Evidence, Mechanisms, and Complexity

2021 ◽  
pp. 25-39
Author(s):  
James Wilson
Keyword(s):  
Public Policy ◽  
Randomized Controlled Trials ◽  
Clinical Medicine ◽  
Evidence Base ◽  
Controlled Trials ◽  
Confounding Factors ◽  
What Works ◽  
Number Of Factors ◽  
Wide Range

This chapter examines the role of evidence in public policy. Randomized controlled trials (RCTs) are often thought to provide the most rigorous way of establishing causal claims. On this basis it has been claimed that what public policy requires is a solid evidence base of RCTs, which are then synthesized into an account of ‘what works’. The chapter argues that this is mistaken. Even if it can be shown with confidence that an intervention had a particular size of effect within a trial population at a particular time, this does not show that the intervention will work in a wide range of contexts, or in a policymaker’s particular context. A number of factors, including the greater difficulty of controlling for confounding factors, and the greater variability in causal networks, make evidence less likely to travel in public policy than in clinical medicine.

scholarly journals Vitamin D supplementation, COVID-19 and disease severity: a meta-analysis

QJM ◽  
2021 ◽  
Author(s):  
K Shah ◽  
D Saxena ◽  
D Mavalankar
Keyword(s):  
Vitamin D ◽  
Randomized Controlled Trials ◽  
Usual Care ◽  
Odds Ratio ◽  
Meta Analysis ◽  
Vitamin D Supplementation ◽  
Hospitalized Patients ◽  
Controlled Trials ◽  
Randomized Controlled

Abstract Objective: Current meta-analysis aims to understand the effect of oral supplementation of vitamin D on intensive care unit (ICU) requirement and mortality in hospitalized COVID-19 patients. Methods: Databases PubMed, preprint servers, and google scholar were searched from December 2019 to December 2020. Authors searched for the articles assessing role of vitamin D supplementation on COVID-19. Cochrane RevMan tool was used for quantitative assessment of the data, where heterogeneity was assessed using I2 and Q statistics and data was expressed using odds ratio with 95% confidence interval. Results: Final meta-analysis involved pooled data of 532 hospitalized patients (189 on vitamin D supplementation and 343 on usual care/placebo) of COVID-19 from three studies (Two randomized controlled trials, one retrospective case-control study). Statistically (p<0.0001) lower ICU requirement was observed in patients with vitamin D supplementation as compared to patients without supplementations (odds ratio: 0.36; 95% CI: 0.210-0.626). However, it suffered from significant heterogeneity, which reduced after sensitivity analysis. In case of mortality, vitamin D supplements has comparable findings with placebo treatment/usual care (odds ratio: 0.93; 95% CI: 0.413-2.113; p=0.87). The studies did not show any publication bias and had fair quality score. Subgroup analysis could not be performed due to limited number of studies and hence dose and duration dependent effect of vitamin D could not be evaluated. Conclusions: Although the current meta-analysis findings indicate potential role of vitamin D in improving COVID-19 severity in hospitalized patients, more robust data from randomized controlled trials are needed to substantiate its effects on mortality.

Editorial: The Vital Role of Randomized Controlled Trials inArthritis & Rheumatology

2015 ◽  
Vol 67 (10) ◽  
pp. 2555-2556 ◽  
Author(s):  
Daniel H. Solomon ◽  
Michael E. Weinblatt ◽  
Richard J. Bucala
Keyword(s):  
Randomized Controlled Trials ◽  
Vital Role ◽  
Controlled Trials ◽  
Randomized Controlled

Mechanical Thromboprophylaxis in Critically Ill Patients: A Systematic Review and Meta-Analysis

2006 ◽  
Vol 15 (4) ◽  
pp. 402-412 ◽  
Author(s):  
Anthony Limpus ◽  
Wendy Chaboyer ◽  
Ellen McDonald ◽  
Lukman Thalib
Keyword(s):  
Intensive Care ◽  
Randomized Controlled Trials ◽  
Observational Studies ◽  
Meta Analysis ◽  
Controlled Trials ◽  
Trauma Patients ◽  
Intensive Care Patients ◽  
Randomized Controlled ◽  
Confounding Variables

