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

Darbepoetin alfa administered every other week maintains hemoglobin levels over 52 weeks in patients with chronic kidney disease converting from once-weekly recombinant human erythropoietin: results from simplify the treatment of anemia with Aranesp (STAAR)

BACKGROUND/AIM

Darbepoetin alfa, an effective treatment for anemia of chronic kidney disease (CKD), can be administered at extended intervals. Simplify the Treatment of Anemia with Aranesp (STAAR), a multicenter, 52-week study, was conducted to assess the efficacy of darbepoetin alfa administered subcutaneously every other week (Q2W) in maintaining hemoglobin (Hb) in CKD patients not receiving dialysis.

METHODS

This is a subgroup analysis of subjects converted from once-weekly (QW) recombinant human erythropoietin (rHuEPO; US Aranesp package insert) and who received up to 52 weeks of darbepoetin alfa therapy (evaluation period 20-32 weeks). Enrolled subjects had a creatinine clearance < or = 70 ml/min or an estimated glomerular filtration rate < or = 60 ml/min and transferrin saturation > or = 20%. Darbepoetin alfa doses were titrated to maintain Hb levels < or = 12 g/dl. The primary endpoint was mean Hb during evaluation.

RESULTS

There were 524 subjects enrolled in the study who were previously receiving rHuEPO QW. Mean Hb +/- standard deviation was 11.2 +/- 1.27 g/dl at baseline, and the least squares mean +/- SE was 11.4 +/- 0.04 during evaluation. The mean +/- SD Q2W darbepoetin alfa dose was 49.7 +/- 21.9 microg at baseline and 48.9 +/- 35.5 microg at evaluation. Darbepoetin alfa was well tolerated.

CONCLUSIONS

Study subjects with CKD receiving QW rHuEPO were effectively converted to Q2W darbepoetin alfa, which was well tolerated. Hb levels were maintained over 52 weeks without a significant change in darbepoetin alfa dose.

Association of kidney function with mortality in patients with chronic kidney disease not yet on dialysis: a historical prospective cohort study

Significant mortality occurs in populations with chronic kidney disease (CKD), but the relative contributions of lower glomerular filtration rate (GFR) itself, accompanying comorbidities, and the numerous abnormalities that develop with advancing CKD are poorly studied. We examined all-cause predialysis mortality in 861 United States veterans with CKD stage 3 to 5 not yet on dialysis. The association of GFR with mortality was analyzed by the Kaplan-Meier method, and the effects of several confounding variables on mortality were assessed in a Cox proportional-hazards model. Overall death rate was 102.1/1,000 person-years (95% CI: 90.2 to 115.6). Lower kidney function was associated with higher mortality (relative risk [95%CI] for GFR less than 20 v 41 to 60 mL/min/1.73 m2: 2.56 [1.61 to 4.07], P<0.001) after adjustment for age, race, diabetes mellitus, cardiovascular disease, smoking status, body mass index, mean arterial pressure, serum albumin, blood cholesterol, haemoglobin, and 24-hour urine protein. For every 10 mL/min/1.73 m2 lower estimated GFR, the adjusted relative risk of mortality (95% CI) was 1.28 (1.12 to 1.45), P<0.001. Lower kidney function is associated with increased mortality in patients with moderate and advanced CKD. This association is present even after adjustment for several confounders.

Contrast-induced nephrotoxicity: clinical landscape

Over 80 million doses of iodinated intravascular contrast media (CM) were administered in the most recent tabulations of 2003, corresponding to approximately 8 million liters, making it one of the highest volume medical drugs used compared to any other pharmaceutical. The evolution of CM has focused on minimizing adverse events by eliminating ionicity, increasing hydrophilicity, lowering osmolality and increasing the number of iodine atoms per molecule. Contrast media are classified into three general categories based on their osmolality relative to blood: high osmolar (5 times or greater than blood), low osmolar (2-3 times blood) and iso-osmolar (the same as blood). All imaging modalities that employ CM, especially computerized tomography (CT), have shown rapid growth. In the last two decades, the use of CT scanning has increased by 800%. From 1979 to 2002, the number of cardiac catheterization procedures in the USA increased by 390% and in Europe from 1992 to 1999 by 112%. There is a general consensus that renal insufficiency and diabetes are major risk factors for contrast-induced nephropathy (CIN), particularly when co-existing. The US Renal Data System documents a 'relentless' increase in kidney failure, projecting a 90% increase by 2010. Diabetes affects 194 million people worldwide and the number is anticipated to increase by 75% by 2025. The unavoidable conclusion is that patient exposure and prevalence of risk factors for CIN will continue to increase.

Vascular calcification in patients with chronic kidney disease

Chronic kidney disease (CKD) represents an extremely common condition, and cardiovascular diseases are frequently reported in this patient population. Traditional risk factors are not accurate prognostic predictors in CKD patients, and new potential markers to predict the cardiovascular involvement in uremic patients need to be identified. Vascular calcification (VC) represents a hallmark of the atherosclerotic process in CKD. This review summarizes the processes responsible for VC (particularly focusing on the mechanisms operative in the presence of renal dysfunction), discusses the utility of computer tomography modalities in the detection of VC in patients with CKD, and reports the potential role of VC as pathophysiological link between kidney disease and cardiovascular events.

Kidneys, hearts, hormones and immunomodulators: integrated understandings

The biological processes governing vascular endothelial cell health are complex and highly redundant. The mechanisms involved in cell injury and repair remain an area of intense study. This paper attempts to review current knowledge regarding hormones such as vitamin D, erythropoietin and aldosterone within the context of what we understand of the inflammatory cascade. This is not a comprehensive review of vascular biology, and many important details and background information have been omitted due to space and complexity considerations. The integration of exocrine and endocrine functions within the kidney, the intimate relationship of those functions with vascular health, and the clinical observations of high prevalence of cardiovascular disease in chronic kidney disease warrant a better understanding of this area by clinicians and basic researchers.

The impact of accepting living kidney donors with mild hypertension or proteinuria on transplantation rates

BACKGROUND

As waiting times for kidney transplantation increase, individuals with hypertension or proteinuria may be considered as eligible living donors. We set out to determine how frequently donors are excluded because of hypertension or proteinuria and to what extent accepting such donors would increase transplantation rates.

METHODS

Wait lists from 4 Canadian transplantation centers were examined for causes of living kidney donor exclusion. Donors with hypertension (clinic blood pressure >140/90 mm Hg or requiring antihypertensive medication) or proteinuria historically have been excluded at these centers. We define potentially acceptable hypertension as a clinic blood pressure less than 150/100 mm Hg or less than 140/90 mm Hg if administered a single antihypertensive medication and define acceptable proteinuria as protein of 0.15 to 0.3 g/d.

RESULTS

Only 35% (124 of 352 patients) of wait-listed patients had a living donor evaluated (n = 180 potential donors). Primary reasons for donor exclusion were immunologic: a positive cross-match (32%; n = 59) or blood group type incompatibility (22%; n = 40). Hypertension or proteinuria were less common (17%; n = 31). Of 31 donors excluded for hypertension or proteinuria, only 13 had results in the acceptable range. Acceptance of these donors would have resulted in transplantation of 3% (12 of 352 patients) of the wait-list population.

CONCLUSION

Accepting living donors with mild hypertension and proteinuria will lead to a slight increase in transplantation rates. Efforts to improve living donor awareness and overcome immunologic barriers to transplantation may have a greater impact.

Epidemiology of chronic renal disease in the Galician population: results of the pilot Spanish EPIRCE study

BACKGROUND

Chronic kidney disease (CKD) is a major social health problem because of the aging of the population, the high incidence of diabetes mellitus, and the epidemic of silent CKD resulting from inadequate diagnosis of early chronic renal insufficiency

METHODS

The sociodemographic, baseline characteristics and CKD prevalence measured by the Modification of Diet in Renal Disease formula were studied in a randomly selected sample of people aged 20 years or older in the general population. We report the results of the analysis of the EPIRCE (Estudio Epidemiológico de la Insuficiencia Renal en España) pilot study performed in Galicia, Spain, in the last quarter of 2004.

