Autosomal Dominant Polycystic Kidney Disease Population Research Articles

Health Disparities in Kidney Failure Among Patients With Autosomal Dominant Polycystic Kidney Disease: A Cross-Sectional Study

Understanding potential differences in patterns of kidney failure among patients with autosomal dominant polycystic kidney disease (ADPKD) may provide insights into improving disease management. We sought to characterize patients with ADPKD and kidney failure across different race/ethnicities. Cross-sectional study. Kaiser Permanente Southern California members diagnosed with ADPKD between January1, 2002, and December 31,2018. ADPKD. Kidney failure, dialysis, or receipt of kidney transplant. Differences in characteristics by race/ethnicity were assessed using analysis of variance F test and χ2 test. To compare the range and distribution of the average age at onset of kidney failure by race/ethnicity and sex, we used box plots and confidence intervals. Multivariable logistic regression was used to estimate OR for kidney transplant. Among 3,677 ADPKD patients, 1,027 (27.3%) had kidney failure. The kidney failure cohort was comprised of Black (n=138; 30.7%), White (n=496; 30.6%), Hispanic (n=306; 24.7%), and Asian (n=87; 23.6%) patients. Hispanic patients had the youngest mean age of kidney failure onset (50 years) compared to Black (56 years) and White (57 years) patients. Black (44.2%; OR, 0.72) and Hispanic (49.7%; OR, 0.65) patients had lower rates of kidney transplantation compared to White (53.8%) patients. Preemptive kidney transplantations occurred in 15.0% of patients. Retrospective study design and possible misclassification of ADPKD cases. Kidney function calculations were based on equations incorporating race, potentially overestimating kidney function in African Americans. The study was conducted within a single, integrated health care system in 1 geographic region and may not be generalizable to all ADPKD patients. Among a large diverse ADPKD population, we observed racial/ethnic differences in rates of kidney failure, age of kidney failure onset, and rates of kidney transplantation. Our real-world ADPKD cohort provides insight into racial/ethnic variation in clinical features of disease and potential disparities in care, which may affect ADPKD outcomes.

Drug Development for Cystic Kidney Diseases.

Inherited cystic diseases include a spectrum of disorders, such as autosomal dominant polycystic kidney disease (ADPKD), autosomal recessive polycystic kidney disease (ARPKD), autosomal dominant polycystic liver disease, and an expanding group of recessively inherited diseases collectively termed hepatorenal fibrocystic disorders. ADPKD is the most common monogenic disorder that can lead to kidney failure, with a prevalence of 600,000 people in the United States (1). ARPKD is associated with significant kidney- and liver-related morbidity and mortality in children, with >50% of affected individuals progressing to kidney failure within the first decade of life (2). Although one therapy (tolvaptan) has been approved in the United States and other regions for the treatment of ADPKD, the development of clear regulatory pathways and viable end points would be critical for further development in the area of polycystic kidney and liver disorders. On May 19–20, 2021, representatives from academia, industry, regulatory agencies (US Food and Drug Administration and European Medicines Agency), and the patient community came together to discuss the unmet needs in ADPKD and ARPKD drug and regulatory development as part of the 2021 PKD Regulatory Summit. The conference was organized by the PKD Outcomes Consortium from Critical Path Institute in partnership with the PKD Foundation. The issues discussed covered a broad range of topics, including obstacles to drug development for early ADPKD and ARPKD, clinical trial design in ADPKD, development of novel biomarkers for disease progression, development of clinical outcome assessment tools, and disease progression modeling. The following series of Perspective articles summarize the salient points from the three sessions of the Summit, including drug development for ARPKD, early ADPKD, and clinical trial design for ADPKD. The conclusions drawn from these Perspective articles emphasize: (1) The importance of international collaborations and large observational studies, which are critical for shedding light on the different risk patterns in ARPKD (given its multiple temporal disease manifestations), thus paving the way for future interventional trials. The criticality of stringent patient selection, clinical descriptions, and biosampling as part of the trial process will be essential for progress (3). (2) The need to define the best timing for interventions and identifying novel targets that are relevant in the early ADPKD disease stage. Challenges to this include the identification and validation of indicators, both measuring and predicting disease progression from childhood, and distinguishing slow from rapid progressors in the early-stage ADPKD population (4). (3) The importance of standardization of the key elements of an ADPKD pivotal trial template that can serve to derisk and potentially accelerate the development of therapies. As well as the importance of designing trials that are accessible to patients to enter and remain across the ≥2 year study duration that ADPKD trials would require (5). Much unmet need remains in polycystic kidney disease, both on the regulatory and therapeutic sides. Continued collaboration and data-sharing efforts in the field among relevant stakeholders are needed to achieve enhanced prognostic and therapeutic biomarkers, end points, and a feasible regulatory pathway (for all forms of PKD including ARPKD), which will hopefully lead to more therapies becoming available for affected individuals. Disclosures S. Fedeles reports being employed by the Critical Path Institute and is an author on the WO2015057894A1 patent (published in April 2015) “Methods for treating polycystic kidney disease and polycystic liver disease.” R.D. Perrone reports having consultancy agreements with Caraway, Navitor, Otsuka, Palladiobio, Reata, and Sanofi-Genzyme; having other interests in, or relationships with, Critical Path Institute, PKD Foundation, and UpToDate; serving on a speakers bureau for Haymarket Media; receiving research funding from Kadmon, Palladiobio, Reata, and Sanofi; serving in an advisory or leadership role for Otsuka, PalladioBio, and Sanofi-Genzyme; and receiving honoraria from Otsuka, Reata, and Sanofi-Genzyme. Funding This work was supported by Otsuka Pharmaceutical and PKD Foundation.

