Perspective: Network Meta-analysis Reaches Nutrition Research: Current Status, Scientific Concepts, and Future Directions

Association between substituting macronutrients and all-cause mortality: a network meta-analysis of prospective observational studies

Background

Suboptimal diet quality is a key risk factor for premature death. Assuming relatively stable energy intake among individuals, changes in nutrient intakes occur by exchanging different nutrients. Therefore we aimed to examine the association of isocaloric substitution of dietary (macro)nutrients with all-cause mortality using network meta-analysis (NMA).

Methods

For this systematic review and NMA of prospective observational studies MEDLINE, Embase, and Scopus were searched from inception to February 13th, 2024. Eligible studies reported substitution analyses for quantity and/or quality of macronutrients, including carbohydrates, proteins, and fatty acids on all-cause mortality. Random-effects NMA were used in order to evaluate the pooled hazard ratios (HR) and 95% confidence intervals (CI) of substituting each included nutrient with another. We assessed risk of bias with the ROBINS-E tool, and the certainty of evidence (CoE) using the Grading of Recommendations Assessment, Development and Evaluations (GRADE) approach. This study is registered with PROSPERO (CRD42023450706).

Findings

Thirty-nine studies with 1,737,644 participants, 395,491 deaths, 297 direct comparisons, and seven nutrient-specific networks were included. Moderate CoE was found for an association with lower mortality risk when replacing 5% of energy intake from carbohydrates with polyunsaturated fatty acids (PUFA; HR: 0.90; 95%CI: 0.84, 0.95), n-6 PUFA (0.85; 0.77, 0.94), n-3 PUFA (0.72; 0.59, 0.86), and plant monounsaturated fatty acids (MUFA; 0.90; 0.85, 0.95), and when replacing 5% of energy from saturated fatty acids (SFA) and trans-fatty acids (TFA), with PUFA, MUFA, and plant-MUFA (HRrange: 0.75 to 0.91). A lower mortality risk was additionally found when 5% of animal-MUFA was replaced with plant-MUFA, and when replacing animal protein, and SFA with plant protein (HRrange: 0.81 to 0.87, moderate CoE).

Interpretation

Our results provide practical knowledge for public health professionals and can inform upcoming dietary guidelines. The beneficial association of increasing PUFA (both n-3 and n-6) and (plant-) MUFA intake while reducing carbohydrates, SFA and TFA, along with replacing animal protein and animal-MUFA with plant-based sources of protein and fat (MUFA) on the all-cause mortality risk, underscores the importance of plant-based dietary recommendations.

Funding

None.

Efficacy and safety of Chinese patent medicines combined with antidepressants for treatment of depression in adults: A multiple-treatment meta-analysis

BACKGROUND

Combinations of Chinese patent medicines (CPM) with antidepressants (including selective serotonin reuptake inhibitors (SSRI), selective serotonin-norepinephrine reuptake inhibitors (SNRI), tricyclic antidepressants (TCA), and noradrenergic and specific serotonergic antidepressants (NaSSA)) are frequently utilized for treating depression in adults. However, the efficacy and safety of these combination treatments remain to be established.

METHODS

Systematic search was conducted in seven electronic databases, regulatory websites and international registers of trials from 1994 to 2023 that included adult patients with depressive disorders who received CPM combined with antidepressants. The Multiple-Treatment Meta-Analysis (MTMA) was conducted using a random effects model with Stata/MP17 and R4.3.5 software. Primary outcomes were total efficacy rate, Hamilton Depression Scale (HAMD) score, and Treatment Emergency Symptom Scale (TESS) score. Secondary outcomes included brain-derived neurotrophic factor (BDNF) levels.

RESULTS

A total of 146 randomized controlled trials (13,754 participants: 6929 in intervention and 6825 in control groups) were included. For total effective rate, Multiple-Treatment Meta-Analysis results showed that the overall effect of combined intervention was better compared with antidepressants alone, where Jieyuanshenkeli (JYASKL) presented the optimal option for improving total efficacy (OR = 5.39, 95% CI [2.60, 11.18], SUCRA = 84.50%). In reduding the HAMD, Shuganjieyujiaonang (SGJYJN) was most likely to reduce the HAMD score (SMD = -2.20, 95% CI [-3.06, -1.33], SUCRA = 86.10%), Jieyuanshenkeli (JYASKL),Tianewangbuxindan (TWBXD), Shuyukeli (SYKL), Anshenbuxinwan (ASBXW) combination intervention did not appear to be statistically superior to antidepressants alone. In theTreatment Emergency Symptom Scale (TESS), Wulinjiaonang induced the most significant reduction in TESS score (SMD = -1.98, 95% CI [-3.59, -0.36], SUCRA = 90.40%). Tianmengjiaonang (TMJN) + Antidepressants(AD) (SUCRA = 88.30%) displayed the highest scores in increasing the levels of BDNF, although not statistically significant compared to Antidepressants(AD) alone (SMD = 1.23, 95% CI [0.90, 1.55]).

