1,720,963 research outputs found
When an external pilot is successful, should it be possible to transform it into an internal pilot by continuing recruitment into the full trial is ready? A case study of the cord pilot trial
No full textBackground: the Cord Pilot Trial recruited for one year at 8 sites to assess feasibility of a definitive UK trial, comparing timing of cord clamping for very preterm births. This was a complex study, funded as part of an NIHR programme for applied research. This paper will present and discuss our experience of trying to transform an external pilot into an internal pilot.Methods: at one year, recruitment was above target and other pre-specified feasibility criteria had been met. The TSC advised that recruitment should continue whilst funding for the full trial was sought, to maintain momentum, avoid loss of equipoise, and maximise efficiency. This was strongly supported by sites, endorsed by the DMC, and agreed with funder and sponsor.Results: a pathway for submission to NIHR HTA was agreed, as the usual research led call would require pilot sites to continue for 18 months. In view of the timescales, full trial preparation continued in parallel with grant submission. The full stage application was rejected, and the pilot trial therefore closed. A closure plan was agreed with sponsor and TSC, to allow sites to either close immediately, or to randomise women who had given consent if they remained eligible. Recruitment and compliance were maintained during phase 2.Conclusions: when an external pilot trial is successful, transforming it into an internal pilot by continuing into the full trial may maximise efficiency and value for money, but is a challenge to achieve
Cord pilot trial: update to randomised trial protocol
No full textBackground: the Cord Pilot Trial aimed to assess the feasibility of conducting a large UK randomised trial to compare the effects of alternative polices for timing of cord clamping (immediate within 20 seconds or deferred after at least 2 minutes) for very preterm birth before 32 weeks gestation. Initial recruitment was from March 2013 to February 2014, phase 2 was from March 2014 to February 2015. This paper updates the pilot trial protocol (Trials 15(1):258, 2014) and presents the changes for phase 2. Methods: an electronic randomisation system was introduced at three of the eight pilot sites. For follow-up of children, the Parent Report of Children's Abilities - Revised (PARCA-R) will not be used. For children recruited to the trial during phase 2, follow-up at age 2 years (corrected for gestation at birth) will be by parent completed Ages and Stages Questionnaire (Squire J, Ages and Stages Questionnaires (ASQ), 2009) alone unless funds can be secured for the additional Bayley Scales of Infant Development III (Bayley N, Bayley Scales of Infant and Toddler Development, Third Edition. (Bayley-III), 2005) assessments. To assess accuracy of the cranial ultrasound diagnosis of intraventricular haemorrhage: (i) quality of the scans will be assessed using the British Society of Paediatric Radiology recommendations, and (ii) scan results will be confirmed by independent adjudication. Within and between adjudicator reliability will be assessed. In addition to the analyses planned to assess feasibility of the full trial based on data from the first year of recruitment, data on compliance and outcomes will be presented by allocated group for all women and babies recruited. Trial registration: ISRCTN21456601, registered on 28 February 2013.</p
Cord pilot trial - immediate versus deferred cord clamping for very preterm birth (before 32 weeks gestation): study protocol for a randomized controlled trial
No full textBackground: Preterm birth is the most important single determinant of adverse outcome in the United Kingdom; one in every 70 babies (1.4%) is born before 32 weeks (very preterm), yet these births account for over half of infant deaths.
Deferring cord clamping allows blood flow between baby and placenta to continue for a short time. This often leads to increased neonatal blood volume at birth and may allow longer for transition to the neonatal circulation. Optimal timing for clamping the cord remains uncertain, however. The Cochrane Review suggests that deferring umbilical cord clamping for preterm births may improve outcome, but larger studies reporting substantive outcomes and with long-term follow-up are needed. Studies of the physiology of placental transfusion suggest that flow in the umbilical cord at very preterm birth may continue for several minutes. This pilot trial aims to assess the feasibility of conducting a large randomised trial comparing immediate and deferred cord clamping in the UK.
Methods/Design: Women are eligible for the trial if they are expected to have a live birth before 32 weeks gestation. Exclusion criteria are known monochorionic twins or clinical evidence of twin-twin transfusion syndrome, triplet or higher order multiple pregnancy, and known major congenital malformation. The interventions will be cord clamping within 20 seconds compared with cord clamping after at least two minutes. For births with cord clamping after at least two minutes, initial neonatal care is at the bedside. For the pilot trial, outcomes include measures of recruitment, compliance with the intervention, retention of participants and data quality for the clinical outcomes.
Information about the trial is available to women during their antenatal care. Women considered likely to have a very preterm birth are approached for informed consent. Randomisation is close to the time of birth. Follow-up for the women is for one year, and for the children to two years of age (corrected for gestation at birth). The target sample size is 100 to 110 mother-infant pairs recruited over 12 months at eight sites.
Trial registration: ISRCTN21456601, registered on 28 February 2013
Randomised trial of cord clamping and initial stabilisation at very preterm birth
No full textObjectives: for very preterm births, to compare alternative policies for umbilical cord clamping and immediate neonatal care.Design: parallel group randomised (1:1) trial, using sealed opaque numbered envelopes.Setting: eight UK tertiary maternity units.Participants: 261 women expected to have a live birth before 32 weeks, and their 276 babies.Interventions: cord clamping after at least 2 min and immediate neonatal care with cord intact, or clamping within 20 s and immediate neonatal care after clamping.Main outcome measures: intraventricular haemorrhage (IVH), death before discharge.Results: 132 women (137 babies) were allocated clamping ≥2 min and neonatal care cord intact, and 129 (139) clamping ≤20 s and neonatal care after clamping; six mother-infant dyads were excluded (2, 4) as birth was after 35+6 weeks, one withdrew (death data only available) (0, 1). Median gestation was 28.9 weeks for those allocated clamping ≥2 min, and 29.2 for those allocated clamping ≤20 s. Median time to clamping was 120 and 11 s, respectively. 7 of 135 infants (5.2%) allocated clamping ≥2 min died and 15 of 135 (11.1%) allocated clamping ≤20 s; risk difference (RD) -5.9% (95% CI -12.4% to 0.6%). Of live births, 43 of 134 (32%) had IVH vs 47 of 132 (36%), respectively; RD -3.5% (-14.9% to 7.8%). There were no clear differences in other outcomes for infants or mothers.Conclusions: this is promising evidence that clamping after at least 2 min and immediate neonatal care with cord intact at very preterm birth may improve outcome; a large trial is urgently needed.Trial Registration: ISRCTN 21456601.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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