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

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.

A Scoping Review of Current Guidelines on Dietary Fat and Fat Quality.

INTRODUCTION: We conducted a scoping review of dietary guidelines with the intent of developing a position paper by the "IUNS Task force on Dietary Fat Quality" tasked to summarize the available evidence and provide the basis for dietary recommendations. METHODS: We systematically searched several databases and Web sites for relevant documents published between 2015 and 2019. RESULTS: Twenty documents were included. Quantitative range intake recommendations for daily total fat intake included boundaries from 20 to 35% of total energy intake (TEI), for monounsaturated fat (MUFA) 10-25%, for polyunsaturated fat (PUFA) 6-11%, for saturated-fat (SFA) ≤11-≤7%, for industrial trans-fat (TFA) ≤2-0%, and <300-<200 mg/d for dietary cholesterol. The methodological approaches to grade the strength of recommendations were heterogeneous, and varied highly between the included guidelines. Only the World Health Organization applied the GRADE approach and graded the following recommendation as "strong": to reduce SFA to below 10%, and TFA to below 1% and replace both with PUFA if SFA intake is greater than 10% of TEI. CONCLUSION: Although the methodological approaches of the dietary guidelines were heterogeneous, most of them recommend total fat intakes of 30-≤35% of TEI, replacement of SFA with PUFA and MUFA, and avoidance of industrial TFA.

An Empirical Evaluation of the Impact Scenario of Pooling Bodies of Evidence from Randomized Controlled Trials and Cohort Studies in Nutrition Research.

Only very few Cochrane nutrition reviews include cohort studies (CSs), but most evidence in nutrition research comes from CSs. We aimed to pool bodies of evidence (BoE) from randomized controlled trials (RCTs) derived from Cochrane reviews with matched BoE from CSs. The Cochrane Database of Systematic Reviews and MEDLINE were searched for systematic reviews (SRs) of RCTs and SRs of CSs. BoE from RCTs were pooled together with BoE from CSs using random-effects and common-effect models. Heterogeneity, 95% prediction intervals, contributed weight of BoE from RCTs to the pooled estimate, and whether integration of BoE from CSs modified the conclusion from BoE of RCTs were evaluated. Overall, 80 diet-disease outcome pairs based on 773 RCTs and 720 CSs were pooled. By pooling BoE from RCTs and CSs with a random-effects model, for 45 (56%) out of 80 diet-disease associations the 95% CI excluded no effect and showed mainly a reduced risk/inverse association. By pooling BoE from RCTs and CSs, median I2 = 46% and the median contributed weight of RCTs to the pooled estimates was 34%. The direction of effect between BoE from RCTs and pooled effect estimates was rarely opposite (n = 17; 21%). The integration of BoE from CSs modified the result (by examining the 95% CI) from BoE of RCTs in 35 (44%) of the 80 diet-disease associations. Our pooling scenario showed that the integration of BoE from CSs modified the conclusion from BoE of RCTs in nearly 50% of the associations, although the direction of effect was mainly concordant between BoE of RCTs and pooled estimates. Our findings provide insights for the potential impact of pooling both BoE in Cochrane nutrition reviews. CSs should be considered for inclusion in future Cochrane nutrition reviews, and we recommend analyzing RCTs and CSs in separate meta-analyses, or, if combined together, with a subgroup analysis.

Pooling of cohort studies and RCTs affects GRADE certainty of evidence in nutrition research.

