Umbrella Review of the DASH Dietary Pattern and Cardiometabolic Risk
Umbrella Review of the DASH Dietary Pattern and Cardiometabolic Risk
The European Association for the Study of Diabetes (EASD) guidelines have not made any
 specific recommendations regarding the Dietary Approaches to Stop Hypertension (DASH) diet, a
 dietary pattern that emphasizes fruits and vegetables, low-fat or non-fat dairy, limiting
 saturated fat intake and usually also recommends limiting sodium intake. To update the
 recommendations, the Diabetes and Nutrition Study Group (DNSG) of the EASD commissioned an
 umbrella review of systematic reviews and meta-analyses using the Grading of Recommendations
 Assessment, Development, and Evaluation (GRADE) approach to summarize the available evidence
 from recent systematic reviews and meta-analyses of prospective cohort studies and randomized
 and non-randomized controlled trials of the relationship between the DASH dietary pattern and
 cardiometabolic risk.
Background: The DASH Dietary Pattern, which emphasizes intake of fruits and vegetables,
 low-fat or non-fat dairy, nuts, and legumes and limits saturated fat and red meat intake, is
 associated with reduced cardiovascular disease and diabetes risk in prospective cohort
 studies and has been shown to lower blood pressure and other intermediate cardiometabolic
 risk factors in randomized controlled trials. Despite the endorsement of the DASH Dietary
 Pattern by major international diabetes and cardiovascular guidelines, the European
 Association for the Study of Diabetes (EASD) guidelines for nutrition therapy have not made
 any specific recommendations for the DASH dietary pattern. The present umbrella review using
 the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was
 commissioned by the Diabetes and Nutrition Study Group (DNSG) of the EASD to summarize the
 available evidence from recent systematic reviews and meta-analyses of prospective cohort
 studies and randomized and non-randomized controlled trials of the relationship between the
 DASH dietary pattern and cardiometabolic risk.

 Need for proposed research: Public health policy and clinical practice guidelines are
 established with the use of systematic reviews and meta-analyses of randomized and
 non-randomized controlled trials and prospective cohort studies, which are regarded as the
 highest levels of evidence. As dietary guidelines and public health policy have shifted
 toward food and dietary-pattern based recommendations, there is a need to summarize the
 evidence from systematic reviews and meta-analyses assessing the effect of the DASH dietary
 pattern trials on cardiometabolic risk factors.

 Objective: The investigators will conduct an umbrella review of systematic reviews and
 meta-analyses using GRADE to summarize the relation of the DASH dietary pattern with incident
 cardiometabolic disease outcomes in prospective cohort studies and the effect the DASH
 dietary pattern on intermediate cardiometabolic risk factors in randomzied and non-randomized
 controlled trials.

 Design: The umbrella review will be conducted according to the principals of the Cochrane
 Handbook for Systematic Reviews of Interventions for the controlled clinical trials and the
 GRADE handbook with reporting according to the Meta-analysis Of Observational Studies in
 Epidemiology (MOOSE) guidelines for prospective cohort studies and the Preferred Reporting
 Items for Systematic Reviews and Meta-Analyses (PRISMA) for controlled trials.

 Data sources: MEDLINE and EMBASE will be searched using appropriate search terms. Authors
 will be contacted for applicable missing data.

 Study selection: The investigators will include the most recent and/or comprehensive
 systematic reviews and meta-analyses assessing the relation of the DASH dietary pattern with
 incident cardiometabolic diseases (CVD, coronary heart disease (CHD), stroke, diabetes) in
 prospective cohort studies and the effect on intermediate cardiometabolic risk factors (blood
 pressure, blood lipids, glycemic control, adiposity, and inflammation) in randomized and
 non-randomized controlled trials. If the search did not identify an existing systematic
 review and meta-analysis on any of our pre-specified outcomes (please refer to Outcomes), we
 then conducted a systematic search for that outcome and performed a meta-analysis on all
 studies retrieved which assess the effect in controlled trials (or association for
 prospective cohorts) of the DASH diet compared to a control diet on that outcome.

 Data extraction: Two or more investigators will independently extract relevant data and
 assess risk of bias of the individual studies using the Newcastle-Ottawa Scale for
 observational studies and the Cochrane Risk of Bias Tool for controlled clinical trials. All
 disagreements will be resolved by consensus.

 Outcomes: The primary outcome will be incident cardiovascular disease (CVD) in the
 prospective cohort studies and systolic blood pressure in the randomized and non-randomized
 controlled trials. Secondary outcomes will include incident coronary heart disease (CHD),
 stroke, and diabetes in the prospective cohort studies and diastolic blood pressure, blood
 lipids (total-C, LDL-C, HDL-C, and triglycerides), glycemic control (HbA1c, fasting blood
 glucose, fasting blood insulin, homeostasis model assessment of insulin resistance
 [HOMA-IR]), adiposity (body weight), and inflammation (C-reactive protein) in controlled
 trials.

 Evidence Assessment: The certainty of the evidence for each outcome will be assessed using
 the Grading of Recommendations Assessment, Development and Evaluation (GRADE).

 Knowledge translation plan: The results will be disseminated through interactive
 presentations at local, national, and international scientific meetings and publication in
 high impact factor journals. Target audiences will include the public health and scientific
 communities with interest in nutrition, diabetes, obesity, and cardiovascular disease.
 Feedback will be incorporated and used to improve the public health message and key areas for
 future research will be defined. Applicant/Co-applicant Decision Makers will network among
 opinion leaders to increase awareness and participate directly as committee members in the
 development of future guidelines.

 Significance: The proposed project will aid in knowledge translation related to the role of
 the DASH dietary pattern in cardiometabolic risk, strengthening the evidence-base for
 guidelines and improving health outcomes by educating healthcare providers and patients,
 stimulating industry innovation, and guiding future research design.
Inclusion Criteria:

 -  Systematic reviews and meta-analyses of prospective cohorts or controlled clinical
 trials

 -  Assessment of the DASH dietary pattern

 -  Viable outcome data with ≥ 1 outcome of interest

 Exclusion Criteria:

 -  Non-systematic review and meta-analysis publications

 -  Non-human studies

 -  No assessment of the exposure of the DASH dietary pattern

 -  No viable outcome data