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

Elevated serum uric acid predicts chronic kidney disease

INTRODUCTION

The question of whether elevated serum uric acid is an independent risk factor for chronic kidney disease in a longitudinal manner was assessed in Japanese subjects undergoing a health checkup.

METHODS

A total of 14,399 participants (8,161 men and 6,238 women) without medication for hyperuremia in both 2000 and 2005 were included. After exclusion of participants taking treatments influencing serum uric acid and having chronic kidney disease defined as estimated glomerular filtration rate <60 mL/min/1.73 m(2), in 2000, multiple logistic regression analyses were performed for 6,887 men (48.4 ± 9.9 years) and 5,340 women (49.9 ± 9.0 years) to identify independent factors for newly diagnosed chronic kidney disease in 2005. Adjustment was made for age, body mass index, elevated blood pressure or hypertension, hypertriglyceridemia, impaired fasting glucose, either urinary protein or occult blood, alcohol drinking and smoking.

RESULTS

The prevalence of chronic kidney disease and the values of body mass index, systolic and diastolic blood pressure and triglyceride were significantly higher in the participants with elevated serum uric acid quartiles. Chronic kidney disease was newly diagnosed in 4.1% of men and 3.7% of women, within the 5-year period. In multivariate models, the higher quartiles of serum uric acid were associated with increased risk of chronic kidney disease in both sexes. The odds ratio and 95% confidence interval for 1 increment of serum uric acid were 1.42 and 1.28 to 1.58 in men and 1.32 and 1.12 to 1.56 in women, respectively.

CONCLUSIONS

Elevated serum uric acid predicts chronic kidney disease in subjects undergoing a health checkup.

Nocturia is associated with an increased risk of coronary heart disease and death

What's known on the subject? and What does the study add? Nocturia has been associated with multiple chronic conditions, however, previous studies have been conducted only at a single time. We found that nocturia preceded the development CHD in young men. Moderate nocturia may be an early marker of CHD in young men.

OBJECTIVE

To determine whether nocturia is associated with the development of diabetes mellitus, hypertension, coronary heart disease (CHD) and occurrence of death.

MATERIALS AND METHODS

We studied data obtained from a retrospective cohort of randomly selected men, aged 40-79 years in 1990, from Olmsted County, MN, USA. Moderate nocturia was defined as waking to urinate ≥2 times per night. Men were followed every 2 years through repeated questionnaires and community medical records to assess development of diabetes mellitus and hypertension, and occurrence of death. CHD was ascertained through ongoing surveillance of heart disease in Olmsted County. Cox proportional hazard models were used to estimate associations between baseline nocturia and each of the outcomes.

RESULTS

A total of 2447 men were followed for a median of 17.1 years (25th and 75th percentiles: 15.0, 17.4 years). Moderate nocturia was not significantly associated with the later development of diabetes mellitus or hypertension in this study. Younger men (<60 years of age) with moderate nocturia were more likely to develop CHD later in life than younger men without nocturia (hazard ratio [HR]: 1.68; 95% confidence interval [CI]: 1.13, 2.49). This association was no longer significant when adjusted for age, body mass index (BMI) and urological medications (HR: 1.36; 95% CI: 0.87, 2.12). Older men (≥60 years of age) with moderate nocturia were more likely to die than older men without moderate nocturia, even after adjusting for age, BMI, urological medications and CHD (HR: 1.48; 95% CI: 1.15, 1.91).

CONCLUSION

Nocturia may be a marker for increased risk of CHD in younger men, and death in older men.

Preventing renal and cardiovascular risk by renal function assessment: insights from a cross-sectional study in low-income countries and the USA

OBJECTIVE

To assess the prevalence of microalbuminuria and kidney dysfunction in low-income countries and in the USA.

DESIGN

Cross-sectional study of screening programmes in five countries.

SETTING

Screening programmes in Nepal, Bolivia, the USA (National Health and Nutrition Examination Survey (NHANES) 2005-2008) Bangladesh and Georgia.

PARTICIPANTS

General population in Nepal (n=20 811), Bolivia (n=3436) and in the USA (n=4299) and high-risk subjects in Bangladesh (n=1518) and Georgia (n=1549).

PRIMARY AND SECONDARY OUTCOME MEASURES

Estimated glomerular filtration rate (eGFR)<60ml/min/1.73 m(2) and microalbuminuria (defined as urinary albumin creatinine ratio values of 30-300 mg/g) were the main outcome measures. The cardiovascular (CV) risk was also evaluated on the basis of demographic, clinical and blood data.

RESULTS

The prevalence of eGFR<60ml/min/1.73 m(2) was 19%, 3.2% and 7% in Nepal, Bolivia and the USA, respectively. In Nepal, 7% of subjects were microalbuminuric compared to 8.6% in the USA. The prevalence of participants with predicted 10-year CV disease (CVD) risk ≥10% was 16.9%, 9.4% and 17% in Nepal, Bolivia and in the USA, respectively. In Bangladesh and Georgia, subjects with eGFR<60 ml/min/1.73 m(2) were 8.6% and 4.9%, whereas those with microalbuminuria were 45.4% and 56.5%, respectively. Predicted 10-year CVD risk ≥10% was 25.4% and 25% in Bangladesh and Georgia, respectively.

CONCLUSIONS

Renal abnormalities are common among low-income countries and in the USA. Prevention programmes, particularly focused on those with renal abnormalities, should be established worldwide to prevent CVD and progression to end-stage renal disease.

Is there anything good in uric acid?

High uric acid (UA) levels can cause gout, urolithiasis and acute and chronic nephropathy, all of which are due to the deposit of urate crystals. There is also increasing evidence of relationships of hyperuricemia with other important disorders, including hypertension, chronic renal disease, metabolic syndrome and cardiovascular disease, as well as an increased mortality, although a causal relationship between these conditions has not been clearly established. On the other hand, low UA levels are not known to cause any disorder or disease. However, in the last few years a higher prevalence and progression of some neurological diseases have been associated with a low UA, and it is possible that they may predispose to some other disorders, mainly due to the decrease in its antioxidant activity. In this article, the known negative effects of UA are reviewed, as well as the much less-known possible positive actions, and their therapeutic implications.