BACKGROUND: There is a little empirical evidence of the impact of pooling randomized controlled trials (RCTs) and cohort studies (CSs) on the certainty-of-evidence. To evaluate the hypothetical-scenario of pooling bodies-of-evidence from RCTs with matched bodies-of-evidence from CSs on the certainty-of-evidence. METHODS: We extracted GRADE ratings of bodies-of-evidence from RCTs in Cochrane reviews, and rated the certainty-of-evidence from matched bodies-of-evidence from CSs. We then evaluated the impact of pooling both bodies-of-evidence on the overall certainty-of-evidence, and on individual GRADE domains. RESULTS: Fourty-two pooled bodies-of-evidence were rated, ranging from very-low (bodies-of-evidenceRCTs: 9.5%; bodies-of-evidenceCSs: 40.5%; pooled-bodies-of-evidence: 0%) to low (bodies-of-evidenceRCTs: 38.1%; bodies-of-evidenceCSs: 45.2%; pooled-bodies-of-evidence: 19.1%), moderate (bodies-of-evidenceRCTs: 33.4%; bodies-of-evidenceCSs: 14.3%; pooled-bodies-of-evidence: 57.1%), and high (bodies-of-evidenceRCTs: 19%; bodies-of-evidenceCSs: 0%; pooled-bodies-of-evidence: 23.8%). Certainty-of-evidence was downgraded mostly for imprecision and risk of bias for bodies-of-evidence from RCTs, and for risk of bias and inconsistency for bodies-of-evidence from CSs. Pooling both bodies-of-evidence mitigates rating down for imprecision compared to bodies-of-evidence from RCTs and inconsistency compared to bodies-of-evidence from CSs. CONCLUSION: Our hypothetical study suggests that pooling both bodies-of-evidence would reduce the amount of very-low and low certainty-of-evidence ratings, but how to integrate RCTs and CSs and whether or not to pool these bodies-of-evidence requires proper guidance before systematic review authors or guideline developers should consider this approach.

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

OBJECTIVE: To identify and describe the use of the GRADE approach for rating the certainty of evidence in nutrition systematic reviews (SRs). STUDY DESIGN AND SETTING: We systematically searched for SRs using GRADE that were published between 2015 and 2019 in the 10 "nutrition" journals with the highest impact factor according to the JCR 2018. RESULTS: Out of 800 SRs, 55 SRs of randomized control trials (RCTs) and/or nonrandomized studies (NRSs) used GRADE. Forty-seven SRs (5.9%) rated the outcome specific certainty of evidence (n = 36 in 2018/2019). We identified a total of 465 certainty of evidence outcome ratings (n = 335 RCT ratings), ranging from very-low (28.8%) to low (41%), moderate (26.5%), and high (3.7%). Very-low and high certainty of evidence ratings accounted for 61.4% and 0.8% of ratings in SRs of NRSs, compared to 16.1% and 4.8% in SRs of RCTs. Certainty of evidence was downgraded mostly for risk of bias (37.8%) and imprecision (33%) in SRs of RCTs and for imprecision (32.7%), risk of bias (29.4%) and inconsistency (29%) in SRs of NRSs. CONCLUSION: Our study suggests a need for directing more attention toward strengthening acceptance of GRADE as well as building knowledge of the GRADE methodology in nutrition evidence synthesis.

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

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 I2 and τ2. 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; I2=68%; τ2=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.

Scaling up Business Plans in Tajikistan: a qualitative study of the history, barriers, facilitators and lessons learnt.

BACKGROUND: To improve health planning at primary health care (PHC) level, Business Plans were introduced in Tajikistan by the Enhancing Primary Health Care (EPHC) Services Project. OBJECTIVE: To describe the history and process of implementation of Business Plans and to identify barriers, facilitators and lessons learnt from scaling up Business Plans. METHODS: Set in a qualitative research design, we conducted a desk review of project and official documents and seventeen semi-structured interviews with key stakeholders at national and sub-national levels between May and July 2020. We used an interview guide informed by the ExpandNet/WHO framework and analyzed the data following a content analysis approach facilitated by MAXQDA. RESULTS: With the participation of various user organizations and resource teams and through a variety of strategic scale-up choices, Business Plans have been scaled up from a vertical pilot project to institutionalized health management tools covering 45% of Tajikistan's PHC facilities. The most prominent facilitators for scaling up Business Plans were the institutionalization and integration of the tool into the Tajik health system, the close collaboration with Community Health Teams (CHTs), the high acceptance of the tool among the users, the advocacy through champions and policy-makers and the large dissemination network. The most outstanding barriers to scaling up Business Plans were insufficient financial or human resources, general weaknesses in health governance, the lack of a strategic scale-up plan and strategic decisions, the lack of motivation or overall vision to implement Business Plans at a large scale and difficulties in donor coordination. CONCLUSION: To ensure the continuity of scaling up Business Plans, developing a scale-up strategy, strengthening cross-sectoral collaboration and participation during scaling up, and capacitating the user organizations of Business Plans are important next steps to ensure the sustainability and effectiveness of Business Plans in the future.