African American polycystic kidney patients receive higher risk kidneys, but do not face increased risk for graft failure or post-transplant mortality

African Americans (AA) are disproportionately affected by end-stage renal disease (ESRD) and have worse outcomes following renal transplantation. Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic condition leading to ESRD necessitating transplant. We explored this population with respect to race by conducting a retrospective analysis of the UNOS database between 2005 and 2019. Our study included 10,842 (AA n = 1661; non-AA n = 9181) transplant recipients whose primary diagnosis was ADPKD. We further stratified the AA ADPKD population with respect to blood groups (AA blood type B n = 295 vs AA non-B blood type n = 1366), and also compared this cohort to AAs with a diagnosis of DM (n = 16,706) to identify unique trends in the ADPKD population. We analyzed recipient and donor characteristics, generated survival curves, and conducted multivariate analyses. African American ADPKD patients waited longer for transplants (924 days vs 747 days P < .001), and were more likely to be on dialysis (76% vs 62%; p < .001). This same group was also more likely to have AA donors (21% vs 9%; p < .001) and marginally higher KDPI kidneys (0.48 vs 0.45; p < .001). AA race was a risk factor for delayed graft function (DGF), increasing the chance of DGF by 45% (OR 1.45 95% CI 1.26–1.67; p < .001). AA race was not associated with graft failure (HR 1.10 95% CI 0.95–1.28; p = .21) or patient mortality (HR 0.84 95% CI 0.69–1.03; p = .09). Racial disparities exist in the ADPKD population. They should be continually studied and addressed to improve transplant equity.

Detection and characterization of mosaicism in autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is an inherited, progressive nephropathy accounting for 4-10% of end stage renal disease worldwide. PKD1 and PKD2 are the most common disease loci, but even accounting for other genetic causes, about 7% of families remain unresolved. Typically, these unsolved cases have relatively mild kidney disease and often have a negative family history. Mosaicism, due to de novo mutation in the early embryo, has rarely been identified by conventional genetic analysis of ADPKD families. Here we screened for mosaicism by employing two next generation sequencing screens, specific analysis of PKD1 and PKD2 employing long-range polymerase chain reaction, or targeted capture of cystogenes. We characterized mosaicism in 20 ADPKD families; the pathogenic variant was transmitted to the next generation in five families and sporadic in 15. The mosaic pathogenic variant was newly discovered by next generation sequencing in 13 families, and these methods precisely quantified the level of mosaicism in all. All of the mosaic cases had PKD1 mutations, 14 were deletions or insertions, and 16 occurred in females. Analysis of kidney size and function showed the mosaic cases had milder disease than a control PKD1 population, but only a few had clearly asymmetric disease. Thus, in a typical ADPKD population, readily detectable mosaicism by next generation sequencing accounts for about 1% of cases, and about 10% of genetically unresolved cases with an uncertain family history. Hence, identification of mosaicism is important to fully characterize ADPKD populations and provides informed prognostic information.

Early Urinary Biomarkers in Pediatric Autosomal Dominant Polycystic Kidney Disease (ADPKD): No Evidence in the Interest of Urinary Neutrophil Gelatinase-Associated Lipocalin (uNGAL).

