American Society of Nephrology Presidential Address 2006: Chronic Kidney Disease as a Public Health Threat—New Strategy for a Growing Problem

Marker for kidney fibrosis is associated with inflammation and deterioration of kidney function in people with type 2 diabetes and microalbuminuria

BACKGROUND

Diabetic kidney disease is a major cause of morbidity and mortality. Dysregulated turnover of collagen type III is associated with development of kidney fibrosis. We investigated whether a degradation product of collagen type III (C3M) was a risk marker for progression of chronic kidney disease (CKD), occurrence of cardiovascular disease (CVD), and mortality during follow up in people with type 2 diabetes (T2D) and microalbuminuria. Moreover, we investigated whether C3M was correlated with markers of inflammation and endothelial dysfunction at baseline.

METHODS

C3M was measured in serum (sC3M) and urine (uC3M) in 200 participants with T2D and microalbuminuria included in an observational, prospective study at Steno Diabetes Center Copenhagen in Denmark from 2007-2008. Baseline measurements included 12 markers of inflammation and endothelial dysfunction. The endpoints were CVD, mortality, and CKD progression (>30% decline in eGFR).

RESULTS

Mean (SD) age was 59 (9) years, eGFR 90 (17) ml/min/1.73m2 and median (IQR) urine albumin excretion rate 102 (39-229) mg/24-h. At baseline all markers for inflammation were positively correlated with sC3M (p≤0.034). Some, but not all, markers for endothelial dysfunction were correlated with C3M. Median follow-up ranged from 4.9 to 6.3 years. Higher sC3M was associated with CKD progression (with mortality as competing risk) with a hazard ratio (per doubling) of 2.98 (95% CI: 1.41-6.26; p = 0.004) adjusted for traditional risk factors. uC3M was not associated with CKD progression. Neither sC3M or uC3M were associated with risk of CVD or mortality.

CONCLUSIONS

Higher sC3M was a risk factor for chronic kidney disease progression and was correlated with markers of inflammation.

20 year trends in renal disease mortality in Ghana: A review of autopsies

AIM

Data on the changing levels in renal morbidity and mortality are scant globally. We sought to assess trends in renal disease mortality and attributable causes over a 20 year period in Ghana.

METHODS

A retrospective analysis of 20 year autopsy records of the Pathology Departments of leading teaching hospitals in Ghana, (Korle-Bu Teaching Hospital (KBTH) in Accra and Komfo Anokye Teaching Hospital (KATH) in Kumasi) from January 1994 to December 2013. Data comprising autopsies from in-patients, community cases and coroners' cases were used. We defined primary cause of death as death directly due to renal disease and secondary cause of death as death in which renal disease was a comorbid or contributing factor.

RESULTS

Over the period, there were a total of 94 309 deaths, of which 5608 were attributed to renal disease (5.9/100). Mortality rate remained fairly the same from 1994 to 2009 (5.0%), but doubled from 2010 to 2013 (10.8%). Similar trends were observed among males and females during the same period. However, males had slightly higher mortality rates (6.6%; 95% CI: 46.1%-6.8%) compared to females (5.6%; 95% CI: 5.4%-5.8%; P = 0.271). The major leading attributable causes of renal disease death include end stage renal disease 45.0% and acute pyelonephritis accounting for 20.9% of the cases. Hypertensive heart disease accounted for 30.0% of all secondary cause of death while congestive heart disease and septicaemia accounted for 13.0% and 12.0%, respectively.

CONCLUSIONS

We observed marked increase in the renal disease mortality rate during the last few years predominantly driven by chronic and infectious related renal diseases as a main cause, and hypertensive heart disease and congestive heart failure as the main secondary causes. Measures geared towards prevention, treatment and managing such conditions may impact on the reduction of renal disease mortality rate among Ghanaian populations.

