Risk factors for end-stage renal disease: 25-year follow-up

Risk factors for progression of chronic kidney disease

PURPOSE OF REVIEW

The present review provides an overview of the identified risk factors for chronic kidney disease (CKD) progression emphasizing the pediatric population.

RECENT FINDINGS

Over the past 10 years, there have been significant changes to our understanding and study of preterminal kidney failure. Recent refinements in the measurement of glomerular filtration rate and glomerular filtration rate estimating equations are important tools for identification and association of risk factors for CKD progression in children. In pediatric CKD, lower level of kidney function at presentation, higher levels of proteinuria, and hypertension are known markers for a more rapid decline in glomerular filtration rate. Anemia and other reported risk factors from the pregenomic era require further study and validation. Genome-wide association studies have identified genetic loci that have provided novel genetic risk factors for CKD progression.

SUMMARY

With cohort studies of children with CKD becoming mature, they have started to yield important refinements to the assessment of CKD progression. Although many of the traditional risk factors for renal progression will certainly be assessed, such cohorts will be important for evaluating novel risk factors identified by genome-wide studies.

Can we slow the progression of chronic kidney disease?

PURPOSE OF REVIEW

Childhood chronic kidney disease usually progresses towards end-stage renal failure once a critical impairment of renal function has occurred. This process is largely independent of the underlying renal disease. Recent clinical trials have provided evidence that the progressive course of chronic kidney disease can be slowed substantially by pharmacological intervention.

RECENT FINDINGS

Hypertension and proteinuria are the most important independent risk factors for renal disease progression in both adult and pediatric nephropathies. Pharmacological blockade of the renin-angiotensin system provides efficient control of blood pressure and proteinuria, and superior long-term renoprotection compared with other antihypertensive agents. Recent pediatric evidence supports the renoprotective efficacy of tight blood pressure control aiming for the low-normal range. In addition, promising preliminary findings suggest an additional renoprotective potential by correction of metabolic acidosis and hyperuricemia and by administration of antiproliferative and antioxidative drugs.

SUMMARY

Pharmacological renoprotection currently focuses on antihypertensive and antiproteinuric treatment by blockade of the renin-angiotensin system. Intensified blood pressure control can improve 5-year renal survival by 35% in children with chronic kidney disease. Additional complementary strategies under current clinical evaluation bear potential to improve renal survival even further.

The databases: renal replacement therapy since 1989--the European Renal Association and European Dialysis and Transplant Association (ERA-EDTA)

Chronic kidney disease is now considered a public health priority, and the prevalence of this disease is approximately 10% in both North American and European countries. Such a phenomenon raises concern about the future increased incidence of ESRD. A recent analysis in the European Renal Association-European Dialysis and Transplant Association Registry shows that the incidence rates in Northern European countries have stabilized at approximately 110 per million people, a phenomenon that is associated with a parallel stabilization in the incidence of ESRD caused by diabetes. Such a stabilization has occurred in the face of an increasing prevalence of diabetes and hypertension in the general population, suggesting that this improvement may be the result of better prevention. Genetic factors, competing risks with other diseases, and other medical factors explain only in part the variability in the incidence of renal replacement therapy in European countries. Health care financing priorities have an obvious influence on the outcome of ESRD. Nonmedical factors seem to be of importance at least equal to that of medical factors. In this respect, Dialysis Outcomes and Practice Patterns Study Europe has revealed relevant differences in clinical policies that are related to ESRD treatment among European countries.

New role for plasmin in sodium homeostasis

PURPOSE OF REVIEW

Hypertension and edema are clinical manifestations of the extracellular volume expansion generated by abnormal renal sodium handling. Perturbations in epithelial sodium channel (ENaC) activity disrupt volume homeostasis. ENaC activity can be enhanced by proteases that cleave its long extracellular domains. Recent evidence suggests that this mechanism may be involved in individuals with volume overload and proteinuria.

RECENT FINDINGS

Several observations indicate a link between proteinuria and hypertension, with proteinuria preceding and predicting the onset of incident hypertension in some individuals. Recently, enhanced cleavage of ENaC's extracellular loops was identified in kidney tissue of proteinuric mice. Plasmin, a serine protease known for its role in fibrinolysis, has been implicated as an activator of ENaC in proteinuric states as nephrotic urine activates ENaC expressed in a mouse collecting duct cell line, aprotinin-affinity precipitation of nephrotic urine abolishes its ability to activate ENaC, plasmin is a major component within aprotinin-affinity purified nephrotic urine and is absent in nonproteinuric urine, and plasmin activates ENaC by cleaving the extracellular loop of its gamma subunit.

SUMMARY

Enhancement of ENaC activity by proteases represents a likely mechanism for extracellular volume overload relevant to some individuals with proteinuria. Proteases not normally found in the urine can enter the urinary space across damaged glomeruli and activate ENaC. Further understanding of this mechanism may guide targeted therapeutics in individuals with proteinuria, edema, and hypertension.

