Influence of Reported Study Design Characteristics on Intervention Effect Estimates From Randomized, Controlled Trials

ABSTRACT Background The endothelium plays a key role in the maintenance of vascular health and represents a potential physiological target for dietary and other lifestyle interventions designed to reduce the risk of cardiovascular diseases (CVD) including stroke or coronary heart disease. Objective To conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) investigating the effects of the Mediterranean dietary pattern (MedDiet) on endothelial function. Methods Medline, Embase, and Scopus databases were searched from inception until January 2019 for studies that met the following criteria: 1) RCTs including adult participants, 2) interventions promoting the MedDiet, 3) inclusion of a control group, and 4) measurements of endothelial function. A random-effects meta-analysis was conducted. Metaregression and subgroup analyses were performed to identify whether effects were modified by health status (i.e., healthy participants versus participants with existing comorbidities), type of intervention (i.e., MedDiet alone or with a cointervention), study duration, study design (i.e., parallel or crossover), BMI, and age of participants. Results Fourteen articles reporting data for 1930 participants were included in the meta-analysis. Study duration ranged from 4 wk to 2.3 y. We observed a beneficial effect of the MedDiet on endothelial function [standardized mean difference (SMD): 0.35; 95% CI: 0.17, 0.53; P <0.001; I2 = 73.68%]. MedDiet interventions improved flow-mediated dilation (FMD)—the reference method for noninvasive, clinical measurement of endothelial function—by 1.66% (absolute change; 95% CI: 1.15, 2.17; P <0.001; I2 = 0%). Effects of the MedDiet on endothelial function were not modified by health status, type of intervention, study duration, study design, BMI, or age of participants (P >0.05). Conclusions MedDiet interventions improve endothelial function in adults, suggesting that the protective effects of the MedDiet are evident at early stages of the atherosclerotic process with important implications for the early prevention of CVD. This study has the PROSPERO registration number: CRD42018106188.

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The Alzheimer's Prevention Initiative Generation Program: Study design of two randomized controlled trials for individuals at risk for clinical onset of Alzheimer's disease

Alzheimer s & Dementia Translational Research & Clinical Interventions ◽

10.1016/j.trci.2019.02.005 ◽

2019 ◽

Vol 5 (1) ◽

pp. 216-227 ◽

Cited By ~ 14

Author(s):

Cristina Lopez Lopez ◽

Pierre N. Tariot ◽

Angelika Caputo ◽

Jessica B. Langbaum ◽

Fonda Liu ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

At Risk ◽

Randomized Controlled Trials ◽

Study Design ◽

Controlled Trials ◽

Randomized Controlled ◽

Clinical Onset

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Myo-inositol effects in women with PCOS: a meta-analysis of randomized controlled trials

Endocrine Connections ◽

10.1530/ec-17-0243 ◽

2017 ◽

Vol 6 (8) ◽

pp. 647-658 ◽

Cited By ~ 36

Author(s):

Vittorio Unfer ◽

Fabio Facchinetti ◽

Beatrice Orrù ◽

Barbara Giordani ◽

John Nestler

Keyword(s):

Randomized Controlled Trials ◽

Sequential Analysis ◽

Polycystic Ovary ◽

Meta Analysis ◽

Trial Sequential Analysis ◽

Controlled Trials ◽

Model Assessment ◽

Intervention Effect ◽

Randomized Controlled ◽

Firm Evidence

Myo-inositol (MI) supplementation in women with polycystic ovary syndrome (PCOS) has been evaluated over the last years. Many hormonal and reproductive impairments associated with this disorder seem relieved by the supplement. The objective of the meta-analysis was to assess the effects of MI alone or combined with d-chiro-inositol (DCI) on the endocrine and metabolic abnormalities of women with PCOS. Literature was retrieved from selected databases, MEDLINE, EMBASE, PubMed and Research Gate (up to November 2016). Only randomized controlled trials (RCTs) investigating the effects of MI alone or combined with DCI were reviewed. Nine RCTs involving 247 cases and 249 controls were included. Significant decreases in fasting insulin (SMD = −1.021 µU/mL, 95% CI: −1.791 to −0.251, P = 0.009) and homeostasis model assessment (HOMA) index (SMD = −0.585, 95% CI: −1.145 to −0.025, P = 0.041) were identified after MI supplementation. The trial sequential analysis of insulin meta-analysis illustrates that the cumulative z-curve crossed the monitoring boundary, providing firm evidence of the intervention effect. A slight trend toward a reduction of testosterone concentration by MI with respect to controls was found (SMD = −0.49, 95% CI: −1.072 to 0.092, P = 0.099), whereas androstenedione levels remained unaffected. Throughout a subgroup’s meta-analysis, a significant increase in serum SHBG was observed only in those studies where MI was administered for at least 24 weeks (SMD = 0.425 nmol/L, 95% CI: 0.050–0.801, P = 0.026). These results highlight the beneficial effect of MI in improving the metabolic profile of women with PCOS, concomitantly reducing their hyperandrogenism.

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Person-Centered Research: A novel approach to Randomized Controlled Trials

European Journal for Person Centered Healthcare ◽

10.5750/ejpch.v6i2.1435 ◽

2018 ◽

Vol 6 (2) ◽

pp. 209

Author(s):

Reza A Badian ◽

Brendan McCormack ◽

Vibeke Sundling

Keyword(s):

Randomized Controlled Trial ◽

Randomized Controlled Trials ◽

Study Design ◽

Controlled Trial ◽

Controlled Trials ◽

Evidence Based ◽

Randomized Controlled ◽

Centered Care ◽

Based Medicine ◽

Novel Design

Introduction: Integrating person-centered values with randomized controlled trials methodology is a novel idea. Person-centeredness is gaining steadily more prominence and attention in healthcare and health-related policy and research. Randomized controlled trials are considered as the gold standard in evidence-based medicine for evaluating the effects of treatment or determining the causal effect. A wide array of study designs is available, but there is a lack of designs with both strong person-centered principles and a strong position with respect to the level of evidence. In this paper we intend to introduce a novel design to fill such a gap.Aims and objectives: The aim of this paper is to introduce a novel study design where essential values of person-centered care (PCC) are integrated with randomized controlled trial (RCT) methodology into a novel study design termed a person-centered randomized controlled trial (PC-RCT).Methods: In this paper we discuss the importance and role of evidence in clinical research, levels of evidence, as well as the significance of study design in evidence-based medicine. Moreover, we discuss randomized controlled trials that are considered the gold standard to achieve high quality evidence. In this paper we will explain what the concept of person-centered care is and discuss the values associated with person-centeredness.The theoretical and methodological considerations that are relevant in applying this concept will be discussed before presenting how we intend to incorporate person-centered values into a randomized controlled trial in a novel study design that is both person-centered and randomized controlled (PC-RCT). Different aspects of this proposed novel study design will be discussed, including the theory and methods underlying this new proposed design, its novelty, different stages and practical steps involved in this proposed design. Challenges, drawbacks and possible solutions for addressing challenges of this novel design will be explored, focusing on the construct, dynamics, advantages, disadvantages and novelty of PC-RCT design.Conclusion: This paper presents how person-centered values and traditional randomised controlled trial principal values are integrated into one study design where the strengths of both concepts are merged into one. The proposed novel study design has stronger person-centered characteristics and is solid in its RCT features. This design ensures that participants have much more active participation in decision-making and gain more choice in their treatment. The proposed novel study design in this paper has clearly an important role to play in satisfying the need for a study design that can address both the need for rendering higher levels of evidence as well as simultaneously securing greater integration of person-centered values in the same study design.

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