The epidemiology of uric acid and fructose

During the past few decades, the mean serum uric acid levels and the prevalence of hyperuricemia in the general population appear to have increased. Correspondingly, the prevalence and incidence of gout have doubled. Potential reasons behind these trends include the increasing prevalence of obesity and metabolic syndrome, Western lifestyle factors, increased prevalence of medical conditions (eg, renal conditions, hypertension, and cardiovascular disorders), and use of medications that increase uric acid levels (eg, diuretics and low-dose aspirin). The substantial increase in sugar-sweetened soft drinks and associated fructose consumption also has coincided with the secular trend of hyperuricemia and gout. Recently, several large-scale epidemiologic studies have clarified a number of these long-suspected risk factors in relation with hyperuricemia and gout. Furthermore, recent studies have illuminated the substantial comorbidities of hyperuricemia and gout, particularly metabolic-cardiovascular-renal conditions. Although many prospective studies have suggested an independent association between serum uric acid levels and the future risk of cardiovascular-metabolic morbidities and mortality, only a limited number of randomized clinical trials and observational studies recently have shown that the use of allopurinol can be beneficial against these outcomes. Because these data are scarce and the effects of allopurinol might not be limited to decreasing serum uric acid levels, the potential causal role of uric acid on these outcomes remains to be clarified with further studies.

Moving from viral suppression to comprehensive patient-centered care: the high prevalence of comorbid conditions and health risk factors in HIV-1-infected patients in Australia

HIV clinicians today need to move from focusing on viral suppression to a chronic disease model in which comorbid conditions and risk factors are comprehensively identified and addressed to reduce rates of serious non-AIDS-related morbidity and mortality. This study aimed to determine the prevalence of comorbid conditions in an Australian HIV-positive population. Of 180 patients included, there was a median CD4 count of 0.520 cells/mm(3). The majority (88%) of patients were currently receiving highly active antiretroviral therapy (HAART). There were high rates of failure to attend clinical appointments (30%), current smoking (42%), hypertension (16%), and dyslipidemia (17%). Significant rates of dipstick-positive proteinuria (16%) and elevated blood glucose (15%) were recorded. Risk factors were commonly not addressed by the treating clinician. There is an urgent need to systematize detection and management of high-prevalence comorbid conditions to prevent premature mortality associated with serious non-AIDS events.

Albuminuria and racial disparities in the risk for ESRD

The causes of the increased risk for ESRD among African Americans are not completely understood. Here, we examined whether higher levels of urinary albumin excretion among African Americans contributes to this disparity. We analyzed data from 27,911 participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study who had urinary albumin-to-creatinine ratio (ACR) and estimated GFR (eGFR) measured at baseline. We identified incident cases of ESRD through linkage with the United States Renal Data System. At baseline, African Americans were less likely to have an eGFR <60 ml/min per 1.73 m(2) but more likely to have an ACR ≥ 30 mg/g. The incidence rates of ESRD among African Americans and whites were 204 and 58.6 cases per 100,000 person-years, respectively. After adjustment for age and gender, African Americans had a fourfold greater risk for developing ESRD (HR 4.0; 95% CI 2.8 to 5.9) compared with whites. Additional adjustment for either eGFR or ACR reduced the risk associated with African-American race to 2.3-fold (95% CI 1.5 to 3.3) or 1.8-fold (95% CI 1.2 to 2.7), respectively. Adjustment for both ACR and eGFR reduced the race-associated risk to 1.6-fold (95% CI 1.1 to 2.4). Finally, in a model that further adjusted for both eGFR and ACR, hypertension, diabetes, family income, and educational status, African-American race associated with a nonsignificant 1.4-fold (95% CI 0.9 to 2.3) higher risk for ESRD. In conclusion, the increased prevalence of albuminuria may be an important contributor to the higher risk for ESRD experienced by African Americans.

Serum uric acid is a GFR-independent long-term predictor of acute and chronic renal insufficiency: the Jerusalem Lipid Research Clinic cohort study

BACKGROUND

Kidney disease is commonly accompanied by hyperuricemia. However, the contribution of serum uric acid (SUA) to kidney injury is debated. Our objective was to assess the long-term prediction of renal failure by SUA.

METHODS

Visit 2 participants in the Jerusalem Lipid Research Clinic cohort with normal baseline kidney function were followed for 24-28 years. SUA levels were assessed for associations with acute renal failure (ARF) and chronic renal failure (CRF) as defined by hospital discharge records, and mortality, ascertained through linkage with the national population registry.

RESULTS

Among 2449 eligible participants (1470 men, 979 women aged 35-78 years in 1976-79), SUA was positively linked with male sex, serum creatinine and components of the metabolic syndrome but was lower in smokers and in diabetic subjects. The 22- to 25-year incidence of hospital-diagnosed kidney failure (145 first events, 67% CRF) and the 24- to 28-year mortality (587 events) were higher in subject with hyperuricemia (>6.5 mg/dL in men and >5.3 mg/dL in women, reflecting the upper quintiles), independent of baseline kidney function and covariates. Hyperuricemia conferred adjusted hazard ratios of 1.36 (P = 0.003), 2.14 (P < 0.001) and 2.87 (P = 0.003) for mortality, CRF and ARF, respectively.

CONCLUSIONS

SUA predicts renal failure incidence and all-cause mortality independently of demographic and clinical covariates. These results lend support to the undertaking of clinical trials to examine the effect of uric acid-lowering strategies on kidney outcomes.

Bariatric surgery and renal function

Obesity causes a significant healthcare burden and has been shown to be an important risk factor in the development of cardiovascular disease, type 2 diabetes, and increasingly chronic kidney disease. Bariatric surgery is the most effective treatment for obesity and has been shown to drastically improve both blood pressure and diabetic control. However, the interaction of bariatric surgery and renal function is less clear. This review focuses on the effect of bariatric surgery on renal function both in the acute situation, with respect to acute kidney injury, and also on changes in renal function parameters post-bariatric surgery weight loss. The interaction of obesity, bariatric surgery, and nephrolithiasis as a precipitant of acute kidney injury will also be considered. The role of bariatric surgery in pre- and post-renal transplant recipients is discussed as well as possible mechanisms underlying the improvement in renal function.

