scholarly journals Best (but oft-forgotten) practices: sample size and power calculation for a dietary intervention trial with episodically consumed foods

2020 ◽  
Vol 112 (4) ◽  
pp. 920-925
Author(s):  
Wei Zhang ◽  
Aiyi Liu ◽  
Zhiwei Zhang ◽  
Tonja Nansel ◽  
Susan Halabi
Keyword(s):  
Sample Size ◽  
Ad Hoc ◽  
Intervention Studies ◽  
Dietary Intervention ◽  
Dietary Guidelines ◽  
Control Group ◽  
Power Calculation ◽  
Sample Sizes ◽  
Dietary Interventions ◽  
Dietary Intervention Trial

ABSTRACT Dietary interventions often target foods that are underconsumed relative to dietary guidelines, such as vegetables, fruits, and whole grains. Because these foods are only consumed episodically for some participants, data from such a study often contains a disproportionally large number of zeros due to study participants who do not consume any of the target foods on the days that dietary intake is assessed, thus generating semicontinuous data. These zeros need to be properly accounted for when calculating sample sizes to ensure that the study is adequately powered to detect a meaningful intervention effect size. Nonetheless, this issue has not been well addressed in the literature. Instead, methods that are common for continuous outcomes are typically used to compute the sample sizes, resulting in a substantially under- or overpowered study. We propose proper approaches to calculating the sample size needed for dietary intervention studies that target episodically consumed foods. Sample size formulae are derived for detecting the mean difference in the amount of intake of an episodically consumed food between an intervention and a control group. Numerical studies are conducted to investigate the accuracy of the sample size formulae as compared with the ad hoc methods. The simulation results show that the proposed formulae are appropriate for estimating the sample sizes needed to achieve the desired power for the study. The proposed method for sample size is recommended for designing dietary intervention studies targeting episodically consumed foods.

scholarly journals Monoclonal Antibody-Based Time-Resolved Fluorescence Immunoassays for Daidzein, Genistein, and Equol in Blood and Urine: Application to the Isoheart Intervention Study

2007 ◽  
Vol 53 (4) ◽  
pp. 748-756 ◽  
Author(s):  
Duncan CS Talbot ◽  
Richard M Ogborne ◽  
Tony Dadd ◽  
Herman Adlercreutz ◽  
Geoff Barnard ◽  
...  
Keyword(s):  
Large Scale ◽  
Intervention Studies ◽  
Intervention Study ◽  
Dietary Intervention ◽  
Blood Analysis ◽  
Gas Chromatography Mass Spectrometry ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Ether Extraction ◽  
Dietary Intervention Trial

Abstract Background: Time-resolved fluorescence immunoassays (TR-FIAs) for phytoestrogens in biological samples are an alternative to mass spectrometric methods. These immunoassays were used to test urine and plasma samples from individuals in a dietary intervention trial aimed at determining the efficacy of dietary isoflavones in reducing the risk of coronary heart disease in postmenopausal women. Methods: We established murine monoclonal TR-FIA methods for daidzein, genistein, and equol. These assays could be performed manually or adapted to an automated analyzer for high throughput and increased accuracy. Analysis of urine was conducted on nonextracted samples. Blood analysis was performed on nonextracted samples for daidzein, whereas genistein and equol required diethyl-ether extraction. Results: Comparison of monoclonal TR-FIA, commercial polyclonal antibody–based TR-FIA, and gas chromatography–mass spectrometry showed correlations (r, 0.911–0.994) across the concentration range observed in the Isoheart study (50 mg/day isoflavones). The concentrations of urinary daidzein and genistein observed during intervention demonstrated good compliance, and a corresponding increase in serum daidzein and genistein confirmed bioavailability of the isoflavone-rich foods; 33 of the 117 volunteers (28.2%) were classified as equol producers on the basis of their urinary equol concentration (>936 nmol/L), and significant differences in the numbers of equol producers were observed between Berlin and the 3 other European cohorts studied. Conclusions: The validated monoclonal TR-FIA methods are applicable for use in large-scale human phytoestrogen intervention studies and can be used to monitor compliance, demonstrate bioavailability, and assess equol producer status.

scholarly journals Free-Living Dietary Intervention Studies: Theory-Based Protocols to Improve Subject Compliance

2021 ◽  
Vol 5 (Supplement_2) ◽  
pp. 1282-1282
Author(s):  
Priscilla Macias ◽  
Celine Heskey
Keyword(s):  
Literature Review ◽  
Intervention Studies ◽  
Dietary Intervention ◽  
Food Group ◽  
Vegetarian Diet ◽  
Dietary Guidelines ◽  
Free Living ◽  
Eating Pattern ◽  
Study Protocols ◽  
Dietary Guidelines For Americans

Abstract Objectives Subject compliance in free-living dietary intervention studies is difficult to achieve. Published studies suggest various theoretically based strategies that can be used to improve compliance. Methods A weight-management dietary intervention for free-living subjects, based on a vegetarian dietary pattern, was created. Development of 7-day menus was conducted using McGraw Hills’ NutritionCalc Plus software. Menus utilized a framework from the 2015–2020 Dietary Guidelines for Americans’ Healthy Vegetarian Eating Pattern (macronutrient ratios and food group servings). A literature review was conducted to identify various counseling and technology strategies that may be effective at increasing subject compliance with their assigned study diet. The findings of the literature review was used to create study protocols. Protocol development for a food demonstration was also explored. Results A 1-week menu cycle for a vegetarian diet intervention was created, including a set of menus each for 1200,1800, and 2000 calories levels. The menus are inclusive of foods and portions that meet the Dietary Guidelines for Americans. Three study protocols were developed for strategies that may improve subject compliance: 1. A nutrition counseling protocol based on motivational interviewing; 2. A technology protocol on use of a dietary-self monitoring app; and 3. A food demonstration protocol highlighting vegetarian recipes. The protocols are designed to be used by study clinicians/dietitians in future intervention studies. Conclusions Theory-based protocols can be used to develop standardized protocols for research studies. These protocols theoretically may help to improve subject compliance. Funding Sources NIH BUILD PODER.

scholarly journals MOPower: an R-shiny application for the simulation and power calculation of multi-omics studies.

2021 ◽  
Author(s):  
Hamzah Syed ◽  
Georg W Otto ◽  
Daniel Kelberman ◽  
Chiara Bacchelli ◽  
Philip L Beales
Keyword(s):  
Sample Size ◽  
Power Calculation ◽  
Sample Sizes ◽  
Data Types ◽  
Data Simulation ◽  
Methods Development ◽  
Study Results ◽  
R Shiny ◽  
Underlying Mechanisms ◽  
Shiny Application

Background: Multi-omics studies are increasingly used to help understand the underlying mechanisms of clinical phenotypes, integrating information from the genome, transcriptome, epigenome, metabolome, proteome and microbiome. This integration of data is of particular use in rare disease studies where the sample sizes are often relatively small. Methods development for multi-omics studies is in its early stages due to the complexity of the different individual data types. There is a need for software to perform data simulation and power calculation for multi-omics studies to test these different methodologies and help calculate sample size before the initiation of a study. This software, in turn, will optimise the success of a study. Results: The interactive R shiny application MOPower described below simulates data based on three different omics using statistical distributions. It calculates the power to detect an association with the phenotype through analysis of n number of replicates using a variety of the latest multi-omics analysis models and packages. The simulation study confirms the efficiency of the software when handling thousands of simulations over ten different sample sizes. The average time elapsed for a power calculation run between integration models was approximately 500 seconds. Additionally, for the given study design model, power varied with the increase in the number of features affecting each method differently. For example, using MOFA had an increase in power to detect an association when the study sample size equally matched the number of features. Conclusions: MOPower addresses the need for flexible and user-friendly software that undertakes power calculations for multi-omics studies. MOPower offers users a wide variety of integration methods to test and full customisation of omics features to cover a range of study designs.

scholarly journals Statistical test with sample size and power calculation for paired repeated measures designs of method comparison studies

