Doppler ultrasound surveillance of recently formed haemodialysis arteriovenous fistula: the SONAR observational cohort study.

Background: Arteriovenous fistulas are considered the best option for haemodialysis provision, but as many as 30% fail to mature or suffer early failure. Objective: To assess the feasibility of performing a randomised controlled trial that examines whether, by informing early and effective salvage intervention of fistulas that would otherwise fail, Doppler ultrasound surveillance of developing arteriovenous fistulas improves longer-term arteriovenous fistula patency. Design: A prospective multicentre observational cohort study (the 'SONAR' study). Setting: Seventeen haemodialysis centres in the UK. Participants: Consenting adults with end-stage renal disease who were scheduled to have an arteriovenous fistula created. Intervention: Participants underwent Doppler ultrasound surveillance of their arteriovenous fistulas at 2, 4, 6 and 10 weeks after creation, with clinical teams blinded to the ultrasound surveillance findings. Main outcome measures: Fistula maturation at week 10 defined according to ultrasound surveillance parameters of representative venous diameter and blood flow (wrist arteriovenous fistulas: ≥ 4 mm and > 400 ml/minute; elbow arteriovenous fistulas: ≥ 5 mm and > 500 ml/minute). Mixed multivariable logistic regression modelling of the early ultrasound scan data was used to predict arteriovenous fistula non-maturation by 10 weeks and fistula failure at 6 months. Results: A total of 333 arteriovenous fistulas were created during the study window (47.7% wrist, 52.3% elbow). By 2 weeks, 37 (11.1%) arteriovenous fistulas had failed (thrombosed), but by 10 weeks, 219 of 333 (65.8%) of created arteriovenous fistulas had reached maturity (60.4% wrist, 67.2% elbow). Persistently lower flow rates and venous diameters were observed in those fistulas that did not mature. Models for arteriovenous fistulas' non-maturation could be optimally constructed using the week 4 scan data, with fistula venous diameter and flow rate the most significant variables in explaining wrist fistula maturity failure (positive predictive value 60.6%, 95% confidence interval 43.9% to 77.3%), whereas resistance index and flow rate were most significant for elbow arteriovenous fistulas (positive predictive value 66.7%, 95% confidence interval 48.9% to 84.4%). In contrast to non-maturation, both models predicted fistula maturation much more reliably [negative predictive values of 95.4% (95% confidence interval 91.0% to 99.8%) and 95.6% (95% confidence interval 91.8% to 99.4%) for wrist and elbow, respectively]. Additional follow-up and modelling on a subset (n = 192) of the original SONAR cohort (the SONAR-12M study) revealed the rates of primary, assisted primary and secondary patency arteriovenous fistulas at 6 months were 76.5, 80.7 and 83.3, respectively. Fistula vein size, flow rate and resistance index could identify primary patency failure at 6 months, with similar predictive power as for 10-week arteriovenous fistula maturity failure, but with wide confidence intervals for wrist (positive predictive value 72.7%, 95% confidence interval 46.4% to 99.0%) and elbow (positive predictive value 57.1%, 95% confidence interval 20.5% to 93.8%). These models, moreover, performed poorly at identifying assisted primary and secondary patency failure, likely because a subset of those arteriovenous fistulas identified on ultrasound surveillance as at risk underwent subsequent successful salvage intervention without recourse to early ultrasound data. Conclusions: Although early ultrasound can predict fistula maturation and longer-term patency very effectively, it was only moderately good at identifying those fistulas likely to remain immature or to fail within 6 months. Allied to the better- than-expected fistula patency rates achieved (that are further improved by successful salvage), we estimate that a randomised controlled trial comparing early ultrasound-guided intervention against standard care would require at least 1300 fistulas and would achieve only minimal patient benefit. Trial Registration: This trial is registered as ISRCTN36033877 and ISRCTN17399438. Funding: This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: NIHR135572) and is published in full in Health Technology Assessment; Vol. 28, No. 24. See the NIHR Funding and Awards website for further award information.

