A successful open surgical operation to remove atheromatous carotid artery narrowing that has not yet caused a stroke (asymptomatic carotid stenosis) carries some procedural risk but, if completed ...successfully, halves patients' future annual stroke risk for at least 10 years. A newer, less invasive alternative is carotid stenting, which also carries some procedural risk, especially if the carotid lesion has recently given rise to a stroke (symptomatic carotid stenosis). For both surgery and stenting, improvements in technique (and in medication) have reduced risk. Early studies showed that treating carotid narrowing by stenting, particularly for symptomatic lesions, caused more procedural minor strokes than surgery, but more recent trials in symptomatic and in asymptomatic patients found that both procedures might now be equally safe and effective. However, low patient numbers, short follow-up of the long-term effects on stroke rates and wide confidence intervals mean that worldwide uncertainty persists between carotid surgery and carotid stenting, and national and international guidelines remain unclear as to which is generally better.
The second Asymptomatic Carotid Surgery Trial (ACST-2) compares carotid endarterectomy (CEA) with carotid artery stenting (CAS) directly, randomising patients with asymptomatic carotid stenosis for whom a carotid procedure is considered definitely necessary; both procedures seem anatomically feasible, and there is substantial uncertainty as to which of the two would be better for such individuals. Although it will compare procedural risks, the trial's primary aim is to compare the long-term durability of protection against strokes occurring in the years post procedure due to any remaining or recurrent carotid disease.
Randomised controlled trial comparing CEA with CAS.
Hospitals in the UK and worldwide, in which carotid procedures are common.
Men and women with severely stenotic atherosclerotic carotid artery disease, with or without previous stroke but with no recent symptoms from the randomised artery.
CEA and CAS.
(1) Periprocedural risk defined as myocardial infarction, stroke or death within 30 days after the randomised procedure and (2) long-term rates of disabling or fatal stroke during follow-up of patients.
Measurement of intervention costs and stroke costs (periprocedural and during follow-up) and of quality of life EuroQol-5 Dimensions (EQ-5D
) for patients in the top six recruiting countries (UK, Italy, Belgium, Germany, Serbia and Sweden), who currently constitute 85% of those randomised.
By the end of March 2016, ACST-2 had included 2125 patients, nearly two-thirds of the planned recruitment of 3600; 1061 were randomly allocated to CEA and 1064 to CAS.
Further funding has been secured and recruitment continues, with completion anticipated by the end of 2019. ACST-2 will report initial results in 2021.
Current Controlled Trials ISRCTN21144362.
This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in
; Vol. 21, No. 57. See the NIHR Journals Library website for further project information. Funding was also received from BUPA Foundation BUPAF/33(a)/05.
Carotid artery stenosis is responsible for between 10-20% of all ischaemic strokes. Interventions, such as carotid endarterectomy and carotid stenting, effectively reduce the risk of stroke in ...selected individuals. This review describes the history of carotid interventions, and summarises reliable evidence on the safety and efficacy of these interventions gained from large randomised clinical trials.Early trials comparing carotid endarterectomy to medical therapy alone in symptomatic patients, and asymptomatic patients, demonstrated that endarterectomy halved the risk of stroke and perioperative death in these two unique populations. The absolute risk reduction was smaller in the asymptomatic carotid trials, consistent with their lower absolute stroke risk. More recent trials in symptomatic patients, suggest that carotid stenting has similar long term durability to carotid endarterectomy, but possibly has higher procedural hazards dominated by non-disabling strokes. The Asymptomatic Carotid Surgery Trial-2, along with individual patient data meta-analysis of all asymptomatic trials, will provide reliable evidence for the choice of intervention in asymptomatic patients in whom a decision has been made for carotid revascularisation. Given improvements in effective cardiovascular medical therapy, in particular lipid-lowering medications, there is renewed uncertainty as to whether carotid interventions still provide meaningful net reductions in stroke risk in asymptomatic populations. Four large trials in Europe and the US are currently underway, and are expected to report long-term results in the next decade.It is essential that surgeons, interventionalists, and physicians continue to randomise large numbers of patients from around the world to clarify current uncertainty around the management of asymptomatic carotid stenosis.