Background: Autosomal Dominant Polycystic Kidney Disease (ADPKD) is increasingly diagnosed during childhood by the presence of renal cysts in patients with a positive familial history. No curative treatment is available and early detection and diagnosis confronts pediatricians with the lack of early markers to decide whether to introduce renal-protective agents and prevent the progression of renal failure. Neutrophil Gelatinase-Associated Lipocalin (NGAL) is a tubular protein that has been recently proposed as an early biomarker of renal impairment in the ADPKD adult population.Methods: Urinary NGAL (uNGAL) levels were measured in 15 ADPKD children and compared with 15 age and gender matched controls using parametric, non-parametric, and Bayesian statistics. We also tested the association of uNGAL levels with markers of disease progression, such as proteinuria, albuminuria, blood pressure, and Total Kidney Volume (TKV) using correlation analysis. TKV was calculated by ultrasound, using the ellipsoid method.Results: No difference in mean uNGAL levels was observed between groups (ADPKD: 26.36 ng/ml; Controls: 27.24 ng/ml; P = 0.96). Moreover, no correlation was found between uNGAL and proteinuria (P = 0.51), albuminuria (P = 0.69), TKV (P = 0.68), or mean arterial pressure (P = 0.90). By contrast, TKV was positively correlated with proteinuria (P = 0.04), albuminuria (P = 0.001), and mean arterial pressure (P = 0.03).Conclusion: uNGAL did not confirm its superiority as a marker of disease progression in a pediatric ADPKD population. In the contrary, TKV appears to be an easy measurable variable and may be promising as a surrogate marker to follow ADPKD progression in children.

PSY24 - Impact of Autosomal Dominant Polycystic Kidney Disease (ADPKD) on Caregivers and Families

Autosomal dominant polycystic kidney disease (ADPKD) is a rare, dominantly inherited systemic disease resulting in gradual kidney enlargement and kidney failure over time. Commonly, multiple members of a family across several generations are affected by the disease and often patients with ADPKD also function as caregivers for other family members. This study explored the burden experienced by caregivers for patients with ADPKD. Focus groups with 139 caregivers for patients with ADPKD in 14 countries (Argentina, Australia, Brazil, Canada, China, Czech Republic, Hungary, Japan, Poland, Romania, South Korea, Spain, Taiwan, United States) using iterative, concept elicitation methodology to understand the impacts of caring for a patient with ADPKD. Caregivers for patients with ADPKD (66.9% female, 33.1% male) provide assistance with activities of daily living and emotional support. Furthermore, 25 caregivers (88% female, 12% male) were also diagnosed with ADPKD themselves, which elevated their burden. Almost all caregivers in the study provided care or support for immediate family members (94.8%) while a smaller percentage (2.9%) were assisting a distal relative or friend. Caregivers reported impacts on emotional (74.1%), social (38.5%), work/employment (26.6%), financial (23.7%), and physical (17.3%) aspects of their daily lives. There were slight differences in how caregivers in various regions emphasized impacts, and impacts varied depending on the disease stage of the ADPKD patient and the caregiver-patient relationship. Caregivers for patients reported substantial impacts on their daily lives which was globally consistent. Defining caregiver burden is essential to understanding ways of supporting the ADPKD population in the community.

PSY18 - Comparing the Epidemiology of ADPKD in the US from 2010-2015 Using one Versus two Diagnosis Codes in Claims Data

Autosomal dominant polycystic kidney disease (ADPKD) is a life-threatening genetic disease that progressively leads to end stage renal disease. Recent published literature in EU showed prevalence rates less than 5 in 10,000. However, there is currently very limited epidemiology data in the US. This study assessed the epidemiology of ADPKD using Truven MarketScan™ claims data from January 1, 2010 to December 31, 2015. The population was assessed in two cohorts with either one or two diagnosis of ADPKD required during the study period. The prevalence analysis required at least one (or two) encounter(s) with a diagnosis of ADPKD; the first referenced as Index date, with the incidence analysis requiring an additional step for continuous coverage for one year minus the index date with no encounters of ADPKD to ensure first diagnosis. Overall, annual prevalence rates varied from 14 to 18/100,000 and 10 to 14/100,000 in the one and two encounter groups. The average annual rates over the study period were 15/100,000 and 12/100,000 and would account for 47,850 and 38,280 patients in the one and two encounter groups respectively, assuming a US population of 319,000,000. It should be noted, however, that these prevalence rates account for the ADPKD population that is actively being treated. The incidence analysis was limited in reporting overall rates as less severe patients may appear new and be counted as an incident patient, particularly in slowly progressive diseases such as ADPKD. Therefore, the rates should primarily be used to compare trends over time, which demonstrated to be stable over the study period. This study is the first to assess the epidemiology of the ADPKD population using claims data. Results from both groups demonstrate that the prevalence of ADPKD in the US is low and the disease incidence was relatively stable from 2010 to 2015.

Outcome of autosomal dominant polycystic kidney disease patients on peritoneal dialysis: a national retrospective study based on two French registries (the French Language Peritoneal Dialysis Registry and the French Renal Epidemiology and Information Network).

