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- Beck, AW, et al.
(author)
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Variations in abdominal aortic aneurysm care : a report from the International consortium of vascular registries
- 2016
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In: Circulation. - 0009-7322 .- 1524-4539.
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Journal article (peer-reviewed)abstract
- Background: This project by the ICVR (International Consortium of Vascular Registries), a collaboration of 11 vascular surgical quality registries, was designed to evaluate international variation in the contemporary management of abdominal aortic aneurysm (AAA) with relation to recommended treatment guidelines from the Society for Vascular Surgery and the European Society for Vascular Surgery.Methods: Registry data for open and endovascular AAA repair (EVAR) during 2010 to 2013 were collected from 11 countries. Variations in patient selection and treatment were compared across countries and across centers within countries.Results: Among 51 153 patients, 86% were treated for intact AAA (iAAA) and 14% for ruptured AAA. Women constituted 18% of the entire cohort (range, 12% in Switzerland–21% in the United States; P<0.01). Intact AAAs were repaired at diameters smaller than recommended by guidelines in 31% of men (<5.5 cm; range, 6% in Iceland–41% in Germany; P<0.01) and 12% of women with iAAA (<5 cm; range, 0% in Iceland–16% in the United States; P<0.01). Overall, use of EVAR for iAAA varied from 28% in Hungary to 79% in the United States (P<0.01) and for ruptured AAA from 5% in Denmark to 52% in the United States (P<0.01). In addition to the between-country variations, significant variations were present between centers in each country in terms of EVAR use and rate of small AAA repair. Countries that more frequently treated small AAAs tended to use EVAR more frequently (trend: correlation coefficient, 0.51; P=0.14). Octogenarians made up 23% of all patients, ranging from 12% in Hungary to 29% in Australia (P<0.01). In countries with a fee-for-service reimbursement system (Australia, Germany, Switzerland, and the United States), the proportions of small AAA (33%) and octogenarians undergoing iAAA repair (25%) were higher compared with countries with a population-based reimbursement model (small AAA repair, 16%; octogenarians, 18%; P<0.01). In general, center-level variation within countries in the management of AAA was as important as variation between countries.Conclusions: Despite homogeneous guidelines from professional societies, significant variation exists in the management of AAA, most notably for iAAA diameter at repair, use of EVAR, and the treatment of elderly patients. ICVR provides an opportunity to study treatment variation across countries and to encourage optimal practice by sharing these results.
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- Budtz-Lilly, Jacob, et al.
(author)
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Editor's Choice - Assessment of International Outcomes of Intact Abdominal Aortic Aneurysm Repair over 9 Years
- 2017
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In: European Journal of Vascular and Endovascular Surgery. - : Elsevier BV. - 1078-5884 .- 1532-2165. ; 54:1, s. 13-20
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Journal article (peer-reviewed)abstract
- Background: Case mix and outcomes of complex surgical procedures vary over time and between regions. This study analyses peri-operative mortality after intact abdominal aortic aneurysm (AAA) repair in 11 countries over 9 years. Methods: Data on primary AAA repair from vascular surgery registries in 11 countries for the years 2005-2009 and 2010-2013 were analysed. Multivariate adjusted logistic regression analyses were carried out to adjust for variations in case mix. Results: A total of 83,253 patients were included. Over the two periods, the proportion of patients >= 80 years old increased (18.5% vs. 23.1%; p < .0001) as did the proportion of endovascular repair (EVAR) (44.3% vs. 60.6; p < .0001). In the latter period, 25.8% of AAAs were less than 5.5 cm. The mean annual volume of open repairs per centre decreased from 12.9 to 10.6 between the two periods (p < .0001), and it increased for EVAR from 10.0 to 17.1 (p < .0001). Overall, peri-operative mortality fell from 3.0% to 2.4% (p < .0001). Mortality for EVAR decreased from 1.5% to 1.1% (p < .0001), but the outcome worsened for open repair from 3.9% to 4.4% (p = .008). The peri-operative risk was greater for octogenarians (overall, 3.6% vs. 2.1%, p < .0001; open, 9.5% vs. 3.6%, p < .0001; EVAR, 1.8% vs. 0.7%, p < .0001), and women (overall, 3.8% vs. 2.2%, p < .0001; open, 6.0% vs. 4.0%, p < .0001; EVAR, 1.9% vs. 0.9%, p < .0001). Peri-operative mortality after repair of AAAs <5.5 cm was 4.4% with open repair and 1.0% with EVAR, p < .0001. Conclusions: In this large international cohort, total peri-operative mortality continues to fall for the treatment of intact AAAs. The number of EVAR procedures now exceeds open procedures. Mortality after EVAR has decreased, but mortality for open operations has increased. The peri-operative mortality for small AM treatment, particularly open surgical repair, is still considerable and should be weighed against the risk of rupture.
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- Lees, T, et al.