CONCLUSION

Combinations of CPM and antidepressants showed superior efficacy over antidepressants alone. The optimal combinations were determined as Shuganjieyu Jiaonang (SGJYJN)/SSRIs and Jieyuanshenkeli (JYASKL)/SSRIs. In terms of safety, results showed that combination therapy did not show better TESS efficacy than antidepressants alone.Although some of the combination interventions were not superior than antidepressants alone in reducing HAMD scores,our findings provide a potentially significant alternative option for clinical complementary therapy. However, these results require further validation through larger sample sizes, multicenter randomized controlled trials, and real-world data.

Impact of Quantity and Type of Dietary Protein on Cardiovascular Disease Risk Factors Using Standard and Network Meta-analyses of Randomized Controlled Trials

CONTEXT

Higher protein diets (HPDs) have shown favorable outcomes on weight maintenance and body-composition management; however, their protective effects against cardiovascular diseases (CVDs) remain uncertain and contentious. Furthermore, it is important to consider the influence of other macronutrients in the diet and type of dietary protein when studying HPDs, because this aspect has been overlooked in previous studies.

OBJECTIVE

We assessed the impacts of quantity and type of dietary protein on CVD risk factors.

DATA SOURCES

A database search was conducted in PubMed, Embase, CINAHL, Web of Science, and Cochrane Library and a total of 100 articles met the eligibility criteria.

DATA EXTRACTION

Extracted data from 100 articles were analyzed using standard meta-analysis, and 41 articles were also analyzed using network meta-analysis.

DATA ANALYSIS

In the standard meta-analysis, an HPD had significant favorable effects on systolic blood pressure (SBP) (mean difference [MD] = -1.51 mmHg; 95% CI: -2.77, -0.25), diastolic blood pressure (DBP) (MD = -1.08 mmHg; 95% CI: -1.81, -0.35), and flow-mediated dilation (MD = 0.78%; 95% CI: 0.09, 1.47) compared with lower protein diets. The further network meta-analysis supported that the high-protein, high-carbohydrate, low-fat diet was the most recommended diet to ensure a maximum decrease in SBP, DBP, total cholesterol (TC), and low-density-lipoprotein cholesterol (LDL-C). In comparison to animal-protein-rich diets, plant-protein-rich diets (PPRs) exhibited a significant favorable effects on improving TC (MD = -0.12 mmol/L; 95% CI: -0.19, -0.05), triglyceride (MD = -0.05 mmol/L; 95% CI: -0.09, -0.01), LDL-C (MD = -0.11 mmol/L; 95% CI: -0.18, -0.04), and high-density-lipoprotein cholesterol (MD = 0.03 mmol/L; 95% CI: 0.02, 0.04) levels.

CONCLUSION

Consumption of HPDs and PPRs supports improvements in vascular health and lipid-lipoprotein profiles, respectively. Furthermore, macronutrient composition should be carefully designed in the dietary approach to maximize the effectiveness of HPDs in improving CVD risk factors.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42022369931.

Effect of Dietary Approaches on Glycemic Control in Patients with Type 2 Diabetes: A Systematic Review with Network Meta-Analysis of Randomized Trials

BACKGROUND

Dietary patterns play a critical role in diabetes management, while the best dietary pattern for Type 2 diabetes (T2DM) patients is still unclear. The aim of this network meta-analysis was to compare the impacts of various dietary approaches on the glycemic control of T2DM patients.

METHODS

Relevant studies were retrieved from PubMed, Embase, Web of Knowledge, Cochrane Central Register of Controlled Trials (CENTRAL), and other additional records (1949 to 31 July 2022). Eligible RCTs were those comparing different dietary approaches against each other or a control diet in individuals with T2DM for at least 6 months. We assessed the risk of bias of included studies with the Cochrane risk of bias tool and confidence of estimates with the Grading of Recommendations Assessment, Development, and Evaluation approach for network meta-analyses. In order to determine the pooled effect of each dietary approach relative to each other, we performed a network meta-analysis (NMA) for interventions for both HbA1c and fasting glucose, which enabled us to estimate the relative intervention effects by combing both direct and indirect trial evidence.

RESULTS

Forty-two RCTs comprising 4809 patients with T2DM were included in the NMA, comparing 10 dietary approaches (low-carbohydrate, moderate-carbohydrate, ketogenic, low-fat, high-protein, Mediterranean, Vegetarian/Vegan, low glycemic index, recommended, and control diets). In total, 83.3% of the studies were at a lower risk of bias or had some concerns. Findings of the NMA revealed that the ketogenic, low-carbohydrate, and low-fat diets were significantly effective in reducing HbA1c (viz., -0.73 (-1.19, -0.28), -0.69 (-1.32, -0.06), and -1.82 (-2.93, -0.71)), while moderate-carbohydrate, low glycemic index, Mediterranean, high-protein, and low-fat diets were significantly effective in reducing fasting glucose (viz., -1.30 (-1.92, -0.67), -1.26 (-2.26, -0.27), -0.95 (-1.51, -0.38), -0.89 (-1.60, -0.18) and -0.75 (-1.24, -0.27)) compared to a control diet. The clustered ranking plot for combined outcomes indicated the ketogenic, Mediterranean, moderate-carbohydrate, and low glycemic index diets had promising effects for controlling HbA1c and fasting glucose. The univariate meta-regressions showed that the mean reductions of HbA1c and fasting glucose were only significantly related to the mean weight change of the subjects.

CONCLUSIONS

For glycemic control in T2DM patients, the ketogenic diet, Mediterranean diet, moderate-carbohydrate diet, and low glycemic index diet were effective options. Although this study found the ketogenic diet superior, further high-quality and long-term studies are needed to strengthen its credibility.

Interventions for preventing back pain among office workers - a systematic review and network meta-analysis

OBJECTIVE

Back pain is common in the working population. This systematic review with network meta-analysis (NMA) aimed to compare the effects of interventions for preventing back pain among office workers.

METHODS

We searched eight databases and additional sources up to March 2021. We included randomized controlled trials (RCT) and cluster RCT focusing on office workers, comparing work-related interventions aimed at preventing back pain (defined as pain in any part of the spine) to a control condition and assessing back pain and/or work absence. Further outcomes considered were adverse events and participants' satisfaction. We performed both frequentist and component NMA. Risk of bias (RoB) was evaluated using RoB 2 and certainty of the evidence (CoE) was assessed using GRADE.

RESULTS

We screened 9809 records and included 24 studies with a total of 7080 participants. RoB was assessed as "some concerns" or "high" for all studies and outcomes. Included studies investigated multicomponent interventions, ergonomics, physical activity, education, behavioral interventions and no/minimal interventions. Effects were mostly not statistically significant and based on low/very low CoE. Physical activity probably reduces days of work absence slightly [mean difference (MD) -1.10, 95% confidence interval (CI) -2.07- -0.13], and combining physical activity and ergonomics may reduce back pain intensity (standardized MD -0.41, 95% CI -0.80- -0.02) when compared to no/minimal intervention. A large proportion of participants were satisfied with the interventions, adverse events were rarely assessed.

CONCLUSIONS

We observed mostly minor effects of interventions on back pain and work absence among office workers. The practical relevance of these effects is questionable.

Effects of nutritional intervention strategies in the primary prevention of overweight and obesity in school settings: systematic review and network meta-analysis

Objective

To examine the effects of different nutritional intervention strategies in the school setting on anthropometric and quality of diet outcomes by comparing and ranking outcomes in a network meta-analysis.

Design

Systematic review and network meta-analysis.

Data sources

PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science, Education Resources Information Centre (ERIC), PsycInfo, CAB Abstracts, Campbell Library, Evidence for Policy and Practice Information and Co-ordinating Centre (EPPI-Centre) BiblioMap, Australian Education Index, Joanna Briggs Institute Evidence-Based Practice (JBI EBP) database, Practice-based Evidence in Nutrition (PEN) database, ClinicalTrials.gov, Current Controlled Trials, and World Health Organization International Clinical Trials Registry Platform.

Eligibility criteria for selecting studies

A systematic literature search was performed from inception to 2 May 2022. Cluster randomised controlled trials meeting these study criteria were included: generally healthy school students aged 4-18 years; intervention with ≥1 nutritional components in a school setting; and studies that assessed anthropometric measures (eg, body mass index, body fat) or measures related to the quality of diet (eg, intake of fruit and vegetables), or both. Random effects pairwise meta-analyses and network meta-analyses were performed with a frequentist approach. P scores, a frequentist analogue to surface under the cumulative ranking curve, ranging from 0 to 1 (indicating worst and best ranked interventions, respectively) were calculated. Risk of bias was assessed with Cochrane's RoB 2 tool. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework was used to rate the certainty of evidence.

Results

51 cluster randomised controlled trials involving 75 954 participants and seven intervention nodes were included. Inconsistency could not be assessed (except for intake of fruit and vegetables) because the network meta-analyses were based mainly on star shaped networks with no direct evidence for specific pairs of nutritional interventions. Overall, little or no evidence was found to support a difference in body mass index, body weight, body fat, or waist circumference and moderate improvements in intake of fruit and vegetables with nutritional interventions in a school setting. Low to moderate certainty of evidence further suggested that multicomponent nutritional interventions likely reduced the prevalence (odds ratio 0.66, 95% confidence interval 0.55 to 0.80) and incidence (0.67, 0.47 to 0.96) of overweight compared with a control group. Based on low certainty of evidence, nutrition education and multicomponent interventions may be more effective than a control group (ie, usual practice) for increasing intake of fruit and vegetables. Multicomponent nutritional interventions were ranked the most effective for reducing body mass index (P score 0.76) and intake of fat (0.82). Nutrition education was ranked as best for body mass index z score (0.99), intake of fruit and vegetables (0.82), intake of fruit (0.92), and intake of vegetables (0.88).

Conclusions

The findings suggest that nutritional interventions in school settings may improve anthropometric and quality of diet measures, potentially contributing to the prevention of overweight and obesity in childhood and adolescence. The findings should be interpreted with caution because the certainty of evidence was often rated as low. The results of the network meta-analysis could be used by policy makers in developing and implementing effective, evidence based nutritional intervention strategies in the school setting.

Systematic review registration

PROSPERO CRD42020220451.

Comparative efficacy of various CHIs combined with western medicine for non-small cell lung cancer: A bayesian network meta-analysis of randomized controlled trials

Background: Given the limitations of Western medicine (WM) for the treatment of non-small cell lung cancer (NSCLC) and the wide exploration of Chinese herbal injections (CHIs), systematically evaluate the efficacy of Various CHIs Combined with WM for Non-small Cell Lung Cancer. In this study, we performed a network meta-analysis to evaluate the comparative efficacy of 16 CHIs combined with WM regimens for the treatment of NSCLC.

