Successful restoration of arteriovenous dialysis access patency after late intervention.

BACKGROUND: Arteriovenous dialysis access may be lost due to stenosis and thrombosis. Patency may be restored by thrombectomy or thrombolysis, but this is often not undertaken when the presentation is delayed. The success rate of delayed intervention is largely unknown. METHODS: In this single-centre study, we identified all instances of arteriovenous vascular access (VA) failure treated with angioplasty, thrombectomy or thrombolysis between August 2010 and July 2013. Patency rates immediately after intervention, and after 3 months, were assessed using multilevel mixed effects logistic regression. RESULTS: Sixty failures occurred in 41 accesses (38 patients). The access age at failure was 495 (316-888) days. Intervention was carried out after >48 h in 19 failures (32%). Immediate patency was achieved in 46 failures, of which 32 remained patent after 3 months. Delaying intervention increased the likelihood of achieving immediate patency (OR 0.55, 95% CI 0.31-1.0, P = 0.05). Having lost arteriovenous accesses previously increased the risk of immediate failure (OR 4.0, 95% CI 1.07-14.95, P = 0.04). There was no association between failure-to-intervention-time and 3-month patency rates (P = 0.23). Effect estimates did not differ between arteriovenous fistulae and synthetic arteriovenous grafts. CONCLUSION: Delayed intervention for failed arteriovenous VA may result in superior early patency rates and yields equivalent 3-month patency rates.This is the author's accepted version and will be under embargo until 12 months from the date of publication. The final version is available from OUP at http://ckj.oxfordjournals.org/content/8/1/8

Vitamin K antagonists predispose to calciphylaxis in patients with end-stage renal disease.

BACKGROUND/AIMS: Calciphylaxis is associated with a poor prognosis in dialysis patients, and its pathogenesis remains incompletely understood. Although the use of vitamin K antagonists (VKA) has been implicated, previous reports are conflicting. We aimed to determine if vitamin K antagonists conferred an increased risk of calciphylaxis in patients on dialysis. METHODS: We performed a single-centre, retrospective cohort study of 2,234 patients receiving dialysis, and compared the characteristics of those with and without calciphylaxis. RESULTS: We identified 5 cases of calciphylaxis (all female) between January 2009 and December 2013. Overall, 142 patients (6.4%) were treated with VKA during the study period. Calciphylaxis was more common in the VKA group (4 of 142 patients, OR = 61, 95% CI 6.7-546, p = 0.0001). VKA was withdrawn in all cases and treatment instituted with sodium thiosulphate, cinacalcet and supportive measures. All patients recovered, although there was one sudden cerebrovascular death during follow-up. CONCLUSION: Treatment with VKA predisposes to the development of calciphylaxis.TFH is funded by the Cambridge BRC and NIHR.This is the accepted manuscript for a paper published in Nephron Clinical Practice, Vol. 129, No. 3, 2015, DOI:10.1159/00037144

Per-treatment post-hoc analysis of clinical trial outcomes with Tolvaptan in autosomal dominant polycystic kidney disease

Introduction: In pivotal trials of patients with autosomal dominant polycystic kidney disease at risk of rapid progression, tolvaptan slowed estimated glomerular filtration rate (eGFR) decline in early-to-moderate (TEMPO 3:4 [NCT00428948]) and moderate-to-late stage (REPRISE [NCT02160145]) chronic kidney disease (CKD). Discontinuation was less frequent in REPRISE (15.0%) than TEMPO 3:4 (23.0%), given that in REPRISE, only subjects who tolerated tolvaptan 60/30 mg daily initiated the double-blind phase. We evaluated whether the greater treatment effect in REPRISE was attributable to different completion rates. Methods: We conducted post hoc analyses of TEMPO 3:4 and REPRISE completers, defined as subjects who took trial drug to the end of the treatment period in TEMPO 3:4 (3 years) or REPRISE (1 year). Efficacy (rate of change in eGFR for tolvaptan versus placebo) was analyzed as in each trial. Subjects from TEMPO 3:4 and REPRISE were also matched by propensity score for age, gender, and baseline eGFR to explore potential additional determinants of treatment effect. Results: The annualized tolvaptan treatment effect in TEMPO 3:4 completers (difference versus placebo of 0.98 mL/min/1.73 m2/year) and REPRISE completers (difference of 1.23) was similar to that of the respective total trial populations (TEMPO 3:4: 0.94; REPRISE: 1.27). The treatment effect of tolvaptan was also similar between matched subjects. Conclusion: Greater treatment completion rate did not drive greater treatment effect in REPRISE. The more advanced CKD of REPRISE subjects may be more relevant. More rapid decline in kidney function in later-stage CKD enabled the effects of tolvaptan to be more easily discerned

