Steven D. Soroka

KLHL3 mutations cause familial hyperkalemic hypertension by impairing ion transport in the distal nephron

Familial hyperkalemic hypertension (FHHt) is a Mendelian form of arterial hypertension that is partially explained by mutations in WNK1 and WNK4 that lead to increased activity of the Na+-Cl− cotransporter (NCC) in the distal nephron. Using combined linkage analysis and whole-exome sequencing in two families, we identified KLHL3 as a third gene responsible for FHHt. Direct sequencing of 43 other affected individuals revealed 11 additional missense mutations that were associated with heterogeneous phenotypes and diverse modes of inheritance. Polymorphisms at KLHL3 were not associated with blood pressure. The KLHL3 protein belongs to the BTB-BACK-kelch family of actin-binding proteins that recruit substrates for Cullin3-based ubiquitin ligase complexes. KLHL3 is coexpressed with NCC and downregulates NCC expression at the cell surface. Our study establishes a role for KLHL3 as a new member of the complex signaling pathway regulating ion homeostasis in the distal nephron and indirectly blood pressure.

Health-related Quality of Life in CKD Patients: Correlates and Evolution over Time

BACKGROUND AND OBJECTIVES Very few large-scale studies have investigated the determinants of health-related quality of life (HRQOL) in chronic kidney disease (CKD) patients not on dialysis or the evolution of HRQOL over time. DESIGN AND SETTING A prospective evaluation was undertaken of HRQOL in a cohort of 1186 CKD patients cared for in nephrology clinics in North America. Baseline and follow-up HRQOL were evaluated using the validated Kidney Disease Quality Of Life instrument. RESULTS Baseline measures of HRQOL were reduced in CKD patients in proportion to the severity grade of CKD. Physical functioning score declined progressively with more advanced stages of CKD and so did the score for role-physical. Female gender and the presence of diabetes and a history of cardiovascular co-morbidities were also associated with reduced HRQOL (physical composite score: male: 41.0 +/- 10.2; female: 37.7 +/- 10.8; P < 0.0001; diabetic: 37.3 +/- 10.6; nondiabetic: 41.6 +/- 10.2; P < 0.0001; history of congestive heart failure, yes: 35.4 +/- 9.7; no: 40.3 +/- 10.6; P < 0.0001; history of myocardial infarction, yes: 36.1 +/- 10.0; no: 40.2 +/- 10.6; P < 0.0001). Anemia and beta blocker usage were also associated with lower HRQOL scores. HRQOL measures declined over time in this population. The main correlates of change over time were age, albumin level and co-existent co-morbidities. CONCLUSIONS These observations highlight the profound impact CKD has on HRQOL and suggest potential areas that can be targeted for therapeutic intervention.

Health-related quality of life and hemoglobin levels in chronic kidney disease patients.

BACKGROUND The relationship between quality of life (QofL) and anemia has been the subject of recent debates; it has been suggested that the QofL changes associated with the treatment of anemia of chronic kidney disease (CKD) or ESRD patients should not be used in making decisions to treat anemia in CKD patients. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This study examines the relationship between Kidney Disease Quality of Life (KDQofL) questionnaire domains and hemoglobin (Hgb) levels in 1200 patients with stage 3, 4, and 5 CKD followed in seven centers. QofL measures were compared in a stepwise fashion for hemoglobin levels of <11, 11 to <12, 12 to <13, and > or =13. ANOVA was used to examine the relationship between QofL scores and Hgb level, age, CKD stage, and albumin level; a history of diabetes, congestive heart failure, or myocardial infarction; use of erythropoetic-stimulating agents (ESA); and the interaction of hemoglobin level and ESA. RESULTS The results demonstrate that with increasing Hgb levels there is a statistically significant increase in all four physical domains, the energy/vitality domain, and the physical composite score of the SF-36, and the general health score on the kidney disease component of the questionnaire. The most dramatic improvements in these various domains occurred between the <11 and the 11 to 12 group. CONCLUSIONS Higher Hgb levels are associated with improved QofL domains of the KDQofL questionnaire. These findings have implications for the care of CKD patients in terms of the initiation of and the Hgb target of ESA therapy.

A Nurse-coordinated Model of Care versus Usual Care for Stage 3/4 Chronic Kidney Disease in the Community: A Randomized Controlled Trial

BACKGROUND AND OBJECTIVES It is unclear how to optimally care for chronic kidney disease (CKD). This study compares a new coordinated model to usual care for CKD. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS A randomized trial in nephrology clinics and the community included 474 patients with median estimated GFR (eGFR) 42 ml/min per 1.73 m(2) identified by laboratory-based case finding compared care coordinated by a general practitioner (controls) with care by a nurse-coordinated team including a nephrologist (intervention) for a median (interquartile range [IQR]) of 742 days. 32% were diabetic, 60% had cardiovascular disease, and proteinuria was minimal. Guided by protocols, the intervention team targeted risk factors for adverse kidney and cardiovascular outcomes. Serial eGFR and clinical events were tracked. RESULTS The average decline in eGFR over 20 months was -1.9 ml/min per 1.73 m(2). eGFR declined by ≥4 ml/min per 1.73 m(2) within 20 months in 28 (17%) intervention patients versus 23 (13.9%) control patients. Control of BP, LDL, and diabetes were comparable across groups. In the intervention group there was a trend to greater use of renin-angiotensin blockers and more use of statins in those with initial LDL >2.5 mmol/L. Treatment was rarely required for anemia, acidosis, or disordered mineral metabolism. Clinical events occurred in 5.2% per year. CONCLUSIONS Patients with stage 3/4 CKD identified through community laboratories largely had nonprogressive kidney disease but had cardiovascular risk. Over a median of 24 months, the nurse-coordinated team did not affect rate of GFR decline or control of most risk factors compared with usual care.

A prospective evaluation of renal replacement therapy modality eligibility

BACKGROUND Patient eligibility for renal replacement therapy (RRT) modalities is frequently debated, but little prospective data are available from large patient cohorts. METHODS We prospectively evaluated medical and psychosocial eligibility for the three RRT modalities in patients with chronic kidney disease (CKD) stages III-V who were enrolled in an ongoing prospective cohort study conducted at seven North American nephrology practices. RESULTS Ninety-eight percent of patients were considered medically eligible for haemodialysis (HD), 87% of patients were assessed as medically eligible for peritoneal dialysis (PD) and 54% of patients were judged medically eligible for transplant. Age was the leading cause of non-eligibility for both PD and transplant. Anatomical concerns (adhesions, hernias) were the second most frequent concern for PD eligibility followed by weight. Weight was also a concern for transplant eligibility. The proportion of patients medically eligible for RRT did not vary by CKD stage. There was, however, significant inter-centre variation in the proportion of patients medically eligible for PD and transplant. Ninety-five percent of patients were considered psychosocially eligible for HD, 83% of patients were assessed as psychosocially eligible for PD and 71% of patients were judged psychosocially eligible for transplant. The percentage of patients who were assessed as having neither medical nor psychosocial contraindications for RRT was 95% for HD, 78% for PD and 53% for transplant. CONCLUSIONS Most CKD patients are considered by their medical care providers to be suitable for PD. Enhanced patient education, promotion of home dialysis for suitable patients and empowerment of patient choice are expected to augment growth of home dialysis modalities.

Cost-effectiveness analysis of a randomized trial comparing care models for chronic kidney disease.

BACKGROUND AND OBJECTIVES Potential cost and effectiveness of a nephrologist/nurse-based multifaceted intervention for stage 3 to 4 chronic kidney disease are not known. This study examines the cost-effectiveness of a chronic disease management model for chronic kidney disease. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Cost and cost-effectiveness were prospectively gathered alongside a multicenter trial. The Canadian Prevention of Renal and Cardiovascular Endpoints Trial (CanPREVENT) randomized 236 patients to receive usual care (controls) and another 238 patients to multifaceted nurse/nephrologist-supported care that targeted factors associated with development of kidney and cardiovascular disease (intervention). Cost and outcomes over 2 years were examined to determine the incremental cost-effectiveness of the intervention. Base-case analysis included disease-related costs, and sensitivity analysis included all costs. RESULTS Consideration of all costs produced statistically significant differences. A lower number of days in hospital explained most of the cost difference. For both base-case and sensitivity analyses with all costs included, the intervention group required fewer resources and had higher quality of life. The direction of the results was unchanged to inclusion of various types of costs, consideration of payer or societal perspective, changes to the discount rate, and levels of GFR. CONCLUSIONS The nephrologist/nurse-based multifaceted intervention represents good value for money because it reduces costs without reducing quality of life for patients with chronic kidney disease.

Canadian Society of Nephrology Commentary on the 2009 KDIGO Clinical Practice Guideline for the Diagnosis, Evaluation, and Treatment of CKD–Mineral and Bone Disorder (CKD-MBD)

Professional societies throughout the world, ncluding the Canadian Society of Nephrology CSN), agree there is a need for developing linical practice guidelines for patients with hronic kidney disease (CKD). However, as illusrated by the case of the plethora of anemia uidelines for CKD that have been completed and updated) by many national professional ocieties since 2000, creation of guidelines by ndividual professional societies results in signifiant duplication of effort. In this context, KDIGO Kidney Disease: Improving Global Outcomes) as established in 2003 with its stated mission to improve the care and outcomes of kidney disase patients worldwide through promoting coorination, collaboration, and integration of initiaives to develop and implement clinical practice uidelines.” The KDIGO Clinical Practice Guideline for he Diagnosis, Evaluation, Prevention, and Treatent of Chronic Kidney Disease–Mineral and

