Prevalence of chronic kidney disease and decreased kidney function in the adult US population: Third National Health and Nutrition Examination Survey

Acute and chronic renal failure

Renal failure is defined as a deterioration of kidney function that results in the retention of nitrogenous waste products. It is increasingly prevalent in older populations, individuals with diabetes or hypertension, and postoperative patients. Therefore, podiatric physicians caring for these populations can expect to encounter this condition frequently. This article describes the epidemiology, causes, complications, and appropriate evaluation of renal failure relevant to a practicing podiatric physician. Also highlighted are treatment considerations, renal dosing of medications, and prevention of contrast nephropathy.

Relevancia de la insuficiencia renal en el pronóstico cardiovascular de los pacientes con hipertensión arterial esencial

Recently published guidelines recognize the relevance of the finding of chronic kidney disease in the stratification of risk of the hypertensive patient. Determination of the presence of microalbuminuria and estimation of glomerular filtration rate are mandatory in order to ensure an adequate evaluation of global cardiovascular risks in the hypertensive patient. The presence of subtle elevations of serum creatinine concentrations and/or proteinuria are also potent predictors of a poor cardiovascular prognosis. Clustering of associated risk factors seems to justify the elevated cardiovascular risk observed in patients with essential hypertension and mild alterations of renal function.

The role of renin-angiotensin-aldosterone system inhibition in chronic kidney disease

Chronic kidney disease (CKD) is emerging as a new health pandemic. Underlying the global rise in CKD is an increase in diabetes, hypertension and other cardiovascular risk factors leading to progressive renal dysfunction. Emerging evidence strongly suggests that achieving target blood pressure goals via inhibition of the renin-angiotensin-aldosterone system confers significant renal and cardioprotection for patients with CKD. Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) lower blood pressure, reduce proteinuria and reduce both the progression of CKD and adverse cardiovascular events. The role of aldosterone inhibition and combination therapy, such as ACEI/ARB, in CKD are under investigation. As our understanding of the basic mechanisms underlying CKD progression advances, novel therapies targeting post-translational endothelial and mesangial messengers downstream from angiotensin II and aldosterone may become available for clinical use.

Unreferred chronic kidney disease: a longitudinal study

BACKGROUND

Chronic kidney disease (CKD) is a major health problem. A better understanding of the epidemiological characteristics of the different stages of CKD and the associated adverse outcomes is needed to establish and implement appropriate management strategies.

METHODS

A serum creatinine (SCr) level of 2.03 mg/dL or greater (> or =180 micromol/L) in men and 1.53 mg/dL or greater (> or =135 micromol/L) in women was used to identify patients with moderate to severe CKD in a predominantly Caucasian area of the United Kingdom. Patients who were unknown to renal services were identified and followed up to establish survival, rate of referral, and change in glomerular filtration rate (GFR).

RESULTS

The prevalence of CKD defined by SCr cutoff values was 5,554 per million population (pmp). Median calculated GFR of the cohort was 28.5 mL/min/1.73 m2 (range, 4.1 to 42.8 mL/min/1.73 m2), and median age was 83 years (range, 18 to 103 years). A total of 84.8% of patients were unknown to renal services. During a mean follow-up of 31.3 months, 8.1% of patients were referred. Median survival of the unreferred population was 28.1 months. Cardiovascular disease, cancer, and infection were the most common causes of death. Male sex, low GFR, and nonreferral were associated with poor outcome. The majority of unreferred patients had stable renal function. The incidence of new unreferred CKD during the first year of follow-up was 2,435 pmp, such that the prevalence remained stable at 4,910 pmp. Significant anemia (hemoglobin < 11 g/dL [<110 g/L]) was seen in 27.5% of the unreferred cohort.

CONCLUSION

Referral of all patients with CKD is unrealistic and inappropriate. Management strategies aimed at improving adverse outcomes need to take account of this and be developed and implemented through collaboration between primary care and secondary care.