Pathological features of autosomal dominant polycystic kidney disease (ADPKD) include enlarged kidney volume, higher frequency of digestive diverticulitis and abdominal wall hernias. Therefore, many nephrologists have concerns about the use of peritoneal dialysis (PD) in ADPKD patients. We aimed to analyse survival and technique failure in ADPKD patients treated with PD. We conducted two retrospective studies on patients starting dialysis between 2000 and 2010. We used two French registries: the French Renal Epidemiology and Information Network (REIN) and the French language Peritoneal Dialysis Registry (RDPLF). Using the REIN registry, we compared the clinical features and outcomes of ADPKD patients on PD (n = 638) with those of ADPKD patients on haemodialysis (HD) (n = 4653); with the RDPLF registry, those same parameters were determined for ADPKD patients on PD (n = 797) and compared with those of non-ADPKD patients on PD (n = 12059). A total of 5291 ADPKD patients and 12059 non-ADPKD patients were included. Analysis of the REIN registry found that ADPKD patients treated with PD represented 10.91% of the ADPKD population. During the study period, PD was used for 11.2% of the non-ADPKD population. Compared with ADPKD patients on HD, ADPKD patients on PD had higher serum albumin levels (38.8 ± 5.3 versus 36.8 ± 5.7 g/dL, P < 0.0001) and were less frequently diabetic (5.31 versus 7.71%, P < 0.03). The use of PD in ADPKD patients was positively associated with the occurrence of a kidney transplantation but not with death [hazard ratio 1.15 (95% confidence interval 0.84-1.58)]. Analysis of the RDPLF registry found that compared with non-ADPKD patients on PD, ADPKD patients on PD were younger and had fewer comorbidities and better survival. ADPKD status was not associated with an increased risk of technique failure or an increased risk of peritonitis. According to our results, PD is proposed to a selected population of ADPKD patients, PD does not have a negative impact on ADPKD patients' overall survival and PD technique failure is not influenced by ADPKD status. Therefore PD is a reasonable option for ADPKD patients.

End-Stage Kidney Disease in Patients With Autosomal Dominant Polycystic Kidney Disease: A 12-Year Study Based on the Canadian Organ Replacement Registry.

Background:Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disease, with afflicted patients often progressing to end-stage kidney disease (ESKD) requiring renal replacement therapy (RRT). As the timelines to ESKD are predictable over decades, it follows that ADPKD patients should be optimized regarding kidney transplantation, home dialysis therapies, and vascular access.Objectives:To examine the association of kidney transplantation, dialysis modalities, and vascular access in ADPKD patients compared with a matched, non-ADPKD cohort.Setting:Canadian patients from 2001-2012 excluding Quebec.Patients:All adult incident ESKD patients who received dialysis or a kidney transplant.Measurements:ADPKD as defined by the treating physician.Methods:ADPKD and non-ADPKD patients were propensity score (PS) matched (1:4) using demographics, comorbidities, and lab values. Conditional logistic regression and Cox proportional hazards models were used to examine associations with kidney transplantation (preemptive or any), dialysis modality (peritoneal, short daily, home, or in-center hemodialysis [HD]), vascular access (arteriovenous fistula [AVF], permanent or temporary central venous catheter [CVC]), and dialysis survival.Results:We matched 2120 ADPKD (99.9%) with 8283 non-ADPKD with no significant imbalances between the groups. ADPKD was significantly associated with preemptive kidney transplantation (odds ratio [OR] = 7.13, 95% confidence interval [CI] = 5.74-8.87), any kidney transplant (OR = 2.37, 95% CI = 2.14-2.63), and initial therapy of nocturnal daily HD (OR = 2.74, 95% CI = 1.38-5.44), whereas in-center intermittent HD was significantly less likely in the ADPKD population (OR = 0.59, 95% CI = 0.54-0.65). There was no difference in peritoneal dialysis (PD) as initial RRT but lower use of any PD among the ADPKD group (OR = 0.85, 95% CI = 0.77-0.95). ADPKD patients were significantly more likely to have an AVF (OR = 3.25, 95% CI = 2.79-3.79) and less likely to have either a permanent (OR 0.68, 95% CI 0.59-0.78) or temporary (OR = 0.49, 95% CI = 0.41-0.59) CVC as compared with the non-ADPKD cohort. Survival on either in-center HD or PD was better for ADPKD patients (HD: hazard ratio [HR] 0.48, 95% CI 0.44-0.53; PD: HR 0.73, 95% CI 0.60-0.88).Limitations:Conservative care patients were not captured; despite PS matching, the possibility of residual confounding remains.Conclusions:ADPKD patients were more likely to receive a kidney transplant, use home HD, dialyze with an AVF, and have better survival relative to non-ADPKD patients. Conversely, they were less likely to receive PD either as initial therapy or anytime during ESKD. This may be attributed to higher transplantation or clinical decision-making processes susceptible to education and intervention.

Combined renin-angiotensin-aldosterone system blockade and statin therapy effectively reduces the risk of cerebrovascular accident in autosomal dominant polycystic kidney disease: a nationwide population-based cohort study.

