Renal replacement therapy for autosomal dominant polycystic kidney disease (ADPKD) in Europe: prevalence and survival--an analysis of data from the ERA-EDTA Registry

Axial Spondyloarthritis and Autosomal Dominant Polycystic Kidney Disease in Two Siblings: A Rare Cooccurrence

Autosomal dominant polycystic kidney disease (ADPKD) is the most frequently occurring hereditary kidney disease, and axial spondyloarthritis (SpA) is one of the most frequently occurring rheumatic diseases. Treatment-related decisions for axial SpA may pose a challenge in case of renal involvement. The authors describe two siblings with cooccurrence of these two diseases. The association of these two diseases is not well known. Practitioners should monitor renal function in SpA patients and take treatment-related decisions regarding renal involvement. Antitumor necrosis factor-alpha (anti-TNF-α) agents may be used in case nonsteroidal anti-inflammatory drugs (NSAIDs) cannot be utilized.

Are Pax proteins potential therapeutic targets in kidney disease and cancer?

Pax genes encode developmental regulators that are expressed in a variety of tissues and control critical events in morphogenesis. In the kidney, Pax2 and Pax8 are expressed in embryonic development and in specific renal diseases associated with aberrant epithelial cell proliferation. Prior genetic and cell biological studies suggest that reducing the activity of Pax proteins in renal cancer or in polycystic kidney disease can slow the progression of these conditions. The Pax proteins may be critical for providing tissue and locus specificity to recruit epigenetic modifiers that control gene expression and chromatin structure. Although they are nuclear, targeting Pax proteins to inhibit function may be feasible with small molecules. Such inhibition of Pax protein function may provide novel therapies for subsets of renal disorders that are tissue- and cell type-specific and avoid systemic effects on non-Pax-expressing cells and tissues. Given the paucity of effective treatments for renal cancer and cystic disease, the Pax family of proteins represents new pharmaceutical targets that merit exploration and further development.

Cystic Kidney Diseases From the Adult Nephrologist's Point of View

Cystic kidney diseases affect patients of all age groups with the onset spanning from prenatal disease to late adulthood. Autosomal-dominant polycystic kidney disease (ADPKD) is by far the most common renal cystic disease. However, there are various cystic kidney diseases, the onset of which occurs at different times in life and depends on the type of the disease and the causative genes involved. When genetic kidney diseases are discussed in the adult setting this view is usually limited on autosomal-dominant kidney disease, the most frequent genetic disorder causing adult onset ESRD. Other diseases-such as autosomal-recessive polycystic kidney disease-are often being viewed as a disorder only important in pediatric nephrology. However, more recent data has revealed that, despite clear age peaks of onset for each disorder, all of them can also show highly variable phenotypes with classical adult onset genetic diseases being of importance in pediatrics and vice versa. Furthermore, the affected children need to be seen by adult nephrologists in the long term after transition, requiring knowledge on the underlying pediatric disease, potential extrarenal manifestations, and genetic counseling. Consequently, the view on these diseases should be widened on both ends. Close interaction between pediatric and adult nephrology is key to appropriate care of patients suffering from genetic kidney disease to profit from each other's experience.

Prevalence of autosomal dominant polycystic kidney disease in the European Union

Background

Autosomal dominant polycystic kidney disease (ADPKD) is a leading cause of end-stage renal disease, but estimates of its prevalence vary by >10-fold. The objective of this study was to examine the public health impact of ADPKD in the European Union (EU) by estimating minimum prevalence (point prevalence of known cases) and screening prevalence (minimum prevalence plus cases expected after population-based screening).

Methods

A review of the epidemiology literature from January 1980 to February 2015 identified population-based studies that met criteria for methodological quality. These examined large German and British populations, providing direct estimates of minimum prevalence and screening prevalence. In a second approach, patients from the 2012 European Renal Association‒European Dialysis and Transplant Association (ERA-EDTA) Registry and literature-based inflation factors that adjust for disease severity and screening yield were used to estimate prevalence across 19 EU countries (N = 407 million).

Results

Population-based studies yielded minimum prevalences of 2.41 and 3.89/10 000, respectively, and corresponding estimates of screening prevalences of 3.3 and 4.6/10 000. A close correspondence existed between estimates in countries where both direct and registry-derived methods were compared, which supports the validity of the registry-based approach. Using the registry-derived method, the minimum prevalence was 3.29/10 000 (95% confidence interval 3.27-3.30), and if ADPKD screening was implemented in all countries, the expected prevalence was 3.96/10 000 (3.94-3.98).

Conclusions

ERA-EDTA-based prevalence estimates and application of a uniform definition of prevalence to population-based studies consistently indicate that the ADPKD point prevalence is <5/10 000, the threshold for rare disease in the EU.

A model to predict disease progression in patients with autosomal dominant polycystic kidney disease (ADPKD): the ADPKD Outcomes Model

Background

Autosomal dominant polycystic kidney disease (ADPKD) is the leading inheritable cause of end-stage renal disease (ESRD); however, the natural course of disease progression is heterogeneous between patients. This study aimed to develop a natural history model of ADPKD that predicted progression rates and long-term outcomes in patients with differing baseline characteristics.

Methods

The ADPKD Outcomes Model (ADPKD-OM) was developed using available patient-level data from the placebo arm of the Tolvaptan Efficacy and Safety in Management of ADPKD and its Outcomes Study (TEMPO 3:4; ClinicalTrials.gov identifier NCT00428948). Multivariable regression equations estimating annual rates of ADPKD progression, in terms of total kidney volume (TKV) and estimated glomerular filtration rate, formed the basis of the lifetime patient-level simulation model. Outputs of the ADPKD-OM were compared against external data sources to validate model accuracy and generalisability to other ADPKD patient populations, then used to predict long-term outcomes in a cohort matched to the overall TEMPO 3:4 study population.

Results

A cohort with baseline patient characteristics consistent with TEMPO 3:4 was predicted to reach ESRD at a mean age of 52 years. Most patients (85%) were predicted to reach ESRD by the age of 65 years, with many progressing to ESRD earlier in life (18, 36 and 56% by the age of 45, 50 and 55 years, respectively). Consistent with previous research and clinical opinion, analyses supported the selection of baseline TKV as a prognostic factor for ADPKD progression, and demonstrated its value as a strong predictor of future ESRD risk. Validation exercises and illustrative analyses confirmed the ability of the ADPKD-OM to accurately predict disease progression towards ESRD across a range of clinically-relevant patient profiles.

Conclusions

The ADPKD-OM represents a robust tool to predict natural disease progression and long-term outcomes in ADPKD patients, based on readily available and/or measurable clinical characteristics. In conjunction with clinical judgement, it has the potential to support decision-making in research and clinical practice.

Electronic supplementary material

The online version of this article (10.1186/s12882-017-0804-2) contains supplementary material, which is available to authorized users.

Is the light at the end of the tunnel nigh? A review of ADPKD focusing on the burden of disease and tolvaptan as a new treatment

Autosomal dominant polycystic kidney disease (ADPKD) causes pathological cystic changes to the kidney and is characterized by numerous renal and systemic manifestations. ADPKD is the fourth most common renal disease requiring renal replacement therapy. In this report, we present a detailed review of ADPKD, with a particular focus on its major economic, psychological, and social burden in affected patients. Treatment of this disease has been based on prophylactic and supportive measures. However, in recent years, new drugs have emerged as promising agents that may retard the progression of ADPKD, such as tolvaptan. In this report, we provide an in-depth discussion of tolvaptan, which has shown an effect in decreasing annual total kidney volume growth and renal function decline, thus slowing disease progression. The mechanism of action, side effects, and available data on cost-effectiveness are discussed together with the results of the first clinical trials and the most recent trials with regard to its efficacy and safety. Tolvaptan has recently received approval and been granted marketing authorization in Japan, Canada, Korea, Switzerland, and Europe. A demand for widely accepted guidelines for its use has emerged since its approval. The currently available series of recommendations and guidelines as to when to start treatment with tolvaptan, as well as which patients should be treated, are also reviewed in this report. We lastly offer some considerations for future trials, and raise unanswered questions.

Practical approaches to the management of autosomal dominant polycystic kidney disease patients in the era of tolvaptan

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disease worldwide. The renal phenotype is characterized by progressive cystic enlargement of the kidneys leading to a decline in renal function, hypertension and often end-stage renal disease (ESRD). Supportive care with blood pressure control and management of pain, urinary infections and renal stone disease has, until recently, been the mainstay of treatment. With the recent approval of tolvaptan for use in ADPKD, the disease progression may now be targeted specifically. Algorithms that guide treatment initiation have been proposed but a more pragmatic and patient-individualized approach is often needed to make decisions regarding therapy. It is highly important to identify ADPKD patients with rapidly progressive disease who are likely to benefit most from this treatment and avoid treatment in patients that are unlikely to reach ESRD.

METHODS AND RESULTS

Here we present a series of cases of ADPKD patients in whom therapy with tolvaptan has been considered and report the rationale for the treatment decisions based on available lifestyle, clinical, biochemical, radiological and genetic data.

CONCLUSIONS

These cases provide a discussion for the use of tolvaptan in ADPKD within the nephrology clinic and allow insights into the practicalities of using this therapy outside of clinical trials.

Tolvaptan in the treatment of autosomal dominant polycystic kidney disease: patient selection and special considerations

Standard of care therapies for autosomal dominant polycystic kidney disease (ADPKD) may limit morbidity and mortality due to disease-related complications, but they do not delay disease progression. Tolvaptan, a selective vasopressin V2 receptor antagonist, delays the increase in kidney volume (a surrogate marker for disease progression), slows the decline in renal function, and reduces pain in ADPKD patients with relatively preserved renal function. The most common adverse events of tolvaptan are linked to its aquaretic effect, and rare cases of idiosyncratic hepatitis were observed. Additional ongoing studies will determine whether the benefits are sustained over time, whether they can be observed in patients with advanced kidney disease, and whether they can be translated in terms of quality of life and cost/effectiveness parameters. Tolvaptan is currently approved in Europe and several countries throughout the world. In real-life conditions, selection of patients that would be good theoretical candidates to tolvaptan is a key but complex question. Eligibility criteria slightly differ from one country to another, and several models (based on conventional data, genetics, renal volume) were recently proposed to identify patients with evidence or risk of rapid disease progression. Eligible patients will ultimately make the decision to start tolvaptan, after complete information, consideration, and balancing of benefits, adverse events, and risks.

Early Markers of Cardiovascular Risk in Autosomal Dominant Polycystic Kidney Disease

BACKGROUND/AIMS

Cardiovascular disease is the most frequent cause of morbidity and mortality in autosomal dominant polycystic kidney disease (ADPKD) patients, often before the onset of renal failure, and the pathogenetic mechanism is not yet well elucidated. The aim of the study was to identify early and noninvasive markers of cardiovascular risk in young ADPKD patients, in the early stages of disease.

METHODS

A total of 26 patients with ADPKD and 24 control group, matched for age and sex, were enrolled, and we have assessed inflammatory indexes, mineral metabolism, metabolic state and markers of atherosclerosis and endothelial dysfunction (carotid intima media thickness (IMT), ankle brachial index (ABI), flow mediated dilation (FMD), renal resistive index (RRI), left ventricular mass index (LVMI)) and cardiopulmonary exercise testing (CPET), maximal O2 uptake (V'O2max), and O2 uptake at lactic acid threshold (V'O2@LT).

RESULTS

The ADPKD patients compared to control group, showed a significant higher mean value of LVMI, RRI, homocysteine (Hcy), Homeostasis Model Assessment-insulin resistance (HOMA-IR), serum uric acid (SUA), Cardiac-troponinT (cTnT) and intact parathyroid hormone (iPTH) (p<0.001, p<0.001, p<0.001, p<0.001, p<0.001, p=0.007, p=0.019; respectively), and a lower value of FMD and 25-hydroxyvitaminD (25-OH-VitD) (p<0.001, p<0.001) with reduced parameters of exercise tolerance, as V'O2max, V'O2max/Kg and V'O2max (% predicted) (p<0.001, p<0.001, p=0.018; respectively), and metabolic response indexes (V'O2@LT, V'O2 @LT%, V'O2@LT/Kg,) (p<0.001, p=0.14, p<0.001; respectively). Moreover, inflammatory indexes were significantly higher in ADPKD patients, and we found a positive correlation between HOMA-IR and C-reactive protein (CRP) (r=0.507, p=0.008), and a negative correlation between HOMA-IR and 25-OH-VitD (r=-0.585, p=0.002).

CONCLUSION

In our study, ADPKD patients, in the early stages of disease, showed a greater insulin resistance, endothelial dysfunction, inflammation and mineral metabolism disorders, respect to control group. Moreover, these patients presented reduced tolerance to stress, and decreased anaerobic threshold to CPET. Our results indicate a major and early cardiovascular risk in ADPKD patients. Therefore early and noninvasive markers of cardiovascular risk and CPET should be carried out, in ADPKD patients, in the early stages of disease, despite the cost implication.

Standardised Outcomes in Nephrology-Polycystic Kidney Disease (SONG-PKD): study protocol for establishing a core outcome set in polycystic kidney disease

Background

Autosomal dominant polycystic kidney disease (ADPKD) is the most common potentially life threatening inherited kidney disease and is responsible for 5–10% of cases of end-stage kidney disease (ESKD). Cystic kidneys may enlarge up to 20 times the weight of a normal kidney due to the growth of renal cysts, and patients with ADPKD have an increased risk of morbidity, premature mortality, and other life-time complications including renal and hepatic cyst and urinary tract infection, intracranial aneurysm, diverticulosis, and kidney pain which impair quality of life. Despite some therapeutic advances and the growing number of clinical trials in ADPKD, the outcomes that are relevant to patients and clinicians, such as symptoms and quality of life, are infrequently and inconsistently reported. This potentially limits the contribution of trials to inform evidence-based decision-making. The Standardised Outcomes in Nephrology—Polycystic Kidney Disease (SONG-PKD) project aims to establish a consensus-based set of core outcomes for trials in PKD (with an initial focus on ADPKD but inclusive of all stages) that patients and health professionals identify as critically important.

Methods

The five phases of SONG-PKD are: a systematic review to identify outcomes that have been reported in existing PKD trials; focus groups with nominal group technique with patients and caregivers to identify, rank, and describe reasons for their choices; qualitative stakeholder interviews with health professionals to elicit individual values and perspectives on outcomes for trials involving patients with PKD; an international three-round Delphi survey with all stakeholder groups (including patients, caregivers, healthcare providers, policy makers, researchers, and industry) to gain consensus on critically important core outcome domains; and a consensus workshop to review and establish a set of core outcome domains and measures for trials in PKD.

Discussion

The SONG-PKD core outcome set is aimed at improving the consistency and completeness of outcome reporting across ADPKD trials, leading to improvements in the reliability and relevance of trial-based evidence to inform decisions about treatment and ultimately improve the care and outcomes for people with ADPKD.

Screening for intracranial aneurysms in autosomal dominant polycystic kidney disease is cost-effective

Intracranial aneurysm rupture is a dramatic complication of autosomal dominant polycystic kidney disease (ADPKD). It remains uncertain whether screening should be widespread or only target patients with risk factors (personal or familial history of intracranial aneurysm), with an at-risk profession, or those who request screening. We evaluated this in a single-center cohort of 495 consecutive patients with ADPKD submitted to targeted intracranial aneurysm screening. Cerebral magnetic resonance angiography was proposed to 110 patients with a familial history of intracranial aneurysm (group 1), whereas it was not our intention to propose it to 385 patients without familial risk (group 2). Magnetic resonance angiography results, intracranial aneurysm prophylactic repair, rupture events, and cost-effectiveness of intracranial aneurysm screening strategies were retrospectively analyzed. During a median follow up of 5.9 years, five non-fatal intracranial aneurysm ruptures occurred (incidence rate 2.0 (0.87-4.6)/1000 patients-year). In group 1, 90% of patients were screened and an intracranial aneurysm was detected in 14, treated preventively in five, and ruptured in one patient despite surveillance. In group 2, 21% of patients were screened and an intracranial aneurysm was detected in five, and treated preventively in one. Intracranial aneurysm rupture occurred in four patients in group 2. Systematic screening was deemed cost-effective and provides a gain of 0.68 quality-adjusted life years compared to targeted screening. Thus, the intracranial aneurysm rupture rate is high in ADPKD despite targeted screening, and involves mostly patients without familial risk factors. Hence, cost-utility analysis suggests that intracranial aneurysm screening could be proposed to all ADPKD patients.

Tolerability of Aquaretic-Related Symptoms Following Tolvaptan for Autosomal Dominant Polycystic Kidney Disease: Results From TEMPO 3:4

Introduction

In the randomized placebo-controlled Tolvaptan Efficacy and Safety in Management of Autosomal Dominant Polycystic Kidney Disease and its Outcomes (TEMPO) 3:4 trial, tolvaptan slowed kidney growth and renal function decline in subjects with autosomal dominant polycystic kidney disease (ADPKD). Consistent with its primary pharmacologic activity, tolvaptan use was commonly associated with aquaretic adverse events (AAEs) attributable to excess free water clearance.

Methods

A post hoc analysis of tolvaptan-related discontinuations from the pivotal randomized controlled trial TEMPO 3:4 and its open-label extension TEMPO 4:4.

Results

In total, 750 of 961 tolvaptan-treated subjects (78%) in TEMPO 3:4 reported at least one AAE. Of these 750 subjects, 72 (10%) discontinued because of an AAE (aquaretic-discontinued group) and 573 (76%) continued (aquaretic-continued group). The aquaretic-discontinued subjects were younger, had better baseline renal function, and had higher fasting urine osmolality than aquaretic-continued subjects. Of the 750 subjects reporting an AAE, 105 (14%) discontinued for another reason (non-aquaretic-discontinued group). Compared to non-aquaretic-discontinued subjects, aquaretic-discontinued subjects were more commonly male, had better baseline renal function, and discontinued the study drug faster. After 3 years of therapy, 75% of tolvaptan subjects indicated that they could tolerate their current dose for the rest of their lives, compared to 85% of placebo subjects. These findings were corroborated by results in the open-label extension trial TEMPO 4:4.

Discussion

In this study, AAEs were common but well tolerated in ADPKD patients on tolvaptan. ADPKD patients in earlier stages of disease progression may be more sensitive to aquaretic symptoms, which may help in guiding tolvaptan dosing and titration decisions in the future.

Detecting PKD1 variants in polycystic kidney disease patients by single-molecule long-read sequencing

A genetic diagnosis of autosomal-dominant polycystic kidney disease (ADPKD) is challenging due to allelic heterogeneity, high GC content, and homology of the PKD1 gene with six pseudogenes. Short-read next-generation sequencing approaches, such as whole-genome sequencing and whole-exome sequencing, often fail at reliably characterizing complex regions such as PKD1. However, long-read single-molecule sequencing has been shown to be an alternative strategy that could overcome PKD1 complexities and discriminate between homologous regions of PKD1 and its pseudogenes. In this study, we present the increased power of resolution for complex regions using long-read sequencing to characterize a cohort of 19 patients with ADPKD. Our approach provided high sensitivity in identifying PKD1 pathogenic variants, diagnosing 94.7% of the patients. We show that reliable screening of ADPKD patients in a single test without interference of PKD1 homologous sequences, commonly introduced by residual amplification of PKD1 pseudogenes, by direct long-read sequencing is now possible. This strategy can be implemented in diagnostics and is highly suitable to sequence and resolve complex genomic regions that are of clinical relevance.

The effect of disease severity markers on quality of life in autosomal dominant polycystic kidney disease: a systematic review, meta-analysis and meta-regression

Background

Little is known about determinants of quality of life (QoL) in autosomal dominant polycystic kidney disease (ADPKD). Recent studies suggest that QoL in ADPKD is determined by more factors than mere renal function. We investigated the effect of ADPKD on QoL and evaluated how Qol is affected by disease severity markers renal function, kidney volume and liver volume.

Methods

We performed a systematic review, meta-analysis and meta-regression analyses of cohort studies and randomized controlled trials investigating patient-reported QoL in adult patients with ADPKD not yet on dialysis. EMBASE, MEDLINE, and Web of Science were searched to August 2015 without language restrictions. Two investigators independently reviewed title, abstracts and full text of potentially relevant citations to determine eligibility. We compared pooled QoL summary scores of ADPKD patients using a random-effects meta-analytic model. These scores were compared with mean and age-corrected reference scores of the general population. In a meta-regression analysis, we investigated the univariate effect of renal function, kidney volume and liver volume on QoL.

Results

We included nine studies in meta-analysis including 1623 patients who completed the SF-36 questionnaire. Pooled physical (PCS) and mental component scores (MCS) of the SF-36 of individuals with ADPKD were lower than those of the reference population (45.7 vs. 50.0 and 47.8 vs. 50.0 points, both P < 0.001). QoL of ADPKD patients remained lower after comparison with age-corrected reference values (age 35–44 year; PCS 52.2, MCS 49.9 points, both P < 0.05). Larger liver volume negatively impacted PCS (P < 0.001) and MCS (P = 0.001), whereas there was no association with renal function (PCS P = 0.1, MCS P = 0.9) and kidney volume (PCS P = 0.5, MCS P = 0. 5). Total liver and kidney volume had no impact on PCS (P = 0.1), but did have impact on MCS (P = 0.02).

Conclusions

QoL reported by non-dialysis patients with ADPKD is impaired compared to the general population. Large liver volume was the most important factor that diminishes QoL.

PROSPERO International Registry number CRD42015026428.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-017-0578-6) contains supplementary material, which is available to authorized users.

Healthcare resource consumption and cost of care among patients with polycystic kidney disease in Italy

Objective

The aim of this study was to assess healthcare resource consumption and its associated costs among patients with polycystic kidney disease (PKD) in a real-world setting.

Methods

An observational retrospective cohort analysis was conducted using data from the administrative databases of four Italian local health units. Data for patients who were diagnosed with PKD during the inclusion period (January 1, 2010 to December 31, 2012) were extracted. The date on which a patient’s first PKD hospitalization occurred during the inclusion period was defined as the index date (ID), and the ID was defined as the date of the first dialysis treatment recorded during the inclusion period for patients undergoing dialysis. Data regarding the clinical characteristics of patients included in the study during the 12 months prior to the ID (pre-ID; characterization period) were collected. All patients were then followed up for the 12 months following the ID (post-ID; follow-up period). Healthcare consumption and its associated costs were analyzed during the follow-up period. All costs are reported in euros (€).

Results

A total of 1,123 patients with PKD were included in this study, 61.9% of whom were male; the mean age of the patients was 57.7±24.5 years. At diagnosis, 11.2% and 1.1% of patients were affected by the dominant and recessive forms of PKD, respectively. Approximately 8% of the included patients were undergoing dialysis at ID (baseline). The incidence of dialysis was fourfold greater among patients with autosomal-dominant PKD (ADPKD) than among the total cohort (33.3% compared with an overall 8.3%). During the follow-up period, the average annual rates of healthcare resource consumption were greater among dialyzed than non-dialyzed patients. The average healthcare expenditures were €45,059.62 and €3,913.89 (p<0.001) per year for dialyzed and non-dialyzed PDK patients, respectively. Our findings suggest that in the real-world Italian context, consumption of healthcare among patients with PKD has increased at dialysis initiation due to the cost of outpatient specialist healthcare services as well as other costs. Research on the prevention of PKD-related complications and disease progression may help to facilitate a decrease in the costs associated with this condition.

Defective glycolysis and the use of 2-deoxy-D-glucose in polycystic kidney disease: from animal models to humans

Autosomal dominant polycystic kidney disease (ADPKD) is an inherited renal disease characterized by bilateral renal cyst formation. ADPKD is one of the most common rare disorders, accounting for ~10% of all patients with end-stage renal disease (ESRD). ADPKD is a chronic disorder in which the gradual expansion of cysts that form in a minority of nephrons eventually causes loss of renal function due to the compression and degeneration of the surrounding normal parenchyma. Numerous deranged pathways have been identified in the cyst-lining epithelia, prompting the design of potential therapies. Several of these potential treatments have proved effective in slowing down disease progression in pre-clinical animal studies, while only one has subsequently been proven to effectively slow down disease progression in patients, and it has recently been approved for therapy in Europe, Canada and Japan. Among the affected cellular functions and pathways, recent investigations have described metabolic derangement in ADPKD as a major trait offering additional opportunities for targeted therapies. In particular, increased aerobic glycolysis (the Warburg effect) has been described as a prominent feature of ADPKD kidneys and its inhibition using the glucose analogue 2-deoxy-D-glucose (2DG) proved effective in slowing down disease progression in preclinical models of the disease. At the same time, previous clinical experiences have been reported with 2DG, showing that this compound is well tolerated in humans with minimal and reversible side effects. In this work, we review the literature and speculate that 2DG could be a good candidate for a clinical trial in humans affected by ADPKD.

Identifying and integrating consumer perspectives in clinical practice guidelines on autosomal-dominant polycystic kidney disease

AIM

This study aimed to identify consumer perspectives on topics and outcomes to integrate in the Kidney Health Australia Caring for Australasians with Renal Impairment (KHA-CARI) clinical practice guidelines on autosomal-dominant polycystic kidney disease (ADPKD).

METHODS

A workshop involving three concurrent focus groups with 18 consumers (patients with ADPKD (n = 15), caregivers (n = 3)) was convened. Guideline topics, interventions and outcomes were identified, and integrated into guideline development. Thematic analysis was used to analyse the reasons for their choices.

RESULTS

Twenty-two priority topics were identified, with most focussed on non-pharmacological management (diet, fluid intake, physical activity, complementary medicine), pain management and psychosocial care (mental health, counselling, cognitive and behavioural training, education, support groups). They also identified 26 outcomes including quality of life (QoL), progression of kidney disease, kidney function, cyst growth and nephrotoxity. Almost all topics and outcomes suggested were identified by health professionals with the exception of five topics/outcomes. Six themes reflected reasons for their choices: clarifying ambiguities, resolving debilitating pain, concern for family, preparedness for the future, taking control and significance of impact.

CONCLUSION

Although there was considerable concordance between the priority topics and outcomes of health professionals and consumers for guidelines of ADPKD, there was also important discordance with consumers focused on fewer issues, but particularly on lifestyle, psychosocial support, pain, and QoL and renal outcomes. Active consumer engagement in guidelines development can help to ensure the inclusion of patient-centred recommendations, which may lead to better management of disease progression, symptoms, complications, and psychosocial impact.

Renal volume and cardiovascular risk assessment in normotensive autosomal dominant polycystic kidney disease patients

Cardiovascular disease, closely related to an early appearance of hypertension, is the most common mortality cause among autosomal dominant polycystic kidney disease patients (ADPKD). The development of hypertension is related to an increase in renal volume. Whether the increasing in the renal volume before the onset of hypertension leads to a major cardiovascular risk in ADPKD patients remains unknown.Observational and cross-sectional study of 62 normotensive ADPKD patients with normal renal function and a group of 28 healthy controls. Renal volume, blood pressure, and renal (urinary albumin excretion), blood vessels (carotid intima media thickness and carotid-femoral pulse wave velocity), and cardiac (left ventricular mass index and diastolic dysfunction parameters) asymptomatic organ damage were determined and were considered as continuous variables. Correlations between renal volume and the other parameters were studied in the ADPKD population, and results were compared with the control group. Blood pressure values and asymptomatic organ damage were used to assess the cardiovascular risk according to renal volume tertiles.Even though in the normotensive range, ADPKD patients show higher blood pressure and major asymptomatic organ damage than healthy controls. Asymptomatic organ damage is not only related to blood pressure level but also to renal volume. Multivariate regression analysis shows that microalbuminuria is only associated with height adjusted renal volume (htTKV). An htTKV above 480 mL/m represents a 10 times higher prevalence of microalbuminuria (4.8% vs 50%, P < 0.001). Normotensive ADPKD patients from the 2nd tertile renal volume group (htTKV > 336 mL/m) show higher urinary albumin excretion, but the 3rd tertile htTKV (htTKV > 469 mL/m) group shows the worst cardiovascular risk profile.Normotensive ADPKD patients show in the early stages of the disease with slight increase in renal volume, higher cardiovascular risk than healthy controls. An htTKV above 468 mL/m is associated with the greatest increase in cardiovascular risk of normotensive ADPKD patients with normal renal function. Early strategies to slow the progression of the cardiovascular risk of these patients might be beneficial in their long-term cardiovascular survival.

Vasopressin-related copeptin is a novel predictor of early endothelial dysfunction in patients with adult polycystic kidney disease

Background

In this study, we examined the relative usefulness of serum copeptin levels as a surrogate marker of vasopressin (AVP) in adult polycystic kidney disease (ADPKD) by correlating it with baseline and longitudinal changes in markers of both renal function and common CVD manifestations (hypertensive vascular disease, atherosclerosis and endothelial dysfunction) that accompany the progression of this disease.

Methods

We studied a cohort of young and otherwise healthy ADPKD patients (n = 235) and measured cardiovascular function using flow-mediation dilatation (FMD), carotid intima media thickness (cIMT) and pulse wave velocity (PWV), as well as serum copeptin (commercial ELISA, a stable marker of AVP activity). The same analyses were carried out at baseline and after 3 years of follow-up.

Results

At baseline, median eGFR was 69 mL/min./1.73 m², mean FMD 6.9 ± 0.9%, cIMT 0.7 ± 0.1 mm, and PWV 8.1 ± 1.2 m/s. At follow-up, equivalent values were 65 (44–75) mL/min./1.73 m², 5.8 ± 0.9%, 0.8 ± 0.1 mm. and 8.2 ± 1.3 m/s. with all changes statistically significant. Plasma copeptin also rose from 0.62 ± 0.12 to 0.94 ± 0.19 ng/mL and this change correlated with ΔeGFR (-0.33, p < 0.001), ΔFMD (0.599, p < 0.001), ΔcIMT (0.562, p < 0.001) and ΔPWV (0.27, p < 0.001) also after linear regression modeling to correct for confounders. Finally, ROC analysis was done for a high baseline copeptin with ΔeGFR [cut-off:≤59], ΔFMD [cut-off: ≤7.08], ΔcIMT [cut-off:>0.76], and ΔPWV [cut-off:≤7.80].

Conclusions

Vascular dysfunction as reflected by FMD and cIMT, but not PWV or an altered cardiac geometry, precede most other signs of disease in ADPKD but is predicted by elevated levels of the circulating AVP-marker copeptin.

The Longitudinal Study of Liver Cysts in Patients With Autosomal Dominant Polycystic Kidney Disease and Polycystic Liver Disease

Introduction

Although polycystic liver disease (PCLD) is one of the extrarenal complications in patients with autosomal dominant polycystic kidney disease (ADPKD), longitudinal changes and the association with total liver volume (TLV) have not been clearly elucidated yet.

Methods

Patients with ADPKD were chosen who underwent computed tomography or magnetic resonance imaging twice or more during August 2003 through December 2015. TLV, each cyst volume, and the proportion of parenchyma were measured. The natural history of liver cysts and the association between TLV and liver cysts were evaluated. To compare with liver cysts in ADPKD patients with PCLD, simple liver cysts in patients without ADPKD were also evaluated.

Results

TLV at baseline and its growth rate in all the patients with ADPKD, whose serum creatinine, estimated glomerular filtration rate, and total kidney volume were 1.45 mg/dl (0.76–2.32 mg/dl), 38.5 ml/min per 1.73 m² (18.7–57.9 ml/min per 1.73 m²), and 1394 ml (773–2861 ml), were 1431 ml (1062–1749 ml) and −0.95%/yr (−3.16 to 4.94%/yr), respectively, in the observation period (median, 1063 days). Neither TLV nor its growth rate was significantly different between ADPKD patients with PCLD and those without PCLD. The growth rate of 79 liver cysts was 39.5%/yr (17.5–80.8%/yr) in PCLD patients with ADPKD. It was significantly larger than that of 60 simple liver cysts in the non-ADPKD group, 11.0%/yr (−2.2 to 33.1%/yr). Moreover, the proportion of parenchyma reduced, whereas that of total cyst volume increased significantly (P = 0.001).

Discussion

The reduction of parenchyma was accompanied by the growth of liver cysts during time course in PCLD patients with ADPKD.

Hypokalemic Hypertension Leading to a Diagnosis of Autosomal Dominant Polycystic Kidney Disease

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited renal disease. Hypertension is common and occurs before decline in renal function. However, the coexistence of hypertension and hypokalemia is rare in ADPKD patients. We report on a 32-year-old woman with secondary aldosteronism. Magnetic resonance imaging of the renal arteries revealed multiple cysts of varying sizes in both the kidneys and the liver, compatible with ADPKD. Increased reninangiotensin-aldosterone system activity was secondary to cyst expansion. After initiation of angiotensin II receptor blocker, her blood pressure was controlled without additional requirement of potassium.

Percutaneous radiofrequency ablation with contrast-enhanced ultrasonography for solitary and sporadic renal cell carcinoma in patients with autosomal dominant polycystic kidney disease

Background

The aim of this study was to assess the functional and oncologic outcomes of percutaneous radiofrequency ablation (RFA) with contrast-enhanced ultrasonography (CEUS) for renal cell carcinoma in patient with autosomal dominant polycystic kidney.

Methods

We performed a retrospective review of five patients with renal cell carcinoma (RCC) in autosomal dominant polycystic kidney disease (ADPKD) from January 2009 to December 2014 with a media follow-up of 33 months. The tumors were ablated with Cool-tip RFA system under the guidance of CEUS. Routine follow-up included contrast-enhanced computed tomography/magnetic resonance imaging (CT/MRI) and renal function tests.

Results

Media diameter of the treated renal tumors was 3.1 cm (range 1.7–5.2 cm). Initial ablation success rate was 4/5. After over 6 months contrast-enhanced CT/MRI follow-up after RFA, no patients experienced local tumor recurrence. No patients required dialysis in the periprocedural period. Minor complications only developed in two cases. There was no significant difference in estimated glomerular filtration rate (eGFR) between pre- and post-RFA.

Conclusions

Our initial experience of this technique for RCC in ADPKD was favorable with good renal function preservation and oncologic outcomes. It may be a good choice for RCC in ADPKD.

Hyperaldosteronism and cardiovascular risk in patients with autosomal dominant polycystic kidney disease

Hypertension is commonly associated with autosomal dominant polycystic kidney disease (ADPKD), often discovered before the onset of renal failure, albeit the pathogenetic mechanisms are not well elucidated. Hyperaldosteronism in ADPKD may contribute to the development of insulin resistance and endothelial dysfunction, and progression of cardiorenal disease. The aim of study was to evaluate the prevalence of primary aldosteronism (PA) in ADPKD patients and identify some surrogate biomarkers of cardiovascular risk.We have enrolled 27 hypertensive ADPKD patients with estimated glomerular filtration rate (eGFR) ≥ 60 mL/min, evaluating the renin-angiotensin-aldosterone system (RAAS), inflammatory indexes, nutritional status, homocysteine (Hcy), homeostasis model assessment-insulin resistance (HOMA-IR), mineral metabolism, microalbuminuria, and surrogate markers of atherosclerosis [carotid intima media thickness (cIMT), ankle/brachial index (ABI), flow mediated dilation (FMD), renal resistive index (RRI) and left ventricular mass index (LVMI)]. Furthermore, we have carried out the morpho-functional magnetic resonance imaging (MRI) with high-field 3 T Magnetom Avanto.We have divided patients into group A, with normal plasma aldosterone concentration (PAC) and group B with PA, present in 9 (33%) of overall ADPKD patients. Respect to group A, group B showed a significant higher mean value of LVMI, HOMA-IR and Hcy (P = 0.001, P = 0.004, P = 0.018; respectively), and a lower value of FMD and 25-hydroxyvitamin D (25-OH-VitD) (P = 0.037, P = 0.019; respectively) with a higher prevalence of non-dipper pattern at Ambulatory Blood Pressure Monitoring (ABPM) (65% vs 40%, P < 0.05) at an early stage of the disease.In this study, we showed a high prevalence of PA in ADPKD patients, associated to higher LVMI, HOMA-IR, Hcy, lower FMD, and 25-OH-VitD, considered as surrogate markers of atherosclerosis, compared to ADPKD patients with normal PAC values. Our results indicate a higher overall cardiovascular risk in ADPKD patients with inappropriate aldosterone secretion, and a screening for PA in all patients with ADPKD is recommended.

Is peritoneal dialysis a therapeutic option for polycystic kidney disease? 15 years' experience in a single center

BACKGROUND

Peritoneal dialysis (PD) is often avoided for patients with polycystic kidney disease (PKD) because of increased risk of complications and technique failure due to limited intra-abdominal space. In this study, we have aimed to determine clinical outcomes, patient and technique survivals in patients with PKD performing PD and to define whether PD is appropriate for these patients.

METHODS

Totally 99 patients: 33 with PKD and 66 with diseases other than PKD were included in this retrospective study. All patients started PD between 2001 and 2015 years and have been matched by time of PD therapy initiation. Socio-demographic characteristics, clinical data and complications during the specified period were evaluated. The factors associated with mortality and patient and technique survival were investigated for all patients.

RESULTS

The two groups were similar in terms of demographic, baseline and last visit clinical and laboratory parameters, additional systemic diseases, with the exception of higher pretreatment and last visit serum albumin levels in PKD patients (P=0.03 and 0.01 respectively) and younger age of non-PKD patients (P=0.002). Incidence of peritonitis and catheter exit-site/tunnel infections were similar among the two groups (P=0.26 and 0.12 respectively). The two groups were similar in terms of leak and hernia developments (P=0.07 and 0.57, respectively). By the end of the study period; in PKD group, 10 patients had been transferred to HD and had kidney transplantation and only 6 patients had died. In non-PKD group, 19 patients had been transferred to HD, 11 patients had kidney transplantation and 23 patients had died. Mortality was lower in PKD group (log rank=0.034). The two groups were similar regarding death and HD transfer reasons (P=0.35 and 0.36 respectively). The technique survival rates were similar among the two groups (log rank=0.37).

CONCLUSIONS

Peritoneal dialysis may be a suitable renal replacement therapy option for PKD patients. PKD is not an additional risk factor in patients treated by PD. Mortality is similar with non-diabetic PD patients. Peritoneal dialysis in PKD patients is associated with a similar overall rate of technique survival, incidences of hernia, leak and infectious complications as in non-PKD patients.

Creating an effective clinical registry for rare diseases

The exposure of clinicians to patients with rare gastrointestinal diseases is limited. This hurts clinical studies, which impedes accumulation of scientific knowledge on the natural disease course, treatment outcomes and prognosis in these patients. An excellent method to detect patterns on an aggregate level that would not be possible to discover in individual cases, is a registry study. This paper aims to describe a template to create a successful international registry for rare diseases. We focus mainly on rare hepatic diseases, but lessons from this paper serve other fields in medicine, as well.

Refining Genotype-Phenotype Correlation in Autosomal Dominant Polycystic Kidney Disease

Renal disease variability in autosomal dominant polycystic kidney disease (ADPKD) is strongly influenced by the gene locus (PKD1 versus PKD2). Recent studies identified nontruncating PKD1 mutations in approximately 30% of patients who underwent comprehensive mutation screening, but the clinical significance of these mutations is not well defined. We examined the genotype-renal function correlation in a prospective cohort of 220 unrelated ADPKD families ascertained through probands with serum creatinine ≤1.4 mg/dl at recruitment. We screened these families for PKD1 and PKD2 mutations and reviewed the clinical outcomes of the probands and affected family members. Height-adjusted total kidney volume (htTKV) was obtained in 161 affected subjects. Multivariate Cox proportional hazard modeling for renal and patient survival was performed in 707 affected probands and family members. Overall, we identified pathogenic mutations in 84.5% of our families, in which the prevalence of PKD1 truncating, PKD1 in-frame insertion/deletion, PKD1 nontruncating, and PKD2 mutations was 38.3%, 4.3%, 27.1%, and 30.3%, respectively. Compared with patients with PKD1 truncating mutations, patients with PKD1 in-frame insertion/deletion, PKD1 nontruncating, or PKD2 mutations have smaller htTKV and reduced risks (hazard ratio [95% confidence interval]) of ESRD (0.35 [0.14 to 0.91], 0.10 [0.05 to 0.18], and 0.03 [0.01 to 0.05], respectively) and death (0.31 [0.11 to 0.87], 0.20 [0.11 to 0.38], and 0.18 [0.11 to 0.31], respectively). Refined genotype-renal disease correlation coupled with targeted next generation sequencing of PKD1 and PKD2 may provide useful clinical prognostication for ADPKD.

The Risk for New-Onset Diabetes Mellitus after Kidney Transplantation in Patients with Autosomal Dominant Polycystic Kidney Disease: A Systematic Review and Meta-Analysis

OBJECTIVES

New-onset diabetes after kidney transplantation (NODAT) is associated with both renal allograft failure and increased rates of mortality. The objective of this meta-analysis was to evaluate the risk for NODAT in patients with autosomal dominant polycystic kidney disease (ADPKD).

METHODS

A literature search was performed using MEDLINE, EMBASE and Cochrane Database of Systematic Reviews from inception through July 2015. Studies that reported relative risks, odd ratios or hazard ratios comparing the risk for NODAT in patients with ADPKD were included. Pooled risk ratios (RRs) and 95% confidence intervals (CIs) were calculated using a random-effect, generic inverse variance method.

RESULTS

Included in the analysis were 12 cohort studies, which comprised 1379 patients with ADPKD of a total of 9849 patients who had undergone kidney transplants. The pooled RRs of NODAT in patients with ADPKD were 1.92 (95% CI, 1.36 to 2.70). When meta-analysis was limited only to studies with confounder-adjusted analysis, the pooled RRs for NODAT were 1.98 (95% CI, 1.33 to 2.94). However, the association between NODAT requiring insulin treatment was insignificant, with pooled RRs of 1.57 (95% CI, 0.75 to 3.27).

CONCLUSIONS

Our meta-analysis demonstrates a significant association between ADPKD and NODAT in recipients of kidney transplants. The findings of this study may impact clinical management and follow up for patients with ADPKD after kidney transplantation.

Peritoneal dialysis for autosomal dominant polycystic kidney disease: a retrospective study

To describe the long-term clinical outcomes of patients with autosomal dominant polycystic kidney disease (ADPKD) who are on peritoneal dialysis (PD) therapy. We performed a retrospective matched-cohort analysis comparing the clinical outcomes of 30 ADPKD patients with those of 30 non-diabetic patients who had bilateral small kidneys between July 1 2007 and July 31 2014. The patient groups were matched by age, gender, and time of PD initiation. There were no significant differences in the demographic or biochemical parameters, comorbid conditions, residual glomerular filtration rate, or Charlson comorbidity score at the beginning of PD. The median renal volume was 1315 ml for the ADPKD group and 213 ml for the control group. Patients with ADPKD had similar 3-year patient survival (90.6% versus 86.3%, P=0.807) and technique survival (89.2% versus 74.3%, P=0.506) compared with non-ADPKD patients. Also, there was no significant difference in the peritonitis-free survival between the ADPKD and control groups (P=0.22), and rates of peritonitis were similar (0.19 versus 0.21 episodes per patient-year, P=0.26). No differences were observed in the incidence of PD-related complications, such as hernia and dialysate leak. ADPKD is not a contraindication for PD, and a subgroup of ADPKD patients with relatively small kidney volume can be treated using PD.

Screening for Unruptured Intracranial Aneurysms in Autosomal Dominant Polycystic Kidney Disease: A Survey of 420 Nephrologists

Background

Despite a high prevalence of intracranial aneurysm (ICA) in autosomal dominant polycystic kidney disease (ADPKD), rupture events are rare. The current recommendations for ICA screening are based on expert opinions and studies with low levels of evidence.

Objectives

The aim of our study was to describe the attitudes of practicing nephrologists in Europe towards screening for ICA using magnetic resonance angiography (MRA).

Methods

We conducted a web-based survey among 1315 European French-speaking nephrologists and nephrology residents. An anonymous, electronic questionnaire including 24 independent questions related to ICA screening modalities, indications and participant profiles was sent by email between September and December 2014. Four hundred and twenty nephrologists (mostly from France) participated, including 31 nephrology residents; the response rate was 32%.

Results

Systematic screening for ICA was advocated by 28% of the nephrologists. A family history of ICA rupture, sudden death, stroke and migraine were consensual indications for screening (> 90% of the panel). In other clinical situations largely not covered by the recommendations (pregnancy, nephrectomy, kidney transplantation, cardiac or hepatic surgery, uncontrolled hypertension, lack of familial ADPKD history, at-risk activity, tobacco use), the attitudes towards screening were highly divergent. ICA screening was influenced by nephrologists experience with ADPKD and by their practice setting. The majority of participants (57%) would not repeat a normal ICA screening. Only a few participants (22%) knew that non-contrast MRA was the reference diagnostic tool for ICA screening, whereas most participants thought that contrast enhancement was necessary to screen for ICA. The results from the nephrology residents were analyzed separately and yielded similar results.

Conclusion

This practice survey revealed that most nephrologists follow the current recommendations for the initial screening of ICAs. However, more than a quarter of the panel was in favor of systematic ICA screening, most nephrologists did not know that contrast medium was not necessary to screen for ICA using MRA, and many areas of uncertainty remain.

Recommendations for the use of tolvaptan in autosomal dominant polycystic kidney disease: a position statement on behalf of the ERA-EDTA Working Groups on Inherited Kidney Disorders and European Renal Best Practice

Recently, the European Medicines Agency approved the use of the vasopressin V2 receptor antagonist tolvaptan to slow the progression of cyst development and renal insufficiency of autosomal dominant polycystic kidney disease (ADPKD) in adult patients with chronic kidney disease stages 1–3 at initiation of treatment with evidence of rapidly progressing disease. In this paper, on behalf of the ERA-EDTA Working Groups of Inherited Kidney Disorders and European Renal Best Practice, we aim to provide guidance for making the decision as to which ADPKD patients to treat with tolvaptan. The present position statement includes a series of recommendations resulting in a hierarchical decision algorithm that encompasses a sequence of risk-factor assessments in a descending order of reliability. By examining the best-validated markers first, we aim to identify ADPKD patients who have documented rapid disease progression or are likely to have rapid disease progression. We believe that this procedure offers the best opportunity to select patients who are most likely to benefit from tolvaptan, thus improving the benefit-to-risk ratio and cost-effectiveness of this treatment. It is important to emphasize that the decision to initiate treatment requires the consideration of many factors besides eligibility, such as contraindications, potential adverse events, as well as patient motivation and lifestyle factors, and requires shared decision-making with the patient.

The Treatment of Autosomal Dominant Polycystic Kidney Disease

BACKGROUND

About one in 2000 persons in Europe suffers from autosomal dominant polycystic kidney disease (ADPKD). The treatment of this disease up to the present has been limited to the management of complications.

METHODS

This review is based on pertinent publications, mostly of the last three years, that were retrieved by a selective search in PubMed.

RESULTS

Kidney volume is probably the most important predictive factor for the loss of renal function. A measurement of kidney size is, therefore, recommended as soon as the diagnosis is made. ADPKD patients under age 30 with a combined kidney volume above 1500 mL and an estimated glomerular filtration rate (eGFR) below 90 mL/min are at high risk of needing kidney-replacement therapy (dialysis or transplantation) within 20 years, even if their renal function is normal. Ultrasonographic follow-up can identify affected persons whose risk for rapid progression is especially high. Currently available evidence reveals that, in patients at risk whose renal function is normal, the maintenance of blood pressure at or below a target value of 110/75 mmHg lessens renal enlargement, albuminuria, and left-ventricular hypertrophy. In another study, the treatment of selected patients with tolvaptan, a vasopressin-2 receptor (V2R) blocker, was found to delay cyst enlargement and the related decline in renal function for three years. It is unclear, however, how long the effect of tolvaptan persists, or whether persons whose renal function is already impaired can benefit from it. The main side effects are marked polyuria and, in rare cases, liver toxicity.

CONCLUSION

In patients with ADPKD, an effort should be made to keep the arterial blood pressure below 120/80 mmHg. In patients at high risk of progression whose renal function is still intact (eGFR > 60 mL/min), strict blood pressure control (< 110/75 mm Hg) is indicated, and possibly V2R blockade with tolvaptan as well. Tolvaptan is an expensive drug, and patients taking it must be carefully monitored for hepatotoxicity.

Outcome Comparisons Between Patients on Peritoneal Dialysis With and Without Polycystic Kidney Disease: A Nationwide Matched Cohort Study

Polycystic kidney disease (PCKD) is the most common hereditary cause of end-stage renal disease. The complications associated with this disease may affect the performance of peritoneal dialysis (PD). The aim of this study was to compare the outcomes between patients on PD with PCKD and without PCKD.We extracted an incident cohort of adult (≥ 20 years old) patients on long-term PD from the Taiwan National Health Insurance Research Database. Patients with PCKD were identified by specific diagnosis codes. We recorded baseline comorbidities, socioeconomic status, timing of referral to a nephrologist, prior hemodialysis history before PD, and the type of PD modalities. We compared the risk of death, technique failure, peritonitis, hospitalization, and outpatient visiting as well as overall medical expenditure between the patients with PCKD and a groups of patients without PCKD who were propensity-score matched (1:3). The analysis was carried out by various Cox regression models that considered competing risk and time-varying coefficients. We enrolled 139 patients with PCKD and 7739 patients without PCKD who started long-term PD between 1999 and 2010. Patients with PCKD were less comorbid and more often treated with automated PD. In the propensity-score matched analysis, both overall survival and technique survival did not differ between the patients and the result was similar for hospitalization and peritonitis after adjusting for the application of automated PD. Furthermore, the overall annual medical expenditures were similar between the patients with and without PCKD. PD patients with PCKD are comparable to PD patients without PCKD in terms of risk of death, peritonitis, technique failure, and hospitalization in the present study. Furthermore, the medical expenses of the 2 groups after initiation of PD are also indistinguishable.

Native Nephrectomy in Renal Transplant Recipients with Autosomal Dominant Polycystic Kidney Disease

BACKGROUND

Native nephrectomy (NNx) is often done in patients with autosomal dominant polycystic kidney disease (ADPKD). Controversy exists concerning the need and timing of nephrectomy in transplant candidates. We hypothesize that post-transplant NNx does not negatively impact patient and graft survival.

METHODS

Among 470 ADPKD transplant recipients included in the study, 114 (24.3%) underwent pre- (30.7%) or post-transplant (69.3%) NNx. Clinical data was retrieved from electronic records. Follow up was until death, graft loss or June 2014. Perioperative complications were compared between the surgical techniques (open or laparoscopic) and between the pre- and post-transplant nephrectomy groups. The effect of nephrectomy on graft survival was analyzed as a time-dependent covariate when performed post-transplant.

RESULTS

Mean age at transplant was 52.4 years, 53.8% were male, 93% white, 70% were from living donors and 56.8% were pre-emptive. Nephrectomy was done laparoscopically in 31% and 86% in the pre- and post- transplant nephrectomy groups, respectively. Complications were less common in those who underwent nephrectomy post-transplant (26.6% vs. 48%, p=0.03) but were similar regardless of surgical technique (open, 33.3% vs. laparoscopic 33%, p=0.66). Patient and graft survival were similar between those who underwent pre-transplant nephrectomy and the rest of the recipients. In the post-transplant nephrectomy group, nephrectomy did not affect patient (HR 0.77, CI 0.38-1.54, p=0.45) or graft survival (HR 1.0, CI 0.57-1.76, p=0.1).

CONCLUSIONS

Nephrectomy does not adversely affect patient or graft survival. Post-transplant nephrectomy is feasible when indicated without compromising long term graft outcome and has fewer complications than pre-transplant nephrectomy.

Causes of end stage renal failure among haemodialysis patients in Khartoum State/Sudan

Background

End stage renal failure (ESRF) has become a major health problem in Sub Saharan Africa (SSA). There were limited data about causes of ESRF in the Sudan.

Methods

This is a cross sectional hospital based descriptive study. The subjects of the study are ESRF adults’ patients on regular haemodialysis treatment in 15 haemdoialysis centres in Khartoum State—Sudan. Clinical and epidemiological data were obtained from 1583 patients. The medical files of each patient were reviewed to identify the cause of ESRF. Concerning the causes of ESRF, diabetes was diagnosed based on the past medical history and result of the glucose tolerance test, hypertension was diagnosed based on past history of hypertension based on blood pressure of more than 140/90 mmHg, glomerulonephritis was diagnosed based on results of previous kidney biopsies and on clinical grounds, polycystic kidney disease and obstructive uropathy were diagnosed based on abdominal ultrasound and other imaging modalities, sickle cell anaemia was diagnosed based on the result of haemoglobin electrophoresis, systemic lupus erythematosus was diagnosed based on the clinical criteria in addition to lab results of auto antibodies, and analgesic nephropathy was diagnosed based on past medical history of chronic analgesic drugs usage with no other identifiable risk factors. We included all ESRF patients on regular haemodialysis treatment. We excluded ESRF patients less than 18 years old.

Results

The results showed that the mean age of ESRF Patients was 49 ± 15.8 (years) and 63.4 % were male and 76.3 % were unemployed. The mean duration of haemodialysis is 4.38 ± 4.24 (years). The most common cause of ESRF in our patients was hypertension (34.6 %) followed by chronic glomerulonephritis (17.6 %), diabetes mellitus (12.8 %), obstructive uropathy (9.6 %), autosomal dominant poly cystic kidney disease (ADPKD) (4.7 %), chronic pyelonephritis (4.6 %), analgesic nephropathy (3.5 %). However in (10.7 %) no cause was found. In patient aged less than 40 years old the leading cause of ESRF was glomerulonephritis (29.3 %) followed by hypertension (25 %). In patient aged between 40 to 60 years old the leading cause of ESRF was hypertension (38.5 %) followed by diabetes mellitus (14 %). In patient aged older than 60 years the leading cause of ESRF was hypertension (38.4 %) followed by diabetes mellitus (23.3 %).

Conclusions

ESRF in Sudan affects the economically productive age group; unemployment rate among ESRF patients is high. The study showed that hypertension is a leading cause of ESRF in Sudan followed by chronic glomerulonephritis. Hypertension and diabetes mellitus are the leading causes of ESRF among patients over 40 years old.

Unexpected Abscess Localization of the Anterior Abdominal Wall in an ADPKD Patient Undergoing Hemodialysis

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is one of the most common monogenic disorders and the leading inheritable cause of end-stage renal disease worldwide. Cystic and noncystic extrarenal manifestations are correlated with variable clinical presentations so that an inherited disorder is now considered a systemic disease. Kidney and liver cystic infections are the most common infectious complications in ADPKD patients. Furthermore, it is well known that ADPKD is commonly associated with colonic diverticular disease which recently has been reported to be linked to increased risk of infection on hemodialysis patients. Herein, we present a case of anterior abdominal wall abscess caused by Enterococcus faecalis in a patient with ADPKD undergoing hemodialysis. Although the precise pathway of infection remains uncertain, the previous medical history as well as the clinical course of our patient led us to hypothesize an alternative route of infection from the gastrointestinal tract through an aberrant intestinal barrier into the bloodstream and eventually to an atypical location.

Peritoneal dialysis as a treatment option in autosomal dominant polycystic kidney disease

PURPOSE

When choosing a dialysis option for ADPKD patients, peritoneal dialysis (PD) is often discouraged, due to its potential drawbacks: risk of abdominal hernias and dialysis fluid leaks, risk of peritonitis and insufficient dialysis adequacy. The present study was designed to compare the outcomes and dialysis efficacy in ADPKD patients treated with PD, in comparison with non-ADPKD subjects.

METHODS

This study was a retrospective analysis of the data from the national PD registry in which 106 ADPKD and 1606 non-ADPKD incident PD patients were evaluated. Data on dialysis adequacy, risk of dialysis-associated complications, as well as patient and technique survival were compared between the groups.

RESULTS

The ADPKD patients did not differ from the non-ADPKD controls in terms of dialysis adequacy. After a median observation time of 32 months, there were no differences in patient or technique survival. The risk of abdominal hernias and dialysis fluid leaks was twice as high in ADPKD subjects, compared to the non-ADPKD group. However, these complications did not result in a need for a permanent transfer to hemodialysis.

CONCLUSIONS

Dialysis adequacy, and patient and technique survival are similar in the ADPKD and non-ADPKD patients treated with PD. PD seems a feasible treatment option for end-stage renal failure in the course of ADPKD.

Comparative Study of Outcomes among Patients with Polycystic Kidney Disease on Hemodialysis and Peritoneal Dialysis

Polycystic kidney disease (PCKD) is the most common hereditary cause of end-stage renal disease, the complications of which may prevent the choice of peritoneal dialysis (PD). The aim of this study was to explore the effects of dialysis modality on outcomes in patients with PCKD. We extracted a cohort of 1417 adult patients with PCKD initiating long-term dialysis therapy in 1999-2010 from the Taiwan National Health Insurance Research Database, among which 125 patients chose PD. The patients on HD were older and had a higher comorbidity index compared to those on PD. We compared the risks for death, hospitalization and medical expenditures between the patients on PD and propensity-score matched patients on hemodialysis (HD). The overall survival did not differ between the patients on PD and HD. The patients on PD tended to have higher hazard ratios (HR) for the first episode of hospitalization (adjusted HR 1.34 [95% CI, 1.04-1.79]). The annual medical expenses were 10% lower for the patients on PD. PD is an equivalent choice of renal replacement therapy to HD for patients with PCKD in terms of survival. Although the patients on PD had a higher risk for hospitalization, the medical expenditure for PD was 10% lower.

Vasopressin and disruption of calcium signalling in polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is the most common monogenic kidney disease and is responsible for 5-10% of cases of end-stage renal disease worldwide. ADPKD is characterized by the relentless development and growth of cysts, which cause progressive kidney enlargement associated with hypertension, pain, reduced quality of life and eventual kidney failure. Mutations in the PKD1 or PKD2 genes, which encode polycystin-1 (PC1) and polycystin-2 (PC2), respectively, cause ADPKD. However, neither the functions of these proteins nor the molecular mechanisms of ADPKD pathogenesis are well understood. Here, we review the literature that examines how reduced levels of functional PC1 or PC2 at the primary cilia and/or the endoplasmic reticulum directly disrupts intracellular calcium signalling and indirectly disrupts calcium-regulated cAMP and purinergic signalling. We propose a hypothetical model in which dysregulated metabolism of cAMP and purinergic signalling increases the sensitivity of principal cells in collecting ducts and of tubular epithelial cells in the distal nephron to the constant tonic action of vasopressin. The resulting magnified response to vasopressin further enhances the disruption of calcium signalling that is initiated by mutations in PC1 or PC2, and activates downstream signalling pathways that cause impaired tubulogenesis, increased cell proliferation, increased fluid secretion and interstitial inflammation.