RESULTS

Baseline characteristics, sociodemographic characteristics, and results of a clinical examination and blood variables were collected from 237 patients who fulfilled the study's inclusion and exclusion criteria. The mean age of the sample was 49.58 years (95% confidence interval, 47.39-51.76). The prevalence of Kidney Disease Outcomes Quality Initiative grade 3 CKD was 5.1%, but the coexistence of an albumin/creatinine ratio>30 mg/g with grade 1 to 2 CKD raised the final rate to 12.7% in this population. We found a high prevalence of hypertension (31.5%), isolated systolic hypertension (20.1%), diabetes mellitus (8%), obesity (13.1%), smoking habit (22.7%), high atherogenic index (30.8%), and high alcohol intake (24%). Risk factors significantly associated with renal disease were age [P=0.018; odds ratio (OR) 2.7], hypertension (P=0.023; OR 2.13), pulse pressure (P=0.04; OR 0.10), diabetes mellitus (P=0.08; OR 4.48), obesity (P=0.000; OR 7.7), and insulin resistance index (P=0.04; OR 4.95).

CONCLUSION

The prevalence of CKD and conventional cardiovascular risk factors is high in this randomly selected sample of the general population. Secondary preventive measures are needed to detect chronic kidney impairment as early as possible and to reduce the incidence and mortality arising from the associated comorbidities.

The need for optimal and coordinated management of CKD

The prevalence of impaired kidney function has been estimated to be between 10% and 20% of adult populations in most countries worldwide. Reduced kidney function has been recognized as a risk factor for poor outcomes, and thus requires attention. Key aspects of management of CKD have been defined for referred populations, but not necessarily for those unreferred. In order to improve patient outcomes, there is a need to take a more holistic approach to the problem, by coordinating the efforts of policy makers, those involved in health care system redesign, clinicians, and researchers. In so doing, there should be an improvement in both identification and management of patients with impaired kidney function, whether cared for by primary care physicians, specialists, or nephrologists, and irrespective of the health care system.

Progression of kidney dysfunction in the community-dwelling elderly

Despite the high prevalence of chronic kidney disease among the elderly, few studies have described their loss of kidney function. We sought to determine the progression of kidney dysfunction among a community-based cohort of elderly subjects. The cohort included 10 184 subjects 66 years of age or older, who had one or more outpatient serum creatinine measurements during each of two time periods: 1 July to 31 December 2001 and 1 July to 31 December 2003. A mixed effects model, including covariates for age, gender, diabetes mellitus, and comorbidity, was used to determine the rate of decline in estimated glomerular filtration rate (eGFR, in ml/min/1.73 m2) per year over a median follow-up of 2.0 years. Subjects with diabetes mellitus had the greatest decline in eGFR of 2.1 (95% CI 1.8-2.5) and 2.7 (95% CI 2.3-3.1) ml/min/1.73 m2 per year in women and men, respectively. The rate of decline for women and men without diabetes mellitus was 0.8 (95% CI 0.6-1.0) and 1.4 (95% CI 1.2-1.6) ml/min/1.73 m2 per year. Subjects with a study mean eGFR<30 ml/min/1.73 m2, both those with and without diabetes mellitus, experienced the greatest decline in eGFR. In conclusion, we found that the majority of elderly subjects have no or minimal progression of kidney disease over 2 years. Strategies aimed at slowing progression of kidney disease should consider underlying risk factors for progression and the negligible loss of kidney function that occurs in the majority of older adults.

Morbidity, mortality and economic burden of renal impairment in cardiac intensive care

BACKGROUND

Moderate to severe impairment of renal function has emerged as a potent risk factor for adverse short- and long-term outcomes among patients presenting with cardiac disease.

AIMS

We sought to define the clinical, late mortality and economic burden of this risk factor among patients presenting to cardiac intensive care.

METHODS

A clinical audit of patients presenting to cardiac intensive care was undertaken between July 2002 and June 2003. All patients presenting with cardiac diagnoses were included in the study. Baseline creatinine levels were assessed in all patients. Late mortality was assessed by the interrogation of the National Death Register. Renal impairment was defined as estimated glomerular filtration rate <60 mL/min per 1.73 m2, as calculated by the Modified Diet in Renal Disease formula. In-hospital and late outcomes were compared by Cox proportional hazards modelling, adjusting for known confounders. A matched analysis and attributable risk calculation were undertaken to assess the proportion of late mortality accounted for by impairment of renal function and other known negative prognostic factors. The in-hospital total cost associated with renal impairment was assessed by linear regression.

RESULTS

Glomerular filtration rate <60 mL/min per 1.73 m2 was evident in 33.0% of this population. Among these patients, in-hospital and late mortality were substantially increased: risk ratio 13.2; 95% CI 3.0-58.1; P < 0.001 and hazard ratio 6.2; 95% CI 3.6-10.7; P < 0.001, respectively. In matched analysis, renal impairment to this level was associated with 42.1% of all the late deaths observed. Paradoxically, patients with renal impairment were more conservatively managed, but their hospitalizations were associated with an excess adjusted in-hospital cost of $A1676.

CONCLUSION

Impaired renal function is associated with a striking clinical and economic burden among patients presenting to cardiac intensive care. As a marker for future risk, renal function accounts for a substantial proportion of the burden of late mortality. The burden of risk suggests a greater potential opportunity for improvement of outcomes through optimisation of therapeutic strategies.

Designing a molecularly imprinted polymer as an artificial receptor for the specific recognition of creatinine in serums

In this study, molecularly imprinted polymers (MIP) synthesized from two different functional monomers, beta-cyclodextrin (beta-CD) and 4-vinylpyridine (4-Vpy), were prepared. The crosslinkers used for these two monomers were epichlorohydrin (EPI) and divinylbenzene (DVB), respectively. It was attempted to adsorb the target molecule, creatinine, from its mixture solutions. A proper molar ratio of monomer/crosslinker for the preparation of the imprinted poly(beta-CD) was 1:10. Between both polymers mentioned above, the affinity of the imprinted poly(4-Vpy-co-DVB) towards creatinine was comparably superior. The imprinted poly(4-Vpy-co-DVB) for creatinine could reach a specific binding ratio of 3.11. The imprinted poly(4-Vpy-co-DVB) was further utilized to bind creatinine from human serum samples. The binding capacity of the imprinted poly(4-Vpy-co-DVB) for creatinine from the serum samples was plotted against the creatinine concentration. From the correlation, the feasibility of the imprinted poly(4-Vpy-co-DVB) thus prepared for the target analyte, creatinine, was experimentally confirmed.

Anemia and cardiovascular and kidney disease

PURPOSE OF REVIEW

The joint occurrence of cardiovascular disease, kidney disease and anemia has been termed the 'cardio-renal-anemia syndrome'. This review will examine each of these relationships as they pertain to coronary heart disease.

RECENT FINDINGS

Important contributions from the recent literature included observations suggesting that African-Americans with chronic kidney disease and no previous history of cardiovascular disease were more likely than caucasians to have incident cardiovascular disease than caucasians with chronic kidney disease but that this difference did not apply to risk of recurrent cardiovascular disease. Recent reports have brought attention to a continued lack of clinical trials evidence to support anemia treatment for cardioprotection, further concern that higher hemoglobin levels may increase cardiovascular risk and evidence that anemia and kidney function interact to increase risk for coronary heart disease. Finally, additional observational studies and small clinical trials continue to support a role of anemia treatment in protection of residual kidney function, although a recent meta-analysis failed to demonstrate a conclusive benefit of erythropoietin treatment on progressive kidney disease.

SUMMARY

The cardio-renal-anemia syndrome is a set of complex and interrelated phenomena that are poorly understood. Current evidence is insufficient to demonstrate a conclusive benefit of treatment with erythropoietin on risk of cardiovascular disease or progression of kidney disease. Future research is needed to further clarify these issues.

Metabolic syndrome and chronic kidney disease in Okinawa, Japan

We assessed the prevalence of chronic kidney disease (CKD) in a hospital-based screening program in Okinawa, Japan. The significance of metabolic syndrome as a determinant of CKD was examined using multivariate logistic regression analysis. A total of 6980 participants, aged 30-79 years, participated in a screening program in Tomishiro Chuo Hospital. Metabolic syndrome was defined according to the criteria of the Adult Treatment Panel III (ATP III). Data were also analyzed according to the modified criteria of the National Cholesterol Education Program (NCEP) that defines abdominal obesity as a waist circumference of > oe =85 cm in men and > or =90 cm in women. CKD was defined as dipstick proteinuria (> or =1+) or a reduced glomerular filtration rate (GFR). GFR was estimated using the abbreviated Modification of Diet in Renal Disease (MDRD) formula. The prevalence of metabolic syndrome and CKD was 12.8 and 13.7%, respectively. Metabolic syndrome was a significant determinant of CKD (adjusted odds ratio (OR) 1.537 and 95% confidence interval (CI) 1.277-1.850, P<0.0001). The adjusted OR (95% CI) was 1.770 (1.215-2.579, P=0.0029) for those with four metabolic syndrome risk factors compared to those with no metabolic syndrome risk factors. Metabolic syndrome was a significant determinant for younger participants (<60 years; OR 1.686, 95% CI 1.348-2.107, P<0.0001), but not for older participants (> or =60 years; OR 1.254, 95% CI 0.906-1.735, NS). The relationship between the number of metabolic syndrome risk factors and the prevalence of CKD was linear using the modified criteria. The results suggest that metabolic syndrome is a significant determinant of CKD in men under 60 years of age, in Okinawa, Japan.

Prognostic importance of clinic and home blood pressure recordings in patients with chronic kidney disease

Blood pressure (BP) measured only in the clinic substantially misclassifies hypertension in patients with chronic kidney disease (CKD). The role of out-of-clinic recordings of BP in predicting end-stage renal disease (ESRD) and death in patients with CKD is unknown. A prospective cohort study was conducted in 217 Veterans with CKD. BP was measured at home and in the clinic by 'routine' and standardized methods. Patients were followed over a median of 3.5 years to assess the end points of total mortality, ESRD or the composite outcome of ESRD or death. Home BP was 147.0+/-21.4/78.3+/-11.6 mmHg and clinic BPs were 155.2+/-25.6/84.7+/-14.2 mmHg by standardized method and 144.5+/-24.2/75.4+/-14.7 mmHg by the 'routine' method. The composite renal end point occurred in 75 patients (34.5%), death in 52 patients (24.0%), and ESRD in 36/178 patients (20.2%). One standard deviation (s.d.) increase in systolic BP increased the risk of renal end point by 1.27 (95% confidence interval (CI) 1.01-1.60) for routine clinic measurement, by 1.69 (95% CI 1.32-2.17) for standardized clinic measurement and by 1.84 (95% CI 1.46-2.32) for home BP recording. One s.d. increase in home systolic BP increased the risk of ESRD by 1.74 (95% CI 1.04-2.93) when adjusted for standardized clinic systolic BP, proteinuria, estimated glomerular filtration rate, and other risk factors. In patients with CKD, BPs obtained at home are a stronger predictor of ESRD or death compared to BPs obtained in the clinic. Systolic home BP is an independent predictor for ESRD.

The progression of chronic kidney disease: a 10-year population-based study of the effects of gender and age

The increase in demand for renal replacement therapy makes it important to investigate the prognosis of the earlier stages of chronic kidney disease (CKD). We examined the change in glomerular filtration rate (GFR), and patient and renal survival in CKD stage 3 in the municipality of Tromsø, a well-defined European community with a population of 58,000. All patients with estimated GFR between 30 and 59 ml/min/1.73 m(2) for more than 3 months during a 10-year study period were identified from a complete database of all 248 560 measurements of serum creatinine made in the community in the study period. Change in GFR was estimated for each patient using a multilevel model. A complete follow-up with respect to patient and renal survival was obtained from hospital databases. A total of 3047 patients was included. The median number of measurements of creatinine for each patient was 9, and the median observation time was 44 months. Mean estimated change in GFR was--1.03 ml/min/1.73 m(2)/year. Seventy-three percent of the patients experienced a decline in GFR. The 10-year cumulative incidence of renal failure was 0.04 (95% CI 0.03-0.06) and mortality 0.51 (95% CI 0.48-0.55). Female gender was associated with slower decline in GFR and better patient and renal survival. In this population-based study, the decline in GFR in CKD was slower than in previously studied selected patient groups. A high mortality pre-empted the development of renal failure in many patients. The prognosis of CKD depended strongly on gender.

An evaluation of a shared primary and secondary care nephrology service for managing patients with moderate to advanced CKD

BACKGROUND

Chronic kidney disease (CKD) is common, and nephrology services may not cope with the comprehensive referral of patients with CKD. We evaluated a shared primary and secondary care nephrology scheme, hypothesizing that some patients with less progressive moderate to advanced CKD can be identified and safely managed without attending the renal unit.

METHODS

A retrospective review of 949 new referrals with stages 3 to 5 CKD managed in either the hospital nephrology clinic (HC) or the shared care scheme (SCS), in which nephrologists review patients remotely by using regular biochemical tests and clinical data recorded in primary care.

RESULTS

Two hundred sixty-six patients (28%) were enrolled in the SCS and 683 patients (72%) were managed solely in the HC. Median time to entering the SCS was 111 days (interquartile range, 0 to 328 days). Baseline factors independently predictive of enrollment in the SCS were increasing age, greater glomerular filtration rate (GFR) and serum albumin levels, and no diabetic nephropathy. Few SCS patients did not attend reviews. Forty-one patients (15%) required recall to the HC, mostly because of a decline in GFR. Beneficial changes were seen in blood pressure levels and prescribing of angiotensin-system inhibitors from first referral to 3 years in all patients. Those enrolled in the SCS had good prognosis, with a lower risk for death or renal replacement therapy than the HC group after adjustment for age, sex, GFR, diabetic nephropathy, and vascular disease (hazard ratio, 0.64; 95% confidence interval, 0.38 to 0.89; P = 0.003).

CONCLUSION

In this setting, it was possible to select nearly 30% of patients with stages 3 to 5 CKD for management in the SCS. More than half enrolled within 4 months of nephrology referral. Systematic surveillance was effective, and most patients remained stable, with few progressing to renal replacement therapy or death.

Therapy Insight: how changes in renal function with increasing age affect cardiovascular drug prescribing

Age is well recognized as a powerful prognostic factor in the setting of cardiovascular disease. With the aging of the US population, it is projected that more than 50 million people will be aged over 65 years by the year 2020. This growing elderly population has increased rates of morbidity and mortality owing to cardiovascular disease; however, proven therapies for prevention and treatment are often underused in older patients, largely because physicians perceive them as being frail and have limited understanding of age-related unique adverse and therapeutic effects. Advancing age is associated with a number of physiologic and pathophysiologic changes that impact the toxic effects, efficacy and dosing of many medications. Decreases in lean muscle mass affect the volume of distribution, and reductions in hepatic function affect the metabolism of many medications. Age-related reductions in renal function might have the most profound impact on the safety profile and dosing of medications in elderly patients. The strong association between renal and cardiovascular disease makes recognition of renal dysfunction and appropriate dose adjustment particularly important in elderly patients with cardiovascular disease. This article reviews current approaches to the estimation of renal function, and unique considerations related to prescribing medication for elderly patients with concomitant renal and cardiovascular disease.

Kidney function and anemia as risk factors for coronary heart disease and mortality: the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Kidney failure causes anemia and is associated with a very high risk of coronary heart disease (CHD). Mildly to moderately decreased kidney function is far more common and also is associated with an elevated prevalence of anemia and CHD risk. Recent data suggest an even higher risk of CHD when both conditions are present.

METHODS

We investigated the association of kidney dysfunction and anemia with CHD events (fatal or nonfatal CHD or coronary revascularization procedures) and CHD and all-cause mortality over 12 years of follow-up in 14971 adults aged 45 to 64 years in the ARIC Study. Glomerular filtration rate (GFR) was estimated from calibrated serum creatinine using the MDRD Study equation (< 30 mL/min per 1.73 m2 excluded, n = 32). Anemia was defined as hemoglobin level < 13.5 g/dL in men (648/6746, 9.6%) and < 12 g/dL in women (1049/8225, 12.8%).

RESULTS

The prevalence of anemia was progressively higher at lower estimated GFR < 75 mL/min per 1.73 m2 (both P < .001) for both men and women. A total of 1635 (10.9%) participants had a CHD event, 360 (2.4%) died of CHD, and 1722 (11.5%) died of any cause during follow-up. After adjustment for known risk factors, including diabetes, lipid levels, blood pressure, and use of antihypertensive medication, decreased kidney function was associated with a higher risk of recurrent CHD events and mortality from CHD and all causes. These associations were significantly stronger among participants with anemia. The adjusted relative hazards of all-cause mortality associated with moderately decreased versus normal kidney function (GFR 30-59 vs > or = 90 mL/min per 1.73 m2) were 1.7 (95% CI 1.3-2.2) in the absence of anemia and 3.5 (95% CI 2.4-5.1) in the presence of anemia (P interaction = .001).

