-
[show abstract]
[hide abstract]
ABSTRACT: BACKGROUND: Use of kidneys donated after controlled circulatory death has increased the number of transplants undertaken in the UK but there remains reluctance to use kidneys from older circulatory-death donors and concern that kidneys from circulatory-death donors are particularly susceptible to cold ischaemic injury. We aimed to compare the effect of donor age and cold ischaemic time on transplant outcome in kidneys donated after circulatory death versus brain death. METHODS: We used the UK transplant registry to select a cohort of first-time recipients (aged ≥18 years) of deceased-donor kidneys for transplantations done between Jan 1, 2005, and Nov 1, 2010. We did univariate comparisons of transplants from brain-death donors versus circulatory-death donors with χ(2) tests for categorical data and Wilcoxon tests for non-parametric continuous data. We used Kaplan-Meier curves to show graft survival. We used Cox proportional hazards regression to adjust for donor and recipient factors associated with graft-survival with tests for interaction effects to establish the relative effect of donor age and cold ischaemia on kidneys from circulatory-death and brain-death donors. FINDINGS: 6490 deceased-donor kidney transplants were done at 23 centres. 3 year graft survival showed no difference between circulatory-death (n=1768) and brain-death (n=4127) groups (HR 1·14, 95% CI 0·95-1·36, p=0·16). Donor age older than 60 years (compared with <40 years) was associated with an increased risk of graft loss for all deceased-donor kidneys (2·35, 1·85-3·00, p<0·0001) but there was no increased risk of graft loss for circulatory-death donors older than 60 years compared with brain-death donors in the same age group (p=0·30). Prolonged cold ischaemic time (>24 h vs <12 h) was not associated with decreased graft survival for all deceased-donor kidneys but was associated with poorer graft survival for kidneys from circulatory-death donors than for those from brain-death donors (2·36, 1·39-4·02, p for interaction=0·004). INTERPRETATION: Kidneys from older circulatory-death donors have equivalent graft survival to kidneys from brain-death donors in the same age group, and are acceptable for transplantation. However, circulatory-death donor kidneys tolerate cold storage less well than do brain-death donor kidneys and this finding should be considered when developing organ allocation policy. FUNDING: UK National Health Service Blood and Transplant; Cambridge National Institute for Health Research Biomedical Research Centre.
The Lancet 12/2012; · 38.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This report summarizes the geodetic VLBI activities in New Zealand in 2010.
It provides geographical and technical details of WARK12M - the new IVS network
station operated by the Institute for Radio Astronomy and Space Research
(IRASR) of Auckland University of Technology (AUT). The details of the VLBI
system installed in the station are outlined along with those of the collocated
GNSS station. We report on the status of broadband connectivity and on the
results of testing data transfer protocols; we investigate UDP protocols such
as 'tsunami' and UDT and demonstrate that the UDT protocol is more efficient
than 'tsunami' and 'ftp'. In general, the WARK12M IVS network station is fully
equipped, connected and tested to start participating in regular IVS
observational sessions from the beginning of 2011.
03/2011;
-
Leonid Petrov,
Chris Phillips,
Tasso Tzioumis,
Bruce Stansby,
Cormac Reynolds,
Hayley E Bignall,
Sergei Gulyaev,
Tim Natusch,
Neville Palmer, David Collett,
John E Reynolds,
Shaun W Amy,
Randall Wayth,
Steven J Tingay
[show abstract]
[hide abstract]
ABSTRACT: We report the results of a successful 7 hour 1.4 GHz VLBI experiment using two new stations, ASKAP-29 located in Western Australia and WARK12M located on the North Island of New Zealand. This was the first geodetic VLBI observing session with the participation of these new stations. We have determined the positions of ASKAP-29 and WARK12M. Random errors on position estimates are 150–200 mm for the vertical component and 40–50 mm for the horizontal component. Systematic errors caused by the unmodeled ionosphere path delay may reach 1.3 m for the vertical component.
01/2011; 28:107-116.
-
Leonid Petrov,
Chris Phillips,
Tasso Tzioumis,
Bruce Stansby,
Cormac Reynolds,
Hayley Bignall,
Sergei Gulyaev,
Tim Natusch,
Neville Palmer, David Collett,
John Reynolds,
Shaun W Amy,
Randall Wayth,
Steven Tingay
[show abstract]
[hide abstract]
ABSTRACT: We report the results of a successful 7 hour 1.4 GHz VLBI experiment using
two new stations, ASKAP-29 located in Western Australia and WARK12M located on
the North Island of New Zealand. This was the first geodetic VLBI observing
session with the participation of these new stations. We have determined the
positions of ASKAP-29 and WARK12M. Random errors on position estimates are
150-200 mm for the vertical component and 40-50 mm for the horizontal
component. Systematic errors caused by the unmodeled ionosphere path delay may
reach 1.3 m for the vertical component.