Frailty and Mortality in Dialysis: Evaluation of a Clinical Frailty Scale

BACKGROUND AND OBJECTIVES Frailty is associated with poor outcomes for patients on dialysis; however, previous studies have not taken into account the severity of frailty as a predictor of outcomes. The purpose of this study was to assess if there was an association between the degree of frailty and mortality among patients on incident dialysis. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS A cohort study of incident chronic dialysis patients was conducted between January of 2009 and June of 2013 (last follow-up in December of 2013). On the basis of overall clinical impression, the Clinical Frailty Scale (CFS) score was determined for patients at the start of dialysis by their primary nephrologist. This simple scale allocates a single point to different states of frailty (1, very fit; 2, well; 3, managing well; 4, vulnerable; 5, mildly frail; 6, moderately frail; 7, severely frail or terminally ill) with an emphasis on function of the assessed individual. The primary outcome was time to death. Patients were censored at the time of transplantation. RESULTS The cohort consisted of 390 patients with completed CFS scores (mean age of 63±15 years old). Most were Caucasian (89%) and men (67%), and 30% of patients had ESRD caused by diabetic nephropathy. The median Charlson Comorbidity Index score was 4 (interquartile range =3-6), and the median CFS score was 4 (interquartile range =2-5). There were 96 deaths over 750 patient-years at risk. In an adjusted Cox survival analysis, the hazard ratio associated with each 1-point increase in the CFS was 1.22 (95% confidence interval, 1.04 to 1.43; P=0.02). CONCLUSIONS A higher severity of frailty (as defined by the CFS) at dialysis initiation is associated with higher mortality.

Canadian Society of Nephrology Commentary on the 2012 KDIGO Clinical Practice Guideline for Anemia in CKD

The KDIGO (Kidney Disease: Improving Global Outcomes) 2012 clinical practice guideline for anemia management in patients with chronic kidney disease provides the structural and evidence base for the Canadian Society of Nephrology commentary on this guidelines relevancy and application to the Canadian health care system. While in general agreement, we provide commentary on 11 of the 61 KDIGO guideline statements. Specifically, we agreed that a therapeutic trial of iron is appropriate in cases in which a reduction in erythropoiesis-stimulating agent (ESA) dosage or avoidance of ESA and transfusion is desired, transferrin saturations are >30%, and ferritin concentrations are >500 μg/L. However, we concluded that there is insufficient evidence to support an upper target or threshold for ferritin and transferrin saturation levels. We agree with the initiation of ESA treatment when hemoglobin (Hb) level is 90-100 g/L; however, we specifically state that an acceptable range for Hb level is 95-115 g/L, with a target of 100-110 g/L, and add caution to individualization above this range due to concerns regarding the safety of ESAs. We agree that ESAs should be used with considerable caution in patients with active malignancy, history of stroke, or history of malignancy, and we suggest initiating ESA therapy at Hb level of 90 g/L and to aim for a Hb level in the range of 90-105 g/L. The reader is encouraged to note the level of evidence and review the entire KDIGO anemia guideline to interpret the guideline statements and commentary appropriately.

Biomarkers of inflammation, fibrosis, cardiac stretch and injury predict death but not renal replacement therapy at 1 year in a Canadian chronic kidney disease cohort

BACKGROUND Newer biomarkers, reflective of biological processes, such as inflammation and fibrosis, cardiac stretch or damage and vascular health may be useful in understanding clinical events in chronic kidney disease (CKD). We assessed whether these newer biomarkers, alone or as a panel, improve risk prediction for renal replacement therapy or death, over and above conventional clinical, demographic and laboratory variables. METHODS We conducted a prospective observational Canadian cohort study in 2544 CKD patients with estimated glomerular filtration rate (eGFR) of 15-45 mL/min/1.73 m(2), under nephrology care, in urban and rural centers. We measured traditional clinical and laboratory risk factors, as well as newer biomarkers: cystatin C, high sensitivity c-reactive protein (hsCRP), interleukin 6 (IL6), transforming growth factor β1 (TGFβ1), fibroblast growth factor 23 (FGF23), N-terminal probrain natriuretic peptide (NT-proBNP), troponin I and asymmetric dimethylarginine (ADMA). Key outcomes were renal replacement therapy (RRT, dialysis or transplantation) and death, during the first year follow-up after enrollment: a time point important for clinical decision-making for patients and providers. RESULTS Newer biomarkers do not improve the prediction of RRT, when added to conventional risk factors such as eGFR, urine albumin to creatinine ratio, hemoglobin, phosphate and albumin. However, in predicting death within 1 year, cystatin C, NT-proBNP, hsCRP and FGF23 values significantly improved model discrimination and reclassification: c statistic increased by absolute 4.3% and Net Reclassification Improvement for categories of low, intermediate and high risk at 11.2%. CONCLUSIONS Our findings suggest that the addition of newer biomarkers may be useful in predicting death in patients with established CKD within a 1-year timeframe. This information may be useful in informing prognosis and redirect resources to serve patients at higher risk to improve outcomes and sustainability of the nephrology care system.