The Xanthine Oxidase Inhibitor Febuxostat Suppresses the Progression of IgA Nephropathy, Possibly via Its Anti-Inflammatory and Anti-Fibrotic Effects in the gddY Mouse Model

Recent clinical studies have demonstrated the protective effect of xanthine oxidase (XO) inhibitors against chronic kidney diseases, although the underlying molecular mechanisms remain unclear. However, to date, neither clinical nor basic research has been carried out to elucidate the efficacy of XO inhibitor administration for IgA nephropathy. We thus investigated whether febuxostat, an XO inhibitor, exerts a protective effect against the development of IgA nephropathy, using gddY mice as an IgA nephropathy rodent model. Eight-week-old gddY mice were provided drinking water with (15 μg/mL) or without febuxostat for nine weeks and then subjected to experimentation. Elevated serum creatinine and degrees of glomerular sclerosis and fibrosis, judged by microscopic observations, were significantly milder in the febuxostat-treated than in the untreated gddY mice, while body weights and serum IgA concentrations did not differ between the two groups. In addition, elevated mRNA levels of inflammatory cytokines such as TNFα, MCP-1, IL-1β, and IL-6, collagen isoforms and chemokines in the gddY mouse kidneys were clearly normalized by the administration of febuxostat. These data suggest a protective effect of XO inhibitors against the development of IgA nephropathy, possibly via suppression of inflammation and its resultant fibrotic changes, without affecting the serum IgA concentration.

Vascular homeostasis in early (normo-albuminuric) type 2 diabetic nephropathy

Background: Renal microvascular disease and reduction in peritubular capillary flow are generally observed in type 2 diabetic nephropathy (DN). Earlier therapeutic strategy with vasodilators has improved renal function in normo-albuminuric type 2 DN. Objective: Study the mechanism of vascular homeostasis in twenty patients associated with normo-albuminuric type 2 DN. Results: Angiogenic factors were observed in normo-albuminuric type 2 DN, where vascular endothelial growth factor (VEGF), was 420 ± 341 vs. 428±291 pg/mL (normal), and vascular endothelial growth factor - receptor 1 (VEGF-R1) was 60±12 vs. 49±5 ng/mL (normal), which were not significantly different from the controls. Anti-angiogenic factors were observed in normo-albuminuric type 2 DN, where angiopoietin-2, was 2309+1125 vs. 1671±835 pg/mL (normal), and vascular endothelial growth factor - receptor 2 (VEGF-R2) was 5715±1400 vs.6126 ±1060 ng/mL (normal), which were not significantly different from the controls. Conclusion: The mechanism of vascular homeostasis was adequately functional in normo-albuminuric type 2 DN. This mechanism may explain the positive response to vasodilators and improved renal function in early stage of type 2 DN following the vasodilator treatment.

pH-mediated upregulation of AQP1 gene expression through the Spi-B transcription factor

Background

Bicarbonate-based peritoneal dialysis (PD) fluids enhance the migratory capacity and damage-repair ability of human peritoneal mesothelial cells by upregulating AQP1. However, little is known about the underlying molecular mechanisms.

Results

Here we used HEK-293T cells to investigate the effect of pH on AQP1 gene transcription levels. We found that AQP1 mRNA levels increases with pH. Transfection of HEK-293T cells with luciferase reporter vectors containing different regions of the AQP1 promoter identified an upstream region in the AQP1 gene between − 2200 and – 2300 bp as an enhancer required for pH-mediated regulation of AQP1 expression. Site-directed mutagenesis of this specific promoter region revealed a critical region between − 2257 and − 2251 bp, and gene knock-down experiments and ChIP assays suggested that the Spi-B transcription factor SPIB is involved in pH-mediated regulation of AQP1 expression.

Conclusions

We identified an upstream region in the AQP1 gene and the transcription factor SPIB that are critically involved in pH-mediated regulation of AQP1 expression. These findings provide the basis for further studies on the pH- and buffer-dependent effects of PD fluids on peritoneal membrane integrity and function.

Electronic supplementary material

The online version of this article (10.1186/s12867-018-0104-9) contains supplementary material, which is available to authorized users.

On the rationale of population screening for chronic kidney disease: a public health perspective