Special considerations in the treatment of patients with bipolar disorder and medical co-morbidities

BACKGROUND: The pharmacological treatment of bipolar disorder has dramatically improved with multiple classes of agents being used as mood-stabilizers, including lithium, anticonvulsants, and atypical antipsychotics. However, the use of these medications is not without risk, particularly when a patient with bipolar disorder also has comorbid medical illness. As the physician who likely has the most contact with patients with bipolar disorder, psychiatrists must have a high index of suspicion for medical illness, as well as a basic knowledge of the risks associated with the use of medications in this patient population. METHODS: A review of the literature was conducted and papers addressing this topic were selected by the authors. RESULTS AND DISCUSSION: Common medical comorbidities and treatment-emergent illnesses, including obesity, diabetes mellitus, dyslipidemia, cardiac disease, hepatic disease, renal disease, pulmonary disease and cancer are reviewed with respect to concomitant use of mood stabilizers. Guidance to clinicians regarding effective monitoring and treatment is offered. CONCLUSIONS: Mood-stabilizing medications are necessary in treating patients with bipolar disorder and often must be used in the face of medical illness. Their safe use is possible, but requires increased vigilance in monitoring for treatment-emergent illnesses and effects on comorbid medical illness.

Association of high serum creatinine and anemia increases the risk of coronary events: results from the prospective community-based atherosclerosis risk in communities (ARIC) study

Coronary heart disease (CHD) is a major cause of morbidity and mortality in patients with chronic kidney disease or anemia. The purpose of this study was to examine whether the association between renal function and risk of CHD is modified by hemoglobin (Hgb) status. Analyses were based on data from the Atherosclerosis Risk in Communities study, a community-based study of risk factors for CHD in middle-aged people. People with known CHD at baseline were excluded from the analysis. Participants were followed for 9 yr for the occurrence of CHD. Anemia was defined as Hgb <13 g/dl in men and <12 g/dl in women. Cox proportional hazards models were used to assess the relative risk (RR) of CHD occurrence according to Hgb status, after adjusting for other risk factors (demographics, lipids, diabetes, hypertension, smoking, body mass index, and carotid intima-media thickness). A total of 13,329 participants were included. The interaction between Hgb concentration and serum creatinine (Scr) was significant (P = 0.02). Among people with anemia, a Scr >/=1.2 mg/dl in women or >/=1.5 mg/dl in men was associated with a higher risk of CHD (RR, 2.74; 95% confidence interval, 1.42 to 5.28) than those with normal Scr. In contrast, among those without anemia, this association was not noted (RR, 1.20; 95% confidence interval, 0.86 to 1.67). In conclusion, this study indicates that high Scr is associated with almost a threefold risk of CHD among middle-aged people with anemia, whereas no increased risk is found in people with high Scr in the absence of anemia.

Fluvastatin prevents nephropathy likely through suppression of connective tissue growth factor-mediated extracellular matrix accumulation

Diabetic nephropathy is related to glomerular extracellular matrix (ECM) accumulation that leads to glomerulosclerosis. Fluvastatin as a lipid-lowering medicine significantly prevents diabetic nephropathy, probably not only through its lipid-lowering action, but also mainly through its direct suppression of glomerular ECM accumulation. To test this hypothesis, in the present study, a five-sixths nephrectomized (5/6Nx) rat model to induce a renal ECM accumulation without coexistence of hyperlipidemia was used to investigate the effect of fluvastatin on renal function, glomerular ECM accumulation and expression of connective tissue growth factor (CTGF). 5/6Nx induced a significant nephropathy in rats at 13 weeks, indicated by renal dysfunction including increases in blood urine nitrogen, creatinine and urinary protein excretion, and renal histopathological changes. Administration of fluvastatin significantly prevented the renal dysfunction and histological abnormalities in the 5/6Nx rats. Furthermore, both significant suppression of matrix metalloproteinases (MMPs) activity such as MMP-2 and significant activation of tissue inhibitors of MMP (TIMPs) such as TIMP-2 observed in the 5/6Nx rats were almost completely prevented by fluvastatin, resulting in a significant prevention of glomerular ECM accumulation. For upstream mediator of ECM accumulation, 5/6Nx significantly up-regulated CTGF mRNA expression, but fluvastatin treatment prevented CTGF up-regulation. These results suggest that fluvastatin, as one of well-known lipid-lowering agents, plays an important role in the prevention of nephropathy, likely through suppression of CTGF-mediated ECM accumulation. Therefore, fluvastatin may be a potential candidate for developing a pharmaceutical approach to the prevention of diabetic nephropathy due to its both lipid-lowering and direct anti-renal ECM accumulation actions.