Methods: Literature databases were searched from their inception to November 2021, and all randomized control trials (RCTs) involving NSCLC patients treated with a combination of Chinese and WM were retrieved. Outcomes, including disease control rate, survival quality score, incidence of gastrointestinal adverse reactions, incidence of leukopenia, and incidence of thrombocytopenia, were analyzed using RevMan (5.3), Stata17, and R software. Surface under the cumulative ranking curve (SUCRA) probability values were calculated to rank the treatments examined, and clustering analysis was used to compare the effects of CHIs on different outcomes.

Results: A total of 389 studies involving 31,263 patients and 16 CHIs were included. The 16 CHIs were: Aidi injection (ADI), Huachansu injection (HCSI), oil of Ophiopogon injection (OOMI), disodium cantharidinate and vitamin B6 injection (DCI), Shenfu injection (SFI), Shenmai injection (SMI), Shenqi Fuzheng injection (SQFZI), Chansu injection (CSI), Delisheng injection (DLSI), Fufang Kushen injection (FFKSI), Huangqi injection (HQI), Kangai injection (KAI), Kanglaite injection (KLTI), Shengmai injection (SI), Xiangguduotang injection (XGDTI), and Xiaoaiping injection (XAPI). The results of the network meta-analysis showed that, with WM treatment as a co-intervention, CSI was most likely to improve the disease control rate (SUCRA = 80.90%), HQI had the highest probability of being the best option for improving the survival quality score (SUCRA = 82.60%), DCI had the highest probability of reducing the incidence of gastrointestinal adverse reactions (SUCRA = 85.50%), HCSI + WM had the highest probability of reducing the incidence of thrombocytopenia (SUCRA = 91.30%), while SMI had the highest probability of reducing the incidence of leukopenia (SUCRA = 79.10%).

Conclusion: CHIs combined with WM is proved to be more effective than WM alone, which may be beneficial to NSCLC patients. SMI + WM and DCI + WM are most likely the optimal CHI to improve disease control rates, survival quality score, and reduce adverse effects. This study has limitations; therefore, higher quality RCTs and real-world evidence are required to support our conclusions.

Which physical therapy intervention is most effective in reducing secondary lymphoedema associated with breast cancer? Protocol for a systematic review and network meta-analysis

INTRODUCTION

Lymphoedema associated with breast cancer is caused by an interruption of the lymphatic system, together with factors such as total mastectomy, axillary dissection, positive lymph nodes, radiotherapy, use of taxanes and obesity. Physiotherapy treatment consists of complex decongestive therapy, manual lymphatic drainage and exercises, among other interventions. Currently, there are several systematic review and randomised controlled trials that evaluate the efficacy of these interventions. However, at present, there are no studies that compare the effectiveness of all these physical therapy interventions. The purpose of this study is to determine which physical therapy treatment is most effective in reducing breast cancer-related lymphoedema, improving quality of life and reducing pain.

METHODS AND ANALYSIS

MEDLINE, PEDro, CINAHL, EMBASE, LILACS and Cochrane Central Register of Controlled Trials will be searched for reports of randomised controlled trials published from database inception to June 2022. We will only include studies that are written in English, Spanish and Portuguese. We will also search grey literature, preprint servers and clinical trial registries. The primary outcomes are reduction of secondary lymphoedema associated with breast cancer, improvements in quality of life and pain reduction. The risk of bias of individual studies will be evaluated using the Cochrane Risk of Bias 2.0 Tool. A network meta-analysis will be performed using a random-effects model. First, pairs will be directly meta-analysed and indirect comparisons will be made between the different physical therapy treatments. The GRADE system will be used to assess the overall quality of the body of evidence associated with the main results.

ETHICS AND DISSEMINATION

This protocol does not require approval from an ethics committee. The results will be disseminated via peer-reviewed publications.

PROSPERO REGISTRATION NUMBER

CDR42022323541.

Long Term Weight Loss Diets and Obesity Indices: Results of a Network Meta-Analysis

Background

Scientists have been investigating efficient interventions to prevent and manage obesity. This network meta-analysis (NMA) compared the effect of different diets [moderate macronutrients (MMs), low fat/high carbohydrate (LFHC), high fat/low carbohydrate (HFLC), and usual diet (UD)] on weight, body mass index (BMI), and waist circumference (WC) changes at ≥12 months.

Methods

We searched Medline, Embase, PubMed databases, and the Cochrane Library. We systematically assessed randomized controlled trials (RCTs) evaluating dietary interventions on adults (mean BMI ≥ 25 kg/m²) receiving active dietary counseling for ≥12 months. We pooled the data using a random-effect NMA. We assessed the quality of the included RCTs using the Cochrane risk of bias (ROB) tool.

Results

We included 36 trials, 14 of which compared HFLC with MM diets. Compared with UD, all diets were associated with a significant weight loss (WL) at ≥12 months, HFLC [mean difference in kg (95% CI): −5.5 (−7.6; −3.4)], LFHC [−5.0 (−7.1; −2.9)] and MM [−4.7 (−6.8; −2.7)]. HFLC, compared with MM diet, was associated with a slightly higher WL (of −0.77 kg) and drop in BMI (of −0.36 kg/m²), while no significant difference was detected in other dietary comparisons. WC was lower with all diets compared to UD, with no significant difference across specific diets. There was no significant interaction of the results with the pre-specified sub-groups. The ROB was moderate to high, mostly related to unclear allocation concealment, high dropout rate and unclear or lack of blinding of participants, providers, and outcome assessors.

Conclusion

Dietary interventions extending over ≥12 months are superior to UD in inducing weight, BMI and WC loss. HFLC might be associated with a slightly higher WL compared with MM diets.

Systematic Trial Registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=103116, PROSPERO (CRD42018103116).

Effect of Antioxidants on Sperm Quality Parameters in Subfertile Men: A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials

Antioxidant supplementation has been identified as an important intervention for subfertile men. However, the effectiveness of different antioxidants in improving sperm quality remains unclear. In this study, a network meta-analysis (NMA) was designed to evaluate the effects of different antioxidants on sperm quality parameters in subfertile men. Published randomized controlled trials (RCTs) of antioxidants in subfertile men were searched in the PubMed, Embase, and Cochrane Library databases from inception to January 31, 2021. Eight antioxidants (folic acid, zinc, vitamin E, carnitine, selenium, coenzyme q10 [CoQ10], N-acetylcysteine, and vitamin C) and a placebo (control) were included in our study. A Bayesian NMA with random effects was performed for each outcome (sperm concentration, sperm motility, and sperm morphology); the surface under the cumulative ranking curves (SUCRAs) for the effectiveness of each intervention was applied to identify the optimal intervention. Eighteen studies with 1,790 subfertile men were included in the study. CoQ10 elicited a significant increase in sperm concentration (mean difference [MD] = 5.95; 95% confidence interval [CI] 0.05, 10.79) compared with the placebo; it achieved the highest rank in efficacy among all the antioxidants (SUCRA: 79.4%). With regard to sperm motility, carnitine (MD = 12.43; 95% CI 4.07, 20.26) and CoQ10 (MD = 7.33; 95% CI 0.35, 14.17) showed significant beneficial effects compared with the placebo; the efficacy of carnitine was the highest among all the antioxidants (SUCRA: 88.7%). With regard to sperm morphology, the efficacy of vitamin C tended to be the highest (SUCRA: 93.6%), although it did not show significant beneficial effect (MD = 7.73; 95% CI -0.94, 16.33) compared with the placebo. Overall, for subfertile men, CoQ10 and carnitine interventions showed better effectiveness in increasing sperm concentration and sperm motility, respectively.

SIGNIFICANCE

The effectiveness of different antioxidants in improving sperm quality in subfertile men remains unclear. To the best of our knowledge, this is the first study to compare the effectiveness of different antioxidants on sperm quality parameters in subfertile men.

Reporting of Cochrane systematic review protocols with network meta-analyses-A scoping review

Publishing systematic review protocols is a fundamental part of systematic reviews to ensure transparency and reproducibility. In this scoping review, we aimed to evaluate reporting of Cochrane systematic review protocols with network meta-analyses (NMA). We searched all Cochrane NMA protocols published in 2018 and 2019, and assessed the characteristics and reporting of methodologies relevant to NMA. We reported frequencies for each reporting item. Forty-five protocols were assessed, including two for overviews and 43 for intervention reviews. Thirty-three (73%) were labelled as NMA protocols in the title. Forty-two (95%) justified the need of an NMA and 40 (89%) used appropriate search strategies to identify potential eligible studies. About half (24, 53%) considered the transitivity assumption when reporting inclusion criteria and 35 (78%) specified potential effect modifiers. Forty-three (96%) reported statistical software for NMA, 25 (56%) reported NMA model choice, 32 (71%) reported framework choice and 32 (71%) reported assumption about heterogeneity variances. Protocols varied in whether they reported methods for relative ranking (35, 78%), statistical inconsistency (40, 89%), reporting bias (44, 98%) and sources of heterogeneity (39, 87%). In conclusion, Cochrane NMA protocols reported multiple NMA-specific items well, but could be further improved, especially regarding transitivity assumptions. Our recommendations for NMA protocol reporting based on this scoping review could assist authors, reviewers, and editors to improve NMA protocols.

Work-related interventions for preventing back pain-protocol for a systematic review and network meta-analysis

BACKGROUND

Back pain is a widespread health problem that accounts for substantial disability and high costs. The workplace is considered to critically affect the occurrence and persistence of back pain and therefore offers an important opportunity for preventive interventions. Various work-related intervention strategies including both single- and multicomponent interventions have been developed and evaluated so far. To determine their effectiveness, a method of analysis is needed that particularly meets the challenges of the multidimensionality and diversity of these interventions. This planned systematic review and network meta-analysis aims to compare the effects of different work-related interventions for preventing non-specific back pain in people within a formal employment-related context.