Unlike opportunistic screening, population screening is accompanied by stringent quality control measures and careful programme monitoring. Sufficient evidence for benefit together with acceptable harms and costs to society are needed before launching a programme. A screening programme is a complex process organized at the population level involving multiple actors of the health care system that should ideally be supervised by public health authorities and evaluated by an independent and trustful body. Chronic kidney disease is defined by reduced glomerular filtration rate and/or presence of kidney damage for at least three months. Chronic kidney disease is divided into 5 stages with stages 1 to 3 being usually asymptomatic. Chronic kidney disease affects one in ten adults worldwide and its prevalence sharply increases with age. Kidney function is measured using serum creatinine-based, and/or cystatin C-based, equations. Markers of renal function show high intra-individual and inter-laboratory variabilities, highlighting the need for standardized procedures. There is also large inter-individual variability in age-related kidney function decline. Despite these limitations, chronic kidney disease, as currently defined, has been consistently associated with high cardiovascular morbidity and mortality and high risk of end-stage renal disease. Major modifiable risk factors for chronic kidney disease are diabetes, hypertension, obesity and cardiovascular disease. Several treatment options, ranging from antihypertensive and lipid-lowering treatments to dietary measures, reduce all-cause mortality and/or end-stage renal disease in patients with stages 1-3 chronic kidney disease. So far, no randomized controlled trial comparing outcomes with and without population screening for stages 1-3 chronic kidney disease has been published. Population screening for stages 1-3 chronic kidney disease is currently not recommended because of insufficient evidence for benefit. Given the current and future burden attributable to chronic kidney disease, randomized controlled trials exploring benefits and harms of population screening are clearly needed to prioritize resource allocations.

Overview of the cellular and molecular basis of kidney fibrosis

The common pathogenetic pathway of progressive injury in patients with chronic kidney disease (CKD) is epitomized as normal kidney parenchymal destruction due to scarring (fibrosis). Understanding the fundamental pathways that lead to renal fibrosis is essential in order to develop better therapeutic options for human CKD. Although complex, four cellular responses are pivotal. (1) An interstitial inflammatory response that has multiple consequences—some harmful and others healing. (2) The appearance of a unique interstitial cell population of myofibroblasts, primarily derived from kidney stromal cells (fibroblasts and pericytes), that are the primary source of the various extracellular matrix proteins that form interstitial scars. (3) Tubular epithelial cells that have variable and time-dependent roles as early responders to injury and later as victims of fibrosis due to the loss of their regenerative abilities. (4) Loss of interstitial capillary integrity that compromises oxygen delivery and leads to a vicious cascade of hypoxia–oxidant stress that accentuates injury and fibrosis. In the absence of adequate angiogenic responses, a healthy interstitial capillary network is not maintained. The fibrotic ‘scar' that typifies CKD is an interesting consortium of multifunctional macromolecules that not only change in composition and structure over time, but can be degraded via extracellular and intracellular proteases. Although transforming growth factor beta appears to be the primary driver of kidney fibrosis, a vast array of additional molecules may have modulating roles. The importance of genetic and epigenetic factors is increasingly appreciated. An intriguing but incompletely understood cardiorenal syndrome underlies the high morbidity and mortality rates that develop in association with progressive kidney fibrosis.

Prevalence of chronic kidney disease and associated risk factors, and risk of end-stage renal disease: data from the PREVADIAB study

BACKGROUND/AIMS

Chronic kidney disease (CKD) is a growing public health problem. However, data on risk factors and prevalence of CKD exist only in a small number of countries. Portugal has the highest incidence of end-stage renal disease (ESRD) among European countries, but there are huge disparities among countries. Whether these disparities reflect differences in risk factors, prevalence of CKD or other factors is currently unknown.

METHODS

We analyzed data from a nationally representative sample of 5,167 subjects, and estimated the prevalence of CKD and associated risk factors, and combined these prevalence estimates with available data on ESRD.

RESULTS

The prevalence of risk factors such as diabetes (11.7%), obesity (33.7%), and metabolic syndrome (41.5%) was similar to that in the US, but greater than in most European countries. The prevalence of CKD stages 3-5 was 6.1%, which is similar to that in other Western countries. The risk of ESRD was greater than in other European countries, but lower than in the US.

CONCLUSION

The high incidence of ESRD among the Portuguese population is not due to a greater prevalence of CKD. A higher rate of progression associated with the high prevalence of risk factors may account for the high incidence of ESRD. The role of unmeasured factors needs to be evaluated in further studies.

Efficacy and Safety of Carvedilol in Treatment of Heart Failure with Chronic Kidney Disease

Background—

The safety and efficacy of different types of β-blocker therapy in patients with non–dialysis-dependent chronic kidney disease (CKD) and systolic heart failure (HF) are not well described. We assessed whether treatment of systolic HF with carvedilol is efficacious and safe in adults with CKD.