The impact of moderate to severe renal insufficiency on patients with acute myocardial infarction

Background and Objectives

Renal insufficiency (RI) has been reported to be associated with unfavorable clinical outcomes in patients undergoing percutaneous coronary interventions (PCI). However, little data is available regarding the impact of moderate to severe RI on clinical outcomes in patients with acute myocardial infarction (AMI) undergoing PCI.

Subjects and Methods

Between March 2003 and July 2007, 878 patients with AMI who underwent PCI were enrolled. Based on estimated glomerular filtration rate (eGFR) using the Modification of Diet in Renal Disease (MDRD) equation, patients were divided into two groups: eGFR <60 mL/min·m² (moderate to severe RI, group A) and eGFR ≥60 mL/min·m² (normal to mild RI, group B). The primary endpoint was all-cause mortality at 1-year after successful PCI. The secondary endpoints were non-fatal myocardial infarction (MI), target lesion revascularization (TLR), target vessel revascularization (TVR), stent thrombosis (ST) and major adverse cardiac events (MACE) at 1-year.

Results

In group A, patients were more often male and older, with diabetes and hypertension. Compared to patients in group B, group A showed significantly higher incidences of all-cause mortality, cardiac mortality, non-fatal MI and MACE. The needs of TLR and TVR, and the incidence of ST were not significantly different between the two groups. Independent predictors of 1-year mortality were eGFR <60 mL/min·m², male gender, older age and a lower left ventricular ejection fraction.

Conclusion

In patients with AMI, moderate to severe RI was associated with mortality and MACE at 1-year after successful PCI. In addition, eGFR <60 mL/min·m² was a strong independent predictor of 1-year mortality.

Uric acid as a factor in the metabolic syndrome

Hyperuricemia is a prevalent finding in patients presenting metabolic syndrome, although its clinical meaning is still controversial and often underestimated. Men and women have different serum urate levels at all ages, and the impact of hyperuricemia in cardiovascular and renal outcomes is generally associated with a worse prognosis in women. Recent studies also have called attention to another perspective on hyperuricemia, indicating that it may be not only a consequence of insulin resistance states but also a significant predictor of the development of metabolic syndrome. This review discusses recent evidence related to the clinical significance of hyperuricemia in both sexes and the potential benefits of lowering serum uric acid levels.

Measurement of glomerular filtration rate in obese patients: pitfalls and potential consequences on drug therapy

Epidemiological studies have shown that obesity is associated with chronic kidney disease and end stage renal disease. These studies have used creatinine derived equations to estimate glomerular filtration rate (GFR) and have indexed GFR to body surface area (BSA). However, the use of equations using creatinine as a surrogate marker of glomerular filtration and the indexation of GFR for BSA can be questioned in the obese population. First, these equations lack precision when they are compared to gold standard GFR measurements such as inulin clearances; secondly, the indexation of GFR for 1.73 m(2) of BSA leads to a systematic underestimation of GFR compared to absolute GFR in obese patients who have BSA that usually exceed 1.73 m(2). Obesity is also associated with pathophysiological changes that can affect the pharmacokinetics of drugs. The effect of obesity on both renal function and drug pharmacokinetics raises the issue of correct drug dosage in obese individuals. This may be particularly relevant for drugs known to have a narrow therapeutic range or excreted by the kidney.

Time-dependent impact of diabetes on the mortality of patients on renal replacement therapy: a population-based study in Germany (2002-2009)

AIMS

To estimate the impact of diabetes on the mortality of patients with incident renal replacement therapy (RRT).

METHODS

We assessed the mortality of 544 incident RRT patients aged ≥ 30 years between 2002 and 2009 (57.9% men, mean age 70.3 years, 49.6% patients with diabetes) by analyzing the data of all dialysis centers covering a German region. We compared the estimated time-dependent hazard ratios of patients with and without diabetes by using the Cox proportional-hazards regression model.

RESULTS

Overall, 319 patients had died (158 diabetic), approximately 50% after 3 years. Up to about 3 years, the mortality rate was lower in diabetic than in nondiabetic patients. Thereafter, the survival curves crossed (interaction diabetes × time, p = 0.002; adjusted hazard ratios for diabetes: baseline, 0.66; year 1, 0.84; year 2, 1.05; year 3, 1.33; year 4, 1.68). The results were similar in men and women; however, the interaction of diabetes and time was significant only in men (p = 0.004). Further significant risk factors of mortality were age, sex, initial central venous catheter, cardiovascular disease, and malignancy.

CONCLUSIONS

In this population-based study, the influence of diabetes was time-dependent, with a lower mortality in diabetic versus non-diabetic patients in the first three years but a higher mortality in these patients after 3 years. Results were similar in men and women.

Predicting the risk of end-stage renal disease in the population-based setting: a retrospective case-control study

Background

Previous studies of predictors of end-stage renal disease (ESRD) have limitations: (1) some focused on patients with clinically recognized chronic kidney disease (CKD); (2) others identified population-based patients who developed ESRD, but lacked earlier baseline clinical measures to predict ESRD. Our study was designed to address these limitations and to identify the strength and precision of characteristics that might predict ESRD pragmatically for decision-makers--as measured by the onset of renal replacement therapy (RRT).

Methods

We conducted a population-based, retrospective case-control study of patients who developed ESRD and started RRT. We conducted the study in a health maintenance organization, Kaiser Permanente Northwest (KPNW). The case-control study was nested within the adult population of KPNW members who were enrolled during 1999, the baseline period. Cases and their matched controls were identified from January 2000 through December 2004. We evaluated baseline clinical characteristics measured during routine care by calculating the adjusted odds ratios and their 95% confidence intervals after controlling for matching characteristics: age, sex, and year.

Results

The rate of RRT in the cohort from which we sampled was 58 per 100,000 person-years (95% CI, 53 to 64). After excluding patients with missing data, we analyzed 350 cases and 2,114 controls. We identified the following characteristics that predicted ESRD with odds ratios ≥ 2.0: eGFR<60 mL/min/1.73 m² (OR = 20.5; 95% CI, 11.2 to 37.3), positive test for proteinuria (OR = 5.0; 95% CI, 3.5 to 7.1), hypertension (OR = 4.5; 95% CI, 2.5 to 8.0), gout/positive test for uric acid (OR = 2.5; 95% CI, 1.8 to 3.5), peripheral vascular disease (OR = 2.2; 95% CI, 1.4 to 3.6), congestive heart failure (OR = 2.1; 95% CI, 1.4 to 3.3), and diabetes (OR = 2.1; 95% CI, 1.5 to 2.9).

Conclusions

The clinical characteristics needed to predict ESRD--for example, to develop a population-based, prognostic risk score--were often documented during routine care years before patients developed ESRD and required RRT.

Longitudinal trends and influence of BMI mismatch in living kidney donors and their recipients

BACKGROUND AND OBJECTIVES

Age and body mass index (BMI) of kidney donors and recipients affect kidney allograft outcomes. Moreover, while deceased donor and recipient body size mismatch have been reported to influence allograft outcomes, how BMI mismatch in living kidney donor-recipient pairs affect graft survival is not well defined.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

We investigated trends in characteristics of 90,815 US. living kidney donors and their recipients between 1987 and 2008.

RESULTS

Median ages of donors and their recipients have risen over time, and the proportion of living donors age ≥ 50 years increased from 11 to 25%. Median BMI of recipients increased from 22.6 to 26.6 kg/m(2); median BMI of kidney donors for the past 5 years has been 26.4 kg/m(2). Only 35% of living donor-recipient pairs were in the same BMI category (<25, 25-29.9, 30-34.9, or ≥ 35 kg/m(2)). BMI mismatch where the living donor was three categories heavier than the recipient was associated with a significant adjusted risk for death-censored allograft loss (HR 2.31, 95% CI 1.05-5.08).

CONCLUSIONS

Living kidney donors are donating at more advanced ages, and the majority are overweight or obese in recent years. In summary: (1) previous longitudinal studies of living kidney donor outcomes may not be generalizable to recent donors, and studies of contemporary living kidney donor cohorts may be informative, (2) the majority of living donor-recipient pairs have BMI mismatch, and (3) extreme BMI mismatch where the living donor is heavier may confer an independent risk for allograft loss.

Challenges of conducting a trial of uric-acid-lowering therapy in CKD

Observational studies have shown that asymptomatic hyperuricemia is associated with increased risks of hypertension, chronic kidney disease (CKD), end-stage renal disease, cardiovascular events, and mortality. Whether these factors represent cause, consequence or incidental associations, however, remains uncertain. Hyperuricemia could be a consequence of impaired kidney function, diuretic therapy or oxidative stress, such that elevated serum urate level represents a marker, rather than a cause, of CKD. On the other hand, small, short-term, single-center studies have shown improvements in blood-pressure control and slowing of CKD progression following serum urate lowering with allopurinol. An adequately powered randomized controlled trial is required to determine whether uric-acid-lowering therapy slows the progression of CKD. This article discusses the rationale for and the feasibility of such a trial. International collaboration is required to plan and conduct a large-scale multicenter trial in order to better inform clinical practice and public health policy about the optimal management of asymptomatic hyperuricemia in patients with CKD.

A genome-wide association study of serum uric acid in African Americans

Background

Uric acid is the primary byproduct of purine metabolism. Hyperuricemia is associated with body mass index (BMI), sex, and multiple complex diseases including gout, hypertension (HTN), renal disease, and type 2 diabetes (T2D). Multiple genome-wide association studies (GWAS) in individuals of European ancestry (EA) have reported associations between serum uric acid levels (SUAL) and specific genomic loci. The purposes of this study were: 1) to replicate major signals reported in EA populations; and 2) to use the weak LD pattern in African ancestry population to better localize (fine-map) reported loci and 3) to explore the identification of novel findings cognizant of the moderate sample size.

Methods

African American (AA) participants (n = 1,017) from the Howard University Family Study were included in this study. Genotyping was performed using the Affymetrix^® Genome-wide Human SNP Array 6.0. Imputation was performed using MACH and the HapMap reference panels for CEU and YRI. A total of 2,400,542 single nucleotide polymorphisms (SNPs) were assessed for association with serum uric acid under the additive genetic model with adjustment for age, sex, BMI, glomerular filtration rate, HTN, T2D, and the top two principal components identified in the assessment of admixture and population stratification.

Results

Four variants in the gene SLC2A9 achieved genome-wide significance for association with SUAL (p-values ranging from 8.88 × 10^-9 to 1.38 × 10^-9). Fine-mapping of the SLC2A9 signals identified a 263 kb interval of linkage disequilibrium in the HapMap CEU sample. This interval was reduced to 37 kb in our AA and the HapMap YRI samples.

Conclusions

The most strongly associated locus for SUAL in EA populations was also the most strongly associated locus in this AA sample. This finding provides evidence for the role of SLC2A9 in uric acid metabolism across human populations. Additionally, our findings demonstrate the utility of following-up EA populations GWAS signals in African-ancestry populations with weaker linkage disequilibrium.

Matching, an appealing method to avoid confounding?

Matching is a technique used to avoid confounding in a study design. In a cohort study this is done by ensuring an equal distribution among exposed and unexposed of the variables believed to be confounding. In a matched case-control study, a case, affected by the disease, is matched with one or more individuals not affected by the disease, the controls. Because in a matched case-control study case and control group become too similar not only in the distribution of the confounder but also in the distribution of the exposure, one finds a lower effect estimate (odds ratio closer to 1). A matched case-control study requires statistical analysis to correct for this phenomenon. Nonetheless, a matched case-control study is suitable for confounders that are difficult to measure.

Weight loss: a neglected intervention in the management of chronic kidney disease

PURPOSE OF REVIEW

Obesity is being increasingly implicated as an independent risk factor for the development of chronic kidney disease (CKD), raising the question whether reversing obesity can be utilized as a mainstay or an adjunct therapy for CKD and possibly for its prevention. The purpose of this review is to examine the impact of treatment of obesity on renal outcomes.

RECENT FINDINGS

Many observations have pointed to improvement in renal parameters following weight loss. In fact, both surgical and nonsurgical approaches appear to be effective at reducing blood pressure and proteinuria. Weight loss has also been shown to lower glomerular filtration rate (GFR) in obese patients, not an insignificant benefit considering that intra-glomerular hypertension and the subsequent hyperfiltration in the setting of obesity might be a main driver for the development of CKD.

SUMMARY

Urinary protein excretion, blood pressure, and GFR improve with surgical and nonsurgical weight loss interventions. Whether improvements in these surrogate outcomes after weight loss actually translate into a reduction in the risk of CKD or amelioration in the rate of progression of established CKD is yet to be determined.

Mortality and renal function decline among a community-based Chinese population with normal or mildly impaired renal function

BACKGROUND

Longitudinal studies of the mortality and renal outcomes among the population with an estimated glomerular filtration rate (eGFR) >30 mL/min/1.73 m(2) and among the elderly are limited, especially in developing countries.

METHODS

This prospective cohort study included 1563 residents aged 59.5 ± 9.4 years from an urban district of Beijing, China. All participants had an eGFR >30 mL/min/1.73 m(2). Urinary albumin-to-creatinine ratio and eGFR were assessed at baseline, and their relation with mortality and renal function decline after a 4-year follow-up were analyzed.

RESULTS

During 4 years (6142 person-years) of follow-up, 59 deaths occurred (9.6 per 1000 person-years). After adjusting for potential confounders, albuminuria was associated with increased risk of mortality, with an odds ratio (OR) of 3.09 [95% confidence interval (CI) 1.53-6.26]. Altogether 183 patients (12.3%) developed renal function decline, with a median change of eGFR of -20.0 mL/min/1.73 m(2). Presence of albuminuria was significantly associated renal function decline, with an OR of 1.79 (95% CI 1.02-3.15). Plasma uric acid (OR = 1.25/59 μmol/L increase, 95% CI 1.10-1.43) and age (OR = 1.35/5 years increase, 95% CI 1.22-1.50) was also independently associated with renal function decline. Baseline eGFR was not significantly associated with either mortality or renal function decline in our analysis.

CONCLUSIONS

Compared with eGFR, albuminuria is a strong independent predictor for both mortality and renal function decline among a Chinese population with normal or mildly impaired renal function. Furthermore, plasma uric acid level and age are also independently associated with renal function decline and therefore may be used for identifying patients at higher risk of chronic kidney disease progression.

Heart disease and stroke statistics--2011 update: a report from the American Heart Association

Each year, the American Heart Association (AHA), in conjunction with the Centers for Disease Control and Prevention, the National Institutes of Health, and other government agencies, brings together the most up-to-date statistics on heart disease, stroke, other vascular diseases, and their risk factors and presents them in its Heart Disease and Stroke Statistical Update. The Statistical Update is a valuable resource for researchers, clinicians, healthcare policy makers, media professionals, the lay public, and many others who seek the best national data available on disease morbidity and mortality and the risks, quality of care, medical procedures and operations, and costs associated with the management of these diseases in a single document. Indeed, since 1999, the Statistical Update has been cited more than 8700 times in the literature (including citations of all annual versions). In 2009 alone, the various Statistical Updates were cited ≈1600 times (data from ISI Web of Science). In recent years, the Statistical Update has undergone some major changes with the addition of new chapters and major updates across multiple areas. For this year’s edition, the Statistics Committee, which produces the document for the AHA, updated all of the current chapters with the most recent nationally representative data and inclusion of relevant articles from the literature over the past year and added a new chapter detailing how family history and genetics play a role in cardiovascular disease (CVD) risk. Also, the 2011 Statistical Update is a major source for monitoring both cardiovascular health and disease in the population, with a focus on progress toward achievement of the AHA’s 2020 Impact Goals. Below are a few highlights from this year’s Update.

Associations of acculturation and kidney dysfunction among Hispanics and Chinese from the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

Acculturation affects health, but it has never been studied with kidney disease.

METHODS

We studied the association of language spoken at home, generation and birth place with kidney function among Hispanics and Chinese in the Multi-Ethnic Study of Atherosclerosis (n = 2999). Kidney function was determined by cystatin C (eGFRcys) and albumin/creatinine ratio (ACR). We evaluated mediators in models: Model 1 = age, sex, income, education; Model 2 = Model 1 + behaviors; and Model 3 = Model 1 + comorbidities.

RESULTS

Among Hispanics, speaking mixed Spanish/English was significantly associated with lower eGFRcys (- 2.83 mL/min/1.73 m(2), - 5.69-0.04) and higher ACR (RD 40%, 17-68%) compared with speaking Spanish only; this was mildly attenuated by behaviors (- 2.29, - 5.33-0.75; RD 42%, 18-72%) but not comorbidities (- 3.04, - 5.83 to - 0.23); RD 35%, 14-59%). US-born Hispanics had lower eGFRcys compared with foreign-born Hispanics [1.83 mL/min/1.73 m(2) lower (0.97-1.31) for Generation 1; 1.37 mL/min/1.73 m(2) lower (0.75-1.57) for Generation ≥ 2]. In contrast, Chinese who spoke any English had higher eGFRcys (2.53, 95% CI: - 1.70-6.78), but similar ACR (RD - 5%, 95% CI: - 26-23%) compared with those speaking Chinese only, but associations were not statistically significant.

CONCLUSION

Higher acculturation was associated with worse kidney function in Hispanics, mediated perhaps by behavioral factors but not comorbidities. Associations may be in the opposite direction among Chinese. Future studies are needed to elucidate these mechanisms.

Prediction of ESRD and death among people with CKD: the Chronic Renal Impairment in Birmingham (CRIB) prospective cohort study

Background

Validated prediction scores are required to assess the risks of end-stage renal disease (ESRD) and death in individuals with chronic kidney disease (CKD).

Study Design

Prospective cohort study with validation in a separate cohort.

Setting & Participants

Cox regression was used to assess the relevance of baseline characteristics to risk of ESRD (mean follow-up, 4.1 years) and death (mean follow-up, 6.0 years) in 382 patients with stages 3-5 CKD not initially on dialysis therapy in the Chronic Renal Impairment in Birmingham (CRIB) Study. Resultant risk prediction equations were tested in a separate cohort of 213 patients with CKD (the East Kent cohort).

Factors

44 baseline characteristics (including 30 blood and urine assays).

Outcomes

ESRD and all-cause mortality.

Results

In the CRIB cohort, 190 patients reached ESRD (12.1%/y) and 150 died (6.5%/y). Each 30% lower baseline estimated glomerular filtration rate was associated with a 3-fold higher ESRD rate and a 1.3-fold higher death rate. After adjustment for each other, only baseline creatinine level, serum phosphate level, urinary albumin-creatinine ratio, and female sex remained strongly (P < 0.01) predictive of ESRD. For death, age, N-terminal pro-brain natriuretic peptide, troponin T level, and cigarette smoking remained strongly predictive of risk. Using these factors to predict outcomes in the East Kent cohort yielded an area under the receiver operating characteristic curve (ie, C statistic) of 0.91 (95% CI, 0.87-0.96) for ESRD and 0.82 (95% CI, 0.75-0.89) for death.

Limitations

Other important factors may have been missed because of limited study power.

Conclusions

Simple laboratory measures of kidney and cardiac function plus age, sex, and smoking history can be used to help identify patients with CKD at highest risk of ESRD and death. Larger cohort studies are required to further validate these results.

The serum urate-lowering impact of weight loss among men with a high cardiovascular risk profile: the Multiple Risk Factor Intervention Trial

OBJECTIVES

To evaluate the person-level impact of weight loss on serum urate levels among men with a high cardiovascular risk profile.

METHODS

We analysed 12,379 men (mean serum urate level=407 μmol/l) from the Multiple Risk Factor Intervention Trial, using data prospectively collected at baseline and annually over a 7-year period (78,881 visits). Our endpoint was normouricaemia, defined by serum urate levels≤360 μmol/l, a widely accepted therapeutic target. Person-level effects were estimated using conditional logistic regression models to adjust for time-varying covariates (age, congestive heart failure, hypertension, diuretic use, renal function, alcohol intake and dietary factors).

RESULTS

There was a graded relation between weight loss and achieving normouricaemia (P-value for trend<0.001). Compared with no weight change (-0.9 to 0.9 kg), the multivariate odds ratios of achieving normouricaemia for a weight loss of 1-4.9, 5-9.9 and ≥10 kg were 1.43 (95% CI: 1.33, 1.54), 2.17 (1.95, 2.40) and 3.90 (3.31, 4.61), respectively. The corresponding serum urate level changes were -7, -19 and -37 μmol/l (-0.12, -0.31 and -0.62 mg/dl). Similar levels of associations persisted among subgroups stratified by demographics, presence of gout, hypertension, diuretic use, renal insufficiency, alcohol intake, trial group assignment and adiposity categories (all P-values for trend<0.001).

CONCLUSIONS

Weight reduction could help achieve a widely accepted therapeutic urate target level (≤360 μmol/l) among men with a high cardiovascular risk profile. Although the urate-lowering effect appeared weaker than that of urate-lowering drugs, other associated health benefits would make weight reduction important, particularly in this population.

Incidence of renal replacement therapy (RRT) in the diabetic compared with the non-diabetic population in a German region, 2002-08

BACKGROUND

This study was conducted to estimate incidences of renal replacement therapy (RRT) in the diabetic and non-diabetic populations in Germany, as well as relative and attributable risks of RRT due to diabetes.

METHODS

Using the data of a regional dialysis centre (region population of 310 000), we assessed all incident RRT patients aged 30 years or older in 2002-08. We estimated sex- and age-specific and -standardized incidences of RRT in the diabetic and non-diabetic populations, which were estimated by applying diabetes prevalences from a population-based study, and relative and attributable risks due to diabetes.

RESULTS

Of all subjects with incident RRT (n = 544), 49.6% had diabetes. Fifty-eight percent were male, mean age (SD) was 70.3 years (11.4 years). Incidences per 100 000 person-years (standardized to the 2004 German population) in the diabetic and the non-diabetic populations were 213.7 [95% confidence interval (95% CI), 159.5-267.8] and 26.9 (95% CI, 22.5-31.3) in men and 130.2 (95% CI, 65.6-194.9) and 16.4 (95% CI, 13.5-19.3) in women, respectively. Standardized relative risks were 7.9 (5.9-10.8) in men and 8.0 (4.7-13.5) in women. There was a significant interaction between age and diabetes, with lower relative risks in higher ages. Attributable risks among diabetic individuals were 0.87 in men and women, and population-attributable risks were 0.41 and 0.35 in men and women, respectively.

CONCLUSIONS

In this population-based study in a German region, we found the relative risk of RRT in the estimated adult diabetic population to be 8-fold increased compared with the non-diabetic population. A high proportion of the RRT risk can be attributed to diabetes in the diabetic as well as in the whole population.

Nocturia and aging: diagnosis and treatment

Nocturia is a frequently encountered problem in clinical practice and a reason for nephrology consultation. Many studies have clearly shown the negative effect of nocturia on several aspects of health-related quality of life and morbidity. Age-associated physiological, structural, hormonal, and histological changes play an important role in the increasing incidence of nocturia in elderly individuals. Besides urologic conditions, nocturia may also be the initial presenting symptom in chronic kidney disease, as well as other systemic diseases. Therefore, it is essential to understand the complex pathophysiology among these factors to establish a precise diagnosis and appropriate management strategies. This review will provide an overview of the effect of aging on the kidneys and urinary system, the pathophysiology, clinical assessment, and treatment strategies of nocturia, and its effect on health-related quality of life.

Marked association between obesity and glomerular hyperfiltration: a cross-sectional study in an African population

BACKGROUND

Obesity and African American ethnicity are established independent risk factors for the development of chronic kidney disease. No data exist about the association between obesity and renal hemodynamics in the African region.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

301 nondiabetic participants (97 lean, 108 overweight, and 96 obese) of African descent with a positive family history of hypertension from the Seychelles islands.

PREDICTOR

Body mass index (BMI).

OUTCOMES

Glomerular hyperfiltration, glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and filtration fraction.

MEASUREMENTS

GFR and ERPF were measured using inulin and para-aminohippurate clearances, respectively. Participants' baseline demographics, laboratory data, and blood pressure were measured using standard techniques.

