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

BMJ ◽  
2021 ◽  
pp. n1864
Author(s):  
Lukas Schwingshackl ◽  
Sara Balduzzi ◽  
Jessica Beyerbach ◽  
Nils Bröckelmann ◽  
Sarah S Werner ◽  
...  
Keyword(s):  
Cohort Studies ◽  
Randomised Controlled Trials ◽  
Prediction Interval ◽  
Prediction Intervals ◽  
Controlled Trials ◽  
Nutrition Research ◽  
The Difference ◽  
Bodies Of Evidence ◽  
Randomised Controlled ◽  
Risk Ratios

Abstract Objective To evaluate the agreement between diet-disease effect estimates of bodies of evidence from randomised controlled trials and those from cohort studies in nutrition research, and to investigate potential factors for disagreement. Design Meta-epidemiological study. Data sources Cochrane Database of Systematic Reviews, and Medline. Review methods Population, intervention or exposure, comparator, outcome (PI/ECO) elements from a body of evidence from cohort studies (BoE(CS)) were matched with corresponding elements of a body of evidence from randomised controlled trials (BoE(RCT)). Pooled ratio of risk ratios or difference of mean differences across all diet-disease outcome pairs were calculated. Subgroup analyses were conducted to explore factors for disagreement. Heterogeneity was assessed through I 2 and τ 2 . Prediction intervals were calculated to assess the range of possible values for the difference in the results between evidence from randomised controlled trials and evidence from cohort studies in future comparisons. Results 97 diet-disease outcome pairs (that is, matched BoE(RCT) and BoE(CS)) were identified overall. For binary outcomes, the pooled ratio of risk ratios comparing estimates from BoE(RCT) with BoE(CS) was 1.09 (95% confidence interval 1.04 to 1.14; I 2 =68%; τ 2 =0.021; 95% prediction interval 0.81 to 1.46). The prediction interval indicated that the difference could be much more substantial, in either direction. We further explored heterogeneity and found that PI/ECO dissimilarities, especially for the comparisons of dietary supplements in randomised controlled trials and nutrient status in cohort studies, explained most of the differences. When the type of intake or exposure between both types of evidence was identical, the estimates were similar. For continuous outcomes, small differences were observed between randomised controlled trials and cohort studies. Conclusion On average, the difference in pooled results between estimates from BoE(RCT) and BoE(CS) was small. But wide prediction intervals and some substantial statistical heterogeneity in cohort studies indicate that important differences or potential bias in individual comparisons or studies cannot be excluded. Observed differences were mainly driven by dissimilarities in population, intervention or exposure, comparator, and outcome. These findings could help researchers further understand the integration of such evidence into prospective nutrition evidence syntheses and improve evidence based dietary guidelines.

Efficacy of electronic cigarettes for tobacco smoking cessation: An adapted systematic review

2020 ◽  
Vol 30 (Supplement_5) ◽  
Author(s):  
T O'Dowd
Keyword(s):  
Smoking Cessation ◽  
Cohort Studies ◽  
Randomised Controlled Trials ◽  
Electronic Cigarettes ◽  
Controlled Trials ◽  
Significant Heterogeneity ◽  
Smoking Reduction ◽  
Significant Difference ◽  
Randomised Controlled

Abstract Background Worldwide smoking remains the leading cause of preventable morbidity and mortality. Electronic cigarettes (ECs) are increasingly used by tobacco smokers as an aid to smoking cessation; however, their efficacy remains uncertain. Methods Electronic databases, clinical trial registries and grey literature sources were searched. The aim was to examine randomised controlled trials or prospective cohort studies, published since the 2016 Cochrane review on this topic, that assessed the efficacy of ECs in achieving smoking cessation among current smokers. Results Two RCTs and five cohort studies, including a total of 16,460 participants, were eligible for inclusion. One RCT found sustained 1-year abstinence of 18.0% in the EC group versus 9.9% in the nicotine replacement therapy group (RR: 1.83; 95% CI 1.30 to 2.58; P < 0.001). The second RCT did not find a statistically significant difference in abstinence rates between EC users and non-users (RR 0.71). Of the five included cohort studies, four reported statistically significant RRs. Two found a positive association (RRs of 1.45 and 1.84) between EC use and smoking cessation but two studies showed EC use was associated with reduced smoking cessation (RRs of 0.25 and 0.35). Due to significant heterogeneity between the studies the data were deemed unsuitable for pooling into a meta-analysis. All trials assessing smoking reduction reported higher rates of reduction among EC users. No serious adverse events were reported with EC use. Follow-up periods of included trials ranged from one to four years, with an average of 1.6 years. Conclusions There is limited, low-quality evidence that ECs are an effective intervention for smoking cessation and smoking reduction. The overall quality of evidence is low as it is based on a small number of studies with inconsistent and imprecise results. Due to the short follow-up periods of the included trials, the long-term safety of ECs is unclear from this review. Key messages Limited evidence that electronic cigarettes are an effective smoking cessation intervention. Further well-designed randomised controlled trials are required to investigate the efficacy of ECs for smoking cessation.

