The Role of Email Communications in Determining Response Rates and Mode of Participation in a Mixed-mode Design

This article is concerned with the extent to which the propensity to participate in a web-face-to-face sequential mixed-mode survey is influenced by the ability to communicate with sample members by email in addition to mail. Researchers may be able to collect email addresses for sample members and to use them subsequently to send survey invitations and reminders. However, there is little evidence regarding the value of doing so. This makes it difficult to decide what efforts should be made to collect such information and how to subsequently use it efficiently. Using evidence from a randomized experiment within a large mixed-mode national survey, we find that using a respondent-supplied email address to send additional survey invites and reminders does not affect survey response rate but is associated with an increased proportion of responses by web rather than face to face and, hence, lower survey costs

The implications of alternative allocation criteria in adaptive design for panel surveys

Adaptive survey designs can be used to allocate sample elements to alternative data collection protocols in order to achieve a desired balance between some quality measure and survey costs. We compare four alternative methods for allocating sample elements to one of two data collection protocols. The methods differ in terms of the quality measure that they aim to optimise: response rate, R-indicator, coefficient of variation of the participation propensities, or effective sample size. Costs are also compared for a range of sample sizes. The data collection protocols considered are CAPI single-mode and web-CAPI sequential mixed-mode. We use data from a large experiment with random allocation to one of these two protocols. For each allocation method we predict outcomes in terms of several quality measures and costs. Although allocating the whole sample to single-mode CAPI produces a higher response rate than allocating the whole sample to the mixed-mode protocol, we find that two of the targeted allocations achieve a better response rate than single-mode CAPI at a lower cost. We also find that all four of the targeted designs out-perform both single-protocol designs in terms of representativity and effective sample size. For all but the smallest sample sizes, the adaptive designs bring cost savings relative to CAPI-only, though these are fairly modest in magnitude

Applying Prospect Theory to Participation in a CAPI/Web Panel Survey

Prospect theory states that the influential power of avoiding negative outcomes is stronger than that of achieving positive outcomes. In a survey context, this theory has been tested with respect to not only participation in a CATI survey, but also giving consent to data linkage in CATI surveys. No study, however, has tested the theory with respect to participation in a CAPI or web survey. This study does so in a mixed-mode panel context; it also tests the moderating effects of time-in-panel, response history, and mode protocol. Results show that the framing of the survey participation request influences participation propensity in a way consistent with prospect theory, but only for relatively recent panel entrants. The opposite effect is found for long-term panel participants. No difference is found between mode protocols

Understanding Society Innovation Panel Wave 8: results from methodological experiments

This paper presents some preliminary findings from Wave 8 of the Innovation Panel (IP8) of Understanding Society: The UK Household Longitudinal Study. Understanding Society is a major panel survey in the UK. May 2015, the eighth wave of the Innovation Panel went into the field. IP8 used a mixed-mode design, using on-line interviews and face-to-face interviews. This paper describes the design of IP8, the experiments carried and the preliminary findings from early analysis of the data

Understanding Society Innovation Panel Wave 6: results from methodological experiments

This paper presents some preliminary findings from Wave 6 of the Innovation Panel (IP6) of Understanding Society: The UK Household Longitudinal Study. Understanding Society is a major panel survey in the UK. In March 2013, the sixth wave of the Innovation Panel went into the field. IP6 used a mixed-mode design, using on-line interviews and face-to-face interviews. This paper describes the design of IP6, the experiments carried and the preliminary findings from early analysis of the data

Effects of Anesthetic Agents on Brain Blood Oxygenation Level Revealed with Ultra-High Field MRI

During general anesthesia it is crucial to control systemic hemodynamics and oxygenation levels. However, anesthetic agents can affect cerebral hemodynamics and metabolism in a drug-dependent manner, while systemic hemodynamics is stable. Brain-wide monitoring of this effect remains highly challenging. Because T2*-weighted imaging at ultra-high magnetic field strengths benefits from a dramatic increase in contrast to noise ratio, we hypothesized that it could monitor anesthesia effects on brain blood oxygenation. We scanned rat brains at 7T and 17.2T under general anesthesia using different anesthetics (isoflurane, ketamine-xylazine, medetomidine). We showed that the brain/vessels contrast in T2*-weighted images at 17.2T varied directly according to the applied pharmacological anesthetic agent, a phenomenon that was visible, but to a much smaller extent at 7T. This variation is in agreement with the mechanism of action of these agents. These data demonstrate that preclinical ultra-high field MRI can monitor the effects of a given drug on brain blood oxygenation level in the absence of systemic blood oxygenation changes and of any neural stimulation

Peri-operative red blood cell transfusion in neonates and infants: NEonate and Children audiT of Anaesthesia pRactice IN Europe: A prospective European multicentre observational study

