Comparison of seven popular structured dietary programmes and risk of mortality and major cardiovascular events in patients at increased cardiovascular risk: systematic review and network meta-analysis.

OBJECTIVE: To determine the relative efficacy of structured named diet and health behaviour programmes (dietary programmes) for prevention of mortality and major cardiovascular events in patients at increased risk of cardiovascular disease. DESIGN: Systematic review and network meta-analysis of randomised controlled trials. DATA SOURCES: AMED (Allied and Complementary Medicine Database), CENTRAL (Cochrane Central Register of Controlled Trials), Embase, Medline, CINAHL (Cumulative Index to Nursing and Allied Health Literature), and ClinicalTrials.gov were searched up to September 2021. STUDY SELECTION: Randomised trials of patients at increased risk of cardiovascular disease that compared dietary programmes with minimal intervention (eg, healthy diet brochure) or alternative programmes with at least nine months of follow-up and reporting on mortality or major cardiovascular events (such as stroke or non-fatal myocardial infarction). In addition to dietary intervention, dietary programmes could also include exercise, behavioural support, and other secondary interventions such as drug treatment. OUTCOMES AND MEASURES: All cause mortality, cardiovascular mortality, and individual cardiovascular events (stroke, non-fatal myocardial infarction, and unplanned cardiovascular interventions). REVIEW METHODS: Pairs of reviewers independently extracted data and assessed risk of bias. A random effects network meta-analysis was performed using a frequentist approach and grading of recommendations assessment, development and evaluation (GRADE) methods to determine the certainty of evidence for each outcome. RESULTS: 40 eligible trials were identified with 35 548 participants across seven named dietary programmes (low fat, 18 studies; Mediterranean, 12; very low fat, 6; modified fat, 4; combined low fat and low sodium, 3; Ornish, 3; Pritikin, 1). At last reported follow-up, based on moderate certainty evidence, Mediterranean dietary programmes proved superior to minimal intervention for the prevention of all cause mortality (odds ratio 0.72, 95% confidence interval 0.56 to 0.92; patients at intermediate risk: risk difference 17 fewer per 1000 followed over five years), cardiovascular mortality (0.55, 0.39 to 0.78; 13 fewer per 1000), stroke (0.65, 0.46 to 0.93; 7 fewer per 1000), and non-fatal myocardial infarction (0.48, 0.36 to 0.65; 17 fewer per 1000). Based on moderate certainty evidence, low fat programmes proved superior to minimal intervention for prevention of all cause mortality (0.84, 0.74 to 0.95; 9 fewer per 1000) and non-fatal myocardial infarction (0.77, 0.61 to 0.96; 7 fewer per 1000). The absolute effects for both dietary programmes were more pronounced for patients at high risk. There were no convincing differences between Mediterranean and low fat programmes for mortality or non-fatal myocardial infarction. The five remaining dietary programmes generally had little or no benefit compared with minimal intervention typically based on low to moderate certainty evidence. CONCLUSIONS: Moderate certainty evidence shows that programmes promoting Mediterranean and low fat diets, with or without physical activity or other interventions, reduce all cause mortality and non-fatal myocardial infarction in patients with increased cardiovascular risk. Mediterranean programmes are also likely to reduce stroke risk. Generally, other named dietary programmes were not superior to minimal intervention. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42016047939.

How to interpret a meta-analysis?

There is an enormous and ever-growing quantity of healthcare information available and practitioners must transform it into knowledge to be able to use it in their clinical practice. Even readers who do not conduct scientific studies themselves need to understand the scientific method in detail to be able to critically evaluate scientific articles. Evidence-based healthcare (EBH) can be defined as the link between good scientific research and clinical practice and systematic reviews constitute one of the forms of research excellence proposed within EBH. Systematic reviews employ rigorous methods that reduce the occurrence of bias. Systematic reviews with meta-analyses generally optimize the results found, because quantitative analysis of the studies included in the review yields additional information. In this paper, we will discuss how to interpret a meta-analysis and how to apply subset and sensitivity analysis strategies and we will also describe possible sources of heterogeneity and common errors that can affect a meta-analysis.

