scholarly journals A framework for measurement and harmonization of pediatric multiple sclerosis etiologic research studies: The Pediatric MS Tool-Kit

2018 ◽  
Vol 25 (8) ◽  
pp. 1170-1177 ◽  
Author(s):  
Sandra Magalhaes ◽  
Brenda Banwell ◽  
Amit Bar-Or ◽  
Isabel Fortier ◽  
Heather E Hanwell ◽  
...  
Keyword(s):  
Risk Factors ◽  
Multiple Sclerosis ◽  
Vitamin D ◽  
Delphi Study ◽  
Sun Exposure ◽  
Small Sample ◽  
Sample Sizes ◽  
Vitamin D Intake ◽  
Measurement Framework ◽  
Small Sample Sizes

Background: While studying the etiology of multiple sclerosis (MS) in children has several methodological advantages over studying etiology in adults, studies are limited by small sample sizes. Objective: Using a rigorous methodological process, we developed the Pediatric MS Tool-Kit, a measurement framework that includes a minimal set of core variables to assess etiological risk factors. Methods: We solicited input from the International Pediatric MS Study Group to select three risk factors: environmental tobacco smoke (ETS) exposure, sun exposure, and vitamin D intake. To develop the Tool-Kit, we used a Delphi study involving a working group of epidemiologists, neurologists, and content experts from North America and Europe. Results: The Tool-Kit includes six core variables to measure ETS, six to measure sun exposure, and six to measure vitamin D intake. The Tool-Kit can be accessed online ( www.maelstrom-research.org/mica/network/tool-kit ). Conclusion: The goals of the Tool-Kit are to enhance exposure measurement in newly designed pediatric MS studies and comparability of results across studies, and in the longer term to facilitate harmonization of studies, a methodological approach that can be used to circumvent issues of small sample sizes. We believe the Tool-Kit will prove to be a valuable resource to guide pediatric MS researchers in developing study-specific questionnaire

scholarly journals On the Nature of Evidence and ‘Proving’ Causality: Smoking and Lung Cancer vs. Sun Exposure, Vitamin D and Multiple Sclerosis

2018 ◽  
Vol 15 (8) ◽  
pp. 1726 ◽  
Author(s):  
Robyn Lucas ◽  
Rachael Rodney Harris
Keyword(s):  
Risk Factors ◽  
Multiple Sclerosis ◽  
Lung Cancer ◽  
Vitamin D ◽  
Observational Studies ◽  
Animal Studies ◽  
Disease Risk ◽  
Sun Exposure ◽  
Sufficient Evidence

If environmental exposures are shown to cause an adverse health outcome, reducing exposure should reduce the disease risk. Links between exposures and outcomes are typically based on ‘associations’ derived from observational studies, and causality may not be clear. Randomized controlled trials to ‘prove’ causality are often not feasible or ethical. Here the history of evidence that tobacco smoking causes lung cancer—from observational studies—is compared to that of low sun exposure and/or low vitamin D status as causal risk factors for the autoimmune disease, multiple sclerosis (MS). Evidence derives from in vitro and animal studies, as well as ecological, case-control and cohort studies, in order of increasing strength. For smoking and lung cancer, the associations are strong, consistent, and biologically plausible—the evidence is coherent or ‘in harmony’. For low sun exposure/vitamin D as risk factors for MS, the evidence is weaker, with smaller effect sizes, but coherent across a range of sources of evidence, and biologically plausible. The association is less direct—smoking is directly toxic and carcinogenic to the lung, but sun exposure/vitamin D modulate the immune system, which in turn may reduce the risk of immune attack on self-proteins in the central nervous system. Opinion about whether there is sufficient evidence to conclude that low sun exposure/vitamin D increase the risk of multiple sclerosis, is divided. General public health advice to receive sufficient sun exposure to avoid vitamin D deficiency (<50 nmol/L) should also ensure any benefits for multiple sclerosis, but must be tempered against the risk of skin cancers.

scholarly journals Critical Appraisal of Evidence for Improving Gait Speed in People with Multiple Sclerosis

2016 ◽  
Vol 18 (3) ◽  
pp. 105-115 ◽  
Author(s):  
Prudence Plummer
Keyword(s):  
Multiple Sclerosis ◽  
Gait Speed ◽  
Treatment Effects ◽  
Gait Training ◽  
Small Sample ◽  
Current Evidence ◽  
Sample Sizes ◽  
Training Interventions ◽  
Training Studies ◽  
Small Sample Sizes