Summary Background Age was reported to be an effect-modifier in four randomised controlled trials comparing carotid artery stenting (CAS) and carotid endarterectomy (CEA), with better CEA outcomes ...than CAS outcomes noted in the more elderly patients. We aimed to describe the association of age with treatment differences in symptomatic patients and provide age-specific estimates of the risk of stroke and death within narrow (5 year) age groups. Methods In this meta-analysis, we analysed individual patient-level data from four randomised controlled trials within the Carotid Stenosis Trialists' Collaboration (CSTC) involving patients with symptomatic carotid stenosis. We included only trials that randomly assigned patients to CAS or CEA and only patients with symptomatic stenosis. We assessed rates of stroke or death in 5-year age groups in the periprocedural period (between randomisation and 120 days) and ipsilateral stroke during long-term follow-up for patients assigned to CAS or CEA. We also assessed differences between CAS and CEA. All analyses were done on an intention-to-treat basis. Findings Collectively, 4754 patients were randomly assigned to either CEA or CAS treatment in the four studies. 433 events occurred over a median follow-up of 2·7 years. For patients assigned to CAS, the periprocedural hazard ratio (HR) for stroke and death in patients aged 65–69 years compared with patients younger than 60 years was 2·16 (95% CI 1·13–4·13), with HRs of roughly 4·0 for patients aged 70 years or older. We noted no evidence of an increased periprocedural risk by age group in the CEA group (p=0·34). These changes underpinned a CAS-versus CEA periprocedural HR of 1·61 (95% CI 0·90–2·88) for patients aged 65–69 years and an HR of 2·09 (1·32–3·32) for patients aged 70–74 years. Age was not associated with the postprocedural stroke risk either within treatment group (p≥0·09 for CAS and 0·83 for CEA), or between treatment groups (p=0·84). Interpretation In these RCTs, CEA was clearly superior to CAS in patients aged 70–74 years and older. The difference in older patients was almost wholly attributable to increasing periprocedural stroke risk in patients treated with CAS. Age had little effect on CEA periprocedural risk or on postprocedural risk after either procedure. Funding None.
Randomised controlled trials (RCTs) are essential for evidence-based medicine and increasingly rely on front-line clinicians to recruit eligible patients. Clinicians' difficulties with negotiating ...equipoise is assumed to undermine recruitment, although these issues have not yet been empirically investigated in the context of observable events. We aimed to investigate how clinicians conveyed equipoise during RCT recruitment appointments across six RCTs, with a view to (i) identifying practices that supported or hindered equipoise communication and (ii) exploring how clinicians' reported intentions compared with their actual practices.
Six pragmatic UK-based RCTs were purposefully selected to include several clinical specialties (e.g., oncology, surgery) and types of treatment comparison. The RCTs were all based in secondary-care hospitals (n = 16) around the UK. Clinicians recruiting to the RCTs were interviewed (n = 23) to understand their individual sense of equipoise about the RCT treatments and their intentions for communicating equipoise to patients. Appointments in which these clinicians presented the RCT to trial-eligible patients were audio-recorded (n = 105). The appointments were analysed using thematic and content analysis approaches to identify practices that supported or challenged equipoise communication. A sample of appointments was independently coded by three researchers to optimise reliability in reported findings. Clinicians and patients provided full written consent to be interviewed and have appointments audio-recorded. Interviews revealed that clinicians' sense of equipoise varied: although all were uncertain about which trial treatment was optimal, they expressed different levels of uncertainty, ranging from complete ambivalence to clear beliefs that one treatment was superior. Irrespective of their personal views, all clinicians intended to set their personal biases aside to convey trial treatments neutrally to patients (in accordance with existing evidence). However, equipoise was omitted or compromised in 48/105 (46%) of the recorded appointments. Three commonly recurring practices compromised equipoise communication across the RCTs, irrespective of clinical context. First, equipoise was overridden by clinicians offering treatment recommendations when patients appeared unsure how to proceed or when they asked for the clinician's expert advice. Second, clinicians contradicted equipoise by presenting imbalanced descriptions of trial treatments that conflicted with scientific information stated in the RCT protocols. Third, equipoise was undermined by clinicians disclosing their personal opinions or predictions about trial outcomes, based on their intuition and experience. These broad practices were particularly demonstrated by clinicians who had indicated in interviews that they held less balanced views about trial treatments. A limitation of the study was that clinicians volunteering to take part in the research might have had a particular interest in improving their communication skills. However, the frequency of occurrence of equipoise issues across the RCTs suggests that the findings are likely to be reflective of clinical recruiters' practices more widely.
Communicating equipoise is a challenging process that is easily disrupted. Clinicians' personal views about trial treatments encroached on their ability to convey equipoise to patients. Clinicians should be encouraged to reflect on personal biases and be mindful of the common ways in which these can arise in their discussions with patients. Common pitfalls that recurred irrespective of RCT context indicate opportunities for specific training in communication skills that would be broadly applicable to a wide clinical audience.
The aim of this study was to: 1) provide tissue validation of quantitative T
mapping to measure plaque lipid content; and 2) investigate whether this technique could discern differences in plaque ...characteristics between symptom-related and non-symptom-related carotid plaques.