CONCLUSIONS

The combination of moderately decreased kidney function and anemia is associated with an increased risk of CHD events and mortality, emphasizing the need to identify individuals with these conditions and evaluate interventions to treat anemia and slow the progression of chronic kidney disease.

Prevalence of decreased kidney function in Chinese adults aged 35 to 74 years

BACKGROUND

Chronic kidney disease (CKD) is a major public health burden in Western countries but little is known about its impact in developing countries. We estimated the prevalence and absolute burden of CKD in the general adult population in China.

METHODS

A cross-sectional survey was conducted in a nationally representative sample of 15,540 Chinese adults aged 35 to 74 years in 2000 and 2001. Serum creatinine was measured using the modified kinetic Jaffe reaction method at a central laboratory calibrated to the Cleveland Clinic Foundation laboratory. Glomerular filtration rate (GFR) was estimated using the simplified equation developed by the Modification of Diet in Renal Disease study. CKD was defined as an estimated GFR <60 mL/min/1.73m2.

RESULTS

Overall, the age-standardized prevalences of GFR 60 to 89, 30 to 59, and <30 mL/min/1.73m2 were 39.4%, 2.4%, and 0.14%, respectively, in Chinese adults aged 35 to 74 years. The overall prevalence of CKD (GFR <60 mL/min/1.73m2) was 2.53%, representing 11,966,653 persons (1.31% or 3,185,330 men and 3.82% or 8,781,323 women). The age-specific prevalence of CKD was 0.71%, 1.69%, 3.91%, and 8.14% among persons 35 to 44, 45 to 54, 55 to 64, and 65 to 74 years old, respectively. The age-standardized prevalence of CKD was similar in urban (2.60%) and rural (2.52%) residents but was higher in south China (3.05%) than in north China (1.78%) residents.

CONCLUSION

Although the prevalence of CKD in China was relatively low, the population absolute burden is substantial. These data warrant a national program aimed at detection, prevention, and treatment of CKD in China.

Mechanisms of progression and regression of renal lesions of chronic nephropathies and diabetes

The incidence of chronic kidney diseases is increasing worldwide, and these conditions are emerging as a major public health problem. While genetic factors contribute to susceptibility and progression of renal disease, proteinuria has been claimed as an independent predictor of outcome. Reduction of urinary protein levels by various medications and a low-protein diet limits renal function decline in individuals with nondiabetic and diabetic nephropathies to the point that remission of the disease and regression of renal lesions have been observed in experimental animals and even in humans. In animal models, regression of glomerular structural changes is associated with remodeling of the glomerular architecture. Instrumental to this discovery were 3D reconstruction studies of the glomerular capillary tuft, which allowed the quantification of sclerosis volume reduction and capillary regeneration upon treatment. Regeneration of capillary segments might result from the contribution of resident cells, but progenitor cells of renal or extrarenal origin may also have a role. This review describes recent advances in our understanding of the mechanisms and mediators underlying renal tissue repair ultimately responsible for regression of renal injury.

Prescription des statines en cas d’insuffisance rénale

BACKGROUND

Chronic kidney disease (CKD) is extremely common in adults, although often undiagnosed and thus untreated. Cardiovascular disease is the leading cause of death among patients with CKD and reducing its risk in this population is an important priority. Dyslipidemia is almost always present when proteinuria is above 3 gr/24 hours. Roughly two thirds of all patients with end-stage renal failure and kidney transplants suffer from dyslipidemia and should receive lipid-lowering therapy, as suggested by recent Afssaps (French drug agency) and NKF-K/DOQI (National Kidney Foundation-Kidney Disease Outcomes Quality Initiative) guidelines. We reviewed recent studies on efficacy, tolerability and prescription recommendations of statins in CKD and renal transplant patients.

METHODS

We searched Medline, the international medical database, to conduct a systematic review of the literature on the efficacy and tolerability of statins in CKD and renal transplant patients and on specific recommendations for dosage adjustments in this population.

RESULTS

The efficacy of statins in decreasing total cholesterol and LDL-cholesterol levels in dialysis and renal transplant patients is similar to that in the general population. On the other hand, large-scale randomized clinical trials among CKD (4D) and renal transplant (ALERT) patients do not demonstrate that statins significantly decrease rates of cardiovascular disease. They have a beneficial effect on proteinuria and lower the rate of kidney function deterioration in patients with dyslipidemia. Early introduction of a statin in transplant patients did not lead to improved kidney function or prevent loss of the graft. Although most statins are not excreted by the kidneys, the dosage of some must be adapted in CKD patients because of pharmacokinetic modifications induced by renal impairment.

CONCLUSION

Statins at appropriately adapted doses have the same efficacy in CKD patients as in subjects with normal kidney function, and tolerance is not a problem. Their effectiveness in cardiovascular prevention in this population has not been demonstrated to date. Results about statin-induced kidney protection are encouraging but further and more specific studies are needed.

Role of altered renal lipid metabolism and the sterol regulatory element binding proteins in the pathogenesis of age-related renal disease

BACKGROUND

There are well-known changes in age-related renal function and structure, including glomerulosclerosis and decline in glomerular filtration rate (GFR). The purpose of this study was to identify a potential role for lipids in mediating age-related renal disease.

METHODS

Mice of five different age groups (3, 6, 12, 19, and 23 months old) were studied.

RESULTS

We have found that in C57BL/6 mice there was a progressive increase in age-related glomerulosclerosis [increase in periodic acid-Schiff (PAS) staining and accumulation of extracellular matrix proteins including type IV collagen and fibronectin], increased glomerular basement thickness and podocyte width and effacement, and increased proteinuria. These changes were associated with age-related increase in lipid accumulation as determined by increased Oil Red O staining in kidney sections. Biochemical analysis indicated that these lipid deposits corresponded to significant increases in renal triglyceride and cholesterol content. We have also found significant age-related increases in the nuclear transcription factors, sterol regulatory element-binding proteins (SREBP-1 and SREBP-2), protein abundance and increased expression or activity of their target enzymes that play an important role in lipid synthesis.

CONCLUSION

Our results indicated that there was an age-related increase in renal expression of SREBP-1 and SREBP-2 with resultant increases in lipid synthesis and triglyceride and cholesterol accumulation in the kidney. Because we have previously shown that increased expression of SREBPs in the kidney per se results in glomerulosclerosis and proteinuria, our data suggested that increased SREBPs' expression resulting in increased renal lipid accumulation may play an important role in age-related nephropathy.

Health-related quality of life and estimates of utility in chronic kidney disease

BACKGROUND

Health-related quality of life and estimates of utility have been carefully evaluated in persons with end-stage renal disease. Fewer studies have examined these parameters in persons with chronic kidney disease (CKD).

METHODS

To determine the relations among kidney function, health-related quality of life, and estimates of utility, we administered the Kidney Disease Quality of Life Short Form 36 (KDQOL-36), Health Utilities Index (HUI)-3, and Time Trade-off (TTO) questionnaires to 205 persons with CKD. Persons with CKD stages 4 and 5 (estimated GFR <30 mL/min/1.73 m2, N= 115) were tested two to eight times over the subsequent two years. The relations among estimated glomerular filtration rate (eGFR), and changes in health-related quality of life and utility over time were estimated using mixed effect regression models. Models were adjusted for age, sex, race, and diabetes.

RESULTS

Mean scores on the KDQOL-36 generic components, HUI-3, and TTO suggested considerable loss of function and well-being in CKD relative to population norms. On cross-sectional analysis, lower levels of kidney function were associated with significantly lower scores on the SF-12 Physical Health Composite (P= 0.002), the Burden of Kidney Disease subscale (P < 0.0001), and the Effects of Kidney Disease subscale (P < 0.0001) of the KDQOL-36trade mark. Kidney function was significantly associated with the TTO (P= 0.008) and global HUI-3 utility (P= 0.016) although these associations were attenuated after adjustment for diabetes. A decline in eGFR was associated with a significant increase in the reported Burden of Kidney Disease (5.0 point change per year per mL/min/1.73 m2 decline in eGFR) and with marginally significant changes in the Dexterity and Pain attributes of the HUI-3. Mean HUI-3 scores for persons with CKD stages 4 and 5, absent dialysis, were in the range previously reported for persons with stroke and severe peripheral vascular disease.