Mechanisms linking obesity, chronic kidney disease, and fatty liver disease: the roles of fetuin-A, adiponectin, and AMPK

Obesity is a risk factor for chronic kidney disease (CKD) and nonalcoholic fatty liver disease (NAFLD). Recent studies identify mechanisms common to both diseases linked through an interorgan communication orchestrated by fetuin-A and adiponectin. In liver and kidney, the energy sensor 5'-AMP activated protein kinase (AMPK) is pivotal to directing podocytes and hepatocytes to compensatory and potentially deleterious pathways, leading to inflammatory and profibrotic cascades culminating in end-organ damage. Regulation of these early upstream pathways may provide new therapeutic targets for these increasingly common sequelae of obesity.

Uric acid: a novel mediator and marker of risk in chronic kidney disease?

PURPOSE OF REVIEW

To assess the current data suggesting that uric acid-lowering therapy may be useful in the prevention or mitigation of chronic kidney disease (CKD).

RECENT FINDINGS

Eleven observational studies assessing the potential role of serum uric acid in the prevalence and progression of CKD have been published in the past 2 years. Seven suggest an association, whereas four do not. Recent experimental models and clinical trials have mechanistically linked serum uric acid and hypertension, an established risk factor for CKD.

SUMMARY

Elevated serum uric acid is a marker for decreased renal function, may have a mechanistic role in the incidence and progression of renal functional decline and likely has a causal role in hypertension and vascular disease. Clinical trials are needed to determine whether uric acid-lowering therapy will be effective in preventing CKD.

Sugar-sweetened soda consumption, hyperuricemia, and kidney disease

The metabolism of high-fructose corn syrup used to sweeten soda drinks may lead to elevations in uric acid levels. Here we determined whether soda drinking is associated with hyperuricemia and, as a potential consequence, reduced kidney function. At baseline, 15,745 patients in the Atherosclerosis Risk in Communities Study completed a dietary questionnaire and had measurements of their serum creatinine and uric acid. After 3 and 9 years of follow-up, multivariate odds ratios from logistic regressions for binary outcome of hyperuricemia and chronic kidney disease (eGFR less than 60 ml/min per 1.73 m(2)) were evaluated. Compared to participants who drank less, consumption of over one soda per day was associated with increased odds of prevalent hyperuricemia and chronic kidney disease. The odds ratio for chronic kidney disease significantly increased to 2.59 among participants who drank more than one soda per day and had a serum uric acid level over 9.0 mg/dl. In longitudinal analyses, however, drinking more than one soda per day was not associated with hyperuricemia or chronic kidney disease. Neither preexistent hyperuricemia nor development of hyperuricemia modified the lack of association between soda drinking and incident chronic kidney disease. Thus our study shows that high consumption of sugar-sweetened soda was associated with prevalent but not incident hyperuricemia and chronic kidney disease.

Risk of incident ESRD: a comprehensive look at cardiovascular risk factors and 17 years of follow-up in the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Diabetes and hypertension are potent risk factors for end-stage renal disease (ESRD). Previous studies suggest that other cardiovascular risk factors also may increase the risk of ESRD; however, risk associated with a comprehensive cardiovascular risk-factor assessment has not been quantified in a population-based sample.

STUDY DESIGN

The Atherosclerosis Risk in Communities (ARIC) Study, a prospective observational cohort.

SETTING & PARTICIPANTS

15,324 white and African American participants aged 45-64 years from 4 US communities were followed up after a baseline visit that occurred in 1987-1989.

PREDICTOR

A comprehensive collection of cardiovascular risk factors were examined.

OUTCOMES & MEASUREMENTS

Incidence of ESRD (transplant, dialysis, catheter placement or kidney failure, and death) exclusive of acute kidney failure was ascertained through active surveillance of hospitalizations through 2004.

RESULTS

During a median 16-year follow-up, 241 cases of ESRD developed (incidence rate, 1.04 cases/1,000 person-years). Male sex, African American race, diabetes, hypertension, history of coronary heart disease, smoking, older age, body mass index, and triglyceride concentration were associated with increased risk of ESRD after adjustment for baseline estimated glomerular filtration rate (eGFR) and each other. There was a graded curvilinear association between risk of ESRD and lower baseline eGFR at levels < 90 mL/min/1.73 m(2) and moderately increased levels > 120 mL/min/1.73 m(2). The relative risk of eGFR on ESRD risk generally was greater in women and individuals with diabetes than in their counterparts.

LIMITATIONS

Only events occurring in acute-care hospitals were investigated (but there was long-term continuous active surveillance of events).

CONCLUSIONS

We quantify the relative risk of ESRD in a community-based African American and white population associated with established cardiovascular risk factors (diabetes, hypertension, male sex, and African American race) and report prospective data identifying greater risk of ESRD associated with other cardiovascular risk factors: moderately decreased eGFR, increased eGFR, higher body mass index, smoking, and increased triglyceride level.