Pharmacological strategies for kidney function preservation: are there differences by ethnicity?

The prevalence of chronic kidney disease (CKD) is on the rise in all ethnic groups. This is because of the increased prevalence of obesity, diabetes mellitus, the metabolic syndrome, and the inadequate control of elevated blood pressure and other cardiovascular-renal risk factors, especially in ethnic minority populations. The implications of the aforementioned trends in risk factor prevalence and control are profound. Moreover, these trends negatively impact patient quality of life and place an enormous financial burden on the health care system for the provision of care to patients with CKD, end-stage renal disease (ESRD), and/or cardiovascular disease (CVD). Thus, it is of utmost importance to devise strategies that prevent kidney disease and delay progressive loss of kidney function in persons with CKD. Proven strategies include pharmacological interventions that lower blood pressure to less than target levels (<130/80 mm Hg), attainment of optimal glycemic control (Hb A1c <7%), and reducing urinary protein excretion. It is also possible, although yet unproven, that correction of anemia and aggressive treatment of dyslipidemia may forestall the loss of kidney function. In general, ethnic minorities are underrepresented in most large trials. Recently, a few outcome clinical trials in blacks have reinforced the lessons of kidney function preservation already learned in nonblack populations. That is, the reversible risk factors for CKD appear to be virtually identical and, at least in nondiabetic CKD, pharmacological targeting of the renin-angiotensin-aldosterone system (RAAS) with angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers preserves kidney function better than non-RAAS blood pressure-lowering regimens, especially when significant proteinuria exists. Although more CKD studies in ethnic minorities are needed, until they become available, the best available evidence from the existing clinical trial database should be applied to minorities with CKD-even when specific data are not available for a specific racial or ethnic group. Why this approach? First, there are no known unique risk factors for kidney disease in any ethnic group. Second, poor control of reversible risk factors for CKD is universal, particularly in blacks and other ethnic minorities. Thus, it is logical to predict that more efficient use of strategies proven to forestall loss of kidney function will reduce the excess of CKD and ESRD in ethnic minorities relative to non-minority populations. However, medical-based strategies alone are probably not enough. The global epidemic of obesity will fuel the growing population of persons, especially among ethnic minorities, with diabetes, the main cause of CKD, ESRD, and CVD. The obesity and diabetes epidemics are unlikely to abate without innovative and ultimately effective public health approaches.

Calcium channel blockers and the kidney

Although end-stage renal disease (ESRD) currently affects only a small percentage (<0.2%) of the US population, its precursor, the mild and moderate forms of chronic kidney disease (CKD), affects 11% of the population, with significant growth in both ESRD and CKD anticipated in the rapidly aging US population. The primary diagnoses in the majority of ESRD patients are diabetes and hypertension. Results of clinical studies demonstrate that the level of proteinuria and sympathetic activation contribute to the progression of CKD to ESRD. There are sufficient clinical data to demonstrate that the dihydropyridine calcium channel blocker (DHP CCB) class of antihypertensives such as amlodipine and nifedipine, although effective in reducing systemic hypertension, lack activity in reducing proteinuria or attenuating sympathetic activity. Experimental studies and a limited number of clinical studies suggest that non-DHP CCBs, including verapamil and diltiazem, have a mechanism of action that differs from DHP CCBs. Non-DHP CCBs could potentially attenuate sympathetic activity and reduce protein excretion in patients with CKD.