CONCLUSION

Health-related quality of life and estimates of utility are distressingly low in persons with CKD. Self-reported outcomes should be considered when evaluating health policy decisions that affect this population.

Dietary protein restriction benefits patients with chronic kidney disease (Review Article)

The prevalence of chronic kidney disease (CKD) is rapidly increasing so every strategy should be used to avoid the complications of CKD. Most CKD symptoms or uraemia are caused by protein intolerance; symptoms arise because the patient is unable to excrete metabolic products of dietary protein and the ions contained in protein-rich foods. Consequently, CKD patients accumulate salt, phosphates, uric acid and many nitrogen-containing metabolic products, and secondary problems of metabolic acidosis, bone disease and insulin resistance become prominent. These problems can be avoided with dietary planning. Protein-restricted diets do not produce malnutrition and with these diets even patients with advanced CKD maintain body weight, serum albumin and normal electrolyte values. Non-compliance is a problem, but this can be detected using standard techniques to provide the patient with appropriate responses. The role of dietary protein restriction in the progression of CKD has not been proven, but it can reduce albuminuria and will prevent uraemic symptoms. Until a means of preventing kidney disease or progression is found, safe methods of management such as dietary manipulation should be available for CKD patients.

Development of kidney scars after acute uncomplicated pyelonephritis: relationship with clinical, laboratory and imaging data at diagnosis

BACKGROUND

Acute pyelonephritis is a potential cause of kidney scars.

AIM

To evaluate the relationship between clinical, laboratory and imaging data and the development of kidney scars in acute pyelonephritis.

METHODS

All consecutive patients hospitalized for acute uncomplicated pyelonephritis in our nephrology unit from June 1996 to June 2004 were considered: 58 females, median age 25.6 years (16-52). Diagnosis of pyelonephritis required parenchymal lesions shown by CT or NMR scan.

RESULTS

The lesions were bilateral in 17.2% (10/58) patients, unilateral, but multifocal in 81.0% (47/58); at CT or NMR, 65.5% of the lesions were classified as simple, 19% with tendency to colliquation and 15.5% abscessual. The median interval between first symptoms and diagnosis was 5 days (1-25); at referral, only 20.7% had a positive urine culture and 94.8% (55/58) had undergone previous antibiotic treatment. The therapeutic protocol required intravenous therapy for > or = 2 weeks, followed by 2-4 weeks of oral therapy. At 6-8 months, the prevalence of kidney scars was 29.3%. Their development was highly correlated with the type of lesions at diagnosis (highest risk with abscessual lesions; uni- and multivariate analysis). No other clinical or laboratory marker (age, fever, positive cultures, levels of acute phase reactants, interval between onset and diagnosis) was correlated with the outcome (scars).

CONCLUSIONS

The type of lesion at diagnosis of acute uncomplicated pyelonephritis is highly correlated with the development of kidney scars. Further studies are needed to test the therapeutic schedules tailored according to the imaging data.

Prevalence of renal impairment and its association with cardiovascular risk factors in a general population: results of the Swiss SAPALDIA study

BACKGROUND

Impaired renal function is evolving as an independent marker of the risk of cardiovascular morbidity and mortality. Little is known about the prevalence of impaired renal function and its relationship to cardiovascular risk factors in the Swiss general population.

METHODS

SAPALDIA comprises a random sample of the Swiss population established in 1991, originally to investigate the health effects of long-term exposure to air pollution. Participants were reassessed in 2002/3 and blood measurements were obtained (n = 6317). Renal function was estimated using the Cockcroft-Gault equation and the modified MDRD (four-component) equation incorporating age, race, gender and serum creatinine level.

RESULTS

The estimated prevalence of impaired renal function [estimated glomerular filtration rate <60 ml/min/1.73 m(2)] differed substantially between men and women, particularly at higher ages, and amounted to 13% [95% confidence interval (CI) 10-16%] and 36% (95% CI 32-40%) in men and women, respectively, of 65 years or older. Smoking, obesity, blood lipid levels, high systolic blood pressure and hyperuricaemia were all more common in men when compared with women. These cardiovascular risk factors were also associated independently with creatinine in both women and men. Women were less likely to receive cardiovascular drugs, in particular angiotensin-converting enzyme inhibitors and beta-blockers, when compared with men of the same age.

CONCLUSION

Moderate renal impairment seems to be prevalent in the general population, with an apparent excess in females which is not explained by conventional cardiovascular risk factors. The unexpected finding questions the validity of the prediction equations, in particular in females.

Vascular calcification in patients with renal failure: culprit or innocent bystander?

The mortality from cardiovascular events in CKD and dialysis patients is substantially higher than in the general population. VC is ubiquitous and progresses rapidly in this patient population. Although there has been progress in the understanding of the pathogenesis and correlates of VC, much work needs to be done in this area. The role of calcium and, probably, phosphate (obligatory participants) is unquestionable, but the understanding of the paracrine and molecular determinants of VC in renal failure is continuously evolving. VC is probably a dynamic process resulting from the imbalance between molecules that promote and those that inhibit VC. The understanding of latter area has recently evolved with identification of new signaling pathways with molecules such as osteoprotegerin, fetuin-A, and MPG. From a clinical perspective, new modalities such as EBCT and MDCT allow noninvasive detection and quantification of VC. VC may represent a potential useful index for prognostic stratification and treatment planning in patients who have renal failure. At present, however, the data on the prognostic value of VC are available only in populations of patients who have normal renal function. Large-scale, prospective, observational studies should be designed to identify the determinants of VC and to define the prognostic role of calcium scoring in cohorts of patients who have predialysis CKD and with ESRD.

Outcomes of contrast-induced nephropathy: Experience in patients undergoing cardiovascular intervention

Use of iodinated contrast media for diagnostic and interventional procedures is increasing as computed tomography and percutaneous coronary intervention (PCI) technologies provide increasing patient benefit. Although some complications associated with contrast media are mild and transient, contrast-induced nephropathy (CIN) can negatively affect long-term patient morbidity and mortality. The incidence of and outcomes from CIN have been carefully studied in cardiology patients. A number of studies have identified CIN-associated complications in PCI patients, including bleeding, hematoma, stroke, adult respiratory distress syndrome, electrolyte imbalances, and sepsis. In post-PCI patients, rates of myocardial infarction and vessel reocclusion are more common in patients with CIN. Therefore, in-hospital mortality is increased in patients with CIN. In patients requiring dialysis after PCI, several studies have shown the 1-year mortality rate to be >55%. Even moderate renal dysfunction not requiring dialysis is associated with increased mortality in patients with coronary artery disease. Precautionary measures before, during, and after the use of contrast media that reduce the incidence of CIN, such as discontinuation of nephrotoxic medications, adequate hydration, and use of appropriate volumes and types of contrast media, should be considered in all patients with renal insufficiency or with other risk factors for CIN.

Analysis of cardiovascular disease and kidney outcomes in multidisciplinary chronic kidney disease clinics: complex disease requires complex care models

PURPOSE OF REVIEW

Chronic kidney disease is recognized as being highly prevalent in the population, and associated with morbidity and mortality relative to the general population. The complexity of patients and the multiplicity of interventions required to maintain health has forced clinicians to develop different models of healthcare delivery. This publication reviews the current literature on specific interventions to reduce progression of chronic kidney disease and cardiovascular disease, and studies the examination of outcomes of patients exposed to different healthcare delivery models. Specifically we examine the rationale and outcomes of those seen in multidisciplinary clinics.

RECENT FINDINGS

Current evidence supports the use of rennin-angiotensin system blockers, reduction of blood pressure and proteinuria and phosphate control. Additional less robust studies support the need for attention to anemia, hyperparathryoidism, and other more "kidney specific" risk factors. The attendance of identified chronic kidney disease patients at multidisciplinary clinics appears to improve survival once dialysis is started. Despite aggressive management, not all patients are able to meet clinical targets associated with improved outcomes.

SUMMARY

The recognition of the complexity of chronic kidney disease care and the need to develop and test models of care in addition to the single interventions is a challenge for both researchers and clinicians. Current data support the use of multidisciplinary clinics in improving outcomes of referred patients. Future research will help to refine and define appropriate care models for this growing chronic kidney disease population.

Nutrition in Chronic Heart Failure With Coexisting Chronic Kidney Disease

BACKGROUND AND RESEARCH OBJECTIVES

Patients with heart failure (HF) may be predisposed to malnutrition. Little is known about the nutritional status of patients with HF, particularly patients who have coexisting major medical conditions such as chronic kidney disease. The purposes of this study were to (1) describe the nutritional status of 211 patients with chronic HF, (2) examine relationships between nutrition variables and health-related quality of life, and (3) evaluate the nutritional status of the subset of HF patients with coexisting chronic kidney disease.

SUBJECTS AND METHODS

The sample included 211 patients with chronic HF recruited for a larger study about health-related quality of life. Clinical data were retrieved retrospectively from the computerized medical records system at the study site.

RESULTS AND CONCLUSIONS

Mean body mass index of the 122 patients for which height was available was 31.4, and no differences in body mass index were noted among patients with varying New York Heart Association class functional status. Evaluation of the mean laboratory values indicated that patients had abnormal elevations of serum glucose, hemoglobin A1C, creatinine, and low-density lipoprotein cholesterol. Higher hemoglobin A1C levels were significantly correlated with poorer health-related quality-of-life scores, although the magnitude of the correlations was modest. Estimated glomerular filtration rate indicated that 54 (27%) of the HF patients likely had coexisting chronic kidney disease, and these patients had significantly lower serum albumin and worsening anemia. The results indicate the need for future prospective studies that incorporate evaluation of nutritional status and the ways in which coexisting chronic kidney disease influences outcomes.

Dosing Patterns and Treatment Costs of Erythropoietic Agents in Elderly Patients with Pre-Dialysis Chronic Kidney Disease in Managed Care Organisations

OBJECTIVES

To investigate dosing patterns and drug costs of erythropoietic agents and assess the frequency of outpatient nephrologist visits in an elderly population with pre-dialysis chronic kidney disease (pCKD) newly initiated on epoetin alfa (EPO) or darbepoetin alfa (DARB).

METHODS

An analysis of medical claims from more than 30 healthcare plans covering all census regions of the US in the period July 2002 through February 2005 was conducted. Patients were included if they were > or = 65 years of age, had at least one claim for CKD within 90 days prior to the initiation of any erythropoietic agent, were newly commenced on either EPO or DARB, and had received at least two treatment doses. If a patient received renal dialysis, data were censored 30 days prior to the first date of dialysis. Patients diagnosed with cancer or those who had undergone chemotherapy were excluded from the analysis. The average dosing interval for both EPO and DARB was calculated and classified as once weekly (qw), every 2 weeks (q2w) or every 3 weeks or less frequently (> or = q3w). Weighted average weekly doses were scaled based on treatment duration. The frequency of outpatient nephrologist visits was analysed. Average weekly treatment costs were calculated and presented using the May 2005 Wholesale Acquisition Costs.

RESULTS

A total of 293 EPO and 102 DARB patients met the inclusion criteria. The two groups of patients had similar mean age (74.4 years for EPO vs 74.3 years for DARB) and gender distribution (47.4% female for EPO vs 51.0% for DARB). Extended dosing (every 2 weeks or less frequently: > or = q2w) during treatment was observed in both groups (EPO: qw 49.8%, q2w 31.7%, > or = q3w 18.4%; DARB: qw 19.6%, q2w 52.9%, > or = q3w 27.5%). The average dosing interval between injections was 13.6 days for the EPO group and 17.3 days for the DARB group. The weighted average weekly dose was 12,748 units for EPO and 43.5 microg for DARB. The average weekly erythropoietic treatment cost was significantly greater for DARB compared with EPO (190 US dollars vs 155 US dollars per week [2005 values]; p = 0.028). After controlling for covariates, the cost difference between the two groups was more pronounced and remained statistically significant (adjusted cost difference 41 US dollars/week higher for DARB patients; p = 0.013). The frequency of outpatient nephrologist visits during treatment was similar between the two groups (EPO 3.4 vs DARB 3.0 visits).

CONCLUSIONS

Based on this analysis of claims data from more than 30 US healthcare plans, extended dosing (> or = q2w) of EPO and DARB was common in elderly pCKD patients treated with erythropoietic agents, with significantly higher weekly drug costs observed in the DARB group compared with the EPO group. The number of outpatient nephrologist visits was not significantly different between EPO and DARB patients. This study was the first to evaluate the dosing patterns of EPO and DARB in elderly pCKD patients in a large managed care population.

Glomerular filtration rate is a predictor of mortality after endovascular abdominal aortic aneurysm repair

OBJECTIVE

Clinically evident renal disease is a risk factor for mortality after aneurysm repair. Serum creatinine is widely used as a measure of renal function in the preoperative evaluation of patients. Unfortunately, serum creatinine concentration is influenced by muscle mass, hydration status, and glomerular filtration rate (GFR). Calculated GFR, which takes predictors of muscle mass such as age, gender, and weight into account, is a more sensitive determinant of renal function than serum creatinine. We hypothesized that GFR would more accurately predict mortality after EVAR than serum creatinine.

METHODS

We retrospectively evaluated our database of 398 patients who underwent EVAR with the AneuRx device between October 1999 and October 2004. There were 340 men and 58 women with a mean age of 73. GFR was calculated using the Cockcroft-Gault equation. The patients were divided into four quartiles by preoperative GFR: I (7 to 45), II (45 to 60), III (61 to 79), and IV (> or =80). Survival was estimated with the Kaplan-Meier method, and heterogeneity of mortality across strata was evaluated using the log-rank test. The GFR quartiles were compared with clinically accepted criteria for abnormal renal function (serum creatinine level > or =1.7).

RESULTS

Actuarial survival at 48 months was 61.5%, 70.5%, 86.0%, and 85.7% for GFR quartiles I to IV, respectively (P < .003). Thirty-day mortality was 2.2% in quartile I, 3.2% in quartile II, and 0 in quartiles III and IV (P = .03 for q1 + q2 vs q3 + q4, P < .02 for q2 vs q3 + q4). Survival curves for quartiles II to IV were statistically indistinguishable, with quartile II running tangential to the two higher quartiles after the perioperative period. Quartile I fared significantly worse than the other three quartiles for the entire follow-up period (P < .005). According to American Kidney Foundation criteria (GFR <90), 83.3% of patients had abnormal renal function compared with 16.1% with abnormal serum creatinine (>1.7) (P < .0002).

CONCLUSION

The risk of perioperative and long-term mortality in patients undergoing EVAR is more accurately stratified by using calculated GFR than serum creatinine alone. A GFR <45 is associated with decreased survival after EVAR. Perioperative mortality at a GFR of 45 to 60 is comparable with that of the lower quartile (GFR <45), but late survival is comparable with that of patients with GFR >60. The finding of increased risk of early mortality in patients in the 45 to 60 GFR range, with survivors enjoying good long-term outcome, suggests that these patients may most benefit from the use of alternative contrast agents and periprocedural renal protection techniques.

[Prevalence of "hidden" renal failure in the population suffering from type-2 diabetes]

OBJECTIVE

To determine the prevalence of renal failure (RF) in type-2 diabetics and to compare two criteria of definition: that based on the calculation of glomerular filtration by the Cockcroft-Gault formula corrected for body surface area and that based on serous creatinine.

DESIGN

Cross-sectional, descriptive study.

SETTING

El Cristo Health Centre, Oviedo, north of Spain.

PARTICIPANTS

All patients in the catchment area diagnosed with type-2 diabetes.

METHOD

Demographic, clinical, risk factor, and cardiovascular pathology details were gathered. Renal failure was diagnosed on figures of plasma creatinine >=1.3 mg/dL in women and >=1.4 mg/dL in men, and glomerular filtration (GF) calculated by means of the Cockcroft-Gault formula: moderate GF, 60-30 mL/min/1.73 m2; severe GF, 29-15 mL/min/1.73 m2, and terminal GF: <15 mL/min/1.73 m2.