Acute graft thrombosis in patients who underwent renal transplant and received anticoagulant or antiplatelet agents. A systematic review and meta-analysis.

OBJECTIVES: Thrombosis is a major cause of early allograft loss in renal transplantation. Herein, we assessed the frequency of acute graft thrombosis in patients who underwent renal transplant and received anticoagulant or antiplatelet agents. METHODS: We performed a systematic review of all available case series studies of anticoagulant and/or antiplatelet prophylaxis of thrombosis in renal transplantation. The data were pooled in a proportional meta-analysis. RESULTS: Twenty-one case series were identified from 7,160 retrieved titles. A total of 3,246 patients were analyzed (1,718 treated with antiplatelet and/or anticoagulant agents and 1,528 non-treated control subjects). Allograft thrombosis occurred in 7.24% (95% CI 3.45 to 12.27%) of the patients receiving no intervention compared with 3.38% (95% CI 1.45 to 6.1%), 1.2% (95% CI 0.6 to 2.1%) and 0.47% (95% CI 0.001 to 1.79%) of the patients in the anticoagulant, aspirin, and aspirin + anticoagulant groups, respectively. The bleeding complication rate for anticoagulants was significantly higher than in the other groups. CONCLUSIONS: Our data suggests that anticoagulants, and aspirin, either alone or in association with an anticoagulant, seem to have a low frequency of acute allograft thrombosis after kidney transplantation. Higher hemorrhagic complication rates might occur when anticoagulants are used.

Causal language use in systematic reviews of observational studies is often inconsistent with intent: a systematic survey.

OBJECTIVES: We systematically evaluated causal language use in systematic reviews of observational studies and explored the relation between language use and the intent of the investigation. STUDY DESIGN AND SETTING: We searched EMBASE, MEDLINE, and Epistemonikos. We randomly selected 199 reviews published in 2019, stratified in a 1:1 ratio by use and nonuse of the Grading of Recommendations Assessment, Development and Evaluation approach to rating quality of evidence. RESULTS: Of 199 reviews of observational studies 56.8% had causal intent. Reviews with causal intent were more likely to investigate therapeutic clinical intervention (33.6% vs. 12.8%). Although 78.8% of those with causal intent used causal language in one or more sections of the title, abstract, or main text, only 4.4% consistently used causal language throughout the manuscript, and 21.2% did not use causal language at all. Of reviews without causal intent, 51.2% used causal language somewhere in the manuscript. CONCLUSION: Systematic reviews of observational studies sometimes do and sometimes do not have causal intent. Both those are inconsistent in causal language use and often use language inconsistent with the intent. Journal policies would better serve clarity of thinking and appropriateness of inferences by demanding authors clearly specify their intent and consistently use language consistent with that intent.

Como interpretar uma metanálise? / How to interpret a meta-analysis?

Resumo Como a quantidade de informações disponíveis na área da saúde é enorme e crescente, o profissional tem necessidade de transformá-las em conhecimento e utilizá-las em sua prática clínica. Assim, mesmo que o leitor não venha a produzir estudos científicos, é necessário conhecer detalhes da metodologia científica para poder, com espírito crítico, avaliar os artigos científicos. A Saúde Baseada em Evidências (SBE) é definida como o elo entre a boa pesquisa científica e a prática clínica, e uma das pesquisas de excelência propostas pela SBE são as revisões sistemáticas (RSs). As RSs utilizam métodos rigorosos que diminuem a ocorrência de vieses. As RSs com metanálises geralmente otimizam os resultados achados, pois a análise quantitativa dos estudos incluídos na revisão fornece informações adicionais. Neste trabalho, discorreremos sobre como interpretar uma metanálise e como aplicar as estratégias de análises de subgrupo e sensibilidade, além de como descrever possíveis heterogeneidades e erros comuns que acontecem em uma metanálise.