Fairly limited data reported the incidence and risk of cerebrovascular accident (CVA) in autosomal dominant polycystic kidney disease (ADPKD). Additionally, little is known regarding the therapeutic impact of renin-angiotensin-aldosterone system (RAAS) blockade and statin on reducing the occurrence of CVA in ADPKD. We utilized the data from Taiwan National Health Insurance Research Database (NHIRD) to perform a population-based cohort study (1997-2013). A total of 2,647 patients with ADPKD were selected from 1,000,000 general population after excluding patients with age<18, renal replacement therapy and concomitant diagnosis of CVA. Additionally, non-ADPKD subjects were assigned as comparison group by matching study cohort with age, gender, income and urbanization in 1:10 ratio (n=26,470). The results showed that ADPKD group had significantly higher frequency rate and cumulative incidence of CVA as compared with the non-ADPKD group (8.73% v.s. 3.93%, p<0.0001). Furthermore, the frequencies of both hemorrhagic and ischemic strokes were also significantly higher in the ADPKD than non-ADPKD group (all p-values <0.0001). After adjusting for age, gender and atherosclerotic risk factors with multivariate analysis, ADPKD independently carried 2.34- and 5.12-fold risk for occurrence of CVA and hemorrhagic stroke (95% CI: 2.02-2.72 and 4.01-6.54), respectively. Combination therapy [adjusted (a) HR=0.19, 95% CI: 0.11-0.31] was superior to either RAAS blockade (aHR=0.37, 95% CI, 0.28-0.5) or statin (aHR=0.44, 95% CI, 0.24-0.79) alone for reducing the CVA occurrence in the ADPKD population. In conclusion, ADPKD was associated with an increased risk of CVA occurrence. Combined RAAS blockade and statin therapy effectively reduces the risk of CVA in ADPKD.

Intracranial aneurysms in patients with autosomal dominant polycystic kidney disease: prevalence, risk of rupture, and management. A systematic review.

Autosomal dominant polycystic kidney disease (ADPKD) is a genetic disorder associated with high incidences of intracranial aneurysms. We performed a systematic review with the purpose of clarifying the prevalence, risk of rupture, and appropriate management of intracranial aneurysms in the ADPKD population. PRISMA guidelines were followed. We conducted a comprehensive literature search of three databases (PubMed, Ovid MEDLINE, and Ovid EMBASE) on all series reporting ADPKD patients with intracranial aneurysms. Our systematic review included 16 articles with a total of 563 patients with ADPKD and intracranial aneurysms. The prevalence of unruptured aneurysms was 11.5% (95% CI = 10.1-13%), whereas 1.9% (95% CI = 1.3-2.6%) of aneurysms were ruptured. Hypertension was present in 79.3% of patients with ADPKD and renal impairment in 65%. The mean size of ruptured aneurysms was slightly higher than unruptured (6mm vs. 4.4mm). The most common locations of unruptured and ruptured aneurysms were the ICA (40.5%) and MCA (45%), respectively. Asymptomatic patients studied with four-vessel angiography experienced 25% transient complications. Overall, 74% unruptured aneurysms were surgically treated with lower complication rates compared to endovascular treatment (11% vs. 27.7%). Among conservatively treated aneurysms, 2.9% ruptured at follow-up (rupture rate 0.4%/patient-year). Finally, the growth rate was 0.4% per patient-year, and the incidence of de novo aneurysm formation was 1.4% per patient-year. The prevalence of unruptured intracranial aneurysms in the ADPKD population is approximately 11%. Given the non-negligible rate of procedural complications, the management of these patients must be cautious and individualised. The rupture rate appears comparable to that of the general population. On the other hand, the 1.4% rate per patient-year of de novo aneurysms is non-negligible. These findings should be considered when counselling ADPKD patients regarding the appropriate management of intracranial aneurysms.

Endothelial Nitric Oxide Synthase Gene Expression Is Associated with Hypertension in Autosomal Dominant Polycystic Kidney Disease

Background/Aims: Early occurrence of hypertension is the prominent feature of autosomal dominant polycystic kidney disease (ADPKD). The role of angiotensin-converting enzyme (ACE) gene polymorphism and endothelial nitric oxide synthase (eNOS) gene polymorphism in the clinical course of ADPKD is not well understood. However, data about the expression of these genes are lacking. Thus, we aimed to investigate the polymorphisms and expressions of both the ACE and eNOS genes that affect hypertension in ADPKD. Methods: Whole blood samples were obtained from all participants. ACE and eNOS gene polymorphisms and their expressions were analyzed in 78 ADPKD patients and 30 controls. Gene expressions were assessed by quantitative real-time PCR. Twenty-four-hour blood pressure monitoring was performed for the diagnosis of hypertension in all study participants. Results:eNOS expression and the estimated glomerular filtration rate were found to be significantly higher in ADPKD patients without hypertension than in those with hypertension. Each unit of increase in eNOS expression led to a 0.88-fold decrease (95% CI: 0.80-0.96) in the risk of hypertension in multiple logistic regression analysis. Conclusions:eNOS gene expression is independently predictive of hypertension in the ADPKD population. This study showed, for the first time, a novel link between eNOS gene expression and hypertension in ADPKD.