For people with advanced kidney disease, haemodialysis is best provided by an 'arteriovenous fistula', which is created surgically by joining a vein onto an artery at the wrist or elbow. However, these take about 2 months to develop fully ('mature'), and as many as 3 out of 10 fail to do so. We asked whether we could use early ultrasound scanning of the fistula to identify those that are unlikely to mature. This would allow us to decide whether it would be practical to run a large, randomised trial to find out if using early ultrasound allows us to 'rescue' fistulas that would otherwise fail. We invited adults to undergo serial ultrasound scanning of their fistula in the first few weeks after it was created. We then analysed whether we could use the data from the early scans to identify those fistulas that were not going to mature by week 10. Of the 333 fistulas that were created, about two-thirds reached maturity by week 10. We found that an ultrasound scan 4 weeks after fistula creation could reliably identify those fistulas that were going to mature. However, of those fistulas predicted to fail, about one-third did eventually mature without further intervention, and even without knowing what the early scans showed, another third were successfully rescued by surgery or X-ray-guided treatment at a later stage. Performing an early ultrasound scan on a fistula can provide reassurance that it will mature and deliver trouble-free dialysis. However, because scans are poor at identifying fistulas that are unlikely to mature, we would not recommend their use to justify early surgery or X-ray-guided treatment in the expectation that this will improve outcomes.

Early Ultrasound Surveillance of Newly-Created Hemodialysis Arteriovenous Fistula.

Introduction: We assess if ultrasound surveillance of newly-created arteriovenous fistulas (AVFs) can predict nonmaturation sufficiently reliably to justify randomized controlled trial (RCT) evaluation of ultrasound-directed salvage intervention. Methods: Consenting adults underwent blinded fortnightly ultrasound scanning of their AVF after creation, with scan characteristics that predicted AVF nonmaturation identified by logistic regression modeling. Results: Of 333 AVFs created, 65.8% matured by 10 weeks. Serial scanning revealed that maturation occurred rapidly, whereas consistently lower fistula flow rates and venous diameters were observed in those that did not mature. Wrist and elbow AVF nonmaturation could be optimally modeled from week 4 ultrasound parameters alone, but with only moderate positive predictive values (PPVs) (wrist, 60.6% [95% confidence interval, CI: 43.9-77.3]; elbow, 66.7% [48.9-84.4]). Moreover, 40 (70.2%) of the 57 AVFs that thrombosed by week 10 had already failed by the week 4 scan, thus limiting the potential of salvage procedures initiated by that scan's findings to alter overall maturation rates. Modeling of the early ultrasound characteristics could also predict primary patency failure at 6 months; however, that model performed poorly at predicting assisted primary failure (those AVFs that failed despite a salvage attempt), partly because patency of at-risk AVFs was maintained by successful salvage performed without recourse to the early scan data. Conclusion: Early ultrasound surveillance may predict fistula maturation, but is likely, at best, to result in only very modest improvements in fistula patency. Power calculations suggest that an impractically large number of participants (>1700) would be required for formal RCT evaluation.

Cardiorespiratory Optimisation By Arteriovenous fistula Ligation after renal Transplantation (COBALT): study protocol for a multicentre randomised interventional feasibility trial.

INTRODUCTION: Cardiovascular events are a major cause of mortality following successful kidney transplantation.Arteriovenous fistulas (AVFs) are considered the best option for haemodialysis, but may contribute to this excess mortality because they promote adverse cardiac remodelling and ventricular hypertrophy. This raises the question whether recipients with a well-functioning kidney transplant should undergo elective AVF ligation. METHODS AND ANALYSIS: The COBALT feasibility study is a multicentre interventional randomised controlled trial (RCT) that will randomise renal transplant patients with stable graft function and a working AVF on a 1:1 basis to standard care (continued conservative management) or to AVF ligation. All patients will perform cardiopulmonary exercise testing (CPET) on recruitment and 6 months later. Daily functioning and quality of life will be additionally assessed by questionnaire completion and objective measure of physical activity. The primary outcome-the proportion of approached patients who complete the study (incorporating rates of consent, receipt of allocated intervention and completion of both CPETs without withdrawal)-will determine progression to a full-scale RCT. Design of the proposed RCT will be informed by an embedded qualitative assessment of participant and healthcare professional involvement. ETHICS AND DISSEMINATION: This study has been approved by the East Midlands-Derby Research Ethics Committee (22/EM/0002) and the Health Research Authority. The results of this work will be disseminated academically through presentation at national and international renal meetings and via open access, peer-reviewed outputs. Existing networks of renal patient groups will also be used to disseminate the study findings to other key stakeholders. TRIAL REGISTRATION NUMBER: ISRCTN49033491.

