Essai randomisé contrôlé

Résumé

Un essai contrôlé randomisé (ECR), , essai randomisé contrôlé (ERC), essai comparatif randomisé (ECR) (de l'anglais randomized controlled trial ou RCT), essai comparatif aléatoire ou encore essai contrôlé aléatoire (ECA) est un type d'étude scientifique utilisé dans de multiples domaines (psychologie, soins infirmiers, éducation, agriculture, économie) et en particulier en médecine où il occupe un rôle prépondérant. En médecine fondée sur les preuves, les ERC sont considérés (lorsqu'ils peuvent être réalisés) comme faisant partie des meilleurs moyens (en anglais gold standard) d'évaluer les effets bénéfiques et néfastes d'approches thérapeutiques (médicaments, soins, pansements, dispositifs médicaux, chirurgie, etc.) comparées les unes aux autres. Après l'évaluation pour éligibilité dans l'étude puis le recrutement, les participants à l'étude sont aléatoirement répartis (randomisation) parmi les groupes correspondant à chaque approche thérapeutique testée. Dans certains cas, on véri

Source officielle

https://fr.wikipedia.org/wiki/Essai_randomis%C3%A9_contr%C3%B4l%C3%A9

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Development of Visual Memory Capacity Following Early-Onset and Extended Blindness

Marin Vogelsang, Lukas Vogelsang

It is unknown whether visual memory capacity can develop if onset of pattern vision is delayed for several years following birth. We had an opportunity to address this question through our work with an unusual population of 12 congenitally blind individuals ranging in age from 8 to 22 years. After providing them with sight surgery, we longitudinally evaluated their visual memory capacity using an image-memorization task. Our findings revealed poor visual memory capacity soon after surgery but significant improvement in subsequent months. Although there may be limits to this improvement, performance 1 year after surgery was found to be comparable with that of control participants with matched visual acuity. These findings provide evidence for plasticity of visual memory mechanisms into late childhood but do not rule out vulnerability to early deprivation. Our computational simulations suggest that a potential mechanism to account for changes in memory performance may be progressive representational elaboration in image encoding.

SAGE PUBLICATIONS INC2022

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Transforming cumulative hazard estimates

Pal Christie Ryalen, Mats Julius Stensrud

Time-to-event outcomes are often evaluated on the hazard scale, but interpreting hazards may be difficult. Recently in the causal inference literature concerns have been raised that hazards actually have a built-in selection bias that prevents simple causal interpretations. This is a problem even in randomized controlled trials, where hazard ratios have become a standard measure of treatment effects. Modelling on the hazard scale is nevertheless convenient, for example to adjust for covariates; using hazards for intermediate calculations may therefore be desirable. In this paper we present a generic method for transforming hazard estimates consistently to other scales at which these built-in selection biases are avoided. The method is based on differential equations and generalizes a well-known relation between the Nelson–Aalen and Kaplan–Meier estimators. Using the martingale central limit theorem, we show that covariances can be estimated consistently for a large class of estimators, thus allowing for rapid calculation of confidence intervals. Hence, given cumulative hazard estimates based on, for example, Aalen’s additive hazard model, we can obtain many other parameters without much more effort. We give several examples and the associated estimators. Coverage and convergence speed are explored via simulations, and the results suggest that reliable estimates can be obtained in real-life scenarios.

2018

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Effects of N-Acetyl-Cysteine on Neurocognition in a double-blind randomized placebo-controlled trial

Lijing Xin

Wiley-Blackwell2016

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