Noninvasive plaque lipid quantification is appealing both for stratification in treatment selection and as a possible predictor of future plaque rupture. However, current cardiovascular magnetic resonance (CMR) methods are insensitive, require a coalesced mass of lipid core, and rely on multicontrast acquisition with contrast media and extensive post-processing.
Patients scheduled for carotid endarterectomy were recruited for 3-T carotid CMR before surgery. Lipid area was derived from segmented T
maps and compared directly to plaque lipid defined by histology.
Lipid area (%) on T
mapping and histology showed excellent correlation, both by individual slices (R = 0.85, p < 0.001) and plaque average (R = 0.83, p < 0.001). Lipid area (%) on T
maps was significantly higher in symptomatic compared with asymptomatic plaques (31.5 ± 3.7% vs. 15.8 ± 3.1%; p = 0.005) despite similar degrees of carotid stenosis and only modest difference in plaque volume (128.0 ± 6.0 mm
symptomatic vs. 105.6 ± 9.4 mm
asymptomatic; p = 0.04). Receiver-operating characteristic analysis showed that T
mapping has a good ability to discriminate between symptomatic and asymptomatic plaques with 67% sensitivity and 91% specificity (area under the curve: 0.79; p = 0.012).
CMR T
mapping distinguishes different plaque components and accurately quantifies plaque lipid content noninvasively. Compared with asymptomatic plaques, greater lipid content was found in symptomatic plaques despite similar degree of luminal stenosis and only modest difference in plaque volumes. This new technique may find a role in determining optimum treatment (e.g., providing an indication for intensive lipid lowering or by informing decisions of stents vs. surgery).
The effects of ionising radiation (IR) on plants are important for environmental protection but also in agriculture, horticulture, space science, and plant stress biology. Much current understanding ...of the effects of IR on plants derives from acute high-dose studies but exposure to IR in the environment frequently occurs at chronic low dose rates. Chronic low dose-rate studies have primarily been field based and examined genetic or cytogenetic endpoints. Here we report research that investigated developmental, morphological and physiological effects of IR on
grown over 7 generations and exposed for five generations to chronic low doses of either
Cs (at a dose rate of
40 μGy/h from β/γ emissions) or 10 μM CdCl
. In some generations there were significant differences between treatments in the timing of key developmental phases and in leaf area or symmetry but there were, on the basis of the chosen endpoints, no long-term effects of the different treatments. Occasional measurements also detected no effects on root growth, seed germination rates or redox poise but in the generation in which it was measured exposure to IR did decrease DNA-methylation significantly. The results are consistent with the suggestion that chronic exposure to
40 μGy/h can have some effects on some traits but that this does not affect function across multiple generations at the population level. This is explained by the redundancy and/or degeneracy between biological levels of organization in plants that produces a relatively loose association between genotype and phenotype. The importance of this explanation to understanding plant responses to stressors such as IR is discussed. We suggest that the data reported here provide increased confidence in the Derived Consideration Reference Levels (DCRLs) recommended by the International Commission for Radiological Protection (ICRP) by providing data from controlled conditions and helping to contextualize effects reported from field studies. The differing sensitivity of plants to IR is not well understood and further investigation of it would likely improve the use of DCRLs for radiological protection.
Research has shown that recruitment to trials is a process that stretches from identifying potentially eligible patients, through eligibility assessment, to obtaining informed consent. The length and ...complexity of this pathway means that many patients do not have the opportunity to consider participation. This article presents the development of a simple framework to document, understand and improve the process of trial recruitment.
Eight RCTs integrated a QuinteT Recruitment Intervention (QRI) into the main trial, feasibility or pilot study. Part of the QRI required mapping the patient recruitment pathway using trial-specific screening and recruitment logs. A content analysis compared the logs to identify aspects of the recruitment pathway and process that were useful in monitoring and improving recruitment. Findings were synthesised to develop an optimised simple framework that can be used in a wide range of RCTs.
The eight trials recorded basic information about patients screened for trial participation and randomisation outcome. Three trials systematically recorded reasons why an individual was not enrolled in the trial, and further details why they were not eligible or approached, or declined randomisation. A framework to facilitate clearer recording of the recruitment process and reasons for non-participation was developed: SEAR - Screening, to identify potentially eligible trial participants; Eligibility, assessed against the trial protocol inclusion/exclusion criteria; Approach, the provision of oral and written information and invitation to participate in the trial, and Randomised or not, with the outcome of randomisation or treatment received.
The SEAR framework encourages the collection of information to identify recruitment obstacles and facilitate improvements to the recruitment process. SEAR can be adapted to monitor recruitment to most RCTs, but is likely to add most value in trials where recruitment problems are anticipated or evident. Further work to test it more widely is recommended.
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