Cardiovascular risk factors are differently associated with urinary albumin excretion in men and women

Analysis of chronic kidney disease epidemiology in Kazakhstan using nationwide data for 2014-2020 and forecasting future trends of prevalence and mortality for 2030

According to the Global Burden of Disease (GBD) study, chronic kidney disease (CKD) was prevalent in 697.5 million individuals worldwide in 2017. By 2040, it is anticipated that CKD will rank as the fifth most common cause of death. This study aims to examine the epidemiology of CKD in Kazakhstan and to project future trends in CKD prevalence and mortality by 2030. The retrospective analysis was performed on a database acquired from the Unified National Electronic Health System for 703,122 patients with CKD between 2014 and 2020. During the observation period, 444,404 women and 258,718 men were registered with CKD, 459,900 (66%) were Kazakhs and 47% were older than 50. The incidence rate notably decreased: 6365 people per million population (PMP) in 2014 and 4040 people PMP in 2020. The prevalence changed from 10,346 to 38,287 people PMP, and the mortality rate increased dramatically from 279 PMP to 916 PMP. Kazakhstan's central regions, Turkestan and Kyzylorda were identified as the most burdensome ones. The ARIMA model projected 1,504,694 expected prevalent cases in 2030. The predicted mortality climbed from 17,068 cases in 2020 to 37,305 deaths in 2030. By 2030, the prevalence and mortality of CKD will significantly increase, according to the predicted model. A thorough action plan with effective risk factor management, enhanced screening among risk populations, and prompt treatment are required to lessen the burden of disease in Kazakhstan.

Establishment and application of a new 4/6 infarct nephrectomy rat model for moderate chronic kidney disease

PURPOSE

To develop a new 4/6 infarct nephrectomy (INx) model rat mimicking moderate chronic kidney disease (CKD) and to evaluate its application.

METHODS

We modified the conventional 5/6 INx rat model to create the 4/6 INx model by ligating the renal artery branch to induce infarction of one-third of the left kidney after right kidney removal and compared biochemically and histologically both models. To demonstrate the application of the 4/6 INx model, the effects of a supplementary compound containing calcium carbonate, chitosan, palm shell activated charcoal etc., that is effective for both CKD and its complications, were compared between both models.

RESULTS

Impairment of renal function in the 4/6 INx group was significantly more moderate than in the 5/6 INx group (P < 0.05). The 4/6 INx group showed less histological damage in kidney than in the 5/6 INx group. The supplementary compound did not improve CKD in the 5/6 INx group, but ameliorated elevation of blood urea nitrogen in the 4/6 INx group.

CONCLUSIONS

We developed the 4/6 INx model, which is more moderate than the conventional 5/6 INx model. This model could potentially demonstrate the effectiveness of drugs and supplements intended to prevent CKD and its progression.

Differences in the epidemiology, management and outcomes of kidney disease in men and women

Improved understanding of differences in kidney disease epidemiology, management and outcomes in men and women could help nephrologists to better meet the needs of their patients from a sex- and gender-specific perspective. Evidence of sex differences in the risk and outcomes of acute kidney injury is mixed and dependent on aetiology. Women have a higher prevalence of chronic kidney disease (CKD) stages 3-5 than men, whereas men have a higher prevalence of albuminuria and hence CKD stages 1-2. Men show a faster decline in kidney function, progress more frequently to kidney failure and have higher mortality and risk of cardiovascular disease than women. However, the protective effect of female sex is reduced with CKD progression. Women are less likely than men to be aware of, screened for and diagnosed with CKD, started on antiproteinuric medication and referred to nephrologist care. They also consistently report a poorer health-related quality of life and a higher symptom burden than men. Women experience greater barriers than men to access the waiting list for kidney transplantation, particularly with respect to older age and obesity. However, women also have longer survival than men after transplantation, which may partly explain the comparable prevalence of transplantation between the sexes.

Comparison of the Surgical Resection and Infarct 5/6 Nephrectomy Rat Models of Chronic Kidney Disease

The 5/6 nephrectomy rat remnant kidney model is commonly employed to study chronic kidney disease (CKD). This model requires removal of one whole kidney and two-thirds of the other. The two most common ways of producing the remnant kidney are surgical resection of poles, known as the polectomy (Pol) model, or ligation of upper and lower renal arterial branches, resulting in pole infarction (Inf). These models have much in common, but also major phenotypic differences, and thus respectively model unique aspects of human CKD. The purpose of this review is to summarize phenotypic similarities and differences between these two models and their relation to human CKD, while emphasizing their vascular phenotype. In this article we review studies that have evaluated arterial blood pressure, the renin-angiotensin-aldosterone-system (RAAS), autoregulation, nitric oxide, single nephron physiology, angiogenic and anti-angiogenic factors, and capillary rarefaction in these two models. Phenotypic similarities: both models spontaneously develop hallmarks of human CKD including uremia, fibrosis, capillary rarefaction, and progressive renal function decline. They both undergo whole-organ hypertrophy, hyperfiltration of functional nephrons, reduced renal expression of angiogenic factor VEGF, increased renal expression of the anti-angiogenic thrombospondin-1, impaired renal autoregulation, and abnormal vascular nitric oxide physiology. Key phenotypic differences: the Inf model develops rapid-onset, moderate-to-severe systemic hypertension, and the Pol model early normotension followed by mild-to-moderate hypertension. The Inf rat has a markedly more active renin-angiotensin-aldosterone-system. Comparison of these two models facilitates understanding of how they can be utilized for studying CKD pathophysiology (e.g., RAAS dependent or independent pathology).

The Other Way Around: Living With Chronic Kidney Disease From the Perspective of Men

A wealth of evidence has suggested sex (biological) and gender (sociocultural) differences in the prevalence, progression, and outcomes of persons with chronic kidney disease. Much of this evidence tends to emphasize differences in which women are disadvantaged, and less attention is paid to findings in which women are better off or similar to men. However, gender medicine recognizes that men and women have different disease determinants, presentation, and attitudes, and it pertains to both sexes. In this review, we revisit chronic kidney disease through the perspective of men, and illustrate a population segment at need of stringent preventative and management strategies.

The Aggressive Diabetic Kidney Disease in Youth-Onset Type 2 Diabetes: Pathogenetic Mechanisms and Potential Therapies

Youth-onset Type 2 Diabetes Mellitus (T2DM) represents a major burden worldwide. In the last decades, the prevalence of T2DM became higher than that of Type 1 Diabetes Mellitus (T1DM), helped by the increasing rate of childhood obesity. The highest prevalence rates of youth-onset T2DM are recorded in China (520 cases/100,000) and in the United States (212 cases/100,000), and the numbers are still increasing. T2DM young people present a strong hereditary component, often unmasked by social and environmental risk factors. These patients are affected by multiple coexisting risk factors, including obesity, hyperglycemia, dyslipidemia, insulin resistance, hypertension, and inflammation. Juvenile T2DM nephropathy occurs earlier in life compared to T1DM-related nephropathy in children or T2DM-related nephropathy in adult. Diabetic kidney disease (DKD) is T2DM major long term microvascular complication. This review summarizes the main mechanisms involved in the pathogenesis of the DKD in young population and the recent evolution of treatment, in order to reduce the risk of DKD progression.

Longitudinal Studies 2: Modeling Data Using Multivariate Analysis

Statistical models are used to study the relationship between exposure and disease while accounting for the potential role of other factors' impact upon outcomes. This adjustment is useful to obtain unbiased estimates of true effects or to predict future outcomes. Statistical models include a systematic and an error component. The systematic component explains the variability of the response variable as a function of the predictors and is summarized in the effect estimates (model coefficients). The error element of the model represents the variability in the data unexplained by the model and is used to build measures of precisions around the point estimates (Confidence Intervals).

Role of Albuminuria in Detecting Cardio-Renal Risk and Outcome in Diabetic Subjects

The clinical significance of albuminuria in diabetic subjects and the impact of its reduction on the main cardiorenal outcomes by different drug classes are among the most interesting research focuses of recent years. Although nephrologists and cardiologists have been paying attention to the study of proteinuria for years, currently among diabetics, increased urine albumin excretion ascertains the highest cardio-renal risk. In fact, diabetes is a condition by itself associated with a high-risk of both micro/macrovascular complications. Moreover, proteinuria reduction in diabetic subjects by several treatments lowers both renal and cardiovascular disease progression. The 2019 joint ESC-EASD guidelines on diabetes, prediabetes and cardiovascular (CV) disease assign to proteinuria a crucial role in defining CV risk level in the diabetic patient. In fact, proteinuria by itself allows the diabetic patient to be staged at very high CV risk, thus affecting the choice of anti-hyperglycemic drug class. The purpose of this review is to present a clear update on the role of albuminuria as a cardio-renal risk marker, starting from pathophysiological mechanisms in support of this role. Besides this, we will show the prognostic value in observational studies, as well as randomized clinical trials (RCTs) demonstrating the potential improvement of cardio-renal outcomes in diabetic patients by reducing proteinuria.

Long-term vitamin D deficiency promotes renal fibrosis and functional impairment in middle-aged male mice

Renal fibrosis is common especially in the elderly population. Recently, we found that vitamin D deficiency caused prostatic hyperplasia. This study aimed to investigate whether vitamin D deficiency promotes renal fibrosis and functional impairment. All mice except controls were fed with vitamin D-deficient (VDD) diets, beginning from their early life. The absolute and relative kidney weights on postnatal week 20 were decreased in VDD diet-fed male pups but not in female pups. A mild pathological damage was observed in VDD diet-fed male pups but not in females. Further analysis showed that VDD-induced pathological damage was aggravated, accompanied by renal dysfunction in 40-week-old male pups. An obvious collagen deposition was observed in VDD diet-fed 40-week-old male pups. Moreover, renal α-smooth muscle actin (α-SMA), a marker of epithelial-mesenchymal transition (EMT), and Tgf-β mRNA were up-regulated. The in vitro experiment showed that 1,25-dihydroxyvitamin D3 alleviated transforming growth factor-β1 (TGF-β1)-mediated down-regulation of E-cadherin and inhibited TGF-β1-evoked up-regulation of N-cadherin, vimentin and α-SMA in renal epithelial HK-2 cells. Moreover, 1,25-dihydroxyvitamin D3 suppressed TGF-β1-evoked Smad2/3 phosphorylation in HK-2 cells. These results provide experimental evidence that long-term vitamin D deficiency promotes renal fibrosis and functional impairment, at least partially, through aggravating TGF-β/Smad2/3-mediated EMT in middle-aged male mice.

[Nutritional status of individuals with chronic renal failure in hemodialysis in the Unified Health System]

Malnutrition is a major factor in the evolution of patients with chronic kidney disease (CKD) on hemodialysis (HD). It is associated with increased frequency and the duration of hospitalizations. The scope of this study was to evaluate the nutritional status of patients with CKD on HD in public or private clinics of the Unified Health System in the Federal District. Sociodemographic, biochemical and anthropometric data were obtained from 96 participants, 35.5% of which were from public clinics. Parameters for evaluation of malnutrition in CKD included Body Mass Index (BMI) < 23 kg/m2, reduced arm muscle circumference (AMC) and serum albumin < 3.8 g/dL. From all participants, 14.6% were classified as malnourished (60 ± 12 years; 57% male; 69% private clinics); 33.3% presented adequate nutritional status (55 ± 14 years; 53% male; 57% private clinics); 52.1% had at least one parameter related to malnutrition. BMI below the recommended parameter was the most prevalent variable (42.7%), followed by reduced AMC (41.7%) and serum albumin (33.3%). Based on these results, it may be concluded that at least one positive variable was related to malnutrition in half of the sample, which reinforces the importance of nutritional assessment in the context of the treatment of CKD.

Prevalence of chronic kidney disease using estimated glomerular filtration rate among diabetes patients attending a tertiary clinic in Botswana

OBJECTIVES

Diabetes mellitus (DM) is one of the most common contributors of chronic kidney disease (CKD). The epidemiology of CKD, a concern among patients with DM, has not been studied in Botswana. Consequently, the objective of this study was to estimate its prevalence among these patients in Botswana to provide future guidance to both government personnel and physicians.

METHODS

Observational cross-sectional study in a leading clinic in Botswana. Demographic and clinical data were obtained from patients through interviews and from their notes using a standard questionnaire. The study was conducted from July to October 2015. The estimated glomerular filtration rate (eGFR) was calculated using the Modification of Diet for Renal Disease equation. CKD was defined as an eGFR < 60 ml/min/1.73 m². Multivariable logistic regression analyses were performed to assess the associations between CKD and potential factors.

RESULTS

The mean age and duration of DM among study participants were 54.67 years (range 21-92 years) and 5.0 years, respectively. Over half, i.e. 213/370 (57.6%) and 232/370 (62.7%), had an average blood pressure greater than 140/90 mmHg and poor glycemic control (HbA1c > 7%), respectively. 31/370 patients (8.4%) had CKD. However, only 18/370 (4.9%) had a diagnosis of CKD documented in their charts. Age, level of education, and duration of diabetes were independently associated with CKD.

CONCLUSION

The prevalence of CKD by estimated eGFR was low compared to most previous studies. However, half of patients with CKD are not documented resulting in the potential for prescription errors and drug toxicity. A substantial number of our patients had uncontrolled hypertension and poor glycemic control. Older age, low level of education and longer duration of DM were associated with CKD. There is a need to carry out prospective studies to determine the association and role of glycemic and blood pressure control in CKD causation among patients with DM in Botswana.

Differential Association of Vitamin D Deficiency With Albuminuria by Sex in the Korean General Population: A Cross-sectional Study of the Korea National Health and Nutrition Examination Survey 2011-2012

Objectives

Albuminuria has emerged as a biomarker for several medical conditions, and vitamin D has received attention due to its associations with various disorders. We evaluated the association between low serum vitamin D levels and prevalent albuminuria by sex in the Korean general population.

Methods

We analyzed 9823 participants (4401 males, 5422 females) from the Korea National Health and Nutrition Examination Survey 2011-2012 (KNHANES V-2), and categorized them as having a normal range of vitamin D levels, vitamin D insufficiency, or vitamin D deficiency. A multivariable logistic regression model was used to compare the risk of albuminuria across these groups. Stratified analyses were conducted by smoking status, obesity, and renal function.

Results

Albuminuria was found in 325 of the 4401 male participants (7.4%) and in 455 of the 5422 female participants (8.4%). Among the males, vitamin D deficiency was associated with an odds ratio (OR) for albuminuria of 1.78 (95% confidence interval [CI], 1.07 to 2.97, p<0.05). However, such an association was not found in females. The association was stronger in male current smokers (OR, 3.54; 95% CI, 1.47 to 8.50; p=0.005).

Conclusions

The findings of this study suggest that sex differences exist in the association between serum vitamin D deficiency and albuminuria. Additionally, we observed that the association was stronger in current smokers than in the overall male population, but was not seen in non-smokers. Therefore, different approaches by sex and smoking status might be needed when considering using vitamin D as a biomarker for renal function.

Risk factors for increased left ventricular hypertrophy in patients with chronic kidney disease: findings from the CKD-JAC study

Background

Although left ventricular hypertrophy (LVH) has been established as a predictor of cardiovascular events in chronic kidney disease (CKD), the relationship between the prevalence of LVH and CKD stage during the pre-dialysis period has not been fully examined.

Methods

We measured left ventricular mass index (LVMI) in a cross-sectional cohort of participants in the Chronic Kidney Disease Japan Cohort (CKD-JAC) study to identify factors that are associated with increased LVMI in patients with stage 3–5 CKD.

Results

We analyzed the baseline characteristics in 1088 participants (male 63.8%, female 36.2%). Diabetes mellitus was the underlying disease in 41.7% of the patients, and mean age was 61.8 ± 11.1 years. LVH was detected in 23.4% of the patients at baseline. By multivariate logistic analysis, independent risk factors for LVH were past history of cardiovascular disease [odds ratio (OR) 2.364; 95% confidence interval ([CI) 1.463–3.822; P = 0.0004], body mass index (OR 1.108; 95% CI 1.046–1.173; P = 0.0005), systolic blood pressure (OR 1.173; 95% CI 1.005–1.369; P = 0.0433), urinary albumin (OR 1.425; 95% CI 1.028–1.974; P = 0.0333), and serum total cholesterol level (OR 0.994; 95% CI 0.989–0.999; P = 0.0174).

Conclusion

The cross-sectional baseline data from the CKD-JAC study shed light on the association between LVH and risk factors in patients with decreased renal function. Further longitudinal analyses of the CKD-JAC cohort are needed to evaluate the prognostic value of LVH in CKD patients.

Metabolic Syndrome Severity and Risk of CKD and Worsened GFR: The Jackson Heart Study

BACKGROUND/AIMS

The metabolic syndrome (MetS), as assessed using dichotomous criteria, is associated with increased risk of future chronic kidney disease (CKD), though this relationship is unclear among African Americans, who have lower risk for MetS but higher risk for CKD.

METHODS

We performed logistic regression using a sex- and race-specific MetS-severity z-score to assess risk of incident CKD among 2,627 African-American participants of the Jackson Heart Study, assessed at baseline and 8 years later. Based on quartile of baseline MetS severity, we further assessed prevalence of being in the lowest quartile of baseline GFR, the lowest quartile of relative GFR at follow-up, microalbuminuria and incident CKD.

RESULTS

Higher MetS-severity was associated with higher prevalence of GFR in the lowest quartile at baseline among males and females. Among African-American females but not males, higher baseline MetS-severity was associated with a higher prevalence of baseline elevations in microabuminuria (p<0.01), steep decline in GFR (p<0.001) and a higher incidence of CKD (p<0.0001). Women in increasing quartiles of baseline MetS-severity exhibited a linear trend toward higher odds of future CKD (p<0.05), with those in the 4th quartile of MetS-severity (compared to the 1st) having an odds ratio of 2.47 (95% confidence interval 1.13, 5.37); no such relationship was seen among men (p value for trend 0.49).

CONCLUSION

MetS-severity exhibited sex-based interactions regarding risk for future GFR deterioration and CKD, with increasing risk in women but not men. These data may have implications for triggering CKD screening among African-American women with higher degrees of MetS-severity.

Sex and gender disparities in the epidemiology and outcomes of chronic kidney disease

Improved understanding of sex and gender-specific differences in the aetiology, mechanisms and epidemiology of chronic kidney disease (CKD) could help nephrologists better address the needs of their patients. Population-based studies indicate that CKD epidemiology differs by sex, affecting more women than men, especially with regard to stage G3 CKD. The effects of longer life expectancy on the natural decline of glomerular filtration rate (GFR) with age, as well as potential overdiagnosis of CKD through the inappropriate use of GFR equations, might be in part responsible for the greater prevalence of CKD in women. Somewhat paradoxically, there seems to be a preponderance of men among patients starting renal replacement therapy (RRT); the protective effects of oestrogens in women and/or the damaging effects of testosterone, together with unhealthier lifestyles, might cause kidney function to decline faster in men than in women. Additionally, elderly women seem to be more inclined to choose conservative care instead of RRT. Dissimilarities between the sexes are also apparent in the outcomes of CKD. In patients with predialysis CKD, mortality is higher in men than women; however, this difference disappears for patients on RRT. Although access to living donor kidneys among men and women seems equal, women have reduced access to deceased donor transplantation. Lastly, health-related quality of life while on RRT is poorer in women than men, and women report a higher burden of symptoms. These findings provide insights into differences in the underlying pathophysiology of disease as well as societal factors that can be addressed to reduce disparities in access to care and outcomes for patients with CKD.

Sex and gender disparities in the epidemiology and outcomes of chronic kidney disease

Improved understanding of sex and gender-specific differences in the aetiology, mechanisms and epidemiology of chronic kidney disease (CKD) could help nephrologists better address the needs of their patients. Population-based studies indicate that CKD epidemiology differs by sex, affecting more women than men, especially with regard to stage G3 CKD. The effects of longer life expectancy on the natural decline of glomerular filtration rate (GFR) with age, as well as potential overdiagnosis of CKD through the inappropriate use of GFR equations, might be in part responsible for the greater prevalence of CKD in women. Somewhat paradoxically, there seems to be a preponderance of men among patients starting renal replacement therapy (RRT); the protective effects of oestrogens in women and/or the damaging effects of testosterone, together with unhealthier lifestyles, might cause kidney function to decline faster in men than in women. Additionally, elderly women seem to be more inclined to choose conservative care instead of RRT. Dissimilarities between the sexes are also apparent in the outcomes of CKD. In patients with predialysis CKD, mortality is higher in men than women; however, this difference disappears for patients on RRT. Although access to living donor kidneys among men and women seems equal, women have reduced access to deceased donor transplantation. Lastly, health-related quality of life while on RRT is poorer in women than men, and women report a higher burden of symptoms. These findings provide insights into differences in the underlying pathophysiology of disease as well as societal factors that can be addressed to reduce disparities in access to care and outcomes for patients with CKD.

Gender Differences in the Acute Kidney Injury to Chronic Kidney Disease Transition

This study evaluated if there is a sexual dimorphism in the acute kidney injury (AKI) to chronic kidney disease (CKD) transition and the time-course of the potential mechanisms involved in the dimorphic response. Female and male rats were divided into sham-operated or underwent 45-min renal ischemia (F + IR, and M + IR). All groups were studied at 24-h and 1, 2, 3, or 4-months post-ischemia. Additionally, oophorectomized rats were divided into sham or IR groups. After 24-h, AKI extent was simllar in females and males, but female rats exhibited less oxidative stress and increased renal GSH content. After 4-months and despite similar AKI, the M + IR group developed CKD characterized by proteinuria, tubulointerstitial fibrosis, glomerular hypertrophy, increased oxidative stress and a reduction in HIF1α and VEGF from the 1^st-month and persisting throughout the time-course studied. Interestingly, the F + IR group did not develop CKD due to lesser oxidative stress and increased eNOS, TGFβ and HIF1α mRNA levels from the 1^st-month after IR. Whereas, oophorectomized rats did develop CKD. We found a sexual dimorphic response in the AKI to CKD transition. Early antioxidant defense and higher TGFβ, HIF1α and eNOS were among the renoprotective mechanisms that the F + IR group demonstrated.

Prediction of new onset of end stage renal disease in Chinese patients with type 2 diabetes mellitus - a population-based retrospective cohort study

BACKGROUND

Since diabetes mellitus (DM) is the leading cause of end stage renal disease (ESRD), this study aimed to develop a 5-year ESRD risk prediction model among Chinese patients with Type 2 DM (T2DM) in primary care.

METHODS

A retrospective cohort study was conducted on 149,333 Chinese adult T2DM primary care patients without ESRD in 2010. Using the derivation cohort over a median of 5 years follow-up, the gender-specific models including the interaction effect between predictors and age were derived using Cox regression with a forward stepwise approach. Harrell's C-statistic and calibration plot were applied to the validation cohort to assess discrimination and calibration of the models.

RESULTS

Prediction models showed better discrimination with Harrell's C-statistics of 0.866 (males) and 0.862 (females) and calibration power from the plots than other established models. The predictors included age, usages of anti-hypertensive drugs, anti-glucose drugs, and Hemogloblin A1c, blood pressure, urine albumin/creatinine ratio (ACR) and estimated glomerular filtration rate (eGFR). Specific predictors for male were smoking and presence of sight threatening diabetic retinopathy while additional predictors for female included longer duration of diabetes and quadratic effect of body mass index. Interaction factors with age showed a greater weighting of insulin and urine ACR in younger males, and eGFR in younger females.

CONCLUSIONS

Our newly developed gender-specific models provide a more accurate 5-year ESRD risk predictions for Chinese diabetic primary care patients than other existing models. The models included several modifiable risk factors that clinicians can use to counsel patients, and to target at in the delivery of care to patients.

Sex and gender differences in chronic kidney disease: progression to end-stage renal disease and haemodialysis

Sex and gender differences are of fundamental importance in most diseases, including chronic kidney disease (CKD). Men and women with CKD differ with regard to the underlying pathophysiology of the disease and its complications, present different symptoms and signs, respond differently to therapy and tolerate/cope with the disease differently. Yet an approach using gender in the prevention and treatment of CKD, implementation of clinical practice guidelines and in research has been largely neglected. The present review highlights some sex- and gender-specific evidence in the field of CKD, starting with a critical appraisal of the lack of inclusion of women in randomized clinical trials in nephrology, and thereafter revisits sex/gender differences in kidney pathophysiology, kidney disease progression, outcomes and management of haemodialysis care. In each case we critically consider whether apparent discrepancies are likely to be explained by biological or psycho-socioeconomic factors. In some cases (a few), these findings have resulted in the discovery of disease pathways and/or therapeutic opportunities for improvement. In most cases, they have been reported as merely anecdotal findings. The aim of the present review is to expose some of the stimulating hypotheses arising from these observations as a preamble for stricter approaches using gender for the prevention and treatment of CKD and its complications.

Gender-Specific Associations between Low Skeletal Muscle Mass and Albuminuria in the Middle-Aged and Elderly Population

Objective This study assessed gender-specific associations between low muscle mass (LMM) and albuminuria. Methods Data from the Korea National Health and Nutrition Examination Survey 2011 were employed. The study consisted of 1,087 subjects (≥50 years old). Skeletal muscle index (SMI) was defined as the weight-adjusted appendicular skeletal muscle mass. Mild LMM and severe LMM were defined as SMI that were 1-2 and >2 standard deviations below the sex-specific mean appendicular skeletal muscle mass of young adults, respectively. Increased albuminuria was defined as albumin-to-creatinine ratio ≥30mg/g Results Men with mild and severe LMM were significantly more likely to have increased albuminuria (15.2% and 45.45%, respectively) than men with normal SMI (9.86%, P<0.0001), but not women. Severe LMM associated independently with increased albuminuria in men (OR=7.661, 95% CI=2.72-21.579) but not women. Severe LMM was an independent predictor of increased albuminuria in hypertensive males (OR=11.449, 95% CI=3.037-43.156), non-diabetic males (OR=8.782, 95% CI=3.046-25.322), and males without metabolic syndrome (MetS) (OR=8.183, 95% CI=1.539-43.156). This was not observed in males without hypertension, males with diabetes or MetS, and all female subgroups. Conclusion Severe LMM associated with increased albuminuria in men, especially those with hypertension and without diabetes or MetS.

Urinary albumin excretion in healthy adults: a cross sectional study of 24-hour versus timed overnight samples and impact of GFR and other personal characteristics

Background

Urinary albumin can be measured in 24 h or spot samples. The 24 h urinary albumin excretion rate is considered the gold standard, but is cumbersome to collect. Instead, often an overnight sample is collected, and adjusted for dilution. Proxies for 24 h excretion rate have been studied in diabetics, but seldom in healthy individuals. Our aims were to compare 24 h and overnight albumin excretion, to assess the impact of personal characteristics, and to examine correlations between the 24 h excretion rate and proxies such as the albumin to creatinine ratio (ACR).

Methods

Separate 24 h and overnight urine samples were collected from 152 healthy kidney donors. Urinary creatinine, specific gravity, collection time, and sample volume determined. Differences between 24 h and overnight samples were examined, and the effects of age, sex, smoking, body mass, glomerular filtration rate, and urinary flow rate were assessed.

Results

The 24 h albumin excretion rate and ACR were both significantly higher than their overnight counterparts. Unadjusted albumin was unsurprisingly higher in the more concentrated overnight samples, while concentrations adjusted for specific gravity were similar. In multivariate analysis, the 24 h excretion rate and proxies were positively associated with glomerular filtration rate, as was ACR in overnight samples. There were positive associations between urinary albumin and body mass.

Conclusions

Proxies for the 24 h albumin excretion rate showed relatively high correlations with this gold standard, but differences due to sampling period, adjustment method, and personal characteristics were large enough to be worth considering in studies of albumin excretion in healthy individuals.

Longitudinal studies 2: Modeling data using multivariate analysis

Statistical models are used to study the relationship between exposure and disease while accounting for the potential role of other factors impact upon outcomes. This adjustment is useful to obtain unbiased estimates of true effects or to predict future outcomes. Statistical models include a systematic and an error component. The systematic component explains the variability of the response variable as a function of the predictors and is summarized in the effect estimates (model coefficients). The error element of the model represents the variability in the data unexplained by the model and is used to build measures of precisions around the point estimates (Confidence Intervals).

Sex-specific differences in hemodialysis prevalence and practices and the male-to-female mortality rate: the Dialysis Outcomes and Practice Patterns Study (DOPPS)

BACKGROUND

A comprehensive analysis of sex-specific differences in the characteristics, treatment, and outcomes of individuals with end-stage renal disease undergoing dialysis might reveal treatment inequalities and targets to improve sex-specific patient care. Here we describe hemodialysis prevalence and patient characteristics by sex, compare the adult male-to-female mortality rate with data from the general population, and evaluate sex interactions with mortality.

METHODS AND FINDINGS

We assessed the Human Mortality Database and 206,374 patients receiving hemodialysis from 12 countries (Australia, Belgium, Canada, France, Germany, Italy, Japan, New Zealand, Spain, Sweden, the UK, and the US) participating in the international, prospective Dialysis Outcomes and Practice Patterns Study (DOPPS) between June 1996 and March 2012. Among 35,964 sampled DOPPS patients with full data collection, we studied patient characteristics (descriptively) and mortality (via Cox regression) by sex. In all age groups, more men than women were on hemodialysis (59% versus 41% overall), with large differences observed between countries. The average estimated glomerular filtration rate at hemodialysis initiation was higher in men than women. The male-to-female mortality rate ratio in the general population varied from 1.5 to 2.6 for age groups <75 y, but in hemodialysis patients was close to one. Compared to women, men were younger (mean = 61.9 ± standard deviation 14.6 versus 63.1 ± 14.5 y), were less frequently obese, were more frequently married and recipients of a kidney transplant, more frequently had coronary artery disease, and were less frequently depressed. Interaction analyses showed that the mortality risk associated with several comorbidities and hemodialysis catheter use was lower for men (hazard ratio [HR] = 1.11) than women (HR = 1.33, interaction p<0.001). This study is limited by its inability to establish causality for the observed sex-specific differences and does not provide information about patients not treated with dialysis or dying prior to a planned start of dialysis.

CONCLUSIONS

Women's survival advantage was markedly diminished in hemodialysis patients. The finding that fewer women than men were being treated with dialysis for end-stage renal disease merits detailed further study, as the large discrepancies in sex-specific hemodialysis prevalence by country and age group are likely explained by factors beyond biology. Modifiable variables, such as catheter use, showing significant sex interactions suggest interventional targeting. Please see later in the article for the Editors' Summary.

The association between underweight and the development of albuminuria is different between sexes in relatively healthy Korean subjects

BACKGROUND

There are limited data on the association between underweight and albuminuria. The aim of this study is to verify the effect of underweight on the development of albuminuria.

METHODS

Participants who underwent two health check-ups with a 2-year interval at a tertiary hospital in Korea between 2002 and 2009 were studied. After exclusion of participants with estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m(2) or dipstick albuminuria ≥1+ at the first check-up, 53 876 participants were enrolled. We measured the incidence of albuminuria at the second check-up and calculated the odds ratio (OR) for the development of albuminuria according to body mass index (BMI).

RESULTS

After 2 years, 746 cases of incident albuminuria were observed among 53 876 participants. The effect of BMI on the development of albuminuria was modified by sex in a multivariate logistic model with adjustment for age, diabetes, hypertension, dyslipidaemia, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, uric acid, eGFR, current smoking status and alcohol intake (P-value for interaction <0.001). Compared with participants in the normal weight range (BMI, 18.5-22.9), the ORs for incident albuminuria were 1.93 [95% confidence interval (CI), 1.35-2.76; P ≤ 0.001], 1.19 (0.84-1.67; P = 0.329) and 0.71 (0.43-1.17; P = 0.177) in underweight (BMI, <18.5), overweight (BMI, 23.0-24.9) and obese (BMI, ≥25) women. However, the ORs were 0.9 (95% CI, 0.39-2.05; P = 0.794), 1.08 (0.84-1.38; P = 0.567) and 1.38 (1.09-1.75; P = 0.007) for each corresponding group of men.

CONCLUSIONS

Underweight was significantly associated with the development of albuminuria after 2 years in relatively healthy Korean females, but this relationship was not significant in males. This study suggests the need for more studies on the role of underweight in renal injury in men and women.

Hypertension: what's sex got to do with it?

Hypertension is a complex and multifaceted disease, and there are well established sex differences in many aspects of blood pressure (BP) control. The intent of this review is to highlight recent work examining sex differences in the molecular mechanisms of BP control in hypertension to assess whether the "one-size-fits-all" approach to BP control is appropriate with regard to sex.

Endothelial damage in long-term survivors of childhood cancer

PURPOSE

To evaluate the presence of vascular damage in long-term childhood cancer survivors (CCS) and sibling controls, and to evaluate the association between vascular damage parameters and cancer treatment and influence of cardiovascular risk factors.

PATIENTS AND METHODS

Vascular assessment was performed in 277 adult CCSs (median age at diagnosis, 9 years; range, 0 to 20 years; median current age, 28 years; range, 18 to 48 years) treated with potentially cardiovascular toxic anticancer treatment (ie, anthracyclines, platinum, and/or radiotherapy [RT]). Measurements included carotid- and femoral-wall intima-media thickness (IMT), flow-mediated vasodilatation of the brachial artery by ultrasound, assessment of endothelial and inflammatory marker proteins (including tissue-type plasminogen activator [t-PA], plasminogen activator inhibitor type 1 [PAI-I]), and cardiovascular risk factors. CCS assessments were compared with those of 130 sibling controls (median age, 26 years; range, 18 to 51 years).

RESULTS

At a median of 18 years (range, 5 to 31 years) after treatment, carotid and femoral IMTs in CCSs were not different from those of controls. However, CCSs who received RT as part of their treatment regimen had increased carotid and femoral IMTs and higher t-PA and PAI-I levels, indicating vascular damage and persistent endothelial activation. Patients treated with RT to the neck or chest also had greater femoral IMT. Greater IMT was associated with presence of cardiovascular risk factors (eg, hypertension and overweight).

CONCLUSION

After potentially cardiovascular toxic anticancer treatment, CCSs who received RT showed signs of endothelial damage and an unfavorable cardiovascular risk profile compared with controls. CCSs treated with localized RT had increased IMT outside the primary irradiation field. These abnormalities are probably involved in the pathogenesis of cardiovascular morbidity in CCSs.

Sex differences in hypertension-related renal and cardiovascular diseases in Italy: the I-DEMAND study

AIM

The aim of this study is to evaluate the differences in the prevalence of chronic kidney disease (CKD) and of cardiovascular risk factors and diseases between men and women participating in the Italy Developing Education and awareness on MicroAlbuminuria in patients with hyperteNsive Disease (I-DEMAND) study.

METHODS

This is an observational, cross-sectional, multicenter study aimed at assessing prevalence and correlates of CKD among Italian hypertensive patients attending out-patient referral clinics. CKD was defined as glomerular filtration rate (GFR) less than 60 ml/min per 1.73 m(2) [Modification of Diet in Renal Disease (MDRD) study equation and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation] and/or urine albumin-to-creatinine ratio of at least 2.5 mg/mmol in men and of at least 3.5 mg/mmol in women or both. Left-ventricular hypertrophy (LVH) was diagnosed by either ECG or echocardiography.

RESULTS

A total of 3558 study patients with renal data available were considered for this analysis: mean age was 61 ± 4 years and 37% had diabetes mellitus. Female patients (n = 1636, 46%) were older, with a greater prevalence of obesity and lower prevalence of smoking. The prevalence of concomitant coronary artery and peripheral artery diseases, but not of hypertension, diabetes mellitus, or heart failure, was lower in women than in men. The overall prevalence of albuminuria (21 vs. 32%; P = 0.001) and of microalbuminuria (16 vs. 23%; P = 0.001) was lower in women than in men. In women the prevalence of a reduced GFR estimated by both MDRD (33 vs. 21%; P = 0.001) and CKD-EPI equations (32 vs. 23%; P = 0.001) was higher than in men. CKD prevalence was similar in women and men (44 vs. 41%; P = 0.095 and 43 vs. 43%; P = 0.475, respectively, when MDRD and CKD-EPI eGFR estimations were used). The prevalence of LVH (diagnosed by either ECG or echocardiography) was similar in men and women (18 vs. 20%; P = 0.12).The main independent determinants of CKD were age, glycemia, uricemia, pulse pressure, hypertension duration, and previous cardiovascular diseases in men, and increasing age, glycemia, uricemia, pulse pressure, and a lower BMI in women.

CONCLUSION

Renal abnormalities are present in a significant number of female hypertensive patients attending hypertension clinics. Prevalence of reduced eGFR and of microalbuminuria, associated risk factors, and clinical conditions are different between men and women, suggesting the need to develop specific therapeutic strategies to prevent renal dysfunction and reduce associated morbidity and mortality.

Albuminuria is associated with too few glomeruli and too much testosterone

Normally, the glomerular filtration barrier almost completely excludes circulating albumin from entering the urine. Genetic variation and both pre- and postnatal environmental factors may affect albuminuria in humans. Here we determine whether glomerular gene expression in mouse strains with naturally occurring variations in albuminuria would allow identification of proteins deregulated in relatively 'leaky' glomeruli. Albuminuria increased in female B6 to male B6 to female FVB/N to male FVB/N mice, whereas the number of glomeruli/kidney was the exact opposite. Testosterone administration led to increased albuminuria in female B6 but not female FVB/N mice. A common set of 39 genes, many expressed in podocytes, were significantly differentially expressed in each of the four comparisons: male versus female B6 mice, male versus female FVB/N mice, male FVB/N versus male B6 mice, and female FVB/N versus female B6 mice. The transcripts encoded proteins involved in oxidation/reduction reactions, ion transport, and enzymes involved in detoxification. These proteins may represent novel biomarkers and even therapeutic targets for early kidney and cardiovascular disease.

Risk factors for increased left ventricular hypertrophy in patients with chronic kidney disease

Background

Although left ventricular hypertrophy (LVH) has been established as a predictor of cardiovascular events in chronic kidney disease (CKD), the relationship between the prevalence of LVH and CKD stage during the predialysis period has not been fully examined.

Methods

We measured left ventricular mass index (LVMI) in a cross-sectional cohort of participants in the Chronic Kidney Disease Japan Cohort (CKD-JAC) study in order to identify factors that are associated with increased LVMI in patients with stage 3–5 CKD. LVH was defined as LVMI > 125 g/m² in male patients and >110 g/m² in female patients.

Results

We analyzed baseline characteristics in 1185 participants (male 63.7 %, female 36.3 %). Diabetes mellitus was the underlying disease in 41.3 % of patients, and mean age was 61.8 ± 11.1 years. LVH was detected in 21.7 % of patients at baseline. By multivariate logistic analysis, independent risk factors for LVH were past history of cardiovascular disease (odds ratio [OR] 0.574; 95 % confidence interval [CI] 0.360–0.916; P = 0.020), systolic blood pressure (OR 1.179; 95 % CI 1.021–1.360; P = 0.025), body mass index (OR 1.135; 95 % CI 1.074–1.200; P < 0.001), and serum calcium level (OR 0.589; 95 % CI 0.396–0.876; P = 0.009).

Conclusion

Cross-sectional baseline data from the CKD-JAC study shed light on the association between LVH and risk factors in patients with decreased renal function. Further longitudinal analyses of the CKD-JAC cohort are needed to evaluate the prognostic value of LVH in CKD patients.

Factors affecting levels of urinary albumin excretion in the general population of Spain: the Di@bet.es study

The present study was undertaken to examine the prevalence of urinary ACR (albumin/creatinine ratio) >30 mg/g and the associated clinical and environmental factors in a representative sample of the population of Spain. Di@bet.es study is a national, cross-sectional population-based survey conducted in 2009-2010. Clinical, metabolic, socio-demographic, anthropometric data and information about lifestyle habit were collected. Those subjects without KDM (known diabetes mellitus) were given an OGTT (oral glucose tolerance test). Albumin and creatinine were measured in a urinary sample and ACR was calculated. The population prevalence of ACR >30 mg/g was 7.65% (adjusted for sex and age). The prevalence of ACR >30 mg/g increased with age (P<0.001). Subjects with carbohydrate metabolism disorders had a greater prevalence of ACR >30 mg/g but after being adjusted for age, sex and hypertension, was significant only in those subjects with UKDM (unknown diabetes mellitus) {OR (odd ratio), 2.07 [95% CI (confidence interval), 1.38-3.09]; P<0.001] and KDM [OR, 3.55 (95% CI, 2.63-4.80); P<0.001]. Prevalence of ACR >30 mg/g was associated with hypertension [OR, 1.48 (95% CI, 1.12-1.95); P=0.001], HOMA-IR (homoeostasis model assessment of insulin resistance) [OR, 1.47 (95% CI, 1.13-1.92); P≤0.01], metabolic syndrome [OR, 2.17 (95% CI, 1.72-2.72); P<0.001], smoking [OR, 1.40 (95% CI, 1.06-1.83); P≤0.05], physical activity [OR, 0.68 (95% CI, 0.54-0.88); P≤0.01] and consumption of fish [OR, 0.38 (95% CI, 0.18-0.78); P≤0.01]. This is the first study that reports the prevalence of ACR >30 mg/g in the Spanish population. The association between clinical variables and other potentially modifiable environmental variables contribute jointly, and sometimes interactively, to the explanation of prevalence of ACR >30 mg/g. Many of these risk factors are susceptible to intervention.

Physical exercise, fasting glucose, and renal hyperfiltration in the general population: the Renal Iohexol Clearance Survey in Tromsø 6 (RENIS-T6)

BACKGROUND AND OBJECTIVES

Abnormally elevated GFR, or hyperfiltration, is a proposed mechanism for kidney injury in diabetes, prediabetes, and obesity. This study investigated whether lack of physical exercise is associated with hyperfiltration and whether exercise modifies the positive association between fasting glucose and measured GFR.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The Renal Iohexol Clearance Survey in Tromsø 6 measured GFR as single-sample plasma iohexol clearance in 1506 members of the general population (age 50-62 years) without diabetes, cardiovascular disease, or kidney disease. Leisure-time physical exercise was assessed by a self-administered questionnaire. Hyperfiltration was defined as GFR above the 90th percentile after adjustment for sex, age, weight, height, and use of renin-angiotensin system inhibitors.

RESULTS

High-intensity exercise was associated with lower adjusted odds of hyperfiltration in men (odds ratio [OR], 0.47; 95% confidence interval [CI], 0.28-0.80) but not in women (OR, 1.02; 95% CI, 0.60-1.72). In both sexes, high-intensity exercise modified the association between fasting glucose and GFR. A fasting glucose level 1 mmol/L higher was associated with a GFR that was 7.3 (95% CI, 4.0-10.6) and 6.2 (95% CI, 3.4-9.0) ml/min per 1.73 m(2) higher in men and women who never exercised or exercised with low intensity. There was no association between fasting glucose and GFR in men and women who exercised with high intensity (interaction, P<0.001).

CONCLUSIONS

High-intensity exercise was associated with lower odds of hyperfiltration in men and modified the association between glucose and GFR of both sexes in a population without diabetes.

The vulnerable man: impact of testosterone deficiency on the uraemic phenotype

Testosterone deficiency or hypogonadism is a common finding in men undergoing dialysis, to a great extent a consequence of the failing kidney per se. Testosterone restoration in hypogonadism is common practice among endocrinologists. However, there is currently little awareness of this condition among both uremic patients and nephrologists, and in many cases, testosterone deficiency remains unscreened and untreated. This review article summarizes our current understanding of the role of testosterone deficiency at the crossroad of cardiometabolic complications of patients with chronic kidney disease. Pathways discussed include, among others, the plausible role of testosterone deficiency in the development of anaemia and ESA hyporesponsiveness, muscle catabolism, endothelial dysfunction, cognitive dysfunction, decreased libido, cardiovascular disease and mortality. As there are limited sources to guide decision-making, we also review existing testosterone replacement therapy studies in the context of CKD as well as considerations for side and adverse effects. This review makes a case for consideration of screening and better management of hypogonadism in men undergoing dialysis.

Evidence on the prevalence and geographic distribution of major cardiovascular risk factors in Italy

OBJECTIVE

To assess the prevalence and geographic distribution of major cardiovascular risk factors in a large community-wide sample of the Italian population.

DESIGN

A cross-sectional survey. Standardized methods were used to collect and measure cardiovascular risk factors. Data were adjusted for survey weightings. Qualitative and quantitative variables were compared with parametric and non-parametric tests, as appropriate.

SETTING

Towns (n 193) across different Italian regions.

SUBJECTS

Unselected adults (n 24 213; 12 626 men; 11 587 women) aged 18-98 years (mean age 56·9 (sd 15·3) years), who volunteered to participate in a community-wide screening programme over a 2 d period in 2007.

RESULTS

Overall, the prevalence of major cardiovascular risk factors was: obesity, 22·7 % (women 18·9 %, men 26·1 %); overweight, 44·7 % (women 31·6 %, men 56·7 %); hypertension, 59·6 % (women 48·3 %, men 70·0 %); dyslipidaemia, 59·1 % (women 57·7 %, men 60·3 %); diabetes, 15·3 % (women 11·2 %, men 19·0 %) and smoking, 19·8 % (women 14·0 %, men 25·2 %). We found a high prevalence of unhealthy eating habits; fruit and vegetable consumption was below the recommended range in 60 % of the study population. Ninety per cent of the study population had more than one cardiovascular risk factor and 84 % had between two and five cardiovascular risk factors. There were differences among Italian macro-areas mainly for obesity, hypertension, dyslipidaemia and diabetes.

CONCLUSIONS

The study provides alarming evidence on current prevalence data for major cardiovascular risk factors in a large sample of the Italian population. Particularly, obesity and hypertension represent a relevant public health problem. There is a pressing need for effective preventive health measures which must also take into account the differences among Italian macro-areas.

Early improvement in albuminuria in non-diabetic patients after Roux-en-Y bariatric surgery

BACKGROUND

Obesity is a growing epidemic in the USA that has been shown to be associated with chronic kidney disease and albuminuria. Bariatric surgery is an effective means of achieving long-term weight loss and improvements in metabolic derangements including albumin excretion over the long term.

METHODS

We report changes in urinary albumin excretion levels in the early post-operative period for a euglycemic, predominantly Hispanic American cohort undergoing Roux-en-Y gastric bypass surgery.

RESULTS

Our cohort of 38 patients was largely female (89.5%) and predominantly Hispanic (76.3%) with a mean BMI of 46 ± 8.0 kg/m(2). Over half (53.3%) of the patients with significant preoperative albumin excretion in our cohort lowered their albumin excretion levels to <20 mg/g of creatinine. This early reduction in albumin excretion in our cohort correlated significantly with the level of albumin excretion preoperatively but not with the degree of weight loss experienced in this early post-operative period.

CONCLUSIONS

Improvements in microalbuminuria in the early post-operative period after Roux-en-Y surgery may result from an interplay between changes in gastrointestinal hormones, insulin sensitivity, blood pressure, and adipose tissue-and needs further study.

Gender difference in albuminuria and ischemic heart disease in type 2 diabetes

OBJECTIVE

The value of urinary albumin excretion in the prediction of myocardial ischemia in men and women with type 2 diabetes is not well understood. We questioned whether gender influences the albuminuria-ischemic heart disease relationship in patients with type 2 diabetes.

METHODS

We designed a matched case-control study of 926 patients with albuminuria (cases) and 926 age and body mass index matched patients without albuminuria (controls). Ischemic heart disease was defined as the presence of (1) history of angina pectoris or angina equivalent symptoms and critical care unit admission, (2) myocardial infarction and/or electrocardiographic evidence of Q-wave myocardial infarction, (3) coronary revascularization and/or stenting, (4) positive myocardial single-photon emission computed tomography scan, (5) ischemic ST-segment or T-wave changes, and (6) positive stress testing.

RESULTS

Patients with albuminuria had a lower glomerular filtration rate and a longer diabetes duration than patients without albuminuria. In the group of cases, there were a greater number of men with ischemic heart disease (120 of 370; 32.4%) compared to women (97 of 559; 17.4%) (P<0.001). The odds ratio of having ischemic heart disease according to the presence or absence of albuminuria was 1.25 [95% CI: 1.01-1.56] (P<0.05) in all studied populations, 0.79 [95% CI: 0.51-1.21] (P=0.14) in women, and 2.84 [95% CI: 1.68-4.79] (P<0.001) in men. We showed that diabetes duration, high-density lipoprotein, low-density lipoprotein, and hemoglobin A(1c) influence albuminuria in women, while diabetes duration, fasting blood sugar, and diastolic blood pressure influence albuminuria in men.

CONCLUSIONS

Men with albuminuria are at increased risk of ischemic heart disease compared to women. This may be related to the role of high-density lipoprotein on the albuminuria-gender relationship.

Serum phosphorus as a predictor of low-grade albuminuria in a general population without evidence of chronic kidney disease

BACKGROUND

High levels of serum phosphorus, even within the normal range, have been associated with cardiovascular (CV) morbidity. Low-grade albuminuria (LGA) was demonstrated to be related to increased CV events in various study populations. The present study aimed to investigate the association between serum phosphorus levels and LGA in the general population.

METHODS

We examined the individuals who had undergone health inspections. We evaluated the correlation between serum phosphorus and LGA in 8953 participants (mean age, 47.4 years) with estimated glomerular filtration rates (eGFRs)≥60 mL/min/1.73 m2 and urinary albumin-to-creatinine ratios (UACRs)<30 mg/g. Participants who underwent a colonoscopy were excluded.

RESULTS

The mean UACR was significantly higher in the uppermost quartile group of serum phosphorus concentrations than in other quartile groups. In the multivariate regression analysis, serum phosphorus remained an independent predictor of increased UACR (B=0.610, P<0.001). Subgroup analyses showed that this association was maintained irrespective of age, gender, presence of hypertension or diabetes, body mass index and eGFR.

CONCLUSIONS

In our population-based study, higher serum phosphorus was independently related to LGA in individuals without evidence of renal dysfunction. Further investigations are warranted to clarify the precise mechanism of the association between serum phosphorus and LGA.

Self-reported sleep duration and prediction of proteinuria: a retrospective cohort study

BACKGROUND

Although multiple studies have shown that sleep duration is a predictor of cardiovascular diseases and mortality, few studies have reported an association between sleep duration and chronic kidney disease.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

6,834 employees of Osaka University aged 20-65 years who visited Osaka University Healthcare Center for their mandatory annual health examinations between April 2006 and March 2010 and did not have estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m(2), proteinuria, or treatment for self-reported kidney disease.

PREDICTOR

Self-reported questionnaires about life style, including sleep duration, and blood and urine testing at the first examinations during the study period. An association between sleep duration and outcome was assessed using multivariate Poisson regression models adjusting for clinically relevant factors.

OUTCOME

Time to the development of proteinuria defined as 1+ or higher by dipstick test.

RESULTS

Self-reported baseline sleep duration was 6.0 ± 0.9 hours, which reflected the mean sleep duration during a median of 2.5 (25th-75th percentile, 1.4-3.9) years of the observational period. Development of proteinuria was observed in 550 employees (8.0%). A multivariate Poisson regression model clarified that shorter sleep duration, especially 5 or fewer hours, was associated with the development of proteinuria in a stepwise fashion (vs 7 hours; incidence rate ratios of 1.07 [95% CI, 0.87-1.33; P = 0.5], 1.28 [95% CI, 1.00-1.62; P = 0.05], and 1.72 [95% CI, 1.16-2.53; P = 0.007] for 6, 5, and ≤4 hours, respectively), along with younger age, heavier current smoking, trace urinary protein by dipstick test, higher eGFR, higher serum hemoglobin A(1c) level, and current treatment for heart disease. A stepwise association between shorter sleep duration and the development of proteinuria also was verified in 4,061 employees who did not work the night shift.

LIMITATIONS

Self-reported sleep duration might be biased. Results in a single center should be confirmed in the larger cohort including different occupations.

CONCLUSION

Short sleep duration, especially 5 or fewer hours, was a predictor of proteinuria.

Predictors of incident albuminuria in the Framingham Offspring cohort

BACKGROUND

Predictors for incident albuminuria are not well known in population-based cohorts. The purpose of this study is to identify predictors of incident albuminuria in an unselected middle-aged population.

STUDY DESIGN

Observational cohort study.

SETTING & PARTICIPANTS

Framingham Offspring Study participants who attended both the sixth (baseline; 1995-1998) and eighth (2005-2008) examination cycles.

PREDICTORS

Standard clinical predictors were used. Predictors of incident albuminuria were identified using stepwise logistic regression analysis with age and sex forced into the model.

OUTCOMES & MEASUREMENTS

Albuminuria was defined as urine albumin-creatinine ratio (UACR) ≥ 17 mg/g (men) or ≥ 25 mg/g (women). Individuals with albuminuria at baseline were excluded.

RESULTS

1,916 participants were available for analysis (mean age, 56 years; 54% women). Albuminuria developed in 10.0% of participants (n = 192) during 9.5 years. Age (OR, 2.09; P < 0.001), baseline diabetes (OR, 1.93; P = 0.01), smoking (OR, 2.09; P < 0.001), and baseline log UACR (OR per 1-SD increase in log UACR, 1.56; P < 0.001) were associated with incident albuminuria in a stepwise model. An inverse relationship with female sex (OR, 0.53; P < 0.001) and high-density lipoprotein (HDL) cholesterol level (OR, 0.80; P = 0.007) also was observed. Results were similar when participants with baseline chronic kidney disease (n = 102), defined as estimated glomerular filtration rate <60 mL/min/1.73 m(2), were excluded from the model. Age, male sex, low HDL cholesterol level, smoking, and log UACR continued to be associated with incident albuminuria when baseline diabetes (n = 107) was excluded. Age, male sex, and log UACR correlated with incident albuminuria after participants with baseline hypertension were excluded (n = 651).

LIMITATIONS

Causality may not be inferred because of the observational nature of the study. One-third of participants did not return for follow-up, potentially attenuating the observed risks of albuminuria.

CONCLUSIONS

The known cardiovascular risk factors of increasing age, male sex, diabetes, smoking, low HDL cholesterol level, and albuminuria within the reference range are correlates of incident albuminuria in the general population.

The G protein β3 subunit C825T polymorphism is associated with microalbuminuria in hypertensive women and cardiovascular disease in hypertensive men

BACKGROUND

The aim of the study was to examine the association between the G protein β3 subunit C825T polymorphism, associated with cardiovascular risk factors like hypertension (HT) and obesity and microalbuminuria (MA), reflecting the endothelial dysfunction in the atherosclerotic process. Second, we wanted to examine the association between the polymorphism and cardiovascular disease (CVD).

METHODS

In the large population-based, cross-sectional Nord-Trøndelag Health Study, HUNT 1995-1997, a total of 5,755 treated hypertensive individuals attended the MA substudy. A randomly selected sample of 1,000 of these was genotyped. A total of 402 men and 540 women were included in the final analyses. MA was measured as albumin/creatinine ratio (ACR) in three urine samples. Logistic regression was used to calculate odds ratios (ORs) for the association between MA or CVD and the genotype.

RESULTS

The study demonstrated a positive association between the TT genotype and MA in women (OR 3.2, 95% confidence interval (CI): 1.1-8.7, P = 0.03), but not in men. The association became stronger with increasing number of positive urine samples and with increasing cutoff value in women with TT genotype compared to the CC genotype. Additionally, there was a positive association between TT genotype and CVD in men and postmenopausal women without hormone therapy.

CONCLUSIONS

Increased MA in TT homozygous women might be explained by other mechanisms of albuminuria or inflammation than the atherosclerotic process. We postulate that the association between CVD and the genotype are mediated through mechanisms other than the classical risk factors and endothelial dysfunction, reflected by MA, which have to be further investigated.

Sex differences in the impact of diabetes on mortality in chronic dialysis patients

BACKGROUND

Although females have a survival advantage in the general population, women undergoing dialysis have similar mortality to men. Because the reasons for this difference are unknown, we hypothesized that sex differences in cardiovascular disease (CVD) risk profile exist at dialysis initiation and that the association of such risk factors with mortality differs between sexes.

METHODS

This study was a prospective observational cohort study (NECOSAD) of incident dialysis patients with 5 years of follow-up where we calculated male:female odds ratios (OR) and relative risks of mortality (hazard ratio, HR) for the presence of CVD risk factors at the start of dialysis. We also examined the presence of interaction between sex and CVD risk factors in their association with mortality.

RESULTS

In 1577 patients (61% men, 60 ± 15 years), men presented more CVD co-morbidity [OR: 1.88 (95% CI: 1.51, 2.35)] but less diabetes mellitus (OR: 0.70 [0.55, 0.89]) than women. Both sexes presented equal survival [HR 0.98 (0.83, 1.16)]. Women with diabetes had a higher mortality risk [HR 2.93 (2.27, 3.79)] than their male counterparts [HR 1.99 (1.52, 2.59)], showing an interaction effect between sex and diabetes [relative excess risk due to interaction 1.18 (0.37, 2.00)].

CONCLUSION

Despite a lower prevalence of CVD, women starting dialysis had the same mortality risk as men. The mortality risk was strikingly higher in diabetic women than diabetic men. This excess mortality may help explain why dialysis cancels out the female survival advantage. Our study identifies a high-risk group of patients that may warrant further investigation and intensified therapeutic care.

Is longitudinal pulse pressure a better predictor of 24-hour urinary albumin excretion than other indices of blood pressure?

The strong relationship between urinary albumin excretion (UAE) and pulse pressure (PP) in cross-sectional studies suggests that pressure pulsatility may contribute to renal microvascular injury. The longitudinal relationships between UAE and the various indices of blood pressure (BP) are not well studied. We compared the associations of UAE with the longitudinal exposure to PP and systolic, diastolic, and mean BPs. UAE was measured from 24-hour urine collections in 450 community-dwelling subjects (age: 57+/-15 years, 53% women, all with UAE <200 microg/min). For each subject, longitudinal indices of BP were estimated by dividing the area under the curve of serial measurements of BP (median: 5) during 1 to 22 years preceding UAE measurement by the number of follow-up years. Median (interquartile range) UAE was 4.7 microg/min (3.3 to 7.8 microg/min) in women and 5.2 microg/min (3.7 to 9.8 microg/min) in men. In women, UAE was not related to longitudinal indices of BP. In men, in multivariable-adjusted models that included either longitudinal systolic and diastolic BPs or longitudinal PP and mean BP, UAE was independently associated with systolic (standardized regression coefficient [beta]=0.227; P=0.03) but not with diastolic (beta=-0.049; P=0.59) BP and with PP (beta=0.216; P=0.01) but not with mean BP (beta=0.032; P=0.72). Comparisons of these 2 models and stepwise regression analyses both indicated that, of the 4 longitudinal indices of BP, PP was the strongest predictor of UAE in men. The pulsatile component of BP confers the highest risk for BP-induced renal microvascular injury. Future studies should examine whether PP reduction provides additional renoprotection beyond that attained by conventional BP goals alone.

Impact of obesity on renal structure and function in the presence and absence of hypertension: evidence from melanocortin-4 receptor-deficient mice

The purpose of this study was to determine the long-term impact of obesity and related metabolic abnormalities in the absence and presence of hypertension on renal injury and salt-sensitivity of blood pressure. Markers of renal injury and blood pressure salt sensitivity were assessed in 52- to 55-wk-old normotensive melanocortin-4 receptor-deficient (MC4R-/-) mice and lean C57BL/6J wild-type (WT) mice and in 22-wk-old MC4R-/- and WT mice made hypertensive by N(G)-nitro-L-arginine methyl ester (L-NAME) in the drinking water for 8 wk. Old MC4R-/- mice were 60% heavier, hyperinsulinemic, and hyperleptinemic but had similar mean arterial pressure (MAP) as WT mice (115 +/- 2 and 117 +/- 2 mmHg) on normal salt diet (0.4% NaCl). A high-salt diet (4.0% NaCl) for 12 days did not raise MAP in obese or lean mice [DeltaMAP: MC4R (-/-) 4 +/- 2 mmHg; WT, 2 +/- 1 mmHg]. Obese MC4R-/- mice had 23% greater glomerular tuft area and moderately increased GFR compared with WT mice. Bowman's space, total glomerular area, mesangial matrix, urinary albumin excretion (UAE), renal TGF-beta and collagen expression were not significantly different between old MC4R-/- and WT mice. Renal lipid content was greater but renal macrophage count was markedly lower in MC4R-/- than WT mice. Mild increases in MAP during L-NAME treatment (approximately 16 mmHg) caused small, but greater, elevations in UAE, renal TGF-beta content, and macrophage infiltration in MC4R-/- compared with WT mice without significant changes in glomerular structure. Thus despite long-term obesity and multiple metabolic abnormalities, MC4R-/- mice have no evidence of renal injury or salt-sensitivity of blood pressure. These observations suggest that elevations in blood pressure may be necessary for obesity and related metabolic abnormalities to cause major renal injury or that MC4R-/- mice are protected from renal injury by mechanisms that are still unclear.

Albuminuria in hematopoietic cell transplantation patients: prevalence, clinical associations, and impact on survival

Chronic kidney disease (CKD) is common after hematopoietic cell transplantation (HCT). We prospectively measured the urinary albumin:creatinine ratio (ACR) in 142 patients. Total (intact) monomeric albumin was determined by liquid chromatography of untreated urine samples collected weekly to day 100 after HCT. Albuminuria was defined as ACR (mg/g creatinine) > 30; proteinuria, as ACR >300. Cox and logistic regression analyses evaluated ACR as a risk factor for clinical events. The prevalence of albuminuria was 37% at baseline, 64% at day 100, and 50% at 1 year. Proteinuria occurred in 4% of patients at baseline, in 15% at day 100, and in 4% at 1 year. Characteristics associated with albuminuria include age, sex, donor type, hypertension, and sinusoidal obstruction syndrome (SOS). Albuminuria was associated with an increased risk of acute graft-versus-host disease (aGVHD) and bacteremia, but not acute kidney injury (AKI). Albuminuria at day 100 was associated with CKD at 1 year (odds ratio = 4.0; 95% confidence interval [CI] = 1.1 to 14.6). Nonrelapse mortality (NRM) risk was elevated (hazard ratio = 6.8; 95% CI = 1.1 to 41.5) in patients with overt proteinuria at day 100. Albuminuria occurs frequently after HCT and is correlated with aGVHD, bacteremia, hypertension, and progression of renal disease. Proteinuria at day 100 is associated with an 6-fold increased risk of NRM by 1 year after HCT.

Insulin resistance is an independent correlate of increased urine albumin excretion: a cross-sectional study in Iranian Type 2 diabetic patients

AIMS

To assess the association of insulin resistance with increased urinary albumin excretion (UAE) in a cohort of Iranian Type 2 diabetic patients.

METHODS

Three hundred and sixty-one men and 472 women with Type 2 diabetes were enrolled from three different outpatient clinics (Tehran, Iran) during the period 2005-2008. Patients with obstructive uropathy, severe heart failure, liver disease, cancer, autoimmune disease and macroalbuminuria were not included. Microalbuminuria (MA; defined as UAE >or= 30 mg/day) was found in 242 (29.1%) patients; 591 (70.9%) subjects had normoalbuminuria (UAE < 30 mg/day). Insulin resistance was assessed using homeostasis model assessment of insulin resistance (HOMA-IR).

RESULTS

HOMA-IR index values were higher in subjects with MA than those with normoalbuminuria (P < 0.00001). Adjusted values (for age, sex and duration of diabetes) of UAE and HOMA-IR were 11.81 +/- 7.51 (mg/day) and 3.30 +/- 2.21 in normoalbuminuric and 75.36 +/- 55.57 (mg/day) and 4.98 +/- 3.22 in the MA group, respectively (P < 0.00001 for all). Multiple regression analysis showed that UAE was predicted by HOMA-IR, independently of age, duration of diagnosed diabetes, triglycerides, waist circumference, metabolic control, blood pressure and related treatments (P < 0.00001). When patients were categorized into quartiles of HOMA-IR, those of the fourth quartile (i.e. the most insulin resistant) were at a higher risk of increased UAE than other quartiles [odds ratio (OR) 3.7 (95% confidence intervals 2.7-6.2)].

CONCLUSIONS

In Iranian Type 2 diabetic patients, albuminuria was strongly associated with insulin resistance. HOMA-IR is an independent predictor of UAE.

Association of urinary albumin excretion with insulin resistance in Japanese subjects: impact of gender difference on insulin resistance

OBJECTIVE

To investigate the relationship between homeostasis model assessment for insulin resistance (HOMA-R) and urinary albumin excretion in Japanese and clarify gender difference in albuminuria-related insulin resistance.

METHODS

The subject group consisted of 752 Japanese who had no history of diabetes, hypertension or dyslipidemia. After anthropometric examination, fasting blood samples were obtained to determine plasma glucose (FPG), lipids and HOMA-R. The urinary excretion of albumin in the first void urine was expressed as the creatinine ratio (ACR, mg/gCr). Estimated glomerular filtration rate (eGFR) was calculated from serum creatinine using the formula for Japanese.

RESULTS

HOMA-R showed a significant correlation with ACR, and the correlation between HOMA-R and ACR was evident in the subjects with central obesity, whereas no significant correlation was found in the non-obese subjects. There was no correlation between HOMA-R and eGFR. HOMA-R increased according to the quintile of ACR and followed a significant trend. This association was obvious in males; however, in females there was no significant trend. Multiple regression analysis revealed that HOMA-R showed a significant correlation with age, waist circumference, blood pressure and serum triglyceride. In addition, ACR exhibited an independent association with HOMA-R. The association of HOMA-R and ACR was observed only in males, and was not present in females.

CONCLUSION

Microalbuminuria is associated with insulin resistance in Japanese, where central obesity might play an essential role. This association is gender-specific suggesting the involvement of sex hormones in the pathogenesis of albuminuria-related insulin resistance.

Inverse associations between androgens and renal function: the Young Men Cardiovascular Association (YMCA) study

BACKGROUND

Men exhibit higher risk of nondiabetic renal diseases than women. This male susceptibility to renal disease may be mediated by gender-specific factors such as sex hormones.

METHODS

We have undertaken a cross-sectional examination of associations between renal function (creatinine clearance estimated based on Cockcroft-Gault equation) and circulating levels of sex steroids (total testosterone, total estradiol, estrone, androstenedione, dehydroepiandrosterone sulfate (DHEA-S), and dihydrotestosterone) in 928 young (mean age: 18.5 +/- 1.2 years) men.

RESULTS

Both androstenedione and DHEA-S showed inverse linear associations with renal function in the crude analysis of lean men (those with body mass index (BMI) less than median). However, only DHEA-S retained its association with renal function in lean subjects after adjustment--assuming no changes in other independent variables 1 s.d. increase in DHEA-S was associated with 13%-s.d. decrease in creatinine clearance (P = 0.004). Testosterone decreased across tertiles of creatinine clearance only in the crude analysis of nonlean (BMI greater than median) subjects (P < 0.001). The adjusted regression analysis that assumed no changes in other independent variables showed that 1 s.d. increase in total testosterone was associated with 11%-s.d. decrease in creatinine clearance of nonlean men (P = 0.006). Factor analysis confirmed an inverse association of renal function with both sex steroids and a different pattern of their loadings on glomerular filtration-related factors in lean (DHEA-S) and nonlean (testosterone) subjects.

CONCLUSIONS

Our data may suggest that androgens are inversely associated with estