Meta-analysis Of Prospective Observational Studies Research Articles

Relationship between carrot intake, dietary/circulating α-carotene and cancer risk: A systematic review and meta-analysis of prospective observational studies

Carrot consumption reduces tumour development in several animal models. The constituent alpha- carotene has not by itself shown anti-cancer properties, however carrots typically provide >85% of alpha-carotene dietary intake(1-3), justifying its use as an indicator of carrot intake(3). We conducted a meta-analysis to investigate inverse associations of carrot/dietary α-carotene intakes and cancer risk, and to quantify potential dose–response relationships.PubMed, Cochrane Library, Web of Science, Scopus, EBSCO, and JSTOR were searched (from database inception to August 2021) for studies reporting risk estimates with 95% CIs for the relationship between carrot intake or α-carotene and cancer risk. Meta-analyses were conducted using a random-effects model comparing highest and lowest intakes to estimate summary risk estimates (RRs).Of 80 prospective studies included, 15 (with 25738 cases) reported data on carrot intake, 35 (26262 cases) on dietary α-carotene intake and 30 (9331 cases) on plasma α-carotene levels. A significantly (P<0.01) decreased risk of overall cancer was associated with carrot intake (RR = 0·90), dietary α- carotene intake (RR = 0·90) and plasma α-carotene (RR = 0·80). In addition, both carrot intake and plasma α-carotene level manifested linear dose-response relationships with cancer risk, with increasing carrot intake reaching 20% risk reduction at 5 servings (400g) per week (p < 0·0001),and successive 50μg/L increments in plasma α-carotene associated with 11% risk reduction (p < 0·0058).Carrot consumption is robustly associated with decreased cancer risk. Carrot consumption should be encouraged, and the causal mechanisms further investigated.

Mother-to-child transmission of SARS-CoV-2 infection in high-income countries: a systematic review and meta-analysis of prospective observational studies

Mother-to-child transmission of SARS-CoV-2 has been reported since the onset of the COVID-19 pandemic. We conducted a study to summarize evidence on the risk of mother-to-child transmission in the first 30 days after birth in high-income countries and to evaluate the association between preventive measures and the risk of infection for the neonate. A systematic review and meta-analysis were undertaken following PRISMA guidelines. The National Library of Medicine, Web of Science, and Excerpta Medica databases were screened on February 26, 2022. All prospective observational studies addressing the frequency of infection in infants born to mothers SARS-CoV-2 positive were included. Twenty-six studies were included, reporting data of 2653 mothers with SARS-CoV-2 and 2677 neonates. The proportion meta-analysis pointed out an overall estimate of SARS-CoV-2 infection among infants of 2.3% (95% CI: 1.4–3.2%). Data from studies with (1.4%, 95% CI: 0.8–2) and without (1.3%, 95% CI: 0.0–2.7%) rooming-in provided similar risk of infection. Adopting at least two prevention measures during rooming-in resulted in a rate of mother-to-child infection of 1.0% (95%CI: 0.3–1.7%). The results of this study show a low rate of perinatal infection, support the rooming-in and confirm the effectiveness of preventive measures in reducing the risk of mother-to-child viral transmission.

Dietary Factors and All-Cause Mortality in Individuals With Type 2 Diabetes: A Systematic Review and Meta-analysis of Prospective Observational Studies.

Type 2 diabetes is a major health concern associated with mortality. Diet may influence the progression of diabetes; however, systematic reviews are lacking. This study systematically summarized the evidence on diet and all-cause mortality in individuals with type 2 diabetes. PubMed and Web of Science were searched until June 2022. Prospective observational studies investigating dietary factors in association with all-cause mortality in individuals with type 2 diabetes were selected. We identified 107 studies. Moderate certainty of evidence was found for inverse associations of higher intakes of fish (summary risk ratios per serving/week: 0.95; 95% CI 0.92, 0.99; n = 6 studies), whole grain (per 20 g/day: 0.84; 95% CI 0.71, 0.99; n = 2), fiber (per 5 g/day: 0.86; 95% CI 0.81, 0.91; n = 3), and n-3 polyunsaturated fatty acids (per 0.1 g/day: 0.87; 95% CI 0.82, 0.92; n = 2) and mortality. There was low certainty of evidence for inverse associations of vegetable consumption (per 100 g/day: 0.88; 95% CI 0.82, 0.94; n = 2), plant protein (per 10 g/day: 0.91; 95% CI 0.87, 0.96; n = 3), and for positive associations of egg consumption (per 10 g/day: 1.05; 95% CI 1.03, 1.08; n = 7) and cholesterol intake (per 300 mg/day: 1.19; 95% CI 1.13, 1.26; n = 2). For other dietary factors, evidence was uncertain or no association was observed. Higher intake of fish, whole grain, fiber, and n-3 polyunsaturated fatty acids were inversely associated with all-cause mortality in individuals with type 2 diabetes. There is limited evidence for other dietary factors, and, thus, more research is needed.

Carrot Intake is Consistently Negatively Associated with Cancer Incidence: A Systematic Review and Meta-Analysis of Prospective Observational Studies

Carrot Intake is Consistently Negatively Associated with Cancer Incidence: A Systematic Review and Meta-Analysis of Prospective Observational Studies

Is replacing red meat with other protein sources associated with lower risks of coronary heart disease and all-cause mortality? A meta-analysis of prospective studies.

A high amount of red meat consumption has been associated with higher risks of coronary heart disease (CHD) and all-cause mortality in a single food-exposure model. However, this model may overlook the potentially differential influence of red meat on these outcomes depending on the foods replaced by red meat. A PRISMA-compliant meta-analysis of prospective observational studies was performed to quantify the risks of CHD and all-cause mortality associated with the replacement of total, unprocessed, or processed red meat with fish/seafood, poultry, dairy, eggs, nuts, and legumes. The PubMed and Web of Science databases were searched to identify relevant articles published in any language from database inception to October 30, 2021. The prospective observational studies were considered relevant if they reported relative risks (RRs) and 95%CIs for the associations of interest. Thirteen articles were included. A random-effects model was used to estimate the summary RRs and 95%CIs for the associations of interest. Replacing total red meat with poultry (RR, 0.88, 95%CI, 0.82-0.96; I2 = 0%), dairy (RR, 0.90, 95%CI, 0.88-0.92; I2 = 0%), eggs (RR, 0.86, 95%CI, 0.79-0.94; I2 = 7.1%), nuts (RR, 0.84, 95%CI, 0.74-0.95; I2 = 66.8%), or legumes (RR, 0.84, 95%CI, 0.74-0.95; I2 = 7.3%) was associated with a lower risk of CHD, whereas substituting fish/seafood (RR, 0.91, 95%CI, 0.79-1.04; I2 = 69.5%) for total red meat was not associated with the risk of CHD. The replacement of total red meat with fish/seafood (RR, 0.92, 95%CI, 0.89-0.96; I2 = 86.9%), poultry (RR, 0.92, 95%CI, 0.90-0.95; I2 = 61.6%), eggs (RR, 0.91, 95%CI, 0.87-0.95; I2 = 33.8%), or nuts (RR, 0.92, 95%CI, 0.87-0.97; I2 = 81.9%) was associated with a lower risk of all-cause mortality, whereas the substitution of dairy (RR, 0.97, 95%CI, 0.93-1.01; I2 = 33.9%) or legumes (RR, 0.97, 95%CI, 0.93-1.01; I2 = 53.5%) for total red meat was not associated with the risk of all-cause mortality. Lower risks of CHD and all-cause mortality were more consistently observed for processed red meat replacements than for unprocessed red meat replacements. The results did not materially change when the analyses of total, processed, and unprocessed red meat were restricted to the studies that used a uniform substitution amount per unit of 1 serving/d. Keeping red meat, particularly processed red meat, consumption to a minimum along with increasing healthier alternative protein sources to replace red meat in the diet may contribute to the prevention of CHD and premature death. PROSPERO registration no. CRD42021259446.

Abstract WP209: Efficacy And Safety Of Early Anticoagulant Therapy Initiation In Patients With Acute Ischemic Stroke Related To Atrial Fibrillation: A Systematic Review And Meta-analysis

Background: The optimal timing for the initiation of anticoagulation in patients with acute ischemic stroke (AIS) related to atrial fibrillation (AF) remains uncertain. Observational studies assessing early anticoagulant initiation (≤14 days after index AIS) have provided conflicting results from the early use of non-vitamin K oral anticoagulants (NOACs) or vitamin K antagonists (VKAs). Methods: We performed a meta-analysis of prospective observational studies and RCTs to assess the efficacy and safety of early anticoagulation in AF-related AIS. We also compared the efficacy and safety between NOAC and VKA regimens. A random-effects model was used to pool the individual risk ratios (RRs) and corresponding 95% confidence intervals (CIs) between the two groups. Recurrent ischemic stroke was defined as the primary outcome. Results: Nine eligible studies (7 observational, 2 RCTs) were identified, including 6,840 patients with AF-related AIS (pooled mean baseline NIHSS score: 5.5; 95%CI: 3.7-7.2) who received early anticoagulation. The overall ischemic stroke recurrence rate was 5% (95%CI: 3.3-7%) and differed (p=0.05) between studies reporting anticoagulation initiation within a week (2.5%, 95%CI: 0.2-7.4%) or two weeks (6.7%, 95%CI:4.6-9.1%) from index event. The corresponding proportions of patients experiencing a fatal outcome, symptomatic or asymptomatic ICH were 4% (95%CI: 1.6-7.5%), 1.2% (95%CI: 0.3-2.6%) and 13.2% (95%CI: 6.4-22.1%), respectively. Of the 2 identified RCTs, 136 and 135 patients were randomized to early anticoagulation with NOAC or VKA, respectively. Both groups had a similar risk for ischemic stroke recurrence (RR=0.78; 95%CI: 0.32, 1.91; p=0.59). No significant differences were uncovered between early NOAC or early VKA treatment initiation for the outcomes of mortality (RR=0.57; 95%CI: 0.11, 2.97; p=0.51), symptomatic ICH (RR=0.38; 95%CI: 0.02, 9.10; p=0.55) or asymptomatic ICH (RR=1.10; 95%CI: 0.73, 1.67; p=0.64). Conclusions: Preliminary evidence from RCTs on early anticoagulation after AF-related AIS suggest that NOACs have comparable efficacy to VKAs in preventing ischemic stroke recurrence. Large scale RCTs are warranted to evaluate the potential superiority of NOACs in terms of safety endpoints.

Association of cognitive function with increased risk of cancer death and all-cause mortality: Longitudinal analysis, systematic review, and meta-analysis of prospective observational studies.

BackgroundDisturbed cognitive function is associated with several causes of mortality; however, the association between cognitive function and the risk of cancer death has not been extensively investigated yet. We aimed to evaluate the association of cognitive function with the risk of cancer death and all-cause mortality in the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) and Leiden 85-plus Study. Additionally, a systematic review and meta-analysis of longitudinal studies were conducted to evaluate the association of cognitive function and risk of cancer death.MethodsRisk of cancer death and all-cause mortality were reported using hazard ratios (HRs) with 95% confidence interval (CI) in tertiles of cognitive function of PROSPER and Leiden85-Plus Study. Additionally, PubMed, Embase, Web of Science, Cochrane, PsycINFO, Academic Search Premier, CINHAL, and Emcare were searched up to November 1st, 2020 to perform a systematic review and meta-analysis. The relative risks (RRs) with 95%CI of cancer death per each standard deviation lower performance in cognitive measurements were calculated.ResultsParticipants of PROSPER had 1.65-fold (95%CI 1.11–2.47) greater risk of cancer death (P for trend = 0.016) and 1.85-fold (95%CI 1.46–2.34) higher risk of all-cause mortality (P for trend<0.001), in multivariable models. Results of the Leiden-85 Plus Study showed that subjects with MMSE score below 24 had a lower chance of cancer death (HR 0.79, 95%CI 0.36–1.70, P for trend = 0.820) but had 2.18-fold (95%CI 1.57–3.02) higher risk of all-cause mortality compared to the reference group (P for trend<0.001). Besides, the results of systematic review and meta-analysis showed that per each standard deviation lower performance in cognitive function, individuals were at a 10% higher chance of cancer death (RR 1.10, 95%CI 1.00–1.20, P-value = 0.044).ConclusionsLower cognitive function performance is associated with a marginally increased risk of cancer death, in line with a significantly greater risk of all-cause mortality.

724 Cardiovascular morbidity and mortality related to non-alcoholic fatty liver disease: a systematic review and meta-analysis of prospective studies

Abstract Aims Whether non-alcoholic fatty liver disease (NAFLD) is a risk factor for cardiovascular (CV) events is still debated. Currently available evidence derives from non-homogeneous studies yielding conflicting results. We set out to assess the relationship between NAFLD and CV morbidity and mortality by pooling results of previous studies. Methods We performed a systematic review and meta-analysis of prospective observational studies published from 1966 through 2021 reporting summary-level outcome data in subjects with and without NAFLD. Adjusted risk ratios (RRs) and 95% confidence intervals (CIs) for all-cause mortality, CV mortality, myocardial infarction (MI), stroke, major adverse cerebrocardiovascular events (MACCE) and atrial fibrillation (AF) were pooled through inverse variance random-effect meta-analysis to compute the summary effect size. We performed post hoc subgroup analysis stratified by geographical region and univariate mixed-effect model meta-regression analysis to address statistical heterogeneity. Results We identified a total of 29 studies pooling an overall population of 5 626 573 middle-aged individuals (mean age 56 ± 8; male sex 53%; NAFLD 5.8%, n = 326 389). Mean follow-up was 10 ± 6 years. Compared with control population, presence of NAFLD was associated with similar risk of all-cause death (RR 1.17; 95% CI 0.89–1.52) and CV death (RR 0.84; 95% CI 0.64–1.10). When analysed by geographic location, pooled estimates of RR (95% CI) for all-cause death were 1.57 (1.00–2.48) for Western countries, and 0.81 (0.52–1.1.26) for Eastern countries (test for subgroup difference, P = 0.04). Meta-regression analysis showed a stronger relationship between NAFLD and all-cause mortality proportional to increasing body mass index (P = 0.048). NAFLD was associated with increased risk of myocardial infarction (RR 1.35; 95% CI 1.09–1.68), stroke (RR 1.20; 95% CI 1.06–1.35), MACCE (RR 2.09; 95% CI 1.57–2.78), and atrial fibrillation (RR 1.37; 95% CI 1.05–1.78). Conclusion NAFLD portends excess all-cause mortality but only in Western countries. CV mortality was similar in NAFLD and non-NAFLD groups. NAFLD is associated with increased risk of incident MI, stroke, MACCE, and AF.

Association between thyroid dysfunction and type 2 diabetes: a meta-analysis of prospective observational studies

BackgroundDiabetes mellitus and thyroid disease are two areas of broad interest in the field of endocrinology and metabolism. Variation of thyroid hormone concentration, even within the normal range, may portend the onset of type 2 diabetes mellitus (T2DM), especially among those with prediabetes. However, current evidence is mixed.MethodsProspective studies which assessed diabetes incidence were identified using a database search of MEDLINE and Embase through May 1, 2021. The Sidik-Jonkman random-effects model and cubic spline model were used to evaluate the associations and dose-response relationships between thyroid function/hormone levels and risk of T2DM and cardiovascular disease (CVD) risk among T2DM patients.ResultsA total of 12 prospective studies were included. We found that high baseline TSH levels were related to a 17% higher risk of T2DM (RR 1.17, 95% CI 1.01, 1.36; I2=78%, P<0.01), compared with normal TSH levels. Low FT3 (RR 1.40, 95% CI 1.09, 1.80; I2=59%, P=0.03) and low FT4 (RR 1.33, 95% CI 1.04, 1.71; I2=62%, P=0.02) levels were significantly associated with risk of T2DM. The cubic spline model indicated a J-shaped relationship with TSH, but inverted-J-shaped relationships with FT3 and FT4. CVD events and all-cause deaths were prospectively evaluated in four studies, but were not associated with abnormal thyroid function.ConclusionsOur meta-analysis determined that abnormal thyroid hormone level is associated with an increased risk of T2DM, showing a J-shaped relationship with TSH and inverted-J-shaped relationships with FT3 and FT4.Trial registrationRegistered number in PROSPERO: CRD42021225695.

Cardiovascular morbidity and mortality related to non-alcoholic fatty liver disease: a systematic review and meta-analysis of prospective studies

Abstract Background Whether non-alcoholic fatty liver disease (NAFLD) is a risk factor for cardiovascular (CV) events is still debated. Currently available evidence derives from non-homogeneous studies yielding conflicting results. Purpose We set out to assess the relationship between NAFLD and CV morbidity and mortality by pooling results of previous studies. Methods We performed a systematic review and meta-analysis of prospective observational studies published from 1966 through 2021 reporting summary-level outcome data in subjects with and without NAFLD. Adjusted risk ratios (RRs) and 95% confidence intervals (CIs) for all-cause mortality, CV mortality, myocardial infarction (MI), stroke, major adverse cerebrocardiovascular events (MACCE) and atrial fibrillation (AF) were pooled through inverse variance random-effect meta-analysis to compute the summary effect size. We performed post-hoc subgroup analysis stratified by geographical region and univariate mixed-effect model meta-regression analysis to address statistical heterogeneity. Results We identified a total of 29 studies pooling an overall population of 5,626,573 middle-aged individuals (mean age 56±8; male sex 53%; NAFLD 5.8%, n=326,389). Mean follow-up was 10±6 years. Compared with control population, presence of NAFLD was associated with similar risk of all-cause death (RR 1.17; 95% CI 0.89–1.52) and CV death (RR 0.84; 95% CI 0.64–1.10). When analysed by geographic location, pooled estimates of RR (95% CI) for all-cause death were 1.57 (1.00–2.48) for Western countries, and 0.81 (0.52–1.1.26) for Eastern countries (test for subgroup difference, P=0.04). Meta-regression analysis showed a stronger relationship between NAFLD and all-cause mortality proportional to increasing body mass index (P=0.048). NAFLD was associated with increased risk of myocardial infarction (RR 1.35; 95% CI 1.09–1.68), stroke (RR 1.20; 95% CI 1.06–1.35), MACCE (RR 2.09; 95% CI 1.57–2.78) and atrial fibrillation (RR 1.37; 95% CI 1.05–1.78). Conclusion NAFLD portends excess all-cause mortality but only in Western countries. CV mortality was similar in NAFLD and non-NAFLD groups. NAFLD is associated with increased risk of incident MI, stroke, MACCE and AF. Funding Acknowledgement Type of funding sources: None. Figure 1Figure 2

Intake of dietary fats andfatty acids and the incidence of type 2 diabetes: Asystematic review and dose-response meta-analysis of prospective observational studies.

The role of fat quantity and quality in type 2 diabetes (T2D) prevention is controversial. Thus, this systematic review and meta-analysis aimed to investigate the associations between intake of dietary fat and fatty acids and T2D, and to evaluate the certainty of evidence. We systematically searched PubMed and Web of Science through 28 October 2019 for prospective observational studies in adults on the associations between intake of dietary fat and fatty acids and T2D incidence. The systematic literature search and data extraction were conducted independently by 2 researchers. We conducted linear and nonlinear random effects dose-response meta-analyses, calculated summary relative risks (SRRs) with their corresponding 95% confidence intervals (95% CIs), and assessed the certainty of evidence. In total, 15,070 publications were identified in the literature search after the removal of duplicates. Out of the 180 articles screened in full text, 23 studies (19 cohorts) met our inclusion criteria, with 11 studies (6 cohorts) conducted in the US, 7 studies (7 cohorts) in Europe, 4 studies (5 cohorts) in Asia, and 1 study (1 cohort) in Australia. We mainly observed no or weak linear associations between dietary fats and fatty acids and T2D incidence. In nonlinear dose-response meta-analyses, the protective association for vegetable fat and T2D was steeper at lower levels up to 13 g/d (SRR [95% CI]: 0.81 [0.76; 0.88], pnonlinearity = 0.012, n = 5 studies) than at higher levels. Saturated fatty acids showed an apparent protective association above intakes around 17 g/d with T2D (SRR [95% CI]: 0.95 [0.90; 1.00], pnonlinearity = 0.028, n = 11). There was a nonsignificant association of a decrease in T2D incidence for polyunsaturated fatty acid intakes up to 5 g/d (SRR [95% CI]: 0.96 [0.91; 1.01], pnonlinearity = 0.023, n = 8), and for alpha-linolenic acid consumption up to 560 mg/d (SRR [95% CI]: 0.95 [0.90; 1.00], pnonlinearity = 0.014, n = 11), after which the curve rose slightly, remaining close to no association. The association for long-chain omega-3 fatty acids and T2D was approximately linear for intakes up to 270 mg/d (SRR [95% CI]: 1.10 [1.06; 1.15], pnonlinearity < 0.001, n = 16), with a flattening curve thereafter. Certainty of evidence was very low to moderate. Limitations of the study are the high unexplained inconsistency between studies, the measurement of intake of dietary fats and fatty acids via self-report on a food group level, which is likely to lead to measurement errors, and the possible influence of unmeasured confounders on the findings. There was no association between total fat intake and the incidence of T2D. However, for specific fats and fatty acids, dose-response curves provided insights for significant associations with T2D. In particular, a high intake of vegetable fat was inversely associated with T2D incidence. Thus, a diet including vegetable fat rather than animal fat might be beneficial regarding T2D prevention.

Influence of the month of birth on persistence of ADHD in prospective studies: protocol for an individual patient data meta-analysis

IntroductionAttention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder with symptoms, especially the hyperactive ones, that tend to decrease in severity with age. Interestingly, children born just before the school-entry cut-off date...

Evolution of outcome and complications in TAVR: a meta-analysis of observational and randomized studies

Aim of the present analysis was to collect and pool all available data currently in the literature regarding outcomes and complications of all approved TAVR prosthesis and to assess the transition from first to next generation TAVR devices by directly comparing both in regard of procedure related complications. Transcatheter aortic valve replacement is a well established treatment modality in patients with severe aortic stenosis deemed to be inoperable or at unacceptable risk for open heart surgery. First generation prostheses were associated with a high rate of peri-procedural complications like paravalvular regurgitation, valve malpositioning, vascular complications and conduction disorders. Refinement of the available devices incorporate features to address the limitations of the first-generation devices. A PRISMA checklist-guided systematic review and meta-analysis of prospective observational studies, national and device specific registries or randomized clinical trials was conducted. Studies were identified by searching PUBMED, SCOPUS, Cochrane Central Register of Controlled Trials and LILACs from January 2000 to October 2017. We extracted and pooled data on both mortality and complications from 273 studies for twelve different valves prostheses in a total of 68,193 patients. In second generation prostheses as compared to first generation devices, we observed a significant decrease in mortality (1.47 ± 1.73% vs. 5.41 ± 4.35%; p < 0.001), paravalvular regurgitation (1.75 ± 2.43vs. 12.39 ± 9.38, p < 0.001) and MACE. TAVR with contemporary next generation devices has led to an impressive improvement in TAVR safety driven by refined case selection, improved procedural techniques and increased site experience.

Search for multiple myeloma risk factors using Mendelian randomization

AbstractThe etiology of multiple myeloma (MM) is poorly understood. Summary data from genome-wide association studies (GWASs) of multiple phenotypes can be exploited in a Mendelian randomization (MR) phenome-wide association study (PheWAS) to search for factors influencing MM risk. We performed an MR-PheWAS analyzing 249 phenotypes, proxied by 10 225 genetic variants, and summary genetic data from a GWAS of 7717 MM cases and 29 304 controls. Odds ratios (ORs) per 1 standard deviation increase in each phenotype were estimated under an inverse variance weighted random effects model. A Bonferroni-corrected threshold of P = 2 × 10−4 was considered significant, whereas P < .05 was considered suggestive of an association. Although no significant associations with MM risk were observed among the 249 phenotypes, 28 phenotypes showed evidence suggestive of association, including increased levels of serum vitamin B6 and blood carnitine (P = 1.1 × 10−3) with greater MM risk and ω-3 fatty acids (P = 5.4 × 10−4) with reduced MM risk. A suggestive association between increased telomere length and reduced MM risk was also noted; however, this association was primarily driven by the previously identified risk variant rs10936599 at 3q26 (TERC). Although not statistically significant, increased body mass index was associated with increased risk (OR, 1.10; 95% confidence interval, 0.99-1.22), supporting findings from a previous meta-analysis of prospective observational studies. Our study did not provide evidence supporting any modifiable factors examined as having a major influence on MM risk; however, it provides insight into factors for which the evidence has previously been mixed.

Fiber consumption and breast cancer incidence: A systematic review and meta-analysis of prospective studies.

Associations between fiber intake and breast cancer risk have been evaluated in prospective studies, but overall, the evidence is inconsistent.The authors performed a systematic review and meta-analysis of prospective studies to investigate the relation between intake of total and types of fiber with breast cancer incidence. The MEDLINE and Excerpta Medica dataBASE (EMBASE) databases were searched through July 2019 for prospective studies that reported on the association between fiber consumption and incident breast cancer. The pooled relative risk (RR) and 95% confidence intervals (95% CI) were estimated comparing the highest versus the lowest category of total and types of fiber consumption, using a random-effects meta-analysis. The authors identified 17 cohort studies, 2 nested case-control studies, and 1 clinical trial study. Total fiber consumption was associated with an 8% lower risk of breast cancer (comparing the highest versus the lowest category,pooled RR, 0.92; 95% CI, 0.88-0.95 [I2 =12.6%]). Soluble fiber was found to be significantly inversely associated with risk of breast cancer (pooled RR, 0.90 [95% CI, 0.84-0.96; I2 = 12.6%]) and insoluble fiber was found to be suggestively inversely associated with risk of breast cancer (pooled RR, 0.93 [95% CI, 0.86-1.00; I2 = 33.4%]). Higher total fiber intake was associated with a lower risk of both premenopausal and postmenopausal breast cancers (pooled RR, 0.82 [95% CI, 0.67-0.99; I2 =35.2%] and pooledRR, 0.91 [95% CI, 0.88-0.95; I2 =0.0%], respectively). Furthermore, the authors observed a nonsignificant inverse association between intake of total fiber and risk of both estrogen and progesterone receptor-positive and estrogen and progesterone receptor-negative breast cancers. A random-effects meta-analysis of prospective observational studies demonstrated that high total fiber consumption was associated with a reduced risk of breast cancer. This finding was consistent for soluble fiber as well as for women with premenopausal and postmenopausal breast cancer.

Processed meat intake and incidence of colorectal cancer: a systematic review and meta-analysis of prospective observational studies.

The objective was to use accumulated evidence to explore the association between processed meat intake and risk of colorectal cancer (CRC) and to investigate the reliability of associations by evaluating patterns of risk by study population characteristics and research quality parameters. We included 29 observational prospective cohort studies with relative risk estimates and 95% confidence intervals for CRC according to various levels of processed meat consumption. Risk of bias was assessed using Risk Of Bias In Non-randomized Studies-of Interventions (ROBINS-I) tool. Data sources were PubMed and Embase up to January 2017. The summary relative risks for high versus low processed meat consumption and risk of CRC, colon, and rectal cancer were 1.13 (95% CI: 1.01, 1.26), 1.19 (95% CI: 1.09, 1.31), and 1.21 (95% CI: 0.98, 1.49), respectively. Similar estimates were observed for the dose-response analyses. Heterogeneity across studies was detected in most analytical models. The overall judgment showed that two out of 29 studies had a moderate risk of bias, 25 had a serious risk of bias, and 2 had a critical risk of bias. The bias domains most often rated critical were bias due to risk of confounding, bias due to missing data, and selective outcome reporting bias. Although this meta-analysis indicates a modest association between processed meat intake and an increased risk of CRC, our assessment of internal validity warrants a cautious interpretation of these results, as most of the included studies were judged to have serious or critical risks of bias.

Dietary factors and diabetes-related health outcomes in patients with type 2 diabetes: protocol for a systematic review and meta-analysis of prospective observational studies

IntroductionType 2 diabetes (T2D) is a major health concern associated with several comorbidities such as diabetic chronic kidney disease, neuropathy and cardiovascular diseases. Many of these complications may be preventable...

Smoking status and subsequent gastric cancer risk in men compared with women: a meta-analysis of prospective observational studies

BackgroundSmoking is one of the well-established risk factors for gastric cancer incidence, yet whether men are more or equally susceptible to gastric cancer due to smoking compared with women is a matter of controversy. The aim of this study was to investigate and compare the effect of sex on gastric cancer risk associated with smoking.MethodsWe conducted a systemic literature search in MEDLINE, EMBASE, and the Cochrane CENTRAL databases to identify studies published from inception to December 2018. We included prospective observational studies which reported effect estimates with 95% confidence intervals (CIs) for associations of current or former smokers with the incidence of gastric cancer by sex. We calculated the ratio of relative risk (RRR) with corresponding 95% CI based on sex-specific effect estimates for current or former smokers versus non-smokers on the risk of gastric cancer.ResultsWe included 10 prospective studies with 3,381,345 participants in our analysis. Overall, the summary RRR (male to female) for gastric cancer risk in current smokers was significantly increased compared with non-smokers (RRR: 1.30; 95% CI: 1.05–1.63; P = 0.019). Furthermore, there was no significant sex difference for the association between former smokers and gastric cancer risk (RRR: 1.20; 95% CI: 0.92–1.55; P = 0.178). However, the result of sensitivity analysis indicated the pooled result was not stable, which was altered by excluding a nested case-control study (RRR: 1.31; 95% CI: 1.10–1.57; P = 0.002).ConclusionThis systematic review showed a potential sex difference association between current smokers and the risk of gastric cancer. The sex differential in smokers can give important clues for the etiology of gastric cancers and should be examined in further studies.