Abstract There is an enormous and ever-growing quantity of healthcare information available and practitioners must transform it into knowledge to be able to use it in their clinical practice. Even readers who do not conduct scientific studies themselves need to understand the scientific method in detail to be able to critically evaluate scientific articles. Evidence-based healthcare (EBH) can be defined as the link between good scientific research and clinical practice and systematic reviews constitute one of the forms of research excellence proposed within EBH. Systematic reviews employ rigorous methods that reduce the occurrence of bias. Systematic reviews with meta-analyses generally optimize the results found, because quantitative analysis of the studies included in the review yields additional information. In this paper, we will discuss how to interpret a meta-analysis and how to apply subset and sensitivity analysis strategies and we will also describe possible sources of heterogeneity and common errors that can affect a meta-analysis.

Probiotics for the treatment of depression and anxiety: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND & AIM: Probiotics in the gut have been suggested to have a beneficial effect on anxiety response and depressive disorder. Hence we conducted a systematic review and meta-analysis to summarize the effects of probiotics associated with or without pharmacological or psychological therapies in patients with depressive and/or anxiety symptoms or disorders. METHODS: We conducted searches of MEDLINE, EMBASE, CENTRAL, PsycINFO, CINAHL, ProQuest, LILACS, and Web of Science up to February 2020 to identify randomized controlled trials (RCTs) investigating the efficacy of probiotics associated with or without pharmacological or psychological therapies for patient-important outcomes including relief of depressive, anxiety and stress symptoms, cognitive functions, adverse events and quality of life. We used the GRADE approach to rate the overall certainty of the evidence by outcome. The protocol of the systematic review was registered with PROPSERO and published under the number CRD4202016329. RESULTS: 16 RCTs including 1,125 patients proved eligible. Results suggested a significant improvement in using Beck Depression Index (MD, -3.20 [95% CI, -5.91 to -0.49], p = 0.02; I2 = 21%, p = 0.28) for depression symptoms and State-Trait Anxiety Inventory (STAI) (MD, -6.88 [95% CI, -12.35 to -1.41], p = 0.01; I2 = 24%, p = 0.25) for anxiety with overall certainty in evidence rated as moderate and low, respectively. However, Depression Scale (DASS-Depression) (MD, 2.01 [95% CI, -0.80 to 4.82], p = 0.16; I2 = 0%, p = 0.62), Montgomery-Asberg Depression Rating Scale (MADRAS) (MD, -2,41 [95% CI, -10,55 to 5,72], p = 0,56; I2 = 87%, p = 0,006), Anxiety scale (DASS-Anxiety) (MD, 0.49 [95% CI, -4.05 to 5.02], p = 0.83; I2 = 74%, p = 0.05), and Stress Scale (DASS-Stress) (MD, 0.84 [95% CI, -2.64 to 4.33], p = 0.64; I2 = 34%, p = 0.22) showed no significant decrease in the relief of depression, anxiety and stress symptoms of probiotics compared to placebo with overall certainty in evidence rated as very low for all outcomes. We also found no differences in the Beck Anxiety Index (BAI) (MD, -3.21 [95% CI, -6.50 to 0.08], p = 0.06; I2 = 0%, p = 0.88) with overall certainty in evidence rated as low. Results suggested a non-statistically significantly effect of probiotics in the adverse events outcomes. CONCLUSIONS: The current review suggests that probiotics may improve symptoms of depression and anxiety in clinical patients. However, given the limitations in the included studies, RCTs with long-term follow-up and large sample sizes are needed.

Risk of mortality and suicide associated with substance use disorder among healthcare professionals: A systematic review and meta-analysis of observational studies.