Characteristics of uninsured Americans with chronic kidney disease

BACKGROUND

In the United States, public health insurance is available for nearly all persons with end-stage renal disease (ESRD). Little is known about the extent of health insurance coverage for persons with non-dialysis dependent chronic kidney disease (CKD).

OBJECTIVE

To describe patterns of health insurance coverage for adults with non-dialysis dependent CKD and to examine risk factors for progression of CKD to ESRD and management of hypertension among those lacking insurance.

DESIGN AND PARTICIPANTS

Cross-sectional analysis of data from a nationally representative sample of 16,148 US adults aged 20 years or older who participated in the National Health and Nutrition Examination Survey 1999-2006.

MEASUREMENTS

National prevalence estimates of health insurance coverage, ESRD risk factors, and treatment of hypertension.

MAIN RESULTS

An estimated 10.0% (95% CI, 8.3%-12.0%) of US adults with non-dialysis dependent CKD were uninsured, 60.9% (95% CI, 58.2%-63.7%) had private insurance and 28.7% (95% CI, 26.4%-31.1%) had public insurance alone. Uninsured persons with non-dialysis dependent CKD were more likely to be under the age of 50 (62.8% vs. 23.0%, P < 0.001) and nonwhite (58.7%, vs. 21.8%, P < 0.001) compared with their insured counterparts. Approximately two-thirds of uninsured adults with non-dialysis dependent CKD had at least one modifiable risk factor for CKD progression, including 57% with hypertension, 40% who were obese, 22% with diabetes, and 13% with overt albuminuria. In adjusted analyses, uninsured persons with non-dialysis dependent CKD were less likely to be treated for their hypertension (OR, 0.59; 95% CI, 0.40-0.85) and less likely to be receiving recommended therapy with angiotensin inhibitors (OR, 0.45; 95% CI, 0.26-0.77) compared with those with insurance coverage.

CONCLUSIONS

Uninsured persons with non-dialysis dependent CKD are at higher risk for progression to ESRD than their insured counterparts but are less likely to receive recommended interventions to slow disease progression. Lack of public health insurance for patients with non-dialysis dependent CKD may result in missed opportunities to slow disease progression and thereby reduce the public burden of ESRD.

Dialysis-requiring acute renal failure increases the risk of progressive chronic kidney disease

To determine whether acute renal failure (ARF) increases the long-term risk of progressive chronic kidney disease (CKD), we studied the outcome of patients whose initial kidney function was normal or near normal but who had an episode of dialysis-requiring ARF and did not develop end-stage renal disease within 30 days following hospital discharge. The study encompassed 556,090 adult members of Kaiser Permanente of Northern California hospitalized over an 8 year period, who had pre-admission estimated glomerular filtration rates (eGFR) equivalent to or greater than 45 ml/min/1.73 m(2) and who survived hospitalization. After controlling for potential confounders such as baseline level of eGFR and diabetes status, dialysis-requiring ARF was independently associated with a 28-fold increase in the risk of developing stage 4 or 5 CKD and more than a twofold increased risk of death. Our study shows that in a large, community-based cohort of patients with pre-existing normal or near normal kidney function, an episode of dialysis-requiring ARF was a strong independent risk factor for a long-term risk of progressive CKD and mortality.

Uric acid is a strong independent predictor of renal dysfunction in patients with rheumatoid arthritis

Introduction

Recent evidence suggests that uric acid (UA), regardless of crystal deposition, may play a direct pathogenic role in renal disease. We have shown that UA is an independent predictor of hypertension and cardiovascular disease (CVD), and that CVD risk factors associate with renal dysfunction, in patients with rheumatoid arthritis (RA). In this study we investigated whether UA associates with renal dysfunction in patients with RA and whether such an association is independent or mediated through other comorbidities or risk factors for renal impairment.

Methods

Renal function was assessed in 350 consecutive RA patients by estimated glomerular filtration rate (GFR) using the six-variable Modification of Diet in Renal Disease equation. Risk factors for renal dysfunction were recorded or measured in all participants. Linear regression was used to test the independence of the association between GFR and UA.

Results

Univariable analysis revealed significant associations between GFR and age, systolic blood pressure, total cholesterol, triglycerides, RA duration and UA. UA had the most powerful association with renal dysfunction (r = -0.45, P < 0.001). A basic model was created, incorporating all of the above parameters along with body mass index and gender. UA ranked as the first correlate of GFR (P < 0.001) followed by age. Adjustments for the use of medications (diuretics, low-dose aspirin, cyclooxygenase II inhibitors and nonsteroidal anti-inflammatory drugs) and further adjustment for markers of inflammation and insulin resistance did not change the results.

Conclusions

UA is a strong correlate of renal dysfunction in RA patients. Further studies are needed to address the exact causes and clinical implications of this new finding. RA patients with elevated UA may require screening for renal dysfunction and appropriate management.