Dietary and circulating vitamin C, vitamin E, β-carotene and risk of total cardiovascular mortality: a systematic review and dose-response meta-analysis of prospective observational studies.

The present review aimed to quantify the association of dietary intake and circulating concentration of major dietary antioxidants with risk of total CVD mortality. Systematic review and meta-analysis. Systematic search in PubMed and Scopus, up to October 2017.ParticipantsProspective observational studies reporting risk estimates of CVD mortality across three or more categories of dietary intakes and/or circulating concentrations of vitamin C, vitamin E and β-carotene were included. A random-effects meta-analysis was conducted. A total of fifteen prospective cohort studies and three prospective evaluations within interventional studies (320 548 participants and 16 974 cases) were analysed. The relative risks of CVD mortality for the highest v. the lowest category of antioxidant intakes were as follows: vitamin C, 0·79 (95 % CI 0·68, 0·89; I 2=46 %, n 10); vitamin E, 0·91 (95 % CI 0·79, 1·03; I 2=51 %, n 8); β-carotene, 0·89 (95 % CI 0·73, 1·05; I 2=34 %, n 4). The relative risks for circulating concentrations were: vitamin C, 0·60 (95 % CI 0·42, 0·78; I 2=65 %, n 6); α-tocopherol, 0·82 (95 % CI 0·76, 0·88; I 2=0 %, n 5); β-carotene, 0·68 (95 % CI 0·52, 0·83; I 2=50 %, n 6). Dose-response meta-analyses demonstrated that the circulating biomarkers of antioxidants were more strongly associated with risk of CVD mortality than dietary intakes. The present meta-analysis demonstrates that higher vitamin C intake and higher circulating concentrations of vitamin C, vitamin E and β-carotene are associated with a lower risk of CVD mortality.

Association of benign thyroid diseases with thyroid cancer risk: a meta-analysis of prospective observational studies.

Evidence showed that benign thyroid disease was one of the risk factors for thyroid cancer. However, the results of some studies were inconsistent and were previously meta-analyses of case-control studies. Therefore, we performed a meta-analysis of prospective studies to investigate the relationship between benign thyroid diseases and thyroid cancer risk. All eligible studies were identified via systematic searches of multiple literature databases. The combined RR (relative risk)/HR (hazard ratio) or SIR (standardized incidence ratio) with 95% confidence interval was calculated. Heterogeneity was assessed with the I2 test. Publication bias and subgroup analyses were also performed. Twelve studies were eligible for inclusion in the meta-analysis. The pooled RR/HR of thyroid carcinoma in benign thyroid diseases was 4.39 (95% CI 3.22-5.55). The pooled SIR of thyroid carcinoma in benign thyroid diseases was 5.98 (95% CI 4.09-7.86). Subgroup analysis was performed using the type of benign thyroid diseases. Effect value was RR/HR: hyperthyroidism (RR/HR = 3.89, 95% CI = 1.69-6.08), hypothyroidism (RR/HR = 2.72, 95% CI = 1.04-4.41), and goiter (RR/HR = 22.18, 95% CI = 12.09-32.28). Effect value was SIR: hyperthyroidism (RR/HR = 5.96, 95% CI = 1.88-10.03), goiter (RR/HR = 7.65, 95% CI = 6.94-8.37), and thyroiditis (RR/HR = 3.25, 95% CI = 1.62-4.89). Our study has shown that benign thyroid diseases might be associated with increased risk of thyroid cancer, especially in hyperthyroidism, hypothyroidism, and goiter. However, further investigation is needed to better understand the underlying biological mechanisms.