BACKGROUND: Previous studies have suggested that healthcare professionals may be susceptible to substance use disorders, and among the medical specialties, anaesthesia providers appear to be overrepresented. OBJECTIVE: We aimed to compare the prevalence of substance use-related mortality and suicides between anaesthesia and nonanaesthesia professionals. DESIGN: Systematic review of observational studies with meta-analyses. We defined anaesthesia providers as any healthcare professionals belonging to the specialty, regardless of age and duration of employment. Other healthcare professionals served as the control group. DATA SOURCES: Ovid Medline, EMBASE, Web of Science, Scopus, Scielo, LILACS and ProQuest databases up to March 2020. RESULTS: Thirty-nine studies were included, 31 cross-sectional studies involving 13 819 participants and eight cohorts with a total 129 811 participants proved eligible. Results suggested a higher rate of drug-related mortality with odds ratio (OR) 2.69 [95% confidence interval (CI), 1.80 to 4.00; P < 0.001; I2 = 0%, P = 0.55; high-certainty evidence] and suicide (OR 2.18, 95% CI, 1.33 to 3.58; P = 0.002; I2 = 0%, P = 0.68; moderate-certainty evidence) for anaesthesia providers compared with other healthcare professionals. CONCLUSION: High-to-moderate-certainty evidence shows that there is more than a two-fold increased rate of substance use-related mortality and suicide among anaesthesia providers compared with other healthcare professionals. Investigations examining substance abuse between healthcare professionals, with particular attention to working conditions and exposure are essential to further develop preventive strategies.

Spontaneous abortion in women occupationally exposed to inhalational anesthetics: a critical systematic review.

Occupational exposure to inhalational anesthetics has been associated with health problems, including reproductive issues. Considering the scarcity and outdated nature of reviews concerning this relevant topic, which has implications for indoor pollution/environmental science/public health, this critical review aimed to systematically evaluate whether exposure to inhalational anesthetics is associated with abortion. Seven databases were searched with no language or year restrictions. Of the 3881 search results, 18 observational studies were included. Some studies demonstrated a significant association between occupational exposure to inhalational anesthetics and spontaneous abortion, especially among professionals who work for longer periods and/or in an environment without gas scavenging/ventilation systems, which may favor the occurrence of abortion in this population. Due to considerable heterogeneity and limitations, it cannot be concluded whether an association exists between occupational exposure to anesthetics and the occurrence of abortion. However, more well-designed studies should be performed, especially in less economically developed countries that do not have access to quality anesthetic gas scavenging/ventilation systems, thereby bringing this issue into sharp focus. This review highlights the need for scientific knowledge in this area and the extensive use of scavenging equipment and in the workplace to minimize exposure and reduce the risk of abortion.

Rectal Biopsy Technique for the Diagnosis of Hirschsprung Disease in Children: A Systematic Review and Meta-Analysis.

ABSTRACT: The diagnosis of Hirschsprung disease (HD) depends on the histopathological analysis of rectal biopsies. This review aims to define the best rectal biopsy technique. A systematic literature review and proportional meta-analysis of the available case series studies of rectal biopsies were performed in this study. All case series with more than five rectal biopsies in children younger than 18 years of age suspected of HD that described at least one type of rectal biopsy were included. The studies that did not specify the rate of conclusive results and the rate of complications of the biopsy procedures were excluded. According to the literature review, there were four different techniques of rectal biopsy: open, suction, punch, and endoscopic. In the title and abstract screening process, we assessed 496 articles, 159 fulfilled the eligibility criteria, and 71 studies reported our outcomes of interest and were included in the meta-analysis. The pooled proportion of conclusive results was 94% in open biopsies (95% CI 0.89-0.98), 95% in punch (95% CI 0.90-0.98), and 88% in suction group (95% CI 0.85-0.92). The pooled proportion of complication rates was 2% in open biopsies (95% CI 0.00031-0.04), 0.039% in suction (95% CI 0.00023-0.0006), and 2% in punch biopsies (95% CI 0.00075-0.04). Suction, punch, and open techniques presented comparable rates of conclusive results. In the suction group, the association between different methods of histopathological analysis increased conclusive results rates; however, the punch biopsy was associated with significantly higher complication rates than the suction technique.