BACKGROUND: Little is known about current clinical practice concerning peri-operative red blood cell transfusion in neonates and small infants. Guidelines suggest transfusions based on haemoglobin thresholds ranging from 8.5 to 12 g dl-1, distinguishing between children from birth to day 7 (week 1), from day 8 to day 14 (week 2) or from day 15 (≥week 3) onwards. OBJECTIVE: To observe peri-operative red blood cell transfusion practice according to guidelines in relation to patient outcome. DESIGN: A multicentre observational study. SETTING: The NEonate-Children sTudy of Anaesthesia pRactice IN Europe (NECTARINE) trial recruited patients up to 60 weeks' postmenstrual age undergoing anaesthesia for surgical or diagnostic procedures from 165 centres in 31 European countries between March 2016 and January 2017. PATIENTS: The data included 5609 patients undergoing 6542 procedures. Inclusion criteria was a peri-operative red blood cell transfusion. MAIN OUTCOME MEASURES: The primary endpoint was the haemoglobin level triggering a transfusion for neonates in week 1, week 2 and week 3. Secondary endpoints were transfusion volumes, 'delta haemoglobin' (preprocedure - transfusion-triggering) and 30-day and 90-day morbidity and mortality. RESULTS: Peri-operative red blood cell transfusions were recorded during 447 procedures (6.9%). The median haemoglobin levels triggering a transfusion were 9.6 [IQR 8.7 to 10.9] g dl-1 for neonates in week 1, 9.6 [7.7 to 10.4] g dl-1 in week 2 and 8.0 [7.3 to 9.0] g dl-1 in week 3. The median transfusion volume was 17.1 [11.1 to 26.4] ml kg-1 with a median delta haemoglobin of 1.8 [0.0 to 3.6] g dl-1. Thirty-day morbidity was 47.8% with an overall mortality of 11.3%. CONCLUSIONS: Results indicate lower transfusion-triggering haemoglobin thresholds in clinical practice than suggested by current guidelines. The high morbidity and mortality of this NECTARINE sub-cohort calls for investigative action and evidence-based guidelines addressing peri-operative red blood cell transfusions strategies. TRIAL REGISTRATION: ClinicalTrials.gov, identifier: NCT02350348

Etude des mécanismes cérébraux de la perte de conscience au cours de l’anesthésie générale utilisant la neuroimagerie chez le primate non humain