scholarly journals Protective effects of dietary PUFA against chronic disease: evidence from epidemiological studies and intervention trials

2013 ◽  
Vol 73 (1) ◽  
pp. 73-79 ◽  
Author(s):  
Thomas A. B. Sanders
Keyword(s):  
Chronic Disease ◽  
Cohort Studies ◽  
Cardiac Death ◽  
Lower Risk ◽  
Randomised Controlled Trials ◽  
Cochrane Review ◽  
Total Mortality ◽  
Partial Replacement ◽  
Controlled Trials ◽  
Randomised Controlled

This review considers evidence for a protective effect of PUFA on chronic disease. Estimates of PUFA intakes in prospective cohort studies are usually based on FFQ or biomarkers of intake. Cohort studies suggest that both linoleic and linolenic acid intake are associated with a lower risk of CHD. The intake of fish, the major source of long-chainn-3 PUFA is associated with a lower risk of both stroke and CHD, particularly sudden cardiac death. No relationship with common sites of cancer (breast and colon) and PUFA has been found. However, some recent studies suggest an association of high intakes ofn-3 PUFA with risk of prostate cancer. An updated Cochrane review of dietary fat modification (replacing SFA with PUFA) randomised controlled trials to prevent CHD found a 14 % lower incidence and a non-significant 7 % lower mortality from CHD. The effects of an increased intake ofn-3 PUFA on CHD incidence mortality have been tested in patients with pre-existing CHD in randomised controlled trials. Meta-analysis of these trials showed no overall benefit on total mortality or CVD incidence but a trend for lower risk of cardiac death was 0·91 (95 % CI 0·85, 0·98). At present, there is little evidence from other trials demonstrating the clear benefits or harm from increased intakes of PUFA. In conclusion, present evidence intakes benefit from partial replacement of SFA with a balanced mixture ofn-6 andn-3 PUFA which may contribute to CVD prevention.

scholarly journals Comparative effectiveness of interventions for treating interdigital necrobacillosis in cattle: A network meta-analysis

2021 ◽  
Vol 66 (No. 11) ◽  
pp. 461-469
Author(s):  
MA Torehanov ◽  
ZK Tulemissova ◽  
AS Ibazhanova ◽  
ER Rafikova ◽  
‪B Muzapbarov ◽  
...  
Keyword(s):  
Comparative Effectiveness ◽  
Randomised Controlled Trials ◽  
Antimicrobial Agents ◽  
Meta Analysis ◽  
Controlled Trials ◽  
Therapeutic Activity ◽  
Pharmacokinetic Properties ◽  
Randomised Controlled ◽  
Ceftiofur Sodium ◽  
Risk Ratios

The aim of this study was to comparatively evaluate the efficacy of different antimicrobial agents against interdigital necrobacillosis (IN) in cattle to identify the treatment with the greatest benefit. A network meta-analysis was used to synthesise empirical results from randomised controlled trials. Four studies with five interventions for 565 animals were included. The meta-analysis found no significant differences between the risk ratios for the antimicrobials versus placebo. However, ceftiofur sodium administered intramuscularly at a dose of 1.0 µg/kg body weight every 24 h for 3 days showed a better clinical response than 6.6 µg of oxytetracycline, 2.5 µg of tulathromycin, the placebo and 0.1 µg of ceftiofur sodium. The results show the best efficacy for 6.6 µg of oxytetracycline and 1.0 µg of ceftiofur sodium. Nevertheless, the latter is likely to be superior to oxytetracycline in terms of its pharmacodynamic and pharmacokinetic properties. Thus, 1.0 µg of ceftiofur sodium appears to provide the best therapeutic activity against IN in cattle. Further well-designed studies are required.

scholarly journals Patient relevant outcomes of unicompartmental versus total knee replacement: systematic review and meta-analysis

BMJ ◽  
2019 ◽  
pp. l352 ◽  
Author(s):  
Hannah A Wilson ◽  
Rob Middleton ◽  
Simon G F Abram ◽  
Stephanie Smith ◽  
Abtin Alvand ◽  
...  
Keyword(s):  
Systematic Review ◽  
Decision Making ◽  
Total Knee Replacement ◽  
Cohort Studies ◽  
Knee Replacement ◽  
Risk Ratio ◽  
Randomised Controlled Trials ◽  
Controlled Trials ◽  
Total Knee ◽  
Randomised Controlled

AbstractObjectiveTo present a clear and comprehensive summary of the published data on unicompartmental knee replacement (UKA) or total knee replacement (TKA), comparing domains of outcome that have been shown to be important to patients and clinicians to allow informed decision making.DesignSystematic review using data from randomised controlled trials, nationwide databases or joint registries, and large cohort studies.Data sourcesMedline, Embase, Cochrane Controlled Register of Trials (CENTRAL), and Clinical Trials.gov, searched between 1 January 1997 and 31 December 2018.Eligibility criteria for selecting studiesStudies published in the past 20 years, comparing outcomes of primary UKA with TKA in adult patients. Studies were excluded if they involved fewer than 50 participants, or if translation into English was not available.Results60 eligible studies were separated into three methodological groups: seven publications from six randomised controlled trials, 17 national joint registries and national database studies, and 36 cohort studies. Results for each domain of outcome varied depending on the level of data, and findings were not always significant. Analysis of the three groups of studies showed significantly shorter hospital stays after UKA than after TKA (−1.20 days (95% confidence interval −1.67 to −0.73), −1.43 (−1.53 to −1.33), and −1.73 (−2.30 to −1.16), respectively). There was no significant difference in pain, based on patient reported outcome measures (PROMs), but significantly better functional PROM scores for UKA than for TKA in both non-trial groups (standard mean difference −0.58 (−0.88 to −0.27) and −0.29 (−0.46 to −0.11), respectively). Regarding major complications, trials and cohort studies had non-significant results, but mortality after TKA was significantly higher in registry and large database studies (risk ratio 0.27 (0.16 to 0.45)), as were venous thromboembolic events (0.39 (0.27 to 0.57)) and major cardiac events (0.22 (0.06 to 0.86)). Early reoperation for any reason was higher after TKA than after UKA, but revision rates at five years remained higher for UKA in all three study groups (risk ratio 5.95 (1.29 to 27.59), 2.50 (1.77 to 3.54), and 3.13 (1.89 to 5.17), respectively).ConclusionsTKA and UKA are both viable options for the treatment of isolated unicompartmental osteoarthritis. By directly comparing the two treatments, this study demonstrates better results for UKA in several outcome domains. However, the risk of revision surgery was lower for TKA. This information should be available to patients as part of the shared decision making process in choosing treatment options.Systematic review registrationPROSPERO number CRD42018089972.

scholarly journals How reliable are randomised controlled trials for studying the relationship between diet and disease? A narrative review

2016 ◽  
Vol 116 (3) ◽  
pp. 381-389 ◽  
Author(s):  
Norman J. Temple
Keyword(s):  
Cohort Studies ◽  
Randomised Controlled Trials ◽  
Critical Evaluation ◽  
Epidemiological Studies ◽  
Dietary Factors ◽  
Controlled Trials ◽  
Large Numbers ◽  
History Of ◽  
Randomised Controlled

AbstractLarge numbers of randomised controlled trials (RCT) have been carried out in order to investigate diet–disease relationships. This article examines eight sets of studies and compares the findings with those from epidemiological studies (cohort studies in seven of the cases). The studies cover the role of dietary factors in blood pressure, body weight, cancer and heart disease. In some cases, the findings from the two types of study are consistent, whereas in other cases the findings appear to be in conflict. A critical evaluation of this evidence suggests factors that may account for conflicting findings. Very often RCT recruit subjects with a history of the disease under study (or at high risk of it) and have a follow-up of only a few weeks or months. Cohort studies, in contrast, typically recruit healthy subjects and have a follow-up of 5–15 years. Owing to these differences, findings from RCT are not necessarily more reliable than those from well-designed prospective cohort studies. We cannot assume that the results of RCT can be freely applied beyond the specific features of the studies.