Prevalence of Cardiovascular Events in Patients with Autosomal Dominant Polycystic Kidney Disease

Background: This study evaluates the prevalence of cardiovascular events in autosomal dominant polycystic kidney disease (ADPKD) patients. Methods: We distributed surveys to 1,439 subjects from our ADPKD research database. In total, 426 subjects completed and returned surveys; 7 of these were from children and were excluded from the study. Results: The patients who responded were female (63.2%), nonHispanic (88.1%) and white (93.6%). The mean age of the total group was 53.2 ± 13.7 years; 82.8% had a family history of ADPKD and 32.5% had reached end-stage renal disease (ESRD). With respect to cardiovascular risk factors, 86.6% were hypertensive with a mean age at diagnosis of 36.9 ± 12.9 years and hypertension was significantly more prevalent in males. In addition, 19.6% of the subjects were obese, 20.8% were smokers, 8.7% had diabetes, 45.7% had high cholesterol and 17.8% were sedentary. The most prevalent self-reported cardiovascular events were arrhythmias (25.9%), evidence of peripheral vascular disease (16.5%), heart valve problems (14.4%), cardiac enlargement (9.5%), stroke or cerebral bleeding (7.5%), myocardial infarction (6%) and brain aneurysm (5.0%). The most commonly used antihypertensive medications were renin-angiotensin inhibitors used by 75% of ADPKD patients. Older ADPKD patients and those at ESRD had a significantly higher incidence of cardiovascular events. Conclusion: These findings support the high prevalence of cardiovascular risk factors and events in ADPKD patients which contribute to a greater mortality risk. Due to the prevalence of cardiovascular risk factors in the ADPKD population, early diagnosis and clinical intervention are recommended.

Rationale and Design of the TEMPO (Tolvaptan Efficacy and Safety in Management of Autosomal Dominant Polycystic Kidney Disease and Its Outcomes) 3-4 Study

Current management of autosomal dominant polycystic kidney disease (ADPKD) is focused on treating disease complications, not on slowing cyst development or preventing progression to kidney failure. Tolvaptan, a selective vasopressin V2 (vasopressin 2) receptor antagonist, has been proved to inhibit kidney cyst growth and preserve kidney function in multiple animal models of polycystic kidney disease. The TEMPO (Tolvaptan Efficacy and Safety in Management of Autosomal Dominant Polycystic Kidney Disease and Its Outcomes) 3-4 Study will examine the long-term effectiveness and safety of tolvaptan in patients with ADPKD. We report baseline characteristics and revised power calculations for the trial. A prospective, 3-year, multicenter, double-blind, placebo-controlled trial of tolvaptan, a selective V2 receptor antagonist. Primary outcome is total kidney volume percentage of change from baseline for tolvaptan relative to placebo. Secondary outcome parameters include time to ADPKD-associated complications (kidney function decrease, blood pressure control, renal pain, and albuminuria) and safety end points. This trial includes patients with ADPKD with relatively preserved kidney function (baseline estimated creatinine clearance ≥60 mL/min), aged 50 years or younger, and with total kidney volume measured using magnetic resonance imaging ≥750 mL. Administration of placebo or tolvaptan, dose titrated to tolerance. Number of subjects enrolled and baseline characteristics. Total kidney volume, kidney function, albuminuria, kidney pain, and vital signs. 1,445 patients with ADPKD were enrolled between March 2007 and January 2009. Preliminary baseline median total kidney volume was 1.46 L, and estimated creatinine clearance was 105 ± 34 mL/min. A prespecified blinded sample-size recalculation at two-thirds enrollment confirmed the likely power of the study to detect 20% differences from placebo in the primary and key secondary end points at P < 0.05. This is a preselected ADPKD population chosen for its risk of progression to kidney failure and may not represent the general ADPKD population. If study results are positive with regard to the primary end point, positive effects on other secondary clinical outcomes will be required to assess overall benefit. This randomized trial is the largest clinical study of a proposed ADPKD intervention to date. It targets patients with ADPKD with early disease who are projected to have rapid cyst growth and accelerated outcomes. Blockade of vasopressin V2 receptor is hypothesized to inhibit cyst growth, thereby delaying additional adverse clinical outcomes.