Association between deep vein thrombosis and stent patency in symptomatic iliac vein compression syndrome: Systematic review and meta-analysis.

BACKGROUND: The study intended to evaluate stent primary patency rates for patients with iliac vein obstruction related with iliac vein compression syndrome according to clinic presentation. METHODS: A systematic review and meta-analysis was conducted of studies that compared: unexposed patients with nonthrombotic iliac vein lesion (NIVL, group 1) vs exposed patients with iliac acute deep vein thrombosis (DVT, group 2); and NIVL (group 1) vs exposed patients with iliac vein obstruction and post-thrombotic syndrome (PTS, group 3). The following databases were searched: EMBASE, PubMed, Web of Science, Scopus, SciELO, and LILACS. Two reviewers independently selected the potential studies and extracted data. The pooled odds ratio (OR) and 95% confidence interval (95% CI) are shown for each outcome. RESULTS: Five studies with a total of 1050 participants and 1169 lower limbs were included. Five hundred eighty-eight lower limbs presented NIVL (50.3%), 91 lower limbs presented acute DVT (7.7%), and 490 lower limbs presented PTS (42%). The endovascular technical success rate of stenting did not differ in any of the groups: 99.6% in NIVL, 94.5% in acute DVT, and 96.5% in PTS (P = .0632). The primary stent patency rates in the 6-month follow-up were 98.3% in NIVL vs 90.9% in PTS, with a statistical difference showing reduced stent patency rates in PTS (OR, 0.17; 95% CI, 0.06-0.48; P = .0008; I2 = 0%), and 100% in the NIVL group vs 91.6% in acute DVT, with no statistical difference (OR, 0.30; 95% CI, 0.06-2.32; P = .30; I2 = 0%). The primary stent patency rates in the 12-month follow-up were 94.6% in NIVL vs 84.1% in PTS, with a statistical difference showing decreases stent patency rates in the PTS group (OR, 0.29; 95% CI, 0.14-0.63; P = .0008; I2 = 0%), and 91.1% in NIVL vs 90.9% in acute DVT, with no statistical difference (OR, 1.03; 95% CI, 0.26-4.07; P = .96; I2 = 0%). CONCLUSIONS: There is no statistical difference for the stent primary patency rates when the treatment is conducted in NIVL as compared with acute DVT lower limbs (at 6 and 12 months); therefore, other criteria must be considered for the indication of this treatment in NIVL patients. However, because there were better results of stent primary patency rates for NIVL vs PTS patients, this finding favors the treatment of acute DVT instead of PTS in lower limbs, once PTS renders smaller stent patency rates at 6 and 12 months.

Protective effect of fluorides on erosion and erosion/abrasion in enamel: a systematic review and meta-analysis of randomized in situ trials.

OBJECTIVES: To evaluate the effects of different fluoride types and vehicles when compared to water or placebo, on prevention of enamel erosion and erosive tooth wear progression. DESIGN: A systematic review followed by meta-analysis of randomized in situ trials was conducted. PubMeb, Scopus, Web of Science, LILACS, BBO, Scielo, EMBASE and CENTRAL electronic databases were searched. Studies with fluoride compounds (NaF, AmF, Sn, TiF4) and vehicles (toothpaste, mouth rinse, gel, and varnishes) compared to control (water or placebo) for control of enamel loss progression were included. Reviewers independently screened potentially eligible articles, extracted data, and assessed risk of bias. GRADE approach was used to rate the overall certainty of evidence for toothpastes and rinses under erosive/abrasive challenges. RESULTS: Thirty-two studies were elegible. Under erosive/abrasive challenges, enamel loss was significantly lower than control for NaF toothpastes [Mean difference(MD) -1.14; Confidence Interval(CI) -1.89 to -0.40] and Sn/associations [-6.02; -11.09 to -0.95], while no difference was found for AmF [-13.59; -39.7 to -12.52]. For mouth rinses, Sn/associations solutions were effective [-11.49; -16.62 to -6.37], but NaF showed no significant effect [-2.83; -8.04 to 2.38]. CONCLUSION: Overall, fluoride products are able to reduce enamel loss when compared to control, but results must be interpreted with caution. For toothpastes, NaF provided limited protection, with moderate evidence, while Sn/associations exhibited protective effect with low certainty of evidence. For rinses, NaF was not effective, with very low evidence, while the stannnous enriched fluorides offered higher protection regarding enamel erosion and erosive wear, with moderate certainty of evidence.