RESULTS

499 patients were included. 52.3% were women, aged 69.7+/-10.4 years old. Prevalence of RF by serous creatinine was 12%; and by the Cockcroft-Gault formula, 40.5%. Patients with lower glomerular filtration and normal creatinine were older (75.5+/-7.9 vs 65.4+/-9.8; P<.001), mainly female (76.3% vs 41.7%; P<.001), had lower BMI (27.3+/-3.7 vs 30.9+/-4.4) and had worse glucaemia control (HbA1c 7.1+/-1.8% vs 6.9+/-1.9%; P=.007) and higher indices of cardiac failure (6.4% vs 2.1%; 95% CI, 1.1-8.8; P=.02) than patients with normal glomerular filtration and creatinine.

CONCLUSION

Calculation of glomerular filtration by the Cockcroft-Gault formula corrected for body surface area revealed unknown renal failure in 1 in 3 type-2 diabetes patients.

Pulse pressure and inhibition of renin–angiotensin system in chronic kidney disease

BACKGROUND

Elevated pulse pressure (PP) is an indicator of poor outcome in hypertensives in the general population and on haemodialysis. The prognostic value of PP in pre-dialysis patients with chronic kidney disease (CKD) stages 4/5 and its interaction with renin-angiotensin system (RAS) inhibitors is unknown.

METHODS

This retrospective study of 349 patients from the pre-dialysis clinic analysed the effect association of PP and RAS inhibition on adverse outcomes in CKD stages 4/5. Primary endpoints were a composite of death or dialysis.

RESULTS

At baseline, 349 patients (63% males, 34% diabetics) were aged 60+/-0.8 years (mean+/-SEM) with systolic blood pressure (SBP) 149+/-1.3 mmHg, diastolic BP (DBP) 83+/-0.7 mmHg, PP 66+/- 1.0 mmHg, creatinine 442+/-16 micromol/l and haemoglobin 10.7+/-0.1 g/dl. Patients were followed up for 297+/-19 days and 93% took one to seven (2.45+/-0.07) antihypertensives. At presentation, the adverse outcome group had higher SBP (151+/-1.5 vs 145+/-2.4 mmHg; P<0.05), proportion of diabetes (39% vs 23%; P<0.05) and creatinine (478+/-22 vs 354+/-11 micromol/l; P<0.05), but lower haemoglobin (10.6+/-0.1 vs 11.2+/-0.2 g/dl; P<0.05). PP increased with age (r(2): 0.4; P<0.0001). PP >80 mmHg was associated with adverse outcome (Kaplan-Meier survival analysis, log-rank test P<0.05). In a model of proportional hazards regression, adjusted for age, baseline creatinine, diabetes and haemoglobin, elevated PP was associated with poorer outcome (hazards ratio: 1.09; 95% confidence interval: 1.01-1.18; P<0.05) and angiotensin-converting enzyme inhibitor/angiotensin-receptor blocker use was beneficial (hazards ratio: 0.73; 95% confidence interval: 0.53-0.99; P<0.05).

CONCLUSIONS

The study demonstrates that elevated PP indicates high risk of death or dialysis and the benefit of blockade of the RAS is independent of the baseline PP in patients with CKD stages 4/5.

Biomarkers in chronic kidney disease: utility and issues towards better understanding

PURPOSE OF REVIEW

Biomarkers are substances that reflect the presence of a given disease, its pathophysiology or organ damage. These indicators are increasingly proposed to assess prognosis or the response to treatment. This review examines the value of a series of biomarkers which have been recently tested in prospective studies in chronic kidney disease and end-stage renal disease patients.

RECENT FINDINGS

C reactive protein has coherently emerged as an early marker of renal dysfunction. The usefulness of this measurement for predicting the evolution of chronic kidney disease or for monitoring the response to renoprotective treatment, however, still remains unproven. On the other hand the measurement of C reactive protein can be recommended for monitoring the risk of atherosclerotic complications in patients with chronic kidney disease and end-stage renal disease, particularly in those with evidence of coronary heart disease or other cardiovascular complications (i.e. in the vast majority of patients followed up in nephrology clinics). There is growing interest in homocysteine and asymmetric dimethyl arginine as biomarkers of cardiovascular and renal risk but the usefulness of these biomarkers in clinical practice remains to be proven. Brain natriuretic peptide and troponin T are strongly related to cardiovascular outcomes in end-stage renal disease patients but their value in this population still requires to be proper tested in specifically designed intervention studies.

SUMMARY

Among emerging biomarkers C reactive protein is the only one which is very near to fulfilling the methodological requirements for being recommended in clinical practice.

The kidney, a cardiovascular risk marker, and a new target for therapy

Both reduced filtration power and increased excretion of albumin in the urine are powerful markers for renal and cardiovascular progressive function loss. These risk markers indicate the risk above and beyond the conventional existing risk markers/factors. The risk is substantial, because both reduced filtration and microalbuminuria are highly prevalent in the general population, matching in prevalence with the most well-known risk factor, hypertension. Therapeutic interventions to preserve renal and cardiovascular function, such as with angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists, are highly effective, particularly in those patients that have reduced filtration power. In addition, short-term reduction of albuminuria that follows the renin-angiotensin-aldosterone-system intervention appears to be predictive of long-term cardiovascular and renal protection. In conclusion, estimated glomerular filtration rate as well as albumin excretion in the urine are powerful predictors for cardiovascular and renal outcome and should be used as such. Intervention and prevention could be aimed at not only at reducing conventional risk markers, but also at reducing albuminuria.

Chronic renal diseases as a public health problem: epidemiology, social, and economic implications

The impact of chronic kidney disease (CKD) on the global burden of diseases is probably underestimated by current methods of evaluation. However, CKD are emerging as a major health problem. First, the costs of renal replacement therapy are excedingly high and are consuming a significant proportion of health care budgets of developed countries, while in developing countries are out of reach. Second, complex interaction are clearly emerging between chronic kidney, cardiovascular disease, and diabetes.

Prevention of chronic kidney disease: a global challenge

In view of the increasing number of patients requiring renal replacement therapy (RRT) every year worldwide, attention has focused over the last two decades on meeting the health care need of patients with end-stage renal failure (ESRF). More recently, increasing awareness of the growing burden of chronic kidney disease (CKD), with a large percentage of the population affected by early stages of CKD, has shifted attention and health care priority to the prevention and early detection of CKD. This article addresses issues related to general population as well as targeted screening, favoring the latter. It also examines some of the screening initiatives undertaken in both the developing and developed worlds. It also highlights the links between albuminuria, CKD, and cardiovascular disease (CVD) as an increasing number of studies identify albuminuria/proteinuria, as well as CKD as major markers of CVD. Finally, a brief review is included of primary and secondary intervention strategies for CKD and issues related to their implementation: manpower and funding.

Prevalence of chronic kidney disease in a middle and old-aged population of Beijing

BACKGROUND

Chronic kidney disease (CKD) was epidemic worldwide. The prevalence of CKD indicators, including proteinuria, hematuria/uninfectious leukocyturia and reduced GFR, was investigated in the middle and old-aged population of Beijing Shijingshan district.

METHODS

Subjects of 2310 aged > or =40 y were enrolled. Their health conditions were taken by questionnaires and physical check-ups. Spot urine albumin to creatinine ratio, spot urine dipstick and microscopy for urine red cell and leukocyte, and serum creatinine was determined. Using simplified Modification of Diet in Renal Disease Study equation estimated GFR assessed renal function. The associations between age, gender, diabetes mellitus, and hypertension, and indicators of kidney damage were examined.

RESULTS

Through the questionnaires, the history of diabetes mellitus, hypertension and CKD were found in 28%, 47.1% and 3.6% of subjects, respectively. Albuminuria was detected in 8.4% of subjects, hematuria and uninfectious leukocyturia in 0.7%, and reduced GFR in 4.9%. Approximately 12.9% had at least 1 indicator of CKD. The known rate of CKD in the studied population was 7.1%. Age, diabetes mellitus, hyper fasting blood glucose and hypertension were independently associated with albuminuria; age, gender, hyper uric acid and albuminuria with reduced GFR. When proteinuria and reduced GFR were determined using spot urine dipstick protein > or =25 mg/dl and serum creatinine > or =133 micromol/l, the prevalence of proteinuria and reduced GFR were 4.7% and 0.8%, respectively.

CONCLUSION

The prevalence of CKD is common in middle and old-aged population of Beijing, especially in the elderly, but the known rate was relatively low. These findings highlight the clinical and public health importance of CKD.

Renal hyperfiltration in type 2 diabetes: effect of age-related decline in glomerular filtration rate

AIMS/HYPOTHESIS

We sought to characterise the effect of the age-related decline of GFR on hyperfiltration in type 2 diabetes and to identify clinical characteristics associated with hyperfiltration.

MATERIALS AND METHODS

GFR was measured in 662 type 2 diabetic patients by plasma disappearance of 99 m-technetium-diethylene-triamine-penta-acetic acid. The prevalence of hyperfiltration was calculated using both an age-unadjusted GFR threshold of >130 ml min(-1) 1.73 m(-2) and an age-adjusted threshold incorporating a decline of 1 ml min(-1) year(-1) after the age of 40. The hyperfiltering patients were compared with type 2 diabetic subjects who had a GFR between 90 and 130 ml min(-1) 1.73 m(-2) and were matched for age, sex and disease duration to allow for identification of modifiable factors associated with hyperfiltration.

RESULTS

The prevalence of hyperfiltration was 7.4% when age-unadjusted and 16.6% when age-adjusted definitions were used. The age-unadjusted vs -adjusted prevalence rates for hyperfiltration were 50 vs 50%, 12.9 vs 23.4% and 0.3 vs 9.0% for patients aged <40 years, 40 to 65 years and >65 years, respectively. Both the age-unadjusted and -adjusted hyperfiltration groups had lower mean diastolic blood pressure and lower serum creatinine levels than the control groups. Although the age-unadjusted hyperfiltration group had larger kidneys compared to the control group, this difference was no longer significant when the age-adjusted definition was used. There were no differences in HbA(1)c, mean arterial pressure, antihypertensive use, insulin therapy, dyslipidaemia, frequency of macro- or microvascular complications, BMI, urinary sodium, urea and albumin excretion between the groups.

CONCLUSIONS/INTERPRETATION

Hyperfiltration was still more common among younger patients with type 2 diabetes even after adjusting for the expected age-related decline in GFR. Hyperfiltration was associated with a lower mean diastolic blood pressure independent of age.

Chronic kidney disease: A European perspective

There is an exponential growth worldwide of patients with end-stage renal disease (ESRD). Prevalences, outcomes, and underlying causes of ESRD are relatively well documented through different organizations. It is, however, clear that a large part of the bad outcome of ESRD patients is due to deficient follow-up during the earlier chronic kidney disease (CKD) stages. Data on CKD, prevalence of the different stages, and the evolution to ESRD are rather scant, and available data are conflictive. This is at least partly due to the lack of an international standard for measurement of renal function. In addition, there is compiling evidence that presence of proteinuria, even with a normal renal function, predisposes to ESRD. Most authors now prefer the term "kidney injury" rather than "kidney failure" to indicate people at risk for evolution to ESRD or for complications of CKD. Detection of these patients at risk is important to implement measures to slow down progression of CKD and avoid secondary complications. As it is clear that most of these CKD patients die before they reach ESRD, it might be that by taking the necessary preventive measures, the number of ESRD patients might still further increase exponentially.

Kidney Disease and the Metabolic Syndrome

The epidemic of metabolic syndrome contributes to the rapid growth of cardiovascular and renal diseases. Hyper-hemodynamics, impaired pressure natriuresis, excess excretory load, insulin resistance, endothelial dysfunction, chronic inflammation, and prothrombotic status individually and interdependently initiate renal injury in metabolic syndrome. The prevention and treatment of kidney disease require a multifactorial approach. Weight loss through diet control and exercise can reverse many pathophysiologic processes. Pharmacologic intervention includes insulin sensitizers, tight glycemic and lipid control, blockage of renin angiotensin aldosterone system, and anti-inflammatory and antithrombotic therapies. Each peroxisome proliferator-activated receptor isoform plays a distinct role in metabolic syndrome, and their agonists may prevent or reverse the early renal injuries.

Association between body mass index and CKD in apparently healthy men

BACKGROUND

Overweight and obesity are well-established risk factors for cardiovascular disease and decline in kidney function in individuals with existing chronic kidney disease (CKD). Conversely, their association with the development of CKD is less clear.

METHODS

We evaluated the association between body mass index (BMI) and risk for CKD in a cohort of 11,104 initially healthy men who participated in the Physicians' Health Study and provided a blood sample after 14 years. BMI was calculated from self-reported weight and height. We estimated glomerular filtration rate (GFR) by using the abbreviated equation from the Modification of Diet in Renal Disease Study and defined CKD as GFR less than 60 mL/min/1.73 m2 (<1 mL/s/1.73 m2).

RESULTS

After an average 14-year follow-up, 1,377 participants (12.4%) had a GFR less than 60 mL/min/1.73 m2 (<1 mL/s/1.73 m2). Higher baseline BMI was associated consistently with increased risk for CKD. Compared with participants in the lowest BMI quintile (<22.7 kg/m2), those in the highest quintile (>26.6 kg/m2) had an odds ratio (OR) of 1.45 (95% confidence interval [CI], 1.19 to 1.76; P trend <0.001) after adjusting for potential confounders. We found similar associations by using different categories of BMI. Compared with men who remained within a +/-5% range of their baseline BMI, those who reported a BMI increase greater than 10% had a significant increase in risk for CKD (OR, 1.27; 95% CI, 1.06 to 1.53).

CONCLUSION

In this large cohort of initially healthy men, BMI was associated significantly with increased risk for CKD after 14 years. Strategies to decrease CKD risk might include prevention of overweight and obesity.

Detection of early nephropathy in Mexican patients with type 2 diabetes mellitus

BACKGROUND

The aims of this study were to determine the prevalence of early nephropathy in patients with type 2 diabetes mellitus (DM2) attending primary care medical units and to identify risk factors for nephropathy in this population.

METHOD

Seven hundred fifty-six patients with DM2 attending 3 primary care medical units were randomly selected. In a first interview, an albuminuria dipstick and a detailed clinical examination were performed, and a blood sample was obtained. If the albuminuria dipstick was positive, then a 24-hour urine collection was obtained within the next 2 weeks to quantify the albuminuria. In the blood sample, glucose, creatinine, and lipids were determined. Glomerular filtration rate was calculated using the Modification of Diet in Renal Disease Study equation. Demographics and medical history were recorded from clinical examination and medical charts.

RESULTS

Prevalence of early nephropathy (EN) was 40%, normal function (NF) was found in 31%, and overt nephropathy (ON) in 29%. Patients with more severe kidney damage were older (NF: 54 +/- 10; EN: 60 +/- 11; ON: 63 +/- 10 years, P < 0.05) and had a higher proportion of illiteracy (NF: 11%, EN: 17%; ON: 25%, P < 0.05). The more severe the nephropathy, the longer the median duration of DM2 (NF: 6.0; EN: 7.0; ON: 11.0 years; P < 0.05); the higher the frequency of hypertension (NF: 38%; EN: 52%; ON: 68%; P < 0.05); and the higher the systolic blood pressure (NF: 126 +/- 21; EN: 130 +/- 19; ON: 135 +/- 23 mm Hg; P < 0.05). Both nephropathy groups had a significantly higher proportion of family history of nephropathy (NF: 4%; EN: 9%; ON: 13%) and a higher frequency of cardiovascular disease (NF: 5%; EN: 12%; ON: 25%), whereas only patients with ON had peripheral neuropathy (NF: 21%; EN: 22%; ON: 43%) and retinopathy (NF: 12%; EN: 18%; ON: 42%) more frequently than others. Fasting glucose was poorly controlled in all groups (NF: 186 +/- 70; EN: 173 +/- 62; ON: 183 +/- 73 mg/dL). Large body mass index (NF: 29.3 +/- 5.3; EN: 29.7 +/- 5.6; ON: 29.6 +/- 5.5 kg/m(2)), smoking (NF: 45%; EN: 43%; ON: 44%), and alcoholism (NF: 29%, EN: 29%; ON: 26%) were frequently found in this population, although there were no significant differences. In the multivariate analysis, only age, duration of DM2, and presence of retinopathy, hypertension, and cardiovascular disease were significantly associated with nephropathy.

CONCLUSIONS

Two thirds of Mexican patients with DM2 attending primary health care medical units had nephropathy, 40% of whom were at an early stage of the disease. Many modifiable and nonmodifiable risk factors were present in these patients, but the most significant predictors for nephropathy are older age, longer duration of diabetes, and the presence of retinopathy, hypertension, and cardiovascular disease.