Developing a patient-centred tool for pain measurement and evaluation in autosomal dominant polycystic kidney disease.

BACKGROUND: Pain affects 60% of the autosomal dominant polycystic kidney disease (ADPKD) population. Despite being an early and debilitating symptom, it is poorly characterized and management is suboptimal. This study aimed to develop an ADPKD-specific pain assessment tool (APAT) to facilitate pain research. METHODS: Following a systematic review of PATs used in ADPKD studies and against international recommendations for pain trials, our multi-disciplinary team of clinical experts and patients constructed an ADPKD-pain conceptual framework of key pain evaluation themes. We compiled a new APAT covering domains prioritized within our framework using components of questionnaires validated in other chronic pain disorders. The APAT was administered longitudinally within a randomized high-water intake trial (NCT02933268) to ascertain feasibility and provide pilot data on ADPKD pain. RESULTS: Thirty-nine ADPKD participants with chronic kidney disease Stages 1-4 provided 129 APAT responses. Each participant completed a median of 3 (range 1-10) assessments. Respondents' mean ± standard deviation age was 47 ± 13 years; 59% (23) were female; and 69% (27) had enlarged kidneys with median time from diagnosis 14.2 (interquartile range 7.0-25.9) years. Pain (52%) and associated analgesic use (29%) were common. Pain severity was associated with increasing age [odds ratio (OR) = 1.07, P = 0.009], female gender (OR = 4.34, P = 0.018), estimated glomerular filtration rate <60 mL/min/1.73 m2 (OR = 5.45, P = 0.021) and hypertension (OR = 12.11, P = 0.007), but not with kidney size (P = 0.23). The APAT achieved good internal consistency (Cronbach's alpha coefficient = 0.91) and test-retest reliability (domain intra-class correlation coefficients ranging from 0.62 to 0.90). CONCLUSIONS: The APAT demonstrated good acceptability and reliability, and following further validation in a larger cohort could represent an invaluable tool for future ADPKD pain studies.Addenbrookes Charitable Trust Kidney Care UK British Renal Society Kidney Research U

Randomised controlled trial of high versus ad libitum water intake in patients with autosomal dominant polycystic kidney disease: rationale and design of the DRINK feasibility trial.

Introduction Vasopressin stimulates cyst growth in Autosomal Dominant Polycystic Kidney Disease (ADPKD) leading to enlarged kidneys, hypertension and renal failure. Vasopressin receptor blockade slows disease progression. Physiological suppression of vasopressin secretion through high water intake could achieve a similar effect, necessitating a definitive large-scale trial of high water intake in ADPKD. The objective of the DRINK trial is to answer the key design and feasibility questions required to deliver a successful definitive water intake trial. Methods and Analysis We describe the design of a single-centre, open label, prospective, randomised controlled trial. DRINK aims to enroll 50 ADPKD patients, over the age 16years with an eGFR≥20ml/min/1.73m2. Participants will be randomised 1:1 to high water (HW) intake based on an individualised water intake prescription, or to ad libitum(AW) water intake. The HW group will aim for a dilute urine (urine osmolality≤270mOsmo/kg) as a surrogate marker of vasopressin suppression, and those in the AW group will target more concentrated urine. Participants will have an 8week treatment period, and will be seen at week 0, 2,4 and 8, undergoing assessments of fluid status, renal function and serum and urine osmolalities. They will receive dietary advice, and self-monitor urine specific gravity and fluid intake. The trial employs smartphone technology to permit home monitoring and remote direct data capture. The primary feasibility endpoints are recruitment rate and separation between arms in measured urinary osmolality. Key secondary assessments include acceptability, adherence, health-related quality of life, acute effects of high water intake on measured (51Cr-EDTA) and estimated glomerular filtration rate, and ADPKD-related pain. Ethics and Dissemination Ethical approval was awarded by the East of England Essex Research Ethics Committee (16/EE/0026). The results of DRINK will be submitted to peer reviewed journals, and presented to patients via the PKD Charity. Trial Registration Details: NCT02933268 and ISCRTN1679495

Randomised controlled trial of high versus ad libitum water intake in patients with autosomal dominant polycystic kidney disease: rationale and design of the DRINK feasibility trial.

INTRODUCTION: Vasopressin stimulates cyst growth in autosomal dominant polycystic kidney disease (ADPKD) leading to enlarged kidneys, hypertension and renal failure. Vasopressin receptor blockade slows disease progression. Physiological suppression of vasopressin secretion through high water (HW) intake could achieve a similar effect, necessitating a definitive large-scale trial of HW intake in ADPKD. The objective of the DRINK trial is to answer the key design and feasibility questions required to deliver a successful definitive water intake trial. METHODS AND ANALYSIS: We describe the design of a single-centre, open-label, prospective, randomised controlled trial. The "Determining feasibility of R andomisation to high vs. ad libitum water In take in Polycystic K idney Disease" (DRINK) trial aims to enrol 50 patients with ADPKD, over the age of 16 years with an estimated glomerular filtration rate (eGFR) ≥20 mL/min/1.73 m2. Participants will be randomised 1:1 to HW intake based on an individualised water intake prescription, or to ad libitum (AW) water intake. The HW group will aim for a dilute urine (urine osmolality ≤270 mOsm/kg) as a surrogate marker of vasopressin suppression, and those in the AW group will target more concentrated urine. Participants will have an 8-week treatment period, and will be seen at weeks 0, 2, 4 and 8, undergoing assessments of fluid status, renal function and serum and urine osmolalities. They will receive dietary advice, and self-monitor urine specific gravity and fluid intake. The trial employs smartphone technology to permit home monitoring and remote direct data capture. The primary feasibility end points are recruitment rate and separation between arms in measured urinary osmolality. Key secondary assessments include acceptability, adherence, health-related quality of life, acute effects of HW intake on measured (51Cr-EDTA) and eGFR and ADPKD-related pain. ETHICS AND DISSEMINATION: Ethical approval was awarded by the East of England Essex Research Ethics Committee (16/EE/0026). The results of DRINK will be submitted to peer-reviewed journals, and presented to patients via the PKD Charity. TRIAL REGISTRATION NUMBER: NCT02933268 and ISCRTN16794957

Assessing Disease Modifying Therapies in Autosomal Dominant Polycystic Kidney Disease