Comment les agents anesthésiques induisent-ils une perte de conscience lors de l’anesthésie générale? La dissection des mécanismes neuronaux de l’anesthésie générale représente un défi important en neurosciences. L’émergence de l’IRM fonctionnelle (IRMf) chez le primate non-humain donne l’occasion d’étudier l’activité neuronale à l’état éveillé et sous anesthésie en s’affranchissant des contraintes cliniques. Le développement récent de paradigmes auditifs, tel que le paradigme ‘local-global’, qui explore spécifiquement les réseaux cérébraux impliqués dans l’état conscient, nous a permis d’émettre l’hypothèse que la combinaison de l’IRMf chez le primate, de paradigmes auditifs et de protocoles d’anesthésie contrôlés par l’électroencéphalogramme (EEG), pourraient aider à disséquer les mécanismes neuronaux de l’anesthésie générale.Dans une première étape, étant donnée l’utilisation extensive de l’IRM dans notre travail, il était important d’étudier systématiquement l’effet des agents anesthésiques sur l’oxygénation vasculaire cérébrale, paramètre critique pour le signal IRMf. Nous avons donc réalisé une expérience préliminaire, faisant appel à l’IRM à ultra-haut champ magnétique chez le rongeur, afin de détecter les éventuels modifications du signal T2* induits par chacun des agents anesthésiques. Nous avons pu démontrer que le propofol et la kétamine, deux agents anesthésiques utilisés en clinique, affectaient moins l’oxygénation sanguine cérébrale que les anesthésiques volatils.Dans une deuxième étape, nous avons développé une « boîte à outils » pour l’IRMf chez le primate éveillé et anesthésié, et avons validé notre dispositif expérimental avec un paradigme auditif basé sur des sons simples (basse et haute fréquence).Dans une troisième étape, nous avons testé le paradigme auditif ‘local-global’ chez le macaque éveillé et avons pu démontrer que le cerveau du macaque est capable d’un codage prédictif hiérarchique à travers un espace de travail global, composé d’un réseau fronto-pariéto-cingulaire, montrant une forte homologie avec celui de l’Homme.Dans une quatrième étape, nous avons testé le paradigme auditif ‘local-global’, chez le macaque anesthésié et avons pu démontrer une désorganisation progressive de l’espace de travail global neuronal sous anesthésie. Cette désorganisation a été proportionnelle au niveau de sédation sous propofol, et complète sous sédation profonde à la kétamine. Ces résultats sont compatibles avec l’hypothèse selon laquelle le mécanisme de la perte de conscience sous anesthésie, est lié à une désorganisation de l’organisation fonctionnelle hiérarchique de l’espace de travail neuronal. Le cortex pariétal apparaît comme une cible commune aux deux agents anesthésiques.Dans la dernière étape, nous avons étudié le réseau cérébral par défaut (« default mode network ») chez le macaque éveillé et anesthésié. Nous avons pu démontrer que sous anesthésie, le cerveau présentait encore des patrons de connectivité distincts et riches, mais que ces patrons étaient fortement liés à l’organisation anatomique sous-jacente, alors que, à l’état éveillé cette organisation se caractérisait par un haut degré de flexibilité temporelle ce qui permet une exploration non-stéréotypée d’une plus grande variété d’états cérébraux.En conclusion, les agents anesthésiques entraînent une désorganisation de l’espace de travail global neuronal, avec pour conséquence l’altération des dynamiques temporelles de l’activité cérébrale spontanée, induisant ainsi une suppression de la conscience.How can anesthetics induce a loss of consciousness during general anesthesia? A major challenge in neuroscience is to dissect the mechanisms of general anesthesia, which is quite difficult to achieve in the clinical conditions. The dawning of monkey functional MRI (fMRI) in neuroscience is an important opportunity to investigate neuronal activity in awake and anesthetized conditions. The recent development of auditory paradigms, such as the ‘local-global’ paradigm, that specifically explore brain networks thought to be specific of the conscious state led us to hypothesize that the combination of primate fMRI, auditory paradigms and single-drug anesthetic protocols with electroencephalography (EEG) control would help dissect the neuronal mechanisms of general anesthesia. In a first step, because we planned an extensive use of fMRI in our work, it was key to screen anesthetic agents for their effects on brain vascular oxygenation, a critical parameter for fMRI signal. Thus we did a preliminary experiment using ultra-high field MRI in rodents to assess subtle changes of the T2* signal under different anesthetic conditions and could demonstrate that propofol and ketamine, both clinical anesthetics, affects less brain blood oxygenation than volatile agents. In a second step, we developed a toolbox for awake and anesthetized monkey fMRI and validated the experimental set-up with a simple sound paradigm (low and high frequency sounds). In the third step, we tested the ‘local-global’ auditory paradigm in awake monkeys and could demonstrate that the macaque brain was capable of hierarchical predictive coding through a hypothetical macaque Global Neuronal Workspace made of frontal, parietal and cingulate cortices, in a striking homology with humans. In the fourth step, we tested the ‘local-global’ auditory paradigm in anesthetized monkeys and could demonstrate a progressive disorganization of the macaque GNW under anesthesia when increasing the levels of propofol sedation, and a complete suppression of the macaque GNW under deep ketamine sedation. These results are compatible with the hypothesis that the mechanism of loss of consciousness under anesthesia is related to the disorganization of a hierarchical GNW, with the parietal cortex as a common target among anesthetics. In the final step we studied the default network by acquiring resting state in awake and anesthetized monkeys and could demonstrate that under anesthesia, the brain still exhibits distinct and rich connectivity patterns, but these patterns become strongly related to the underlying white-matter structural map in a monotonic manner, while the awake state is characterized by a high degree of temporal flexibility which allows for a non-stereotyped exploration of a greater variety of brain states. In conclusion, by disorganizing the GNW, anesthetics alter the temporal dynamics of spontaneous brain activity, and specifically its departure from mere random fluctuations along established anatomical routes, leading to consciousness suppression

Effet de la stimulation thalamique sur l' anesthésie générale

L objectif de ce travail est d étudier les conséquences de la stimulation thalamique bilatérale aiguë sur l anesthésie générale chez l adulte. La revue de la littérature montre que le thalamus est impliqué dans les réseaux neuronaux responsables des états de conscience, mais sa place dans l anesthésie générale chez l Homme reste méconnue. Cinq patients ayant un tremblement sévère ont été opérés pour une implantation d un neurostimulateur thalamique avec une électrode dans chacun des deux noyaux ventralis intermedius (Vim). En fin d intervention, alors que le patient est toujours sous anesthésie générale stable sous propofol et rémifentanil, le neurostimulateur a été mis en route de manière aiguë (130 Hz) tout en étudiant les conséquences neurophysiologiques (index bispectral) et cliniques. La stimulation thalamique bilatérale aiguë a immédiatement provoqué des signes cliniques de réveil et une augmentation concomitante de l index bispectral au cours d une anesthésie générale stable. Ce réveil a été réversible dès l arrêt de la stimulation électrique.La stimulation cérébrale thalamique bilatérale induit un allègement significatif et réversible du niveau d anesthésie générale à niveau pharmacologique constant. Cette observation démontre le rôle fondamental joué par l activité thalamique dans le phénomène de l anesthésie générale chez l Homme.PARIS6-Bibl.Pitié-Salpêtrie (751132101) / SudocSudocFranceF