Two-year outcomes following a randomised platelet transfusion trial in preterm infants.

OBJECTIVE: Assess mortality and neurodevelopmental outcomes at 2 years of corrected age in children who participated in the PlaNeT-2/MATISSE (Platelets for Neonatal Transfusion - 2/Management of Thrombocytopenia in Special Subgroup) study, which reported that a higher platelet transfusion threshold was associated with significantly increased mortality or major bleeding compared to a lower one. DESIGN: Randomised clinical trial, enrolling from June 2011 to August 2017. Follow-up was complete by January 2020. Caregivers were not blinded; however, outcome assessors were blinded to treatment group. SETTING: 43 level II/III/IV neonatal intensive care units (NICUs) across UK, Netherlands and Ireland. PATIENTS: 660 infants born at less than 34 weeks' gestation with platelet counts less than 50×109/L. INTERVENTIONS: Infants were randomised to undergo a platelet transfusion at platelet count thresholds of 50×109/L (higher threshold group) or 25×109/L (lower threshold group). MAIN OUTCOMES MEASURES: Our prespecified long-term follow-up outcome was a composite of death or neurodevelopmental impairment (developmental delay, cerebral palsy, seizure disorder, profound hearing or vision loss) at 2 years of corrected age. RESULTS: Follow-up data were available for 601 of 653 (92%) eligible participants. Of the 296 infants assigned to the higher threshold group, 147 (50%) died or survived with neurodevelopmental impairment, as compared with 120 (39%) of 305 infants assigned to the lower threshold group (OR 1.54, 95% CI 1.09 to 2.17, p=0.017). CONCLUSIONS: Infants randomised to a higher platelet transfusion threshold of 50×109/L compared with 25×109/L had a higher rate of death or significant neurodevelopmental impairment at a corrected age of 2 years. This further supports evidence of harm caused by high prophylactic platelet transfusion thresholds in preterm infants. TRIAL REGISTRATION NUMBER: ISRCTN87736839.

Effect of Convalescent Plasma on Organ Support-Free Days in Critically Ill Patients With COVID-19: A Randomized Clinical Trial.

IMPORTANCE: The evidence for benefit of convalescent plasma for critically ill patients with COVID-19 is inconclusive. OBJECTIVE: To determine whether convalescent plasma would improve outcomes for critically ill adults with COVID-19. DESIGN, SETTING, AND PARTICIPANTS: The ongoing Randomized, Embedded, Multifactorial, Adaptive Platform Trial for Community-Acquired Pneumonia (REMAP-CAP) enrolled and randomized 4763 adults with suspected or confirmed COVID-19 between March 9, 2020, and January 18, 2021, within at least 1 domain; 2011 critically ill adults were randomized to open-label interventions in the immunoglobulin domain at 129 sites in 4 countries. Follow-up ended on April 19, 2021. INTERVENTIONS: The immunoglobulin domain randomized participants to receive 2 units of high-titer, ABO-compatible convalescent plasma (total volume of 550 mL ± 150 mL) within 48 hours of randomization (n = 1084) or no convalescent plasma (n = 916). MAIN OUTCOMES AND MEASURES: The primary ordinal end point was organ support-free days (days alive and free of intensive care unit-based organ support) up to day 21 (range, -1 to 21 days; patients who died were assigned -1 day). The primary analysis was an adjusted bayesian cumulative logistic model. Superiority was defined as the posterior probability of an odds ratio (OR) greater than 1 (threshold for trial conclusion of superiority >99%). Futility was defined as the posterior probability of an OR less than 1.2 (threshold for trial conclusion of futility >95%). An OR greater than 1 represented improved survival, more organ support-free days, or both. The prespecified secondary outcomes included in-hospital survival; 28-day survival; 90-day survival; respiratory support-free days; cardiovascular support-free days; progression to invasive mechanical ventilation, extracorporeal mechanical oxygenation, or death; intensive care unit length of stay; hospital length of stay; World Health Organization ordinal scale score at day 14; venous thromboembolic events at 90 days; and serious adverse events. RESULTS: Among the 2011 participants who were randomized (median age, 61 [IQR, 52 to 70] years and 645/1998 [32.3%] women), 1990 (99%) completed the trial. The convalescent plasma intervention was stopped after the prespecified criterion for futility was met. The median number of organ support-free days was 0 (IQR, -1 to 16) in the convalescent plasma group and 3 (IQR, -1 to 16) in the no convalescent plasma group. The in-hospital mortality rate was 37.3% (401/1075) for the convalescent plasma group and 38.4% (347/904) for the no convalescent plasma group and the median number of days alive and free of organ support was 14 (IQR, 3 to 18) and 14 (IQR, 7 to 18), respectively. The median-adjusted OR was 0.97 (95% credible interval, 0.83 to 1.15) and the posterior probability of futility (OR <1.2) was 99.4% for the convalescent plasma group compared with the no convalescent plasma group. The treatment effects were consistent across the primary outcome and the 11 secondary outcomes. Serious adverse events were reported in 3.0% (32/1075) of participants in the convalescent plasma group and in 1.3% (12/905) of participants in the no convalescent plasma group. CONCLUSIONS AND RELEVANCE: Among critically ill adults with confirmed COVID-19, treatment with 2 units of high-titer, ABO-compatible convalescent plasma had a low likelihood of providing improvement in the number of organ support-free days. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02735707.

Surveillance arterioveNous fistulAs using ultRasound (SONAR) trial in haemodialysis patients: a study protocol for a multicentre observational study.

INTRODUCTION: Arteriovenous fistulas (AVFs) are considered the best and safest modality for providing haemodialysis in patients with end-stage renal disease. Only 20% of UK centres achieve the recommended 80% target for achieving dialysis of the prevalent dialysis population via permanent access (as opposed to a central venous catheter). This is partly due to the relatively poor maturation rate of newly created fistulas, with as many as 50% of fistulas failing to mature.The Surveillance Of arterioveNous fistulAe using ultRasound study will examine whether a protocolised programme of Doppler ultrasound (US) surveillance can identify, early after creation, potentially correctable problems in those AVFs that subsequently fail to mature. METHODS AND ANALYSIS: This is a multicentre observational study that will assess newly created AVFs by Doppler US performed at 2, 4, 6 and 10 weeks after creation. The primary outcome measure will be primary fistula patency at week 10. Secondary outcome measures include: successful use of the fistula; clinical suitability for dialysis; creation of new fistula or radiological salvage; fistula thrombosis; secondary fistula patency rate and patient acceptability. ETHICS AND DISSEMINATION: The study has been approved by the Cambridgeshire and Hertfordshire Research Ethics Committee and by the Health Research Authority (REC 18/EE/0234). The results generated from this work will be published as open access, within 3 years of trial commencement. We will also present our findings at key national/international renal meetings, as well as support volunteers at renal patient groups to disseminate the trial outcome. TRIAL REGISTRATION NUMBER: ISRCTN36033877.

Randomized Trial of Platelet-Transfusion Thresholds in Neonates.

BACKGROUND: Platelet transfusions are commonly used to prevent bleeding in preterm infants with thrombocytopenia. Data are lacking to provide guidance regarding thresholds for prophylactic platelet transfusions in preterm neonates with severe thrombocytopenia. METHODS: In this multicenter trial, we randomly assigned infants born at less than 34 weeks of gestation in whom severe thrombocytopenia developed to receive a platelet transfusion at platelet-count thresholds of 50,000 per cubic millimeter (high-threshold group) or 25,000 per cubic millimeter (low-threshold group). Bleeding was documented prospectively with the use of a validated bleeding-assessment tool. The primary outcome was death or new major bleeding within 28 days after randomization. RESULTS: A total of 660 infants (median birth weight, 740 g; and median gestational age, 26.6 weeks) underwent randomization. In the high-threshold group, 90% of the infants (296 of 328 infants) received at least one platelet transfusion, as compared with 53% (177 of 331 infants) in the low-threshold group. A new major bleeding episode or death occurred in 26% of the infants (85 of 324) in the high-threshold group and in 19% (61 of 329) in the low-threshold group (odds ratio, 1.57; 95% confidence interval [CI], 1.06 to 2.32; P=0.02). There was no significant difference between the groups with respect to rates of serious adverse events (25% in the high-threshold group and 22% in the low-threshold group; odds ratio, 1.14; 95% CI, 0.78 to 1.67). CONCLUSIONS: Among preterm infants with severe thrombocytopenia, those randomly assigned to receive platelet transfusions at a platelet-count threshold of 50,000 per cubic millimeter had a significantly higher rate of death or major bleeding within 28 days after randomization than those who received platelet transfusions at a platelet-count threshold of 25,000 per cubic millimeter. (Funded by the National Health Service Blood and Transplant Research and Development Committee and others; Current Controlled Trials number, ISRCTN87736839 .).

The Rule of Threes: three factors that triple the likelihood of families overriding first person consent for organ donation in the UK.

Between 1 April 2012 and 31 March 2015, 263 of the 2244 families in the UK whose loved ones had registered to donate organs for transplantation after their death on the NHS Organ Donor Register chose to override this decision; an override rate of 11.7%. Multivariable logistic regression analysis was applied to data relating to various aspects of the family approach in order to identify factors associated with such overrides. The factors associated with family overrides were failure to involve the Specialist Nurse for Organ Donation in the family approach (odds ratio 3.0), donation after circulatory death (odds ratio 2.7) and Black, Asian or Minority Ethnicity (odds ratio 2.7). This highlights the need to further engage with these groups in exploring donation as an end of life choice, and suggests that there may be, from the perspective of the family, fundamental differences between donation after brainstem death and circulatory death. It further adds to the body of data linking involvement of the Specialist Nurse for Organ Donation in the family approach to improved UK consent rates.

Prospective audit to evaluate the potential of the coronial system to increase solid organ donation.

OBJECTIVES: Anecdotal evidence suggests that organ donation from deceased donors referred to the Coroner/Procurator Fiscal (PF) could be increased if all followed best practice. The aim of this prospective audit was to establish how referrals affected organ donation and to develop evidence-based guidelines to ensure that organ donation can be facilitated safely without interfering in the Coroner/PF's investigative process. DESIGN: Prospective audit. SETTING: All acute National Health Service Hospitals in the UK where deceased organ donation was considered. PARTICIPANTS: 1437 deceased patients who met the eligibility criteria for organ donation and were referred to Coroner/PF. MAIN OUTCOME MEASURES: Number of cases where permission for transplantation was given, number of organs where permission was refused and number of organs which might have been transplanted if all had followed best practice. RESULTS: Full permission for organ retrieval was given in 87% cases and partial permission in 9%. However, if full permission had been given where no autopsy was performed or restrictions seemed unjustified, up to 77 organs (22 lungs, 22 kidneys, 9 pancreases, 9 livers, 8 hearts and 7 small bowels) could have been available for transplant. CONCLUSIONS: Coroners/PFs and their officers show strong support for transplantation but improvement in practice could result in a small but significant increase in life-saving and life-enhancing transplants.

Risk of bleeding and use of platelet transfusions in patients with hematologic malignancies: recurrent event analysis.

A recent randomized trial (TOPPS) compared prophylactic platelet transfusions (for counts <10×10(9)/L) with a strategy of no-prophylaxis in adults with hematologic malignancies. Seventy percent of enrolled patients received an autologous hematopoietic stem cell transplant. Statistical models were developed to explore which patient factors or clinical characteristics are important prognostic factors for bleeding. These models were presented for baseline characteristics and for recurrent analysis of bleeding to assess the risks of World Health Organization grade 2-4 bleeding on any given day. Additional analyses explored the importance of fever. Treatment plan (chemotherapy/allogeneic hematopoietic stem cell transplant), female sex, and treatment arm (no-prophylaxis) were significantly associated with an increased number of days of bleeding. The number of days with a platelet count <10×109/L was significantly associated with a grade 2-4 bleed (P<0.0001). Patients with a temperature of at least 38°C had the highest hazard of a grade 2-4 bleed (hazard ratio: 1.7, 95% confidence interval: 1.3 to 2.4, compared with the risk in patients with a temperature <37.5°C). There was no evidence that minor bleeding predicted a grade 2-4 bleed. The results highlighted the limited role of correction of thrombocytopenia by platelet transfusion in reducing the risk of bleeding. Clinically stable patients undergoing autologous hematopoietic stem cell transplantation had the lowest risk of bleeding and benefited least from prophylactic platelet transfusions. Prospective studies are required to address the usefulness of risk factors to support better targeted platelet transfusions. TOPPS Controlled-Trials.com number ISRCTN08758735.