(author)
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International Variations in Infrainguinal Bypass Surgery : A VASCUNET Report
- 2012
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In: European Journal of Vascular and Endovascular Surgery. - : Elsevier BV. - 1078-5884 .- 1532-2165. ; 44:2, s. 185-192
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Journal article (peer-reviewed)abstract
- OBJECTIVES:To compare practice in lower limb bypass surgery in nine countries.DESIGN:A prospective study amalgamating and analysing data from national and regional vascular registries.METHODS:A table of data fields and definitions was agreed by all member countries of the Vascunet Collaboration. Data from January 2005 to December 2009 was submitted to a central database.RESULTS:32,084 cases of infrainguinal bypass (IIB) in nine countries were analysed. Procedures per 100,000 population varied between 2.3 in the UK and 24.6 in Finland. The proportion of women varied from 25% to 43.5%. The median age for all countries was 70 for men and 76 for women. Hungary treated the youngest patients. IIB was performed for claudication for between 15.7% and 40.8% of all procedures. Vein grafts were used in patients operated on for claudication (52.9%), for rest pain (66.7%) and tissue loss (74.1%). Italy had the highest use of synthetic grafts. Among claudicants 45% of bypasses were performed to the below knee popliteal artery or more distally. Graft patency at 30 days varied between 86% and 99%.CONCLUSIONS: Significant variations in practice between countries were demonstrated. These results should be interpreted alongside the known limitations of such registry data with respect to quality and completeness of the data. Variation in data completeness and data validation between countries needs to be improved for useful international comparison of outcomes.
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- Menyhei, G., et al.
(author)
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Outcome Following Carotid Endarterectomy : Lessons Learned From a Large International Vascular Registry
- 2011
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In: European Journal of Vascular and Endovascular Surgery. - : Elsevier BV. - 1078-5884 .- 1532-2165. ; 41:6, s. 735-740
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Journal article (peer-reviewed)abstract
- Objectives: The aim of the study was to assess if technical and patient-related factors are related to outcome after carotid surgery. Design: Vascunet is a collaboration of national and regional registries with 10 contributing countries. Patients and methods: Data from 48 035 carotid endarterectomies (CEAs) performed in 383 centres, during 2003-2007, were merged into a common database. Results: CEA was performed without patch (34%), with patch (40%) or with eversion (26%) in 74% for symptomatic and in 26% for asymptomatic disease. Overall (in-hospital and 30-day) mortality was 0.45%. Type of CEA or anaesthesia did not affect mortality, nor did contralateral occlusion. Mortality was higher in patients above the age of 75 years, for both genders (p < 0.05). The overall (in-hospital) stroke rate was 1.9%, the method of anaesthesia did not affect stroke rate. It was higher in patients with contratateral occlusion (4.6% vs. 2.5%, p = 0.002). Standard CEA without patch had a higher stroke rate than when a patch was used (2.3 vs. 1.7%, p = 0.015). Female patients >75 years had a higher stroke rate than younger women (2.0% vs. 1.6%, p = 0.078); this difference was not observed in men. Conclusions: Although there are limitations with registry data, the large number of cases involved provides useful information on outcomes, supplementing data from the randomised clinical trials (RCTs).
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- Niehues, Iris, et al.
(author)
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Strain Control of Exciton-Phonon Coupling in Atomically Thin Semiconductors
- 2018
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In: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 18:3, s. 1751-1757
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Journal article (peer-reviewed)abstract
- Semiconducting transition metal dichalcogenide (TMDC) monolayers have exceptional physical properties. They show bright photoluminescence due to their unique band structure and absorb more than 10% of the light at their excitonic resonances despite their atomic thickness. At room temperature, the width of the exciton transitions is governed by the exciton-phonon interaction leading to strongly asymmetric line shapes. TMDC monolayers are also extremely flexible, sustaining mechanical strain of about 10% without breaking. The excitonic properties strongly depend on strain. For example, exciton energies of TMDC monolayers significantly redshift under uniaxial tensile strain. Here, we demonstrate that the width and the asymmetric line shape of excitonic resonances in TMDC monolayers can be controlled with applied strain. We measure photoluminescence and absorption spectra of the A exciton in monolayer MoSe 2 , WSe 2 , WS 2 , and MoS 2 under uniaxial tensile strain. We find that the A exciton substantially narrows and becomes more symmetric for the selenium-based monolayer materials, while no change is observed for atomically thin WS 2 . For MoS 2 monolayers, the line width increases. These effects are due to a modified exciton-phonon coupling at increasing strain levels because of changes in the electronic band structure of the respective monolayer materials. This interpretation based on steady-state experiments is corroborated by time-resolved photoluminescence measurements. Our results demonstrate that moderate strain values on the order of only 1% are already sufficient to globally tune the exciton-phonon interaction in TMDC monolayers and hold the promise for controlling the coupling on the nanoscale.
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