Old and new cardiovascular risk factors: from unresolved issues to new opportunities

With the aim of identifying areas that may deserve some further thinking the present review deliberately points out controversial issues in cardiovascular research and risk assessment. In the first part of the review general aspects are addressed regarding the evaluation of risk factors. A first point of concern is the frequent practice of combining different vascular events and effects in different vascular beds into a single endpoint. Furthermore, verification of vascular events in clinical reality may be surprisingly inaccurate. Problems in risk assessment also arise from overlapping properties (shared pathophysiological pathways) of traditional risk factors like hypertension, obesity and diabetes. In the second part of the review unresolved issues concerning selected established and emerging risk factors are discussed. The difficulty of establishing causality in cardiovascular disease is addressed, using modification of LDL cholesterol and accumulating evidence for pleiotropic effects of the LDL cholesterol-lowering statins as an example. As an alternative or supplement to the notion of LDL-related cardiovascular risk it is proposed to distinguish between statin-sensitive and statin-insensitive cardiovascular risk. Finally the future prospects of selected new and emerging risk factors like CRP, homocysteine, asymmetrical dimethylarginine (ADMA), oxLDL, and isoprostanes are evaluated. In summary, imprecise terminology and varying definitions of "cardiovascular risk" may lead to a considerable blurring of our current risk estimates, which may also explain some presently controversial issues. With several new risk factors and substantial changes in lifestyle and treatment patterns on the horizon major changes in the hierarchy of risk factors may be inevitable.

RENAL RESEARCH INSTITUTE SYMPOSIUM: The Longitudinal Chronic Kidney Disease Study: A Prospective Cohort Study of Predialysis Renal Failure

Chronic kidney disease (CKD) is a significant public health problem: every year the number of Americans living with CKD and requiring renal replacement therapy increases. In addition, individuals with CKD have substantially increased morbidity and mortality compared to the general population. The Longitudinal Chronic Kidney Dialysis (LCKD) Study is a multicenter, prospective, observational study of patients with moderate to severe CKD that was designed to better describe the course of the disease and the determinants of patient outcomes. Patients with moderate to severe CKD (glomerular filtration rate [GFR] < 60 ml/min/m2) from four academic nephrology clinics were enrolled between 2000 and 2002. Special cardiac and vascular testing has recently commenced as phase II of this study. Areas that have been or are currently being studied include anemia management, health-related quality of life (HRQOL), medication use, and markers of cardiovascular disease. This article describes the LCKD Study in the context of current knowledge of CKD.

Chronic kidney disease and cardiovascular disease in the Medicare population

BACKGROUND

The extent of diabetes, chronic kidney disease (CKD), and cardiovascular disease (CVD) in the Medicare population is relatively unknown. Also unknown is the effect of these diseases on patient survival before end-stage renal disease (ESRD).

METHODS

Prevalent cohorts of Medicare enrollees from 1996 to 2000 were assessed for diabetes and CKD, presence of CVD, and probability of death versus ESRD in the follow-up period. Hospitalization rates and, in diabetics, lipid testing and glycemic control monitoring were also assessed.

RESULTS

The prevalence of diabetes in the Medicare population increased at 4.4% per year, reaching 18.9% in the 1999-2000 cohort. Approximately 726,000 elderly Medicare enrollees carry a diagnosis code for CKD. Those with CKD are 5 to 10 times more likely to die before reaching ESRD than the non-CKD group. In CKD patients, CVD is twice as common and advances at twice the rate. Cardiovascular disease advances at a similarly higher rate in CKD patients who die and those who survive to ESRD. Heart failure hospitalizations are 5 times greater in CKD patients and only 30% less than those in dialysis patients. Only half of the CKD patients with diabetes who advance to ESRD had a lipid or glycosylated hemoglobin test done in the year before or after dialysis initiation.

CONCLUSION

Diabetes, the leading cause of ESRD, is increasing in the general Medicare population at 4.4% per year. Cardiovascular disease is common, progresses at twice the rate, is associated with death before ESRD, and patients receive suboptimal risk factor monitoring. Active identification and treatment of CKD patients is needed.

Hospitalization during advancing chronic kidney disease

BACKGROUND

The care of patients with end-stage renal disease (ESRD) is associated with substantial costs to society, much of which is accounted for by a high rate of hospitalization. However, the influence of declining kidney function on hospitalization as ESRD approaches is not well understood.