2019 ◽  
Author(s):  
Yun Bai ◽  
Zengri Wang ◽  
Theodore C. Lystig ◽  
Baolin Wu
Keyword(s):  
Sample Size ◽  
Repeated Measures ◽  
Ad Hoc ◽  
Method Comparison ◽  
R Package ◽  
Power Calculation ◽  
Finite Sample ◽  
Numerical Studies ◽  
Two Measures ◽  
Repeated Measures Designs

The paired repeated measures (PRM) design has been commonly used in comparison studies to demonstrate that two measures agree sufficiently up to a pre-specified threshold. Due to the nature of dependence in repeated measures, existing methods for analyzing these comparison studies are often ad hoc and less than satisfactory. We propose a new test together with sample size and power calculation for PRM designs, which exhibit very good finite sample performance. We demonstrate favorable performance of the proposed methods through numerical studies. We provide very efficient R programs for our methods in a publicly available R package. Our proposed methods and developed R package provide practical tools which bridge an existing gap in the field.

scholarly journals Jejunal inflammatory cytokines, barrier proteins and microbiome-metabolome responses to early supplementary feeding of Bamei suckling piglets

2020 ◽  
Author(s):  
Jin Jipeng ◽  
Jianlei Jia ◽  
Liping Zhang ◽  
Qian Chen ◽  
Xiaoyan Zhang ◽  
...  
Keyword(s):  
Inflammatory Cytokines ◽  
Barrier Function ◽  
Dietary Intervention ◽  
Intestinal Barrier ◽  
Supplementary Feeding ◽  
Intestinal Barrier Function ◽  
Control Group ◽  
Average Weight ◽  
Dietary Interventions ◽  
Suckling Piglets

Abstract Background: Dietary intervention has been reported to improve intestinal health. The intestinal microbiota of newborn animals plays a fundamental role in the development of intestinal function and the innate immune system. However, little is currently known about dietary interventions in the gut microbiota and barrier function of livestock, especially suckling Bamei piglets. To this end, we studied the effect of early dietary supplementation on intestinal bacterial communities and intestinal barrier function in piglets.Results: 10 purebred Bamei sows were randomly allocated into two groups. In group one, the piglets received a supplementary milk replacer on day 7 of age, whereas the other control group was allowed sow’s milk alone. At 21 days, 18 and 17, respectively, piglets in each group of average weight were randomly selected and sacrificed. Tissue and digesta samples were collected from the jejunum to evaluate differences in the microbiome-metabolome and the mRNA expression of inflammatory cytokines (TLR4, TNFα and IL-8) and barrier proteins (ZO-1, Occludin and Claudin-1)). Sequencing of 16S rRNA revealed that early supplementary feeding improved (p<0.05) the gut microbiome composition of Bamei suckling piglets. In addition, metabolomics analyses demonstrated simuitaneous responses as, mang gut microflora–related metabolites were also being affected. Meanwhile, early supplementary feeding of Bamei suckling piglets altered the gene expression of inflammatory cytokine and barrier protein in the jejunum. Conclusions: In summary, these results provide important insights on the relationships between jejunal microbiota and related metabolites, and jejunal barrier function during the early life of Bamei suckling piglets.

scholarly journals Investigating hsCRP as a clinical inflammation marker for human Bisphenol A food contamination offers protocol suggestions for conducting replicable, causal dietary intervention studies

2020 ◽  
Author(s):  
W. Lewis Perdue ◽  
Victor I. Reus ◽  
Rebecca L. Yeamans-Irwin
Keyword(s):  
Bisphenol A ◽  
Causal Relationship ◽  
Intervention Studies ◽  
Dietary Intervention ◽  
Clinical Laboratory ◽  
Food Contamination ◽  
High Sensitivity ◽  
Serum Levels ◽  
Blood Levels ◽  
Dietary Interventions