METHODS

We will search the following databases: CENTRAL, MEDLINE, Web of Science, CINAHL, PsycINFO, PEDro, SPORTDiscus, and Academic Search Premier from their inception onwards, as well as additional sources. Randomized controlled trials (RCTs) and cluster-RCTs will be considered if they (1) include people within a formal employment-related context, (2) include people without back pain or mixed samples (i.e., people with and without back pain), (3) compare one or more work-related preventive intervention(s) to a control condition, and (4) assess non-specific back pain (incidence or/and pain intensity), ability to work (numbers of participants or/and numbers of days absent from work), intervention-related adverse events or/and self-reported satisfaction with the intervention. Random-effects pairwise meta-analyses and frequentist network meta-analyses will be conducted where appropriate. We will calculate summary effect sizes for each comparison of interventions and rank interventions according to their P scores. If feasible, we will conduct additional component network meta-analyses. We plan to conduct subgroup analyses for job exposure, intervention duration, baseline back pain, different localizations of back pain, and gender. Risk of bias will be assessed using RoB 2 and the certainty of the evidence will be rated using the GRADE approach.

DISCUSSION

This systematic review aims to identify work-related intervention strategies as well as components within work-related interventions that are effective for preventing back pain. We expect the results to provide guidance for selecting the most promising interventions and foster the purposeful use of resources. Additionally, they may inform the development and implementation of work-related interventions as well as the design of future research in this field.

TRIAL REGISTRATION

PROSPERO CRD42021232469.

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.

Recent Molecular Mechanisms and Beneficial Effects of Phytochemicals and Plant-Based Whole Foods in Reducing LDL-C and Preventing Cardiovascular Disease

Abnormal lipid metabolism leads to the development of hyperlipidemia, a common cause of multiple chronic disorders, including cardiovascular disease (CVD), obesity, diabetes, and cerebrovascular disease. Low-density lipoprotein cholesterol (LDL-C) currently remains the primary target for treatment of hyperlipidemia. Despite the advancement of treatment and prevention of hyperlipidemia, medications used to manage hyperlipidemia are limited to allopathic drugs, which present certain limitations and adverse effects. Increasing evidence indicates that utilization of phytochemicals and plant-based whole foods is an alternative and promising strategy to prevent hyperlipidemia and CVD. The current review focuses on phytochemicals and their pharmacological mode of actions for the regulation of LDL-C and prevention of CVD. The important molecular mechanisms illustrated in detail in this review include elevation of reverse cholesterol transport, inhibition of intestinal cholesterol absorption, acceleration of cholesterol excretion in the liver, and reduction of cholesterol synthesis. Moreover, the beneficial effects of plant-based whole foods, such as fresh fruits, vegetables, dried nuts, flax seeds, whole grains, peas, beans, vegan diets, and dietary fibers in LDL-C reduction and cardiovascular health are summarized. This review concludes that phytochemicals and plant-based whole foods can reduce LDL-C levels and lower the risk for CVD.

Effects of nutrition intervention strategies in the primary prevention of overweight and obesity in school settings: a protocol for a systematic review and network meta-analysis

BACKGROUND

Overweight and obesity in children and adolescents are major public health challenges affecting quality of life and representing important risk factors in the development of non-communicable diseases. School environments provide great possibilities for the primary prevention of overweight and obesity and different school-based nutrition interventions are available. However, existing research on school-based nutrition interventions has important limitations and no network meta-analysis (NMA) has been performed yet to compare all available interventions. Therefore, the present research project aims to investigate the impact of different nutrition interventions in the school setting by comparing and ranking them using NMA methodology.

METHODS/DESIGN

A systematic literature search will be performed in 11 electronic databases (PubMed, the Cochrane Library, Web of Science, ERIC, PsycINFO, CAB Abstracts, Campbell Library, BiblioMap EPPI, Australian Education Index, Joanna Briggs Institute Evidence-Based Practice Database and Practice-based Evidence in Nutrition Database). Parallel or cluster randomized controlled trials (RCTs) meeting the following criteria will be included: (1) generally healthy school students aged 4-18 years, (2) school-based intervention with ≥ 1 nutrition component, and (3) assessed anthropometric (overweight/obesity risk, body weight change, weight Z-score, [standardized] body mass index, body fat, waist circumference) and/or diet-quality measures (daily intake of fruits and vegetables, fat, and sugar-sweetened beverages). Random effects pairwise and NMA will be performed for these outcomes and surface under the cumulative ranking curve (SUCRA) estimated (P-score). Where possible, component NMA (CNMA) will be used additionally. Subgroup analyses are carried out for intervention duration, gender, age of school students, socioeconomic status, and geographical location, and sensitivity analyses by excluding high risk of bias RCTs.

DISCUSSION

This systematic review and NMA will be the first to both directly and indirectly compare and rank different school-based nutrition interventions for the primary prevention of overweight and obesity in childhood and adolescence. Our analyses will provide important insights about the effects of the different interventions and show which are the most promising. The results of our study can help inform the design of new studies and will be of value to anyone interested in developing successful, evidence-based nutrition interventions in school settings.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO: CRD42020220451 .

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.

Impact of Meal Frequency on Anthropometric Outcomes: A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials

The relation between meal frequency and measures of obesity is inconclusive. Therefore, this systematic review and network meta-analysis (NMA) set out to compare the isocaloric effects of different meal frequencies on anthropometric outcomes and energy intake (EI). A systematic literature search was conducted in 3 electronic databases (Medline, Cochrane Library, Web of Science; search date, 11 March 2019). Randomized controlled trials (RCTs) were included with ≥2 wk intervention duration comparing any 2 of the eligible isocaloric meal frequencies (i.e., 1 to ≥8 meals/d). Random-effects NMA was performed for 4 outcomes [body weight (BW), waist circumference (WC), fat mass (FM), and EI], and surface under the cumulative ranking curve (SUCRA) was estimated using a frequentist approach (P-score: value is between 0 and 1). Twenty-two RCTs with 647 participants were included. Our results suggest that 2 meals/d probably slightly reduces BW compared with 3 meals/d [mean difference (MD): -1.02 kg; 95% CI: -1.70, -0.35 kg) or 6 meals/d (MD: -1.29 kg; 95% CI: -1.74, -0.84 kg; moderate certainty of evidence). We are uncertain whether 1 or 2 meals/d reduces BW compared with ≥8 meals/d (MD1 meal/d vs. ≥8 meals/d: -2.25 kg; 95% CI: -5.13, 0.63 kg; MD2 meals/d vs. ≥8 meals/d: -1.32 kg; 95% CI: -2.19, -0.45 kg) and whether 1 meal/d probably reduces FM compared with 3 meals/d (MD: -1.84 kg; 95% CI: -3.72, 0.05 kg; very low certainty of evidence). Two meals per day compared with 6 meals/d probably reduce WC (MD: -3.77 cm; 95% CI: -4.68, -2.86 cm; moderate certainty of evidence). One meal per day was ranked as the best frequency for reducing BW (P-score: 0.81), followed by 2 meals/d (P-score: 0.74), whereas 2 meals/d performed best for WC (P-score: 0.96). EI was not affected by meal frequency. In conclusion, our findings indicate that there is little robust evidence that reducing meal frequency is beneficial.

Dietary sugars and cardiometabolic risk factors: a network meta-analysis on isocaloric substitution interventions

BACKGROUND

There is controversy on the relevance of dietary sugar intake for cardiometabolic health.

OBJECTIVE

The aim of this network meta-analysis (NMA) was to assess how isocaloric substitutions of dietary sugar with other carbohydrates affect cardiometabolic risk factors, comparing different intervention studies.

METHODS

We included randomized controlled trials (RCTs) investigating the isocaloric effect of substituting dietary sugars (fructose, glucose, sucrose) with other sugars or starch on cardiometabolic risk markers, including LDL cholesterol, triacylglycerol (TG), fasting glucose (FG), glycated hemoglobin (HbA1c), insulin resistance (HOMA-IR), uric acid, C-reactive protein (CRP), alanine transaminase (ALT), aspartate transaminase (AST), and liver fat content. To identify the most beneficial intervention for each outcome, random-effects NMA was conducted by calculating pooled mean differences (MDs) with 95% CIs, and by ranking the surface under the cumulative ranking curves (SUCRAs). The certainty of evidence was evaluated using the Confidence In Network Meta-Analysis tool.

RESULTS

Thirty-eight RCTs, including 1383 participants, were identified. A reduction in LDL-cholesterol concentrations was shown for the exchange of sucrose with starch (MD: -0.23 mmol/L; 95% CI: -0.38, -0.07 mmol/L) or fructose with starch (MD: -0.22 mmol/L; 95% CI: -0.39, -0.05 mmol/L; SUCRAstarch: 98%). FG concentrations were also lower for the exchange of sucrose with starch (MD: -0.14 mmol/L; 95% CI: -0.29, 0.01 mmol/L; SUCRAstarch: 91%). Replacing fructose with an equivalent energy amount of glucose reduced HOMA-IR (MD: -0.36; 95% CI: -0.71, -0.02; SUCRAglucose: 74%) and uric acid (MD: -23.77 µmol/L; 95% CI: -44.21, -3.32 µmol/L; SUCRAglucose: 93%). The certainty of evidence was rated very low to moderate. No significant effects were observed for TG, HbA1c, CRP, ALT, and AST.

CONCLUSIONS

Our findings indicate that substitution of sucrose and fructose with starch yielded lower LDL cholesterol. Insulin resistance and uric acid concentrations were beneficially affected by replacement of fructose with glucose. Our findings are limited by the very low to moderate certainty of evidence. This review was registered at www.crd.york.ac.uk/prospero as CRD42018080297.

Comparative effects of different types of tree nut consumption on blood lipids: a network meta-analysis of clinical trials

BACKGROUND

Recent evidence has confirmed that nuts are one of the best food groups at reducing LDL cholesterol and total cholesterol (TC). However, the comparative effects of different types of nuts on blood lipids are unclear.

OBJECTIVES

This network meta-analysis of randomized clinical trials aimed to assess the comparative effects of walnuts, pistachios, hazelnuts, cashews, and almonds on typical lipid profiles.

METHODS

We conducted literature searches to identify studies comparing ≥2 of the following diets-walnut-enriched, pistachio-enriched, hazelnut-enriched, cashew-enriched, almond-enriched, and control diets-for the management of triglycerides (TGs), LDL cholesterol, TC, and HDL cholesterol. Random-effects network meta-analyses, ranking analyses based on the surface under the cumulative ranking (SUCRA) curves, and sensitivity analyses according to the potential sources of heterogeneity across the included studies were performed for each outcome.

RESULTS

Thirty-four trials enrolling 1677 participants were included in this study. The pistachio-enriched diet was ranked best for TG (SUCRA: 85%), LDL cholesterol (SUCRA: 87%), and TC (SUCRA: 96%) reductions. For TG and TC reductions, the walnut-enriched diet was ranked as the second-best diet. Regarding LDL cholesterol reduction, the almond-enriched diet was ranked second best. The pistachio-enriched and walnut-enriched diets were more effective at lowering TG, LDL cholesterol, and TC compared with the control diet. Regarding TG and TC reductions, the pistachio-enriched diet was also more effective than the hazelnut-enriched diet. For TG reduction, the walnut-enriched diet was better than the hazelnut-enriched diet. However, these findings are limited by the low quality of evidence ratings. In addition, the quality of this network meta-analysis was limited by the small number and generally poor reporting of available studies.

CONCLUSIONS

The pistachio-enriched and walnut-enriched diet could be better alternatives for lowering TGs, LDL cholesterol, and TC compared with other nut-enriched diets included in this study. The findings warrant further evaluation by more high-quality studies.This network meta-analysis was registered at www.crd.york.ac.uk/PROSPERO as CRD42019131128.

Impact of different types of olive oil on cardiovascular risk factors: A systematic review and network meta-analysis

BACKGROUND AND AIM

This network meta-analysis (NMA) compares the effects of different types of olive oil (OO) on cardiovascular risk factors.

METHODS AND RESULTS

Literature search was conducted on three electronic databases (Medline, Web of Science, and Cochrane Central).

INCLUSION CRITERIA

Randomized controlled trials (RCTs) (≥3 weeks duration of intervention) comparing at least two of the following types of OO: refined OO (ROO), mixed OO (MOO), low phenolic (extra) virgin OO (LP(E)VOO), and high phenolic (extra) virgin OO (HP(E)VOO). Random-effects NMA was performed for seven outcomes; and surface under the cumulative ranking curve (SUCRA) was estimated, using an analytical approach (P-score). Thirteen RCTs (16 reports) with 611 mainly healthy participants (mean age: 26-70 years) were identified. No differences for total cholesterol, HDL-cholesterol, triacylglycerols, and diastolic blood pressure were observed comparing ROO, MOO, LP(E)VOO and HP(E)VOO. HP(E)VOO slightly reduce LDL-cholesterol (LDL-C) compared to LP(E)VOO (mean difference [MD]: -0.14 mmol/L, 95%-CI: -0.28, -0.01). Both, HP(E)VOO and LP(E)VOO reduces SBP compared to ROO (range of MD: -2.99 to -2.87 mmHg), and HP(E)VOO may improve oxidized LDL-cholesterol (oxLDL-C) compared to ROO (standardized MD: -0.68, 95%-CI: -1.31, -0.04). In secondary analyses, EVOO may reduce oxLDL-C compared to ROO, and a dose-response relationship between higher intakes of phenolic compounds from OO and lower SBP and oxLDL-C values was detected. HP(E)VOO was ranked as best treatment for LDL-C (P-score: 0.83), oxLDL-C (0.88), and SBP (0.75).

CONCLUSIONS

HP(E)VOO may improve some cardiovascular risk factors, however, public health implications are limited by overall low or moderate certainty of evidence.

Impact of different dietary approaches on blood lipid control in patients with type 2 diabetes mellitus: a systematic review and network meta-analysis

The aim of this study was to assess the effects of different dietary approaches on low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglyceride (TG) levels in patients with type 2 diabetes (T2D) by applying network meta-analysis (NMA). Systematic electronic and hand searches were conducted until January 2018. Randomized controlled trials (RCTs) with an intervention period of ≥ 12 weeks, focussing on adults with T2D, and comparing dietary approaches regarding LDL, HDL or TGs, were included. For each outcome measure, random effects NMA was performed in order to determine the effect of each dietary approach compared to every other dietary intervention. Mean differences (MDs) and 95% confidence intervals (95% CIs) were calculated, and for the ranking, the surface under the cumulative ranking curves (SUCRA) was determined. Additionally, the credibility of evidence was evaluated. 52 RCTs (44 for LDL, 48 for HDL and 52 for TGs) comparing nine dietary approaches (low fat, vegetarian, Mediterranean, high protein, moderate carbohydrate, low carbohydrate, control, low glycaemic index/glycaemic load and Palaeolithic diet) enrolling 5360 T2D patients were included. The vegetarian diet most effectively reduced LDL levels [MD (95% CI): - 0.33 (- 0.55, - 0.12) mmol/L; compared to the control diet]. The Mediterranean diet beneficially raised HDL [MD (95% CI): 0.09 (0.04, 0.15) mmol/L] and decreased TG levels [MD (95% CI): - 0.41 (- 0.72, - 0.10) mmol/L] compared to the control diet. The Mediterranean diet was the most effective dietary approach to manage diabetic dyslipidaemia altogether (SUCRA: 79%). The overall findings are mainly limited by low credibility of evidence.