Tradução, adaptação cultural e aplicação de um questionário de dor para pacientes com doença renal policística

Pain is a common symptom in patients with autosomal dominant polycystic kidney disease (ADPKD), affecting around 60% of cases. Translate a pain questionnaire developed and validated for ADPKD in USA into Portuguese and to perform its cultural adaptation and apply it. The cultural adaptation performed by a panel of experts resulted in small changes consisting of words substitution by synonyms or deletion of terms not commonly used in our culture in 12 out of the 46 questions posed, to solve patients difficulties in understanding the questionnaire. There has been equivalence between the adapted form of the instrument with the back-translation. The final form of the questionnaire applied in 97 patients with ADPKD (64F/33M, 35 ± 12 years) showed that 65 (67%) had isolated or associated pain in multiple locations , more often at lumbar region (77%), followed by abdominal (66%), headache (15%) and chest (4%). The questionnaire revealed that after family history, pain was the second factor contributing to the diagnosis of ADPKD in this population (55% and 22% of cases, respectively). Clinical and laboratory data from medical records showed that patients referring pain had renal volume and size of the largest cyst significantly higher than those without pain. We conclude that the use of a specific pain questionnaire for ADPKD population provided a better characterization of this symptom, as well as its relationship with the associated complications that commonly occur in this setting.

Comprehensive Molecular Diagnostics in Autosomal Dominant Polycystic Kidney Disease

Mutation-based molecular diagnostics of autosomal dominant polycystic kidney disease (ADPKD) is complicated by genetic and allelic heterogeneity, large multi-exon genes, duplication of PKD1, and a high level of unclassified variants (UCV). Present mutation detection levels are 60 to 70%, and PKD1 and PKD2 UCV have not been systematically classified. This study analyzed the uniquely characterized Consortium for Radiologic Imaging Study of PKD (CRISP) ADPKD population by molecular analysis. A cohort of 202 probands was screened by denaturing HPLC, followed by direct sequencing using a clinical test of 121 with no definite mutation (plus controls). A subset was also screened for larger deletions, and reverse transcription-PCR was used to test abnormal splicing. Definite mutations were identified in 127 (62.9%) probands, and all UCV were assessed for their potential pathogenicity. The Grantham Matrix Score was used to score the significance of the substitution and the conservation of the residue in orthologs and defined domains. The likelihood for aberrant splicing and contextual information about the UCV within the patient (including segregation analysis) was used in combination to define a variant score. From this analysis, 44 missense plus two atypical splicing and seven small in-frame changes were defined as probably pathogenic and assigned to a mutation group. Mutations were thus defined in 180 (89.1%) probands: 153 (85.0%) PKD1 and 27 (15.0%) PKD2. The majority were unique to a single family, but recurrent mutations accounted for 30.0% of the total. A total of 190 polymorphic variants were identified in PKD1 (average of 10.1 per patient) and eight in PKD2. Although nondefinite mutation data must be treated with care in the clinical setting, this study shows the potential for molecular diagnostics in ADPKD that is likely to become increasingly important as therapies become available.

Follow-up of intracranial aneurysms in autosomal-dominant polycystic kidney disease

Approximately 8% of autosomal-dominant polycystic kidney disease (ADPKD) patients have intracranial aneurysms. The risk of growth and rupture of those discovered by presymptomatic screening is key to the feasibility and success of a screening program. This study was initiated to ascertain this risk. ADPKD patients were offered screening with magnetic resonance (MR) imaging that included three-dimensional time-of-flight MR angiographic and three-dimensional phase-contrast sequences. Patients with aneurysms were recommended periodic surveillance, initially at 6 months and yearly, and less frequently after demonstration of their stability. Twenty-two saccular and one fusiform aneurysms were detected at the initial screening in 21 patients from 19 families (seven men and 14 women, 47.9 +/- 10.6 years old). All the saccular aneurysms were small (mean diameter 3.5 mm, range 2.0 to 6.5 mm) and the majority (77%) in the anterior circulation. Two patients died from unrelated causes without further follow-up. One patient was lost to follow-up. A new 2 mm middle cerebral artery aneurysm developed in one patient. One aneurysm increased from a size of 4 mm to 5 mm after a follow-up of 105 months. No aneurysmal development or growth occurred in the remaining 16 patients. No aneurysmal rupture occurred during a mean imaging follow-up of 81 months and a mean clinical follow-up of 92 months. During the period of the study, two additional ADPKD patients, with three intracranial aneurysms detected elsewhere by presymptomatic MR angiographic screening, were referred for surgical treatment. The larger size of these aneurysms (10, 8, and 8 mm) probably reflects referral bias. Most intracranial aneurysms detected by presymptomatic screening in ADPKD patients are small and in the anterior circulation. The follow-up results do not suggest an increased risk for growth and rupture, compared to those of intracranial aneurysms in the general population. These data do not support widespread screening for intracranial aneurysms in the ADPKD population.

PKD2 mutations in a Czech population with autosomal dominant polycystic kidney disease.