• Objective To systematically review the randomized trials, observational studies, and survey evidence on compression and pneumatic devices for thromboprophylaxis in intensive care patients. • Methods Published studies on the use of compression and pneumatic devices in intensive care patients were assessed. A meta-analysis was conducted by using the randomized controlled trials. • Results A total of 21 relevant studies (5 randomized controlled trials, 13 observational studies, and 3 surveys) were found. A total of 811 patients were randomized in the 5 randomized controlled trials; 3421 patients participated in the observational studies. Trauma patients only were enrolled in 4 randomized controlled trials and 4 observational studies. Meta-analysis of 2 randomized controlled trials with similar populations and outcomes revealed that use of compression and pneumatic devices did not reduce the incidence of venous thromboembolism. The pooled risk ratio was 2.37, indicative of favoring the control over the intervention in reducing the deep venous thrombosis; however, the 95% CI of 0.57 to 9.90 indicated no significant differences between the intervention and the control. A range of methodological issues, including bias and confounding variables, make meaningful interpretation of the observational studies difficult. • Conclusions The limited evidence suggests that use of compressive and pneumatic devices yields results not significantly different from results obtained with no treatment or use of low-molecular-weight heparin. Until large randomized controlled trials are conducted, the role of mechanical approaches to thromboprophylaxis for intensive care patients remains uncertain.

Role of Decompressive Craniectomy in Traumatic Brain Injury – A Meta-analysis of Randomized Controlled Trials

2019 ◽  
Vol 67 (5) ◽  
pp. 1225 ◽  
Author(s):  
Kanwaljeet Garg ◽  
PreetM Singh ◽  
Raghav Singla ◽  
Ankita Aggarwal ◽  
Anuradha Borle ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Randomized Controlled Trials ◽  
Decompressive Craniectomy ◽  
Meta Analysis ◽  
Controlled Trials ◽  
Randomized Controlled

scholarly journals Treatment and Prophylaxis of Catheter-Related Thromboembolic Events in Children

2012 ◽  
Vol 15 (5) ◽  
pp. 632 ◽  
Author(s):  
Lucía Cortejoso ◽  
Silvia Manrique-Rodríguez ◽  
Cecilia M. Fernández-Llamazares ◽  
María Sanjurjo-Sáez
Keyword(s):  
Randomized Controlled Trials ◽  
Scientific Evidence ◽  
Vitamin K Antagonists ◽  
Venous Catheter ◽  
Therapeutic Management ◽  
Controlled Trials ◽  
Thromboembolic Events ◽  
Randomized Controlled ◽  
Wide Range ◽  
Meta Analyses

Purpose. The therapeutic management of catheter-related thromboembolic events in children is still a challenge due to the large number of potentially effective pharmacological alternatives and the insufficient scientific evidence available. A bibliographic review was performed in order to identify the available pharmacological alternatives for the prophylaxis and therapeutic management of catheter-related thrombosis in children. Methods. A literature search was carried out on MEDLINE using the medical subject heading (MeSH) central venous catheter thrombosis and on Google Scholar. The search was limited to review papers, meta-analyses, clinical practice guidelines, and randomized controlled trials performed on pediatric populations until November 2011. Results. The different options for anticoagulation include unfractionated heparin, low molecular weight heparin and vitamin K antagonists. Thrombus resolution is stimulated more rapidly with thrombolytic agents than with anticoagulants, but the risk-benefit ratio must be considered. Streptokinase is not considered an optimal alternative due to the risk of anaphylactic reactions and has been replaced by urokinase, alteplase or the newer reteplase. Preventive strategies have been considered and most centers have protocols for routine flushing of the catheter with heparin or normal saline. Intraluminal application of urokinase and alteplase has also been studied. Conclusions. The wide range of options available for the pharmacotherapeutic management of catheter-related thromboembolism in children and the lack of strong evidence on the comparative efficacy and safety of the different therapeutic options, make its positioning rather difficult. Randomized controlled trials and national plans should be set up urgently. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

scholarly journals Placebo interventions, placebo effects and clinical practice

2011 ◽  
Vol 366 (1572) ◽  
pp. 1905-1912 ◽  
Author(s):  
Klaus Linde ◽  
Margrit Fässler ◽  
Karin Meissner
Keyword(s):  
Clinical Practice ◽  
Randomized Controlled Trials ◽  
Context Effects ◽  
Clinical Investigation ◽  
Controlled Trials ◽  
Placebo Effects ◽  
Randomized Controlled ◽  
Placebo Intervention ◽  
Therapeutic Context

This article reviews the role of placebo interventions and placebo effects in clinical practice. We first describe the relevance of different perspectives among scientists, physicians and patients on what is considered a placebo intervention in clinical practice. We then summarize how placebo effects have been investigated in randomized controlled trials under the questionable premise that such effects are produced by placebo interventions. We further discuss why a shift of focus from the placebo intervention to the overall therapeutic context is necessary and what research methods can be used for the clinical investigation of the relevance of context effects. In the last part of the manuscript, we discuss why placebo or context effects are seen as positive in clinical practice when they are associated with active treatments, while placebo interventions pose major ethical and professional problems and have to be avoided.

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