Correction to: Methods for trustworthy nutritional recommendations NutriRECS (Nutritional Recommendations and accessible Evidence summaries Composed of Systematic reviews): a protocol.

Following publication of the original article [1], the authors reported a change in the 'Competing interests' section as described below.

Pelvic floor and abdominal muscle cocontraction in women with and without pelvic floor dysfunction: a systematic review and meta-analysis.

There is an ongoing discussion regarding abdominal muscle (AbM) and pelvic floor muscle (PFM) synergism. Therefore, this study aimed to investigate the cocontraction between AbMs and PFMs in women with or without pelvic floor dysfunction (PFD). The following databases were searched up to December 21, 2018: MEDLINE, EMBASE, LILACS, PEDro and CENTRAL. We included any study that assessed the cocontraction between PFMs and AbMs in women with and without PFD. Two reviewers independently screened eligible articles and extracted data. The outcomes were extracted and analyzed as continuous variables with random effect models. Twenty studies were included. A meta-analysis did not show differences in women with and without PFD. However, a sensitivity analysis suggested cocontraction of the transversus abdominis (TrA) during PFM contraction in healthy women (standardized mean difference (SMD) -1.02 [95% confidence interval (CI) -1.90 to -0.14], P=0.02; I2= not applicable; very low quality of evidence). Women with PFD during contraction of PFMs showed cocontraction of the obliquus internus (OI) (SMD 1.10 [95% CI 0.27 to 1.94], P=0.01; I2= not applicable; very low quality of evidence), and obliquus externus (OE) (SMD 2.08 [95% CI 1.10 to 3.06], P<0.0001; I2 = not applicable; very low quality of evidence). Increased cocontraction of the TrA may be associated with maximal contraction of PFMs in women without PFD. On the other hand, there is likely an increased cocontraction with the OI and OE in women with PFD.

Red and Processed Meat Consumption and Risk for All-Cause Mortality and Cardiometabolic Outcomes: A Systematic Review and Meta-analysis of Cohort Studies.

This article has been corrected. The original version (PDF) is appended to this article as a Supplement. Background: Dietary guidelines generally recommend limiting intake of red and processed meat. However, the quality of evidence implicating red and processed meat in adverse health outcomes remains unclear. Purpose: To evaluate the association between red and processed meat consumption and all-cause mortality, cardiometabolic outcomes, quality of life, and satisfaction with diet among adults. Data Sources: EMBASE (Elsevier), Cochrane Central Register of Controlled Trials (Wiley), Web of Science (Clarivate Analytics), CINAHL (EBSCO), and ProQuest from inception until July 2018 and MEDLINE from inception until April 2019, without language restrictions, as well as bibliographies of relevant articles. Study Selection: Cohort studies with at least 1000 participants that reported an association between unprocessed red or processed meat intake and outcomes of interest. Data Extraction: Teams of 2 reviewers independently extracted data and assessed risk of bias. One investigator assessed certainty of evidence, and the senior investigator confirmed the assessments. Data Synthesis: Of 61 articles reporting on 55 cohorts with more than 4 million participants, none addressed quality of life or satisfaction with diet. Low-certainty evidence was found that a reduction in unprocessed red meat intake of 3 servings per week is associated with a very small reduction in risk for cardiovascular mortality, stroke, myocardial infarction (MI), and type 2 diabetes. Likewise, low-certainty evidence was found that a reduction in processed meat intake of 3 servings per week is associated with a very small decrease in risk for all-cause mortality, cardiovascular mortality, stroke, MI, and type 2 diabetes. Limitation: Inadequate adjustment for known confounders, residual confounding due to observational design, and recall bias associated with dietary measurement. Conclusion: The magnitude of association between red and processed meat consumption and all-cause mortality and adverse cardiometabolic outcomes is very small, and the evidence is of low certainty. Primary Funding Source: None. (PROSPERO: CRD42017074074).