Autosomal dominant polycystic kidney disease (ADPKD) is genetically heterogeneous and caused by mutations in at least three different loci. Based on linkage analysis, mutations in the PKD2 gene are responsible for approximately 15% of the cases. PKD2-linked ADPKD is supposed to be a milder form of the disease, its mean age of end-stage renal failure (ESRF) approximately 20 years later than PKD1. We screened all coding sequences of the PKD2 gene in 115 Czech patients. From dialysis centres in the Czech Republic and from the Department of Nephrology of the General Hospital in Prague, we selected 52 patients (29 males, 23 females), who reached ESRF after the age of 63, and 10 patients (three males, seven females) who were not on renal replacement therapy at that age. The age of 63 was used as the cut-off because it is between the recently published ages of onset of ESRF for PKD1 and PKD2. From PKD families we also selected 53 patients (26 males, 27 females) who could be linked to either the PKD1 or PKD2 genes by linkage analysis. An affected member from each family was analysed by heteroduplex analysis (HA) for all 15 coding regions. Samples exhibiting shifted bands on gels were sequenced. We detected 22 mutations (six new mutations)-14 mutations in 62 patients (23%) with mild clinical manifestations, eight in 53 families (15%) with possible linkage to both PKD genes. As the detection rate of HA is approximately 70-80%, we estimate the prevalence of PKD2 cases in the Czech ADPKD population to be 18-20%. We identified nonsense mutations in eight patients (36.5%), frameshifting mutations in 12 patients (54.5%) and missense mutations in two patients (9%). In this study in the Czech population we identified 22 mutations (six of which were new mutations). The prevalence of PKD2 cases was 18-20% and the mean age of ESRF was 68.3 years. An at-least weak hot spot in exon 1 of the PKD2 gene was found.

Survival after end-stage renal disease in autosomal dominant polycystic kidney disease: Contribution of extrarenal complications to mortality

Autosomal dominant polycystic kidney disease (ADPKD) accounts for 8% to 10% of patients with end-stage renal disease (ESRD) in the United States and Europe. Progressive expansion of multiple bilateral renal cysts leads to massive enlargement of the kidneys and progressive renal failure. Extrarenal manifestations of ADPKD, such as liver cysts, intracranial aneurysms, cardiac valvular disease, and perhaps diverticulosis, have been documented extensively in cross-sectional studies, but little is known about their natural history. It is thought that extrarenal aspects of ADPKD contribute to increased mortality, yet survival on dialysis of the ADPKD population surpasses that of the general dialysis population. To address this issue, we analyzed the relative risk and causes of death after ESRD in ADPKD versus nondiabetic controls using data from the United States Renal Data System. Relative risk of death from any cause, including the major extrarenal manifestations of ADPKD, was determined as a function of ESRD treatment modality (dialysis or transplantation). We found a lower total mortality rate in ADPKD ESRD patients compared with nondiabetic control ESRD patients (relative risk of death in ADPKD = 0.57; P < 0.001). Mortality rates of extrarenal complications except for polycystic liver disease were similar or lower in ADPKD patients than in nondiabetic controls. Mortality secondary to extrarenal complications was substantially lower than that secondary to cardiovascular or cerebrovascular disease. © 2001 by the National Kidney Foundation, Inc.

Increased prevalence of polycystic kidney disease type 2 among elderly polycystic patients

Autosomal dominant polycystic kidney disease (ADPKD) is genetically heterogeneous, with at least three chromosomal loci (PKD1, PKD2, and PKD3 ) accounting for the disease. Mutations in the PKD2 gene, on the long arm of chromosome 4, are estimated to be responsible for 15% of the cases of ADPKD, based on linkage studies. PKD2 is a milder form of the disease, with a mean age of end-stage renal disease (ESRD) approximately 20 years later than PKD1. The object of this study is to determine the proportion of elderly patients with ADPKD with ESRD who harbor mutations in the PKD2 gene. We analyzed all exons and intron-exon boundaries of the PKD2 gene by single-strand conformation polymorphism analysis and silver staining technique in 46 patients with ADPKD who reached ESRD after the age of 63 years or were not yet undergoing renal replacement therapy (RRT) by that age. We performed exactly the same studies in a control group of 40 patients with ADPKD with unknown gene status aged younger than 63 years. In 22 patients, a mutation in the PKD2 gene was defined: 18 of 46 patients from the elderly group and 4 of 40 patients from the control group. We identified 14 different mutations: 4 nonsense mutations, 1 missense mutation, 5 small deletions, 2 insertions, 1 deletion of the whole PKD2 gene, and 1 splicing mutation. Five of these mutations previously were described by our group. Three of the mutations reported in the present study are recurrent. The prevalence of PKD2 disease among elderly patients with ADPKD undergoing RRT is 39.1%, almost three times the prevalence of the disease in the general ADPKD population.