METHODS

We performed a retrospective cohort study of national data to evaluate the frequency of hospitalizations among patients with chronic kidney disease (CKD) who reached ESRD and had at least 2 years of Medicare eligibility before initiation of dialysis therapy. The study period for each patient extended from 2 years before to 6 months after the initiation of dialysis therapy.

RESULTS

The study cohort was composed of 109,321 patients with a mean age of 75 years, all of whom initiated long-term dialysis therapy between 1995 and 1998. Mean hospitalization rate was 134 hospitalizations/1,000 patient-months at risk (PMAR). Hospitalization rates gradually increased as ESRD approached, peaking in the 3 months immediately after the initiation of dialysis therapy at 487 hospitalizations/1,000 PMAR. Cause-specific hospitalization rates mirrored this trend and were greatest for placement of vascular access and diagnoses related to cardiovascular (CVD) and infectious disease.

CONCLUSION

Hospitalizations during CKD become more frequent with the approach of ESRD. The majority of these hospitalizations, both before and after the initiation of dialysis therapy, are caused by comorbidity related to CKD. These hospitalizations may be favorably impacted on by heightened attention to the prevention and management of CVD and timely placement of vascular access during CKD.

The impact of calcimimetics on mineral metabolism and secondary hyperparathyroidism in end-stage renal disease

The impact of calcimimetics on mineral metabolism and secondary hyperparathyroidism in end-stage renal disease. Secondary hyperparathyroidism is often complicated by elevations in calcium and phosphorus either as a result of the disease per se or due to toxicity from current therapeutic options. These disturbances in mineral metabolism limit the successfulness of therapy and have been implicated as contributing to the development and progression of vascular calcification, an important and often overlooked component of cardiovascular disease in patients on dialysis. Phosphorus, active vitamin D, and calcium all play important roles in the pathogenesis of secondary hyperparathyroidism; however, serum calcium is the primary regulator of minute-to-minute parathyroid hormone secretion. Small changes in serum calcium are detected by a cell surface calcium sensing receptor that has recently been cloned. Calcimimetic agents modulate the activity of the calcium-sensing receptor and result in profound reductions in levels of circulating parathyroid hormone. Additionally, these agents result in decreases in serum calcium, phosphorus, and calcium-phosphorus product. Recently completed phase 2 clinical trials with the second-generation calcimimetic agent cinacalcet HCl confirm that this agent represents a safe and effective novel therapeutic agent which has the potential to dramatically alter the treatment and complications associated with secondary hyperparathyroidism in patients on dialysis.

Dialysis in pregnant women with chronic kidney disease

Pregnancy occurs uncommonly in women with chronic kidney disease (CKD) and fetal outcome tends to be poor, with high rates of prematurity and mortality. Dialysis, by complementing residual renal function, may improve fetal outcome in pregnant women with CKD. Although there are no prospective or randomized trials that examine the relationship between dialysis and fetal outcome, there is evidence that increased solute clearance, by early initiation of or intensification of dialysis, is beneficial for the health of the fetus. Case reports and observational studies from the United States, Belgium, and Saudi Arabia suggest that there is a relationship between successful pregnancy and the amount of dialysis received. Unfortunately, in these reports, measures of residual renal function and dialysis adequacy are lacking or incomplete. Nonetheless, compared to nonpregnant patients with CKD, in pregnant women with CKD it is reasonable to begin dialysis at a higher level of residual renal function in the hope of improving fetal outcome.

An integrated approach to care for patients with chronic kidney disease

Although the Kidney Disease Outcomes and Quality Initiative (K/DOQI) guidelines serve to integrate the multiple stages of chronic kidney disease (CKD), in practice, the treatment of kidney disease over its progressive course may be somewhat fragmented. Because the provision of integrated care across the stages of kidney disease, is likely to be advantageous for both patients and care providers, a conceptual framework which graphically depicts the complex and chronic nature of kidney disease may prove useful. The Life Options Rehabilitation Advisory Council (LORAC) proposes a cycle diagram to reflect the chronicity and complexity of kidney disease and to emphasize a holistic perception of kidney disease from its inception to the worst-case scenario outcome of kidney failure [corrected]. The kidney disease cycle conceptualization can serve as a patient teaching aid and as a reminder of the communication, collaboration, and cooperation that are required among primary care physicians and practitioners in each of the specialty areas that address the spectrum of kidney disease.

