outcomes, small differences were observed between randomised controlled trials and cohort studies. Conclusion On average, the difference in pooled results between estimates from BoE(RCT) and BoE(CS) was small. But wide prediction intervals and some substantial statistical heterogeneity in cohort studies indicate that important differences or potential bias in individual comparisons or studies cannot be excluded. Observed differences were mainly driven by dissimilarities in population, intervention or exposure, comparator, and outcome. These findings could help researchers further understand the integration of such evidence into prospective nutrition evidence syntheses and improve evidence based dietary guidelines.

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Section: Discussionmentioning

confidence: 99%

Section: Potential Implicationsmentioning

confidence: 99%

Evaluating agreement between bodies of evidence from randomised controlled trials and cohort studies in nutrition research: meta-epidemiological study

Schwingshackl

Balduzzi

Beyerbach

et al. 2021

BMJ

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“…SR of prospective cohort studies has shown mainly no detrimental association between SFA-rich foods such as dairy or chocolate and risk of noncommunicable diseases [68, 90-95]. To improve the trustworthiness of such food-disease associations, rating the certainty of evidence [96, 97] and the use of novel statistical methods (e.g., substitution analyses or network MAs) is highly recommended [98, 99]; (iv) SR of prospective cohort studies frequently compared the highest versus lowest intake categories, whereas conducting dose-response (linear and nonlinear) MAs and substitution analyses would be more informative [100]. The SRs findings of RCTs also need to be interpreted with caution since not all primary studies were based on isocaloric substitution, and replacement with other dietary fats, carbohydrates, and/or protein might differ substantially between study arms.…”

Section: Discussionmentioning

confidence: 99%

Total Dietary Fat Intake, Fat Quality, and Health Outcomes: A Scoping Review of Systematic Reviews of Prospective Studies

et al. 2021

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Introduction: We conducted a scoping review of systematic reviews (SRs) on dietary fat intake and health outcomes in human adults within the context of a position paper by the “International Union of Nutritional Sciences Task force on Dietary Fat Quality” tasked to summarize the available evidence and provide dietary recommendations. Methods: We systematically searched several databases for relevant SRs of randomized controlled trials (RCTs) and/or prospective cohort studies published between 2015 and 2019 assessing the association between dietary fat and health outcomes. Results: Fifty-nine SRs were included. The findings from SRs of prospective cohort studies, which frequently compare the highest versus lowest intake categories, found mainly no association of total fat, monounsaturated fatty acid (MUFA), polyunsaturated fatty acid (PUFA), and saturated fatty acid (SFA) with risk of chronic diseases. SRs of RCTs applying substitution analyses indicate that SFA replacement with PUFA and/or MUFA improves blood lipids and glycemic control, with the effect of PUFA being more pronounced. A higher intake of total trans-fatty acid (TFA), but not ruminant TFA, was probably associated with an increased risk of mortality and cardiovascular disease based on existing SRs. Conclusion: Overall, the available published evidence deems it reasonable to recommend replacement of SFA with MUFA and PUFA and avoidance of consumption of industrial TFA.

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“…In the present overview, only 5% of the 101 included SRMAs used an approach or system to assess the overall certainty of the evidence, such as GRADE (Grading of Recommendations, Assessments, Development and Evaluations), which is consistent with a recently published study indicating that, among 800 SRMAs published in higher impact journals in the field of nutrition, only 5.9% used GRADE to assess the certainty of the evidence. 47 The results of the present study, together with the results of other recent reviews, leave no doubt that there is a need to promote the use of study protocols, methodological tools for risk-of-bias assessment, guidelines to assess the certainty of evidence (eg, GRADE), and checklists (eg, PRISMA) that can help to improve the reporting and validity of SRMAs in the field of nutrition in general.…”

Section: Discussionmentioning

confidence: 73%

Are systematic reviews addressing nutrition for cancer prevention trustworthy? A systematic survey of quality and risk of bias

et al. 2022

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Context The last 30 years have yielded a vast number of systematic reviews and/or meta-analyses addressing the link between nutrition and cancer risk. Objective The aim of this survey was to assess overall quality and potential for risk of bias in systematic reviews and meta-analyses (SRMAs) that examined the role of nutrition in cancer prevention. Data Sources MEDLINE, Embase, and the Cochrane Library databases were searched (last search performed November 2018). Study Selection Studies identified as SRMAs that investigated a nutritional or dietary intervention or exposure for cancer prevention in the general population or in people at risk of cancer and in which primary studies had a comparison group were eligible for inclusion. Screening, data extraction, and quality assessment were conducted independently by 2 reviewers. Data Extraction Altogether, 101 studies were randomly selected for analysis. The methodological quality and risk of bias were evaluated using the AMSTAR-2 and ROBIS tools, respectively. Results Most SRMAs included observational studies. Less than 10% of SRMAs reported a study protocol, and only 51% of SRMAs assessed the risk of bias in primary studies. Most studies conducted subgroup analyses, but only a few reported tests of interaction or specified subgroups of interest a priori. Overall, according to AMSTAR-2, only 1% of SRMAs were of high quality, while 97% were of critically low quality. Only 3% had a low risk of bias, according to ROBIS. Conclusions This systematic survey revealed substantial limitations with respect to quality and risk of bias of SRMAs. SRMAs examining nutrition and cancer prevention cannot be considered trustworthy, and results should be interpreted with caution. Peer reviewers as well as users of SRMAs should be advised to use the AMSTAR-2 and/or ROBIS instruments to help to determine the overall quality and risk of bias of SRMAs. Systematic Review Registration PROSPERO registration number CRD42019121116.

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Use of GRADE in evidence syntheses published in high-impact-factor nutrition journals: A methodological survey

Cited by 23 publications

References 72 publications

Evaluating agreement between bodies of evidence from randomised controlled trials and cohort studies in nutrition research: meta-epidemiological study

Evaluating agreement between bodies of evidence from randomised controlled trials and cohort studies in nutrition research: meta-epidemiological study

Total Dietary Fat Intake, Fat Quality, and Health Outcomes: A Scoping Review of Systematic Reviews of Prospective Studies

Are systematic reviews addressing nutrition for cancer prevention trustworthy? A systematic survey of quality and risk of bias

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