ABSTRACTDietary intervention studies thus far have failed to be replicable or causal. The results, therefore, have failed to provide clinicians and the general public with consistent and useful information on which to base reliable food-related health decisions. This is particularly relevant regarding plastic-derived chemicals (PDCs), such as Bisphenol A, now that the federal CLARITY-BPA program has failed to achieve scientific consensus. Investigators propose a novel human dietary protocol that is both replicable and causal, based upon BPA’s demonstrated inflammatory effects in humans. This first-of-a-kind dietary intervention study explores a potential causal relationship between human serum levels of BPA and High-Sensitivity C-Reactive Protein (hsCRP), a proven clinical indicator of inflammation. Investigators used the equivalent of a USDA-defined “typical diet” followed by a PDC-reduced diet to compare blood levels of hsCRP. This proof-of-concept investigation is the first to use an easily accessible, medically-accepted clinical laboratory test to directly measure human health effects of PDC reduction. Unexpected new complications discovered during the investigation indicate that these results may yet be inconclusive for direct causal relationship. However, the novel lessons and techniques developed as a result of those discoveries offer further specific and improved methods and best practices that can enable future dietary interventions to produce replicable, causal results.

scholarly journals Effect of a dietary intervention including minimal and unprocessed foods, high in natural saturated fats, on the lipid profile of children, pooled evidence from randomized controlled trials and a cohort study

PLoS ONE ◽  
2022 ◽  
Vol 17 (1) ◽  
pp. e0261446
Author(s):  
Rosanne Barbra Hendriksen ◽  
Ellen José van der Gaag
Keyword(s):  
Lipid Profile ◽  
Intervention Studies ◽  
Dietary Intervention ◽  
Intervention Group ◽  
Hdl Cholesterol ◽  
Dietary Advice ◽  
Control Group ◽  
Controlled Trials ◽  
Randomized Controlled ◽  
Saturated Fats

Aim To study the possible effects of a dietary intervention with minimal and unprocessed foods, high in natural saturated fats on the lipid profile and body mass index of children. Method This study combines three intervention studies; one non-randomized retrospective cohort study and two randomized controlled trials, to a pooled analysis. The intervention group received a dietary intervention of minimal and unprocessed foods for three to six months, consisting of five times per week green vegetables, three times per week beef, daily 200–300 mL whole cow’s milk (3.4% fat) and whole dairy butter (80% fat) on each slice of bread. The control group continued their usual dietary habits. Raw data of the three intervention studies where combined into one single dataset for data analysis, using mixed effects analysis of covariance to test the effects of the dietary advice on the main study outcomes, which are measurements of the lipid profile. Results In total, 267 children aged 1 to 16 years were followed. 135 children were included in the intervention group and 139 children in the control group. Characteristics (age, gender and follow-up period) were equally distributed between the groups at baseline. In the intervention group HDL-cholesterol increased significantly from 1.22 mmol/L, 95% confidence interval (CI) 1.14–1.32 to 1.42 mmol/L 95% CI 1.30–1.65 (p = 0.007). The increase over time in HDL cholesterol in the intervention group was significantly different compared to the increase in the control group (from 1.26 mmol/L, 95% CI 1.19–1.35, to 1.30 mmol/L, 95% CI 1.26–1.37) (p = 0.04). Due to the increased HDL concentration in the intervention group, the total cholesterol/HDL cholesterol ratio decreased significantly from 3.70 mmol/L, 95% CI 3.38–3.87, to 3.25 mmol/L, 95% CI 2.96–3.31 (p = 0.05). Conclusion Consumption of minimal and unprocessed foods (high in natural saturated fats) has favourable effects on HDL cholesterol in children. Therefore, this dietary advice can safely be recommended to children.

scholarly journals What makes a plant-based diet? a review of current concepts and proposal for a standardized plant-based dietary intervention checklist

2021 ◽  
Author(s):  
Maximilian Andreas Storz
Keyword(s):  
Intervention Studies ◽  
Dietary Intervention ◽  
Nutrition Intervention ◽  
Vegan Diet ◽  
Dietary Interventions ◽  
Consensus Definition ◽  
Animal Products ◽  
Potential Benefits ◽  
Definition Of ◽  
Intervention Reporting

AbstractWithin the last decades, plant-based diets have received increasing interest for their potential benefits to human and environmental health. The concept of plant-based diet, however, varies widely in its definition. Current definitions range from the exclusion of all animal products to diets that include meat, fish, and dairy in varying quantities. Therefore, the main objectives of this review were twofold: (a) to investigate how researchers use the term plant-based diet in nutrition intervention studies and (b) what types of food a plant-based diet may include. Searching two databases, we found that the term “plant-based diet” evokes varying ideas to researchers and clinicians. Fifty percent of the retrieved studies that included a plant-based dietary intervention completely proscribed animal products and used the term plant-based diet interchangeably with a vegan diet. In contrast, an ~33% of trials included dairy products and 20% of dietary interventions emphasized a semi-vegetarian dietary pattern. Based on specific examples, we point out how the usage of the umbrella term “plant-based diet” may cause significant ambiguity. We often encountered incomplete descriptions of plant-based dietary interventions, which makes comparison and reproducibility of studies difficult. As a consequence, we urge others to use the term “plant-based diet” only in conjunction with a detailed dietary description. To facilitate this process, we provide a template of a standardized plant-based intervention reporting checklist. Finally, the present review also highlights the urgent need for a consensus definition of the term plant-based diet and its content.

scholarly journals Dietary modulation of cortical excitation and inhibition

2017 ◽  
Vol 31 (5) ◽  
pp. 632-637 ◽  
Author(s):  
Anika K Smith ◽  
Alex R Wade ◽  
Kirsty EH Penkman ◽  
Daniel H Baker
Keyword(s):  
Dietary Intervention ◽  
Control Group ◽  
Gamma Aminobutyric Acid ◽  
Neural Responses ◽  
Dietary Interventions ◽  
Sensory Stimuli ◽  
Inhibitory Neurotransmitter ◽  
Clinical Benefits ◽  
Cortical Excitation ◽  
The Brain

The balance of excitatory and inhibitory neurotransmitters in the brain affects both neural responses and behaviour in humans and animals. Here we investigated whether dietary intervention aimed at increasing levels of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) can influence neural responses to basic sensory stimuli. Using a steady-state electroencephalography (EEG) paradigm, we found that the neural response to visual patterns was reduced in individuals who consumed a yeast extract product rich in substances associated with the production of GABA (glutamate and B vitamins), but not in a control group who consumed a placebo substance ( n = 14 per group). This demonstrates that the balance of excitation and inhibition in the brain can be influenced by dietary interventions, suggesting possible clinical benefits in conditions (e.g. epilepsy) where inhibition is abnormal.

scholarly journals Sample size calculation for active-arm trial with counterfactual incidence based on recency assay

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Fei Gao ◽  
David V. Glidden ◽  
James P. Hughes ◽  
Deborah J. Donnell
Keyword(s):  
Sample Size ◽  
Sample Size Calculation ◽  
Standard Of Care ◽  
Sub Saharan Africa ◽  
Control Group ◽  
Sample Sizes ◽  
Delivery Methods ◽  
Sub Saharan ◽  
Sex With Men ◽  
Exposure Prophylaxis

Abstract Objectives The past decade has seen tremendous progress in the development of biomedical agents that are effective as pre-exposure prophylaxis (PrEP) for HIV prevention. To expand the choice of products and delivery methods, new medications and delivery methods are under development. Future trials of non-inferiority, given the high efficacy of ARV-based PrEP products as they become current or future standard of care, would require a large number of participants and long follow-up time that may not be feasible. This motivates the construction of a counterfactual estimate that approximates incidence for a randomized concurrent control group receiving no PrEP. Methods We propose an approach that is to enroll a cohort of prospective PrEP users and aug-ment screening for HIV with laboratory markers of duration of HIV infection to indicate recent infections. We discuss the assumptions under which these data would yield an estimate of the counterfactual HIV incidence and develop sample size and power calculations for comparisons to incidence observed on an investigational PrEP agent. Results We consider two hypothetical trials for men who have sex with men (MSM) and transgender women (TGW) from different regions and young women in sub-Saharan Africa. The calculated sample sizes are reasonable and yield desirable power in simulation studies. Conclusions Future one-arm trials with counterfactual placebo incidence based on a recency assay can be conducted with reasonable total screening sample sizes and adequate power to determine treatment efficacy.

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