Receipt of renal replacement therapy in the United States: a population-based study of sociodemographic disparities from the Second National Health and Nutrition Examination Survey (NHANES II)

BACKGROUND

Persons with chronic kidney disease who need kidney replacement therapy to sustain life have health insurance. We examined whether young adults, women, blacks, less-educated persons, the poor, and persons residing in less populated areas receive treatment when health insurance is no longer a barrier.

METHODS

We conducted a case-control study nested in the Second National Health and Nutrition Examination Survey Mortality Study. Cases were persons treated with kidney replacement therapy determined by linkage to the end-stage renal disease treatment registry. Controls were untreated persons with kidney disease who died not appearing in the registry.

RESULTS

During 12 to 16 years, 44 persons developed treated disease, and 145 persons, untreated disease. After adjustment for sex, age, education, population of residential area, and comorbid conditions in logistic regression analysis, younger versus older age and living in a highly populated versus less populated area were both independently associated with treatment (relative odds of treatment, 5.57; 95% confidence interval, 1.72 to 18.0; and 4.33; 95% confidence interval, 2.09 to 8.97, respectively). Race, sex, education, and poverty were not associated with less treatment.

CONCLUSION

We found no disparity in life-saving chronic kidney disease treatment with regard to race or socioeconomic status in this population-based study. Less receipt of treatment by older adults may reflect greater comorbid disease or choices made by persons or their providers. Strategies to render treatment in less populated areas, including incentives to deliver care to such areas, should be encouraged.

Cinacalcet HCl: a calcimimetic agent for the management of primary and secondary hyperparathyroidism

Cinacalcet HCl (AMG 073) is an investigational oral calcimimetic drug currently being evaluated for the treatment of primary and secondary hyperparathyroidism (HPT). Calcimimetics bind to the calcium-sensing receptors of the parathyroid glands and lower the sensitivity for receptor activation by extracellular calcium, thereby diminishing parathyroid hormone release. Cinacalcet HCl has demonstrated efficacy in controlling the hypercalcaemia of severe primary HPT and in reducing parathyroid hormone levels in patients with secondary HPT. Asymptomatic dose-dependent hypocalcaemia has occurred in some clinical trials. This drug has a favourable pharmacokinetic profile compared to its precursors and will prove useful as an additional/alternative agent in patients with primary and secondary HPT.

National Kidney Foundation's Kidney Disease Outcomes Quality Initiative clinical practice guidelines for chronic kidney disease in children and adolescents: evaluation, classification, and stratification

OBJECTIVES

A series of new guidelines has been developed by the National Kidney Foundation's Kidney Disease Outcomes Quality Initiative to improve the detection and management of chronic kidney disease (CKD). In most instances of CKD, the earliest manifestations of the disorder may be identified by relatively simple tests. Unfortunately, CKD is often "underdiagnosed," in part because of the absence of a common definition of CKD and a classification of the stages in its progression. The Kidney Disease Outcomes Quality Initiative clinical practice guidelines for CKD evaluation, classification, and stratification provide a basis to remedy these deficits. The specific goals of the guidelines described in this review are to provide: 1) an overview of the clinical practice guidelines as they pertain to children and adolescents, 2) a simple classification of the stages of CKD, and 3) a practical approach to the laboratory assessment of kidney disease in children and adolescents.

METHODS

The guidelines were developed as part of an evidence-based evaluation of CKD and its consequences in patients of all ages. The data that were used to generate the guidelines in this article were extracted from a structured analysis of articles that reported on children with CKD.

RESULTS AND CONCLUSIONS

This review presents the definition and 5-stage classification system of CKD developed by the work group assigned to develop the guidelines, and summarizes the major recommendations regarding the early detection of CKD. Major emphasis is placed on the identification of children and adolescents with CKD by measuring the protein-to-creatinine ratio in spot urine specimens and by estimating the glomerular filtration rate from serum creatinine using prediction equations.