12/2010;
-
[show abstract]
[hide abstract]
ABSTRACT: A third of all kidneys from deceased donors in the UK are donated after cardiac death, but concerns have been raised about the long-term outcome of such transplants. We aimed to establish these outcomes for kidneys donated after controlled cardiac death versus brain death, and to identify the factors that affect graft survival and function.
We used data from the UK transplant registry to select a cohort of deceased kidney donors and the corresponding transplant recipients (aged ≥18 years) for transplantations done between Jan 1, 2000, and Dec 31, 2007. Kaplan-Meier estimates were used to assess graft survival, and multivariate analyses were used to identify factors associated with graft survival and with long-term renal function, which was measured from estimated glomerular filtration rate (eGFR).
9134 kidney transplants were done in 23 centres; 8289 kidneys were donated after brain death and 845 after controlled cardiac death. First-time recipients of kidneys from cardiac-death donors (n=739) or brain-death donors (n=6759) showed no difference in graft survival up to 5 years (hazard ratio 1·01, 95% CI 0·83 to 1·19, p=0·97), or in eGFR at 1-5 years after transplantation (at 12 months -0·36 mL/min per 1·73 m(2), 95% CI -2·00 to 1·27, p=0·66). For recipients of kidneys from cardiac-death donors, increasing age of donor and recipient, repeat transplantation, and cold ischaemic time of more than 12 h were associated with worse graft survival; grafts from cardiac-death donors that were poorly matched for HLA had an association with inferior outcome that was not significant, and delayed graft function and warm ischaemic time had no effect on outcome.
Kidneys from controlled cardiac-death donors provide good graft survival and function up to 5 years in first-time recipients, and are equivalent to kidneys from brain-death donors. Allocation policy for kidneys from cardiac-death donors should reduce cold ischaemic time, avoid large age mismatches between donors and recipients, and restrict use of kidneys poorly matched for HLA in young recipients.
UK National Health Service Blood and Transplant, and Cambridge National Institute for Health Research Biomedical Research Centre.
The Lancet 10/2010; 376(9749):1303-11. · 38.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The assessment of outcomes after transplantation is important for several reasons: it provides patients with data so that they can make informed decisions about the benefits of transplantation and the success of the transplant unit; it informs commissioners that resources are allocated properly; and it provides clinicians reassurance that results are acceptable or, if they are not, provides early warning so that problems can be identified, corrections can be instituted early, and all interested parties can be reassured that scarce resources are used fairly. The need for greater transparency in reporting outcomes after liver transplantation and for comparisons both between and within centers has led to a number of approaches being adopted for monitoring center performance. We review some of the commonly used methods, highlight their strengths and weaknesses, and concentrate on methods that incorporate risk adjustment. Measuring and comparing outcomes after transplantation is complex, and there is no single approach that gives a complete picture. All those using analyses of outcomes must understand the merits and limitations of individual methods. When used properly, such methods are invaluable in ensuring that a scarce resource is used effectively, any adverse trend in outcomes is identified promptly and remedied, and best performers are identified; they thus allow the sharing of best practices. However, when they are used inappropriately, such measurements may lead to inappropriate conclusions, encourage risk-averse behavior, and discourage innovation.
Liver Transplantation 10/2010; 16(10):1119-28. · 3.39 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: There is a relative lack of donor organs for liver transplantation. Ideally, to maximize the utility of those livers that are offered, donor and recipient characteristics should be matched to ensure the best possible posttransplant survival of the recipient.
With prospectively collected data on 827 patients receiving a primary liver graft for chronic liver disease, we used a self-organizing map (SOM) (one form of a neural network) to predict outcome after transplantation using both donor and recipient factors. The SOM was then validated using a data set of 2622 patients undergoing transplantation in the United Kingdom at other centers.
SOM analysis using 72 inputs and two survival intervals (3 and 12 months) yielded three neurons with either higher or lower probabilities of survival. The model was validated using the independent data set. With 20 patients on the waiting list and 10 sequential donor livers, it was possible to demonstrate that the model could be used to identify which potential recipients were likely to benefit most from each liver offered.
With this approach to matching donor livers and recipients, it is possible to inform transplant clinicians about the optimum use of donor livers and thereby effectively make the best use of a scarce resource.
Transplantation 02/2005; 79(2):213-8. · 4.00 Impact Factor