Methods and Results—

We performed a post hoc analysis of pooled individual patient data (n=4217) from 2 multinational, double-blinded, placebo-controlled, randomized trials, CAPRICORN (Carvedilol Postinfarct Survival Control in Left Ventricular Dysfunction Study) and COPERNICUS (Carvedilol Prospective Randomized, Cumulative Survival study). Primary outcome was all-cause mortality. Secondary outcomes included cardiovascular mortality, HF mortality, first HF hospitalization, the composite of cardiovascular mortality or first HF hospitalization, and sudden cardiac death. Non–dialysis-dependent CKD was defined by estimated glomerular filtration rate ≤60 mL/min/1.73 m 2 , using the abbreviated Modification of Diet in Renal Disease equation. CKD was present in 2566 of 4217 (60.8%) of the cohort, 50.4% of whom were randomly assigned to carvedilol therapy. Within the CKD group, treatment with carvedilol decreased the risks of all-cause mortality (hazard ratio [HR], 0.76; 95% confidence interval [CI], 0.63 to 0.93; P =0.007), cardiovascular mortality (HR, 0.76; 95% CI, 0.62 to 0.94; P =0.011), HF mortality (HR, 0.68; 95% CI, 0.52 to 0.88; P =0.003), first hospitalization for HF (HR, 0.74; 95% CI, 0.61 to 0.88; P =0.0009), and the composite of cardiovascular mortality or HF hospitalization (HR, 0.75; 95% CI, 0.65 to 0.87; P <0.001) but was without significant effect on sudden cardiac death (HR, 0.76; 95% CI, 0.56 to 1.05; P =0.098). There was no significant interaction between treatment arm and study type. Carvedilol was generally well tolerated by both groups of patients, with an increased relative incidence in transient increase in serum creatinine without need for dialysis and other electrolyte changes in the CKD patients. However, in a sensitivity analysis among HF subjects with estimated glomerular filtration rate <45 mL/min/1.73 m 2 (CKD stage 3b), the efficacy of carvedilol was not significantly different from placebo.

Conclusions—

This analysis suggests that the benefits of carvedilol therapy in patients with systolic left ventricular dysfunction with or without symptoms of HF are consistent even in the presence of mild to moderate CKD. Whether carvedilol therapy is similarly efficacious in HF patients with more advanced kidney disease requires further study.

Visfatin is upregulated in type-2 diabetic rats and targets renal cells

Visfatin (also known as pre-B cell colony-enhancing factor) is a newly discovered adipocytokine that is preferentially produced by visceral fat and regulated by cytokines promoting insulin resistance. Here we determined its renal synthesis and physiology in a genetic model of type 2 diabetes in rats. These rats had higher levels of visfatin synthesis in both glomeruli and tubulointerstitium compared to control rats. Plasma visfatin levels were significantly increased in the early stages of diabetic nephropathy and positively correlated with body weight, fasting plasma glucose, and microalbuminuria. Interestingly, visfatin synthesis was found to occur in podocytes and proximal tubular cells, as well as in adipocytes in vitro. Further, in both renal cells, visfatin synthesis was significantly increased by high glucose in the media but not by angiotensin II. Additionally, visfatin treatment induced rapid uptake of glucose and was associated with increased translocation of GLUT-1 to the cellular membrane of both renal cell types. Furthermore, visfatin induced tyrosine phosphorylation of the insulin receptor, activated downstream insulin signaling pathways such as Erk-1, Akt, and p38 MAPK, and markedly increased the levels of TGFbeta1, PAI-1, type I collagen, and MCP-1 in both renal cells. Thus, our results suggest that visfatin is produced by renal cells and has an important paracrine role in the pathogenesis of diabetic nephropathy.

A mildly altered vascular homeostasis in early stage of CKD

BACKGROUND

A continuous increase in number of CKD patients entering ESRD is a growing public health threat, which reflects the present therapeutic failure usually initiating at the late stage of CKD.

OBJECTIVE

To study the mechanism of vascular repair in CKD patients associated with mildly impaired renal function, which included angiogenic factors such as VEFG, angiopoietin-1, and flt-1 (VEGFR1); and antiangiogenic factors such as angiopoietin-2 and KDR (VEGFR2).

RESULTS

A mild defect in angiogenic factor-namely, angiopoietin-1-was observed, whereas VEGF and flt-1 (VEGFR1) were within normal limit. Also, antiangiogenic factor-namely, angiopoietin-2-was mildly elevated, whereas KDR (VEGFR2) remained within normal limit.

CONCLUSION

The mechanism of vascular repair appears to be adequately functional in the early stage of CKD. Therapeutic intervention at this stage can improve renal perfusion and restore renal function as indicated in normoalbuminuric, type 2 diabetic nephropathy. The authors encourage changing the conceptual view of treatment under common treatment at late stage of CKD to treatment at early stage of CKD under an environment favorable for renal regeneration.

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

BACKGROUND

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

STUDY DESIGN

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

SETTING & PARTICIPANTS

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

PREDICTOR

A comprehensive collection of cardiovascular risk factors were examined.

OUTCOMES & MEASUREMENTS

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

RESULTS

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

LIMITATIONS

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

CONCLUSIONS

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

Neurological complications of chronic kidney disease

Chronic kidney disease (CKD) is a critical and rapidly growing global health problem. Neurological complications occur in almost all patients with severe CKD, potentially affecting all levels of the nervous system, from the CNS through to the PNS. Cognitive impairment, manifesting typically as a vascular dementia, develops in a considerable proportion of patients on dialysis, and improves with renal transplantation. Patients on dialysis are generally weaker, less active and have reduced exercise capacity compared with healthy individuals. Peripheral neuropathy manifests in almost all such patients, leading to weakness and disability. Better dialysis strategies and dietary modification could improve outcomes of transplantation if implemented before surgery. For patients with autonomic neuropathy, specific treatments, including sildenafil for impotence and midodrine for intradialytic hypotension, are effective and well tolerated. Exercise training programs and carnitine supplementation might be beneficial for neuromuscular complications, and restless legs syndrome in CKD responds to dopaminergic agonists and levodopa treatment. The present Review dissects the pathophysiology of neurological complications related to CKD and highlights the spectrum of therapies currently available.

Defining incident chronic kidney disease in the research setting: The ARIC Study

Deaths of participants and losses to follow-up pose challenges for defining outcomes in epidemiologic studies. The authors compared several definitions of incident chronic kidney disease (CKD) in terms of incidence, agreement, and risk factor associations. They used data from 14,873 participants in the community-based, multicenter, biracial Atherosclerosis Risk in Communities Study (1987-1999). The estimated glomerular filtration rate (eGFR) was based on serum creatinine at baseline and the 3- and 9-year follow-up visits. Hospitalizations were ascertained continuously. The authors compared 4 definitions of incident CKD: 1) low eGFR (<60 mL/minute/1.73 m(2)); 2) low and declining (> or =25%) eGFR; 3) an increase in serum creatinine (> or =0.4 mg/dL) at 3- or 9-year follow-ups; and 4) CKD-related hospitalization or death. From these definitions, they identified 1,086, 677, 457, and 163 cases, respectively. There was relatively good agreement among definitions 1-3, but definition 4 identified mostly different cases. Risk factor associations were consistent across definitions for hypertension and lipids. Diabetes showed weaker associations with definition 1 (incidence rate ratio = 1.5, 95% confidence interval: 1.2, 1.7) than with definition 4 (incidence rate ratio = 6.3, confidence interval: 4.4, 8.9). Associations with gender differed in direction and magnitude across definitions. Case definition can impact relative risk estimates for CKD risk factors.

Altered vascular homeostasis in type 2 diabetic nephropathy

Type 2 diabetic nephropathy is a primary cause of ESRD worldwide. Therapeutic strategy in patients with microalbuminuric or macroalbuminuric type 2 diabetic nephropathy usually fails to restore renal function but merely slows the renal disease progression. In contrast, a recent study implies that the restoration of renal function as well as renal perfusion can be accomplished in early stage of type 2 diabetic nephropathy (normoalbuminuria) by correcting the hemodynamic maladjustment in renal microcirculation with vasodilators. Therefore, we intend to study the mechanism of vascular homeostasis to explain why treatment in the late stage of diabetic nephropathy during microalbuminuria or macroalbuminuria fails to enhance renal perfusion or restore renal function. The results indicate that such therapeutic failure in late-stage type 2 diabetic nephropathy likely relates to multiple defects in vascular repair, namely deficiencies in angiogenic factors such as endothelial progenitor cell, angiopoietin-1, flt-1 receptor, as well as elevated levels of antiangiogenic factors such as angiopoietin-2 and KDR.