Background: Research has not yet compared the treatment effects of dalfampridine with traditional rehabilitation of gait impairments in multiple sclerosis (MS). The purpose of this review was to critically appraise the evidence for dalfampridine and gait training for increasing gait speed in people with MS. Methods: A systematic search of the research literature was conducted. Consideration was given to only randomized controlled trials (RCTs), systematic reviews, and meta-analyses. For selection of gait training studies, only studies involving task-specific gait training interventions and measuring treatment effects on gait speed were considered. Results: Treatment effects on gait speed were extracted from four studies examining the efficacy of dalfampridine and six gait training RCTs. Overall mean increase in gait speed with dalfampridine was 0.07 m/s (95% confidence interval [CI], 0.04–0.09 m/s) compared to 0.06 m/s (95% CI, 0.02–0.10 m/s) for gait training. Among dalfampridine responders (38% of participants in RCTs), the mean increase in gait speed was 0.16 m/s (95% CI, 0.13–0.18 m/s). Mean increases for individual gait training interventions ranged from 0.01 to 0.39 m/s; however, CIs were wide due to small sample sizes. Conclusions: Current evidence is insufficient to conclude whether dalfampridine or gait training is superior for improving gait speed in people with MS. These findings should be viewed cautiously due to differences in study populations and small sample sizes in gait training studies. Both treatment approaches provide only short-lived improvements. Head-to-head comparison trials and studies combining both treatment modalities are needed.

Sun Exposure, Vitamin D Intake and Progression to Disability among Veterans with Progressive Multiple Sclerosis

2011 ◽  
Vol 37 (1) ◽  
pp. 52-57 ◽  
Author(s):  
Tzu-Yun McDowell ◽  
Sania Amr ◽  
William J. Culpepper ◽  
Patricia Langenberg ◽  
Walter Royal ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Vitamin D ◽  
Sun Exposure ◽  
Progressive Multiple Sclerosis ◽  
Vitamin D Intake

scholarly journals On the nature of evidence and 'proving' causality: smoking and lung cancer vs. sun exposure, vitamin D and multiple sclerosis

2018 ◽  
Author(s):  
Robyn Lucas ◽  
Rachael Rodney Harris
Keyword(s):  
Risk Factors ◽  
Multiple Sclerosis ◽  
Lung Cancer ◽  
Vitamin D ◽  
Observational Studies ◽  
Animal Studies ◽  
Disease Risk ◽  
Sun Exposure ◽  
Sufficient Evidence

If environmental exposures are shown to cause an adverse health outcome, reducing exposure should reduce the disease risk. Links between exposures and outcomes are typically based on ‘associations’ derived from observational studies, and causality may not be clear. Randomised controlled trials to ‘prove’ causality are often not feasible or ethical. Here the history of evidence that tobacco smoking causes lung cancer – in observational studies – is compared to that of low sun exposure and/or low vitamin D status as causal risk factors for the autoimmune disease, multiple sclerosis. Evidence derives from in vitro and animal studies, as well as ecological, case-control and cohort studies, in order of increasing strength. For smoking and lung cancer, the associations are strong, consistent, and biologically plausible – the evidence is coherent or ‘in harmony’. For low sun exposure/vitamin D as risk factors for MS, the evidence is weaker, with smaller effect sizes, but coherent across a range of sources of evidence, and biologically plausible. The association is less direct – smoking is directly toxic and carcinogenic to the lung, but sun exposure/vitamin D modulate the immune system, which in turn may reduce the risk of immune attack on self-proteins in the central nervous system. Opinion about whether there is sufficient evidence to conclude that low sun exposure/vitamin D increase the risk of multiple sclerosis, is divided. General public health advice to receive sufficient sun exposure to avoid vitamin D deficiency (&lt;50nmol/L) should also ensure any benefits for multiple sclerosis.

VITAMIN D LEVELS, VITAMIN D INTAKE AND SUNLIGHT EXPOSURE IN PEDIATRIC MULTIPLE SCLEROSIS

2006 ◽  
Vol 37 (S 1) ◽  
Author(s):  
R Hung ◽  
R Vieth ◽  
R Goldman ◽  
E Sochett ◽  
B Banwell
Keyword(s):  
Multiple Sclerosis ◽  
Vitamin D ◽  
Sunlight Exposure ◽  
Pediatric Multiple Sclerosis ◽  
Vitamin D Intake ◽  
Vitamin D Levels

No Evidence that Experiencing Physical Warmth Promotes Interpersonal Warmth: Two Failures to Replicate Williams and Bargh (2008)

2018 ◽  
Author(s):  
Christopher Chabris ◽  
Patrick Ryan Heck ◽  
Jaclyn Mandart ◽  
Daniel Jacob Benjamin ◽  
Daniel J. Simons
Keyword(s):  
Null Hypothesis ◽  
Small Sample ◽  
Sample Sizes ◽  
Double Blind ◽  
Bayesian Analyses ◽  
Physical Warmth ◽  
Small Sample Sizes ◽  
Interpersonal Warmth

Williams and Bargh (2008) reported that holding a hot cup of coffee caused participants to judge a person’s personality as warmer, and that holding a therapeutic heat pad caused participants to choose rewards for other people rather than for themselves. These experiments featured large effects (r = .28 and .31), small sample sizes (41 and 53 participants), and barely statistically significant results. We attempted to replicate both experiments in field settings with more than triple the sample sizes (128 and 177) and double-blind procedures, but found near-zero effects (r = –.03 and .02). In both cases, Bayesian analyses suggest there is substantially more evidence for the null hypothesis of no effect than for the original physical warmth priming hypothesis.

scholarly journals Candida infective endocarditis: A retrospective study of patient characteristics and risk factors for death in 703 U.S. cases, 2015-2019

2020 ◽  
Author(s):  
Jonathan P Huggins ◽  
Samuel Hohmann ◽  
Michael Z David
Keyword(s):  
Risk Factors ◽  
Hospital Mortality ◽  
Liver Failure ◽  
Patient Characteristics ◽  
Medication Administration ◽  
Small Sample ◽  
Risk Of Death ◽  
Opiate Abuse ◽  
Small Sample Sizes ◽  
Valve Pathology

Abstract Background Candida endocarditis is a rare, sometimes fatal complication of candidemia. Past investigations of this condition are limited by small sample sizes. We used the Vizient clinical database to report on characteristics of patients with Candida endocarditis and to examine risk factors for in-hospital mortality. Methods This was a multicenter, retrospective cohort study of 703 inpatients admitted to 179 United States hospitals between October 2015 and April 2019. We reviewed demographic, diagnostic, medication administration, and procedural data from each patient’s initial encounter. Univariate and multivariate logistic regression analyses were used to identify predictors of in-hospital mortality. Results Of 703 patients, 114 (16.2%) died during the index encounter. One hundred and fifty-eight (22.5%) underwent an intervention on a cardiac valve. On multivariate analysis, acute and subacute liver failure was the strongest predictor of death (OR 9.2, 95% CI 4.8 –17.7). Female sex (OR 1.9, 95% CI 1.2 – 3.0), transfer from an outside medical facility (OR 1.8, 95% CI 1.1 – 2.8), aortic valve pathology (OR 2.7, 95% CI 1.5 – 4.9), hemodialysis (OR 2.1, 95% CI 1.1 – 4.0), cerebrovascular disease (OR 2.2, 95% CI 1.2 – 3.8), neutropenia (OR 2.5, 95% CI 1.3 – 4.8), and alcohol abuse (OR 2.9, 95% CI 1.3 – 6.7) were also associated with death on adjusted analysis, whereas opiate abuse was associated with a lower odds of death (OR 0.5, 95% CI 0.2 – 0.9). Conclusions We found that the inpatient mortality rate was 16.2% among patients with Candida endocarditis. Acute and subacute liver failure was associated with a high risk of death while opiate abuse was associated with a lower risk of death.

scholarly journals G-computation and machine learning for estimating the causal effects of binary exposure statuses on binary outcomes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Florent Le Borgne ◽  
Arthur Chatton ◽  
Maxime Léger ◽  
Rémi Lenain ◽  
Yohann Foucher
Keyword(s):  
Machine Learning ◽  
Support Vector Machine ◽  
Statistical Power ◽  
Small Sample ◽  
Causal Effects ◽  
Small Samples ◽  
Support Vector ◽  
Sample Sizes ◽  
Super Learner ◽  
Small Sample Sizes

AbstractIn clinical research, there is a growing interest in the use of propensity score-based methods to estimate causal effects. G-computation is an alternative because of its high statistical power. Machine learning is also increasingly used because of its possible robustness to model misspecification. In this paper, we aimed to propose an approach that combines machine learning and G-computation when both the outcome and the exposure status are binary and is able to deal with small samples. We evaluated the performances of several methods, including penalized logistic regressions, a neural network, a support vector machine, boosted classification and regression trees, and a super learner through simulations. We proposed six different scenarios characterised by various sample sizes, numbers of covariates and relationships between covariates, exposure statuses, and outcomes. We have also illustrated the application of these methods, in which they were used to estimate the efficacy of barbiturates prescribed during the first 24 h of an episode of intracranial hypertension. In the context of GC, for estimating the individual outcome probabilities in two counterfactual worlds, we reported that the super learner tended to outperform the other approaches in terms of both bias and variance, especially for small sample sizes. The support vector machine performed well, but its mean bias was slightly higher than that of the super learner. In the investigated scenarios, G-computation associated with the super learner was a performant method for drawing causal inferences, even from small sample sizes.

Sign in / Sign up

Export Citation Format

Share Document