scholarly journals Effect of reducing total fat intake on body weight: systematic review and meta-analysis of randomised controlled trials and cohort studies

BMJ ◽  
2012 ◽  
Vol 345 (dec06 1) ◽  
pp. e7666-e7666 ◽  
Author(s):  
L. Hooper ◽  
A. Abdelhamid ◽  
H. J. Moore ◽  
W. Douthwaite ◽  
C. M. Skeaff ◽  
...  
Keyword(s):  
Systematic Review ◽  
Body Weight ◽  
Cohort Studies ◽  
Randomised Controlled Trials ◽  
Meta Analysis ◽  
Controlled Trials ◽  
Fat Intake ◽  
Total Fat ◽  
Randomised Controlled

scholarly journals The impact of maternal diet in pregnancy and lactation on allergy and atopy outcomes in offspring: A systematic review

2021 ◽  
Author(s):  
◽  
Melissa Whitehead
Keyword(s):  
New Zealand ◽  
Cohort Studies ◽  
Allergic Disease ◽  
Randomised Controlled Trials ◽  
Maternal Diet ◽  
Risk Of Bias ◽  
Controlled Trials ◽  
Pregnancy And Lactation ◽  
Randomised Controlled ◽  
In Pregnancy

<p>Allergic disease and atopy create a substantial emotional and financial burden for affected individuals and their families. Significant healthcare costs are also incurred with New Zealand children showing consistently high rates of allergic disease when compared with global statistics. The potential to decrease the incidence of allergic disease and atopy through modification of maternal diet has been the subject of recent attention with the possibility for transgenerational impact being of considerable interest.  The objectives of this systematic review were firstly to investigate the relationship between maternal diet in pregnancy and lactation on allergic outcomes in the offspring, and to then relate these findings to the New Zealand context.   The following databases were accessed as part of this review: PubMed via helicon (advanced search), ProQuest (MEDLINE) via helicon, CINAHL Complete (EBSCO host via helicon). Limits were “humans”. The key search terms were ‘diet’ or ‘supplements’, ‘pregnancy’ or ‘lactation’, ‘allergy’ or ‘atopy’ or ‘asthma; NOT ‘elimination’ or ‘avoidance’. The studies for inclusion in this review were restricted to studies written in the English language. The final search was undertaken 11/04/17 once data extraction completed and one new study found. Initial search was 14/07/16. Search period 14/04/16-11/04/17.  Randomised controlled trials and cohort studies that systematically recorded maternal intake of diet or supplements were included. The health-related outcomes assessed were asthma, wheeze, eczema and allergic rhinitis. Data was extracted for this review using the Cochrane Public Health Group’s template. Risk of bias was assessed using the Cochrane risk of bias assessment tool for the randomised controlled trials and the Newcastle-Ottawa Scale for the cohort studies. Risk of bias was assessed again and presented using the Grade summary of findings tables.  Overall, 54 studies were included in this review, collectively involving more than 100,000 children and comprising of 16 randomised controlled trials and 38 cohort studies that were selected based on predetermined inclusion and exclusion criteria. Data on vitamins, oligo-elements, food groups and dietary patterns during pregnancy and lactation were also collected. A meta-analysis was not performed due to the diversity in variables, multiple outcomes assessed, and the variety of measurements implemented within the studies.   This work presents a comprehensive summary and review of the identified studies that explored the impact of maternal diet in pregnancy and lactation on allergy and atopy outcomes. Although individual studies demonstrated various associations between maternal diet during pregnancy and lactation to impact on health outcomes for the offspring, overall, this work did not show any consistent findings collectively across the studies reviewed. This was due to the differing methods of measurement of association, intake and outcome assessment used in the reviewed studies which further complicated the ability to compare and contrast the findings of the studies with each other. Each study was assessed both for its individual findings and then collectively according to the variables assessed. The findings of this review lend support for the undertaking of additional trials and studies with more consistent and controlled measurements of interventions and outcomes to better facilitate comparisons between studies.   Key findings from the reviewed studies, which included only one New Zealand based study, were related to the New Zealand context. Additional New Zealand based information and related works highlighted a need for personally tailored maternal nutrition information to be delivered consistently by all health professionals interacting with pregnant women.   Key words: diet, supplements, pregnancy, lactation, allergy, atopy, asthma.</p>

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