Neuromuscular disease in the dialysis patient: an update for the nephrologist

Neuromuscular disease is an extremely common complication of end-stage kidney disease (ESKD), manifesting in almost all dialysis patients, and leading to weakness, reduced exercise capacity, and disability. Recent studies have suggested that hyperkalemia may underlie the development of neuropathy. As such, maintenance of serum K(+) within normal limits between periods of dialysis in ESKD patients manifesting early neuropathic symptoms may reduce neuropathy development and progression. For patients with more severe neuropathic syndromes, increased dialysis frequency or a switch to high-flux dialysis may prevent further deterioration, while ultimately, renal transplantation is required to improve and restore nerve function. Exercise training programs are beneficial for ESKD patients with muscle weakness due to neuropathy or myopathy, and are capable of improving exercise tolerance and quality of life. Specific treatments have recently been evaluated for symptoms of autonomic neuropathy, including sildenafil for impotence and midodrine for intra-dialytic hypotension, and have been shown to be effective and well tolerated. Other important management strategies for neuropathy include attention to foot care to prevent callus and ulceration, vitamin supplementation, and erythropoietin. Treatment with membrane-stabilizing agents, such as amitryptiline and gabapentin, are highly effective in patients with painful neuropathy.

Cardiovascular disease in chronic kidney disease

The presence of kidney disease, manifested by low glomerular filtration rates (GFR) and/or large amounts of protein in the urine, is independently associated with increased rates of cardiovascular disease (CVD). The severity of kidney disease is associated with graded increases in risk for CVD and death. Chronic kidney disease (CKD) should be recognized and treatment initiated early to maximize the chances for slowing nephropathy progression and reducing proteinuria. We recommend screening for CKD in all patients with CVD, including computing an estimated GFR and evaluating for proteinuria using a spot urine albumin:creatinine ratio. Aggressive management of traditional cardiovascular risk factors should be employed in this high-risk population, specifically rigorous hypertension control (including the use of angiotensin-converting enzyme inhibitors (ACEI)/angiotensin receptor blocking agents (ARB)), management of hyperglycemia, hyperlipidemia and smoking cessation. Further studies are needed to identify the unique renal failure-related (non-traditional) risk factors that contribute to accelerated atherosclerosis in this population and performance of randomized trials to assess the effects of cardiovascular interventions in individuals with CKD.

Poor glycemic control in diabetes and the risk of incident chronic kidney disease even in the absence of albuminuria and retinopathy: Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Diabetic nephropathy is the leading cause of kidney failure in the United States. The extent to which an elevated glycated hemoglobin (HbA(1c)) concentration is associated with increased risk of chronic kidney disease (CKD) in the absence of albuminuria and retinopathy, the hallmarks of diabetic nephropathy, is uncertain.

METHODS

Glycated hemoglobin concentration was measured in 1871 adults with diabetes mellitus followed up for 11 years in the Atherosclerosis Risk in Communities (ARIC) Study. Incident CKD was defined as an estimated glomerular filtration rate less than 60 mL/min/1.73 m(2) after 6 years of follow-up or a kidney disease-related hospitalization. We categorized HbA(1c) concentrations into 4 clinically relevant categories. Albuminuria and retinopathy were measured midway through follow-up.

RESULTS

Higher HbA(1c) concentrations were strongly associated with risk of CKD in models adjusted for demographic data, baseline glomerular filtration rate, and cardiovascular risk factors. Compared with HbA(1c) concentrations less than 6%, HbA(1c) concentrations of 6% to 7%, 7% to 8%, and greater than 8% were associated with adjusted relative hazard ratios (95% confidence intervals) of 1.4 (0.97-1.91), 2.5 (1.70-3.66), and 3.7 (2.76-4.90), respectively. Risk of CKD was higher in individuals with albuminuria and retinopathy, and the association between HbA(1c) concentration and incident CKD was observed even in participants without either abnormality: adjusted relative hazards, 1.46 (95% confidence intervals, 0.80-2.65), 1.17 (0.43-3.19), and 3.51 (1.67-7.40), respectively; P(trend) = .004.

CONCLUSIONS

We observed a positive association between HbA(1c) concentration and incident CKD that was strong, graded, independent of traditional risk factors, and present even in the absence of albuminuria and retinopathy. Hyperglycemia is an important indicator of risk of both diabetic nephropathy with albuminuria or retinopathy and of less specific forms of CKD.