Reduction of Red and Processed Meat Intake and Cancer Mortality and Incidence: A Systematic Review and Meta-analysis of Cohort Studies.

This article has been corrected. The original version (PDF) is appended to this article as a Supplement. Background: Cancer incidence has continuously increased over the past few centuries and represents a major health burden worldwide. Purpose: To evaluate the possible causal relationship between intake of red and processed meat and cancer mortality and incidence. Data Sources: Embase, Cochrane Central Register of Controlled Trials, Web of Science, CINAHL, and ProQuest from inception until July 2018 and MEDLINE from inception until April 2019 without language restrictions. Study Selection: Cohort studies that included more than 1000 adults and reported the association between consumption of unprocessed red and processed meat and cancer mortality and incidence. Data Extraction: Teams of 2 reviewers independently extracted data and assessed risk of bias; 1 reviewer evaluated the certainty of evidence, which was confirmed or revised by the senior reviewer. Data Synthesis: Of 118 articles (56 cohorts) with more than 6 million participants, 73 articles were eligible for the dose-response meta-analyses, 30 addressed cancer mortality, and 80 reported cancer incidence. Low-certainty evidence suggested that an intake reduction of 3 servings of unprocessed meat per week was associated with a very small reduction in overall cancer mortality over a lifetime. Evidence of low to very low certainty suggested that each intake reduction of 3 servings of processed meat per week was associated with very small decreases in overall cancer mortality over a lifetime; prostate cancer mortality; and incidence of esophageal, colorectal, and breast cancer. Limitation: Limited causal inferences due to residual confounding in observational studies, risk of bias due to limitations in diet assessment and adjustment for confounders, recall bias in dietary assessment, and insufficient data for planned subgroup analyses. Conclusion: The possible absolute effects of red and processed meat consumption on cancer mortality and incidence are very small, and the certainty of evidence is low to very low. Primary Funding Source: None. (PROSPERO: CRD42017074074).

Patterns of Red and Processed Meat Consumption and Risk for Cardiometabolic and Cancer Outcomes: A Systematic Review and Meta-analysis of Cohort Studies.

This article has been corrected. The original version (PDF) is appended to this article as a Supplement. Background: Studying dietary patterns may provide insights into the potential effects of red and processed meat on health outcomes. Purpose: To evaluate the effect of dietary patterns, including different amounts of red or processed meat, on all-cause mortality, cardiometabolic outcomes, and cancer incidence and mortality. Data Sources: Systematic search of MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, CINAHL, Web of Science, and ProQuest Dissertations & Theses Global from inception to April 2019 with no restrictions on year or language. Study Selection: Teams of 2 reviewers independently screened search results and included prospective cohort studies with 1000 or more participants that reported on the association between dietary patterns and health outcomes. Data Extraction: Two reviewers independently extracted data, assessed risk of bias, and evaluated the certainty of evidence using GRADE (Grading of Recommendations Assessment, Development and Evaluation) criteria. Data Synthesis: Eligible studies that followed patients for 2 to 34 years revealed low- to very-low-certainty evidence that dietary patterns lower in red and processed meat intake result in very small or possibly small decreases in all-cause mortality, cancer mortality and incidence, cardiovascular mortality, nonfatal coronary heart disease, fatal and nonfatal myocardial infarction, and type 2 diabetes. For all-cause, cancer, and cardiovascular mortality and incidence of some types of cancer, the total sample included more than 400 000 patients; for other outcomes, total samples included 4000 to more than 300 000 patients. Limitation: Observational studies are prone to residual confounding, and these studies provide low- or very-low-certainty evidence according to the GRADE criteria. Conclusion: Low- or very-low-certainty evidence suggests that dietary patterns with less red and processed meat intake may result in very small reductions in adverse cardiometabolic and cancer outcomes. Primary Funding Source: None. (PROSPERO: CRD42017074074).