RESULTS

The prevalence of glomerular hyperfiltration (defined as GFR >or=140 mL/min) increased across BMI categories (7.2%, 14.8%, and 27.1% for lean, overweight, and obese participants, respectively; P < 0.001). Higher BMI was associated with higher median GFR (99, 110, and 117 mL/min for lean, overweight, and obese participants, respectively; P < 0.001), ERPF (424, 462, and 477 mL/min, respectively; P = 0.01), and filtration fraction (0.23, 0.24, and 0.25; P < 0.001). Multivariate analyses adjusting for age, sex, blood pressure, fasting glucose level, and urinary sodium excretion and accounting for familial correlations confirmed the associations between high BMI (>25 kg/m(2)) and increased GFR, ERPF, and filtration fraction. No association between BMI categories and GFR was found with adjustment for body surface area.

LIMITATIONS

Participants had a positive family history of hypertension.

CONCLUSION

Overweight and obesity are associated with increased GFR, ERPF, and filtration fraction and a high prevalence of glomerular hyperfiltration in nondiabetic individuals of African descent. The absence of associations between BMI categories and GFR indexed for body surface area raises questions regarding the appropriateness of indexing GFR for body surface area in overweight populations.

High-normal serum uric acid increases risk of early progressive renal function loss in type 1 diabetes: results of a 6-year follow-up

OBJECTIVE

We previously described a cross-sectional association between serum uric acid and reduced glomerular filtration rate (GFR) in nonproteinuric patients with type 1 diabetes. Here, we prospectively investigated whether baseline uric acid impacts the risk of early progressive renal function loss (early GFR loss) in these patients.

RESEARCH DESIGN AND METHODS

Patients with elevated urinary albumin excretion (n = 355) were followed for 4-6 years for changes in urinary albumin excretion and GFR. The changes were estimated by multiple determinations of albumin-to-creatinine ratios (ACRs) and serum cystatin C (GFRcystatin).

RESULTS

At baseline, the medians (25th-75th percentiles) for uric acid, ACR, and GFRcystatin values were 4.6 mg/dl (3.8-5.4), 26.2 mg/g (15.1-56.0), and 129 ml/min per 1.73 m(2) (111-145), respectively. During the 6-year follow-up, significant association (P < 0.0002) was observed between serum uric acid and development of early GFR loss, defined as GFRcystatin decline exceeding 3.3% per year. In baseline uric acid concentration categories (in mg/dl: <3.0, 3.0-3.9, 4.0-4.9, 5.0-5.9, and >or=6), the risk of early GFR loss increased linearly (9, 13, 20, 29, and 36%, respectively). This linear increase corresponds to odds ratio 1.4 (95% CI 1.1-1.8) per 1 mg/dl increase of uric acid. The progression and regression of urinary albumin excretion were not associated with uric acid.

CONCLUSIONS

We found a clear dose-response relation between serum uric acid and risk of early GFR loss in patients with type 1 diabetes. Clinical trials are warranted to determine whether uric acid-lowering drugs can halt renal function decline before it becomes clinically significant.

Risk factors for end-stage renal disease in a community-based population: 26-year follow-up of 25,821 men and women in eastern Finland

BACKGROUND AND OBJECTIVE

There are very few European cohort studies assessing the risk factors of end-stage renal disease (ESRD) in a community-based population. This study investigated the predictors of ESRD in Finland.

DESIGN

Prospective cohort study.

SETTING

Eastern Finland.

SUBJECTS

A random sample of 25,821 men and women aged 25-64 years from the national population register participating in three independent cross-sectional population surveys in 1972, 1977 and 1982. Only the subjects without diagnosis of ESRD or chronic kidney disease based on the national register data were included in the study.

MAIN OUTCOME MEASURE

Initiation of renal replacement therapy (dialysis or kidney transplantation) identified from the Finnish Registry for Kidney Diseases through December 31, 2006.

RESULTS

A total of 94 cases with ESRD were identified during a mean follow-up period of 26.5 years. In a multivariate proportional subdistribution hazard regression analysis, taking into account death as a competing risk event, diabetes (hazard ratio [HR] 4.76, 95% confidence interval [CI] 2.32-9.79), hypertension (HR 2.21, 95% CI 1.19-4.12), obesity defined as body mass index > or =30 kg m(-2) (HR 2.02, 95 %CI 1.10-3.71) and male gender (HR 1.68, 95% CI 1.19-4.12) were independent risk factors for ESRD.

CONCLUSION

The findings of the present study confirm that modifiable risk factors play a major role in the development of ESRD in the North-European population. People with diabetes, hypertension or obesity should be considered as the target groups when planning preventive measures to control the future epidemic of ESRD.

The relationship between serum uric acid and chronic kidney disease among Appalachian adults

BACKGROUND

Higher serum uric acid (SUA) levels have been shown to be associated with cardiovascular disease. SUA levels are also associated with hypertension, a strong risk factor for chronic kidney disease (CKD). However, it is unclear whether SUA is independently associated with CKD. We examined the hypothesis that higher SUA levels are positively associated with CKD.

METHODS

We analysed data from the C8 Health Study, a population-based study of Appalachian adults aged ≥18 years and free of cardiovascular disease (n = 49,295, 53% women). SUA was examined as gender-specific quartiles. The outcome of interest was CKD (n = 2,980), defined as an estimated glomerular filtration rate of <60 mL/min/1.73 m(2) from serum creatinine.

RESULTS

Overall, we observed a clear positive association between increasing quartiles of SUA and CKD, independent of confounders. Compared with the lowest quartile of SUA (referent), the multivariable odds ratios (95% confidence interval) for quartiles 2-4, respectively, of CKD were 1.53 (1.31, 1.78), 2.16 (1.86 2.50) and 4.67 (4.07, 5.36); P-trend < 0.0001. This observed positive association persisted in separate analysis among men (P-trend < 0.0001) and women (P-trend < 0.0001).

CONCLUSIONS

In conclusion, higher SUA levels are positively associated with CKD, suggesting that at least part of the reported association between SUA and cardiovascular disease may be mediated by CKD.