Background: Vasopressin stimulates cyst growth in autosomal dominant polycystic kidney disease (ADPKD) and is a key therapeutic target. Evaluation of high water intake (HWI) as an alternative to pharmacological vasopressin blockade is supported by patients. However the feasibility, safety and adherence-promoting strategies required to deliver this were unknown. The aim of this thesis was to assess the feasibility of a definitive randomised HWI trial in ADPKD. Methods: and materials: The work consisted of; 1) the SIPs study was an online survey developed in collaboration with the PKD charity, and administered to ADPKD subjects to inform current water intake practices and research willingness, and identify the potential design challenges of a randomised HWI trial, 2) Retrospective ADPKD cohort studies included analyses of data from the UK National Registry of Rare Kidney Diseases (RaDaR) and the Cambridge renal genetics (RGTD) clinic to provide information on the patterns and predictors of kidney disease progression, and 3) the DRINK study was a prospective open-label randomised trial. Adult ADPKD patients with eGFR ≥20 ml/min/1.73 m2 were randomized to prescribed high water (HW) intake targeting urine osmolality (UOsm) ≤ 270 mOsm/kg, or ad libitum (AW) intake (UOsm >300 mOsm/kg). Smartphone technology was used to facilitate adherence, self-monitoring and remote data capture through the DRINK and SPLASH study apps. Primary outcomes were the proportion achieving target UOsm and the study recruitment rate. Secondary outcomes included changes in GFR, copeptin, adherence and safety. A bespoke ADPKD Pain Assessment Tool (APAT) was formulated and administered longitudinally to participants to ascertain reliability and to provide pilot data on ADPKD pain. Results and Conclusion: The DRINK study achieved successful sustained recruitment indicating that a multi-centre large scale trial would be feasible. The study also confirmed that HWI was a feasible intervention, and that the adherence-promoting methods used resulted in a separation between treatment arms that was of sufficient magnitude to drive clinically meaningful differences in kidney function endpoints for future definitive trials. Observational studies using RaDaR and RGTD cohort data identified risk factors for disease progression consistent with previously observed data, providing the basis for the eligibility criteria that would allow enrichment of the target trial population. Furthermore, assessing the rate of disease progression along with the absence of acute GFR effects in the DRINK study enabled determinations of the optimal primary study outcomes, treatment effect sizes, likely sample size and trial duration. All of these components are critical to the design of a definitive interventional ADPKD trial. Finally, the APAT demonstrated good acceptability and reliability and represents a valuable standardised tool for future ADPKD pain studies. The clinical utility of the tool has been recognised by the National Institute of Health Research (NIHR) through a successful grant award to use the APAT for a large multi-centre observational ADPKD study

Metformin for preventing the progression of chronic kidney disease (Protocol)

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: This review aims to assess the effect of metformin therapy on kidney function in patients with CKD. The safety and dose tolerability of metformin use in this population will also be assessed

Randomised controlled trial of high versus ad libitum water intake in patients with autosomal dominant polycystic kidney disease: rationale and design of the DRINK feasibility trial.

INTRODUCTION: Vasopressin stimulates cyst growth in autosomal dominant polycystic kidney disease (ADPKD) leading to enlarged kidneys, hypertension and renal failure. Vasopressin receptor blockade slows disease progression. Physiological suppression of vasopressin secretion through high water (HW) intake could achieve a similar effect, necessitating a definitive large-scale trial of HW intake in ADPKD. The objective of the DRINK trial is to answer the key design and feasibility questions required to deliver a successful definitive water intake trial. METHODS AND ANALYSIS: We describe the design of a single-centre, open-label, prospective, randomised controlled trial. The "Determining feasibility of R andomisation to high vs. ad libitum water In take in Polycystic K idney Disease" (DRINK) trial aims to enrol 50 patients with ADPKD, over the age of 16 years with an estimated glomerular filtration rate (eGFR) ≥20 mL/min/1.73 m2. Participants will be randomised 1:1 to HW intake based on an individualised water intake prescription, or to ad libitum (AW) water intake. The HW group will aim for a dilute urine (urine osmolality ≤270 mOsm/kg) as a surrogate marker of vasopressin suppression, and those in the AW group will target more concentrated urine. Participants will have an 8-week treatment period, and will be seen at weeks 0, 2, 4 and 8, undergoing assessments of fluid status, renal function and serum and urine osmolalities. They will receive dietary advice, and self-monitor urine specific gravity and fluid intake. The trial employs smartphone technology to permit home monitoring and remote direct data capture. The primary feasibility end points are recruitment rate and separation between arms in measured urinary osmolality. Key secondary assessments include acceptability, adherence, health-related quality of life, acute effects of HW intake on measured (51Cr-EDTA) and eGFR and ADPKD-related pain. ETHICS AND DISSEMINATION: Ethical approval was awarded by the East of England Essex Research Ethics Committee (16/EE/0026). The results of DRINK will be submitted to peer-reviewed journals, and presented to patients via the PKD Charity. TRIAL REGISTRATION NUMBER: NCT02933268 and ISCRTN16794957