Unprocessed Red Meat and Processed Meat Consumption: Dietary Guideline Recommendations From the Nutritional Recommendations (NutriRECS) Consortium.

This article has been corrected. The original version (PDF) is appended to this article as a Supplement. Description: Dietary guideline recommendations require consideration of the certainty in the evidence, the magnitude of potential benefits and harms, and explicit consideration of people's values and preferences. A set of recommendations on red meat and processed meat consumption was developed on the basis of 5 de novo systematic reviews that considered all of these issues. Methods: The recommendations were developed by using the Nutritional Recommendations (NutriRECS) guideline development process, which includes rigorous systematic review methodology, and GRADE methods to rate the certainty of evidence for each outcome and to move from evidence to recommendations. A panel of 14 members, including 3 community members, from 7 countries voted on the final recommendations. Strict criteria limited the conflicts of interest among panel members. Considerations of environmental impact or animal welfare did not bear on the recommendations. Four systematic reviews addressed the health effects associated with red meat and processed meat consumption, and 1 systematic review addressed people's health-related values and preferences regarding meat consumption. Recommendations: The panel suggests that adults continue current unprocessed red meat consumption (weak recommendation, low-certainty evidence). Similarly, the panel suggests adults continue current processed meat consumption (weak recommendation, low-certainty evidence). Primary Funding Source: None. (PROSPERO 2017: CRD42017074074; PROSPERO 2018: CRD42018088854).

Effect of Lower Versus Higher Red Meat Intake on Cardiometabolic and Cancer Outcomes: A Systematic Review of Randomized Trials.

This article has been corrected. The original version (PDF) is appended to this article as a Supplement. Background: Few randomized trials have evaluated the effect of reducing red meat intake on clinically important outcomes. Purpose: To summarize the effect of lower versus higher red meat intake on the incidence of cardiometabolic and cancer outcomes in adults. Data Sources: EMBASE, CENTRAL, CINAHL, Web of Science, and ProQuest from inception to July 2018 and MEDLINE from inception to April 2019, without language restrictions. Study Selection: Randomized trials (published in any language) comparing diets lower in red meat with diets higher in red meat that differed by a gradient of at least 1 serving per week for 6 months or more. Data Extraction: Teams of 2 reviewers independently extracted data and assessed the risk of bias and the certainty of the evidence. Data Synthesis: Of 12 eligible trials, a single trial enrolling 48 835 women provided the most credible, though still low-certainty, evidence that diets lower in red meat may have little or no effect on all-cause mortality (hazard ratio [HR], 0.99 [95% CI, 0.95 to 1.03]), cardiovascular mortality (HR, 0.98 [CI, 0.91 to 1.06]), and cardiovascular disease (HR, 0.99 [CI, 0.94 to 1.05]). That trial also provided low- to very-low-certainty evidence that diets lower in red meat may have little or no effect on total cancer mortality (HR, 0.95 [CI, 0.89 to 1.01]) and the incidence of cancer, including colorectal cancer (HR, 1.04 [CI, 0.90 to 1.20]) and breast cancer (HR, 0.97 [0.90 to 1.04]). Limitations: There were few trials, most addressing only surrogate outcomes, with heterogeneous comparators and small gradients in red meat consumption between lower versus higher intake groups. Conclusion: Low- to very-low-certainty evidence suggests that diets restricted in red meat may have little or no effect on major cardiometabolic outcomes and cancer mortality and incidence. Primary Funding Source: None (PROSPERO: CRD42017074074).