Diabetes care in black and white veterans in the southeastern U.S

OBJECTIVE

Eliminating health disparities is a national priority, but progress has been difficult because of racial/ethnic differences in insurance coverage and access to health care. We investigated whether there were differences in diabetes care in the Veterans Administration (VA), where health care access should be relatively uniform.

RESEARCH DESIGN AND METHODS

A1C and plasma glucose were compared before/after diagnosis of diabetes.

RESULTS

Data were available for 1,456 black and 2,624 white veterans who met criteria for consistent primary care. Over 4-5 years before and after diagnosis, blacks had similar glucose and approximately 0.2% higher A1C levels than whites, and A1C differences could be attributed to glucose-independent associations between race and A1C. Blacks and whites also had comparable intervals between diagnostic-level hyperglycemia and diagnosis and between diagnosis and drug initiation. However, A1C was higher in blacks at the time of diagnosis (7.8 vs. 7.1%) and at initiation of pharmacotherapy (8.5 vs. 7.8%) (both P < 0.001). Differences in A1C at diagnosis and drug initiation were too large to be explained by differences in age, sex, BMI, and glucose-independent associations between race and A1C.

CONCLUSIONS

In the VA, glucose levels are generally comparable in blacks and whites except at the times of diagnosis and initiation of pharmacotherapy, when glucose levels are higher in blacks. While understanding the basis for such residual disparities may be important to improve the health of racial/ethnic minorities in the U.S., a health care system with structure and organization similar to that in the VA may also contribute importantly to relieving disparities in health.

A prescription for lifestyle change in patients with hyperuricemia and gout

PURPOSE OF REVIEW

This review summarizes the recent data on lifestyle factors that influence serum uric acid levels and the risk of gout and attempts to provide holistic recommendations, considering both their impact on gout as well as on other health implications.

RECENT FINDINGS

Large-scale studies have clarified a number of long-suspected relations between lifestyle factors, hyperuricemia, and gout, including purine-rich foods, dairy foods, various beverages, fructose, and vitamin C supplementation. Furthermore, recent studies have identified the substantial burden of comorbidities among patients with hyperuricemia and gout.

SUMMARY

Lifestyle and dietary recommendations for gout patients should consider overall health benefits and risk, since gout is often associated with the metabolic syndrome and an increased future risk of cardiovascular disease (CVD) and mortality. Weight reduction with daily exercise and limiting intake of red meat and sugary beverages would help reduce uric acid levels, the risk of gout, insulin resistance, and comorbidities. Heavy drinking should be avoided, whereas moderate drinking, sweet fruits, and seafood intake, particularly oily fish, should be tailored to the individual, considering their anticipated health benefits against CVD. Dairy products, vegetables, nuts, legumes, fruits (less sugary ones), and whole grains are healthy choices for the comorbidities of gout and may also help prevent gout by reducing insulin resistance. Coffee and vitamin C supplementation could be considered as preventive measures as these can lower urate levels, as well as the risk of gout and some of its comorbidities.

Early recognition and prevention of chronic kidney disease

Chronic kidney disease is a common disorder and its prevalence is increasing worldwide. Early diagnosis on the basis of presence of proteinuria or reduced estimated glomerular filtration rate could permit early intervention to reduce the risks of cardiovascular events, kidney failure, and death that are associated with chronic kidney disease. In developed countries, screening for the disorder is most efficient when targeted at high-risk groups including elderly people and those with concomitant illness (such as diabetes, hypertension, or cardiovascular disease) or a family history of chronic kidney disease, although the role of screening in developing countries is not yet clear. Effective strategies are available to slow the progression of chronic kidney disease and reduce cardiovascular risk. Treatment of high blood pressure is recommended for all individuals with, or at risk of, chronic kidney disease. Use of angiotensin-converting-enzyme inhibitors or angiotensin-receptor blockers is preferred for patients with diabetic chronic kidney disease or those with the proteinuric non-diabetic disorder. Glycaemic control can help prevent the onset of early stages of chronic kidney disease in individuals with diabetes. Use of statins and aspirin is beneficial for most patients with chronic kidney disease who are at high cardiovascular risk, although research is needed to ascertain how to best prevent cardiovascular disease in this cohort. Models of care that facilitate delivery of the many complex aspects of treatment simultaneously could enhance management, although effects on clinical outcomes need further assessment. Novel clinical methods to better identify patients at risk of progression to later stages of chronic kidney disease, including kidney failure, are needed to target management to high-risk subgroups.

Association of uric acid with change in kidney function in healthy normotensive individuals

BACKGROUND

Despite recent evidence, the role of uric acid as a causal factor in the pathogenesis and progression of kidney disease remains controversial, partly because of the inclusion in epidemiologic studies of patients with hypertension, diabetes, and/or proteinuria.

STUDY DESIGN

Prospective observational cohort.

SETTING & PARTICIPANTS

900 healthy normotensive adult blood donors (153 women, 747 men) evaluated at baseline and after 5 years.

PREDICTOR

Serum uric acid level.

OUTCOMES

Decrease in estimated glomerular filtration rate (eGFR) >10 mL/min/1.73 m(2), computed using the Modification of Diet in Renal Disease (MDRD) Study equation, with secondary analyses examining similar decreases using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Cockcroft-Gault equations.

RESULTS

During a median follow-up of 59 months, eGFR decreased from 97 +/- 16 to 88 +/- 14 mL/min/1.73 m(2). Higher serum uric acid levels were associated with a greater likelihood of eGFR decrease in both women and men (HR, 1.13 [95% CI, 1.04-1.39] per each 1-mg/dL increase in uric acid level); in multivariable analyses adjusting for age, sex, body mass index, blood glucose level, total cholesterol level, mean blood pressure, urine albumin-creatinine ratio, and serum triglyceride level, the association remained highly significant (HR, 1.28 [95% CI, 1.12-1.48]). Results were similar using different estimating equations and when the association was examined in sex-specific subgroups.

LIMITATIONS

Analyses were based on a single baseline uric acid measurement. Women are underrepresented.

CONCLUSIONS

In healthy normotensive individuals, serum uric acid level is an independent risk factor for decreased kidney function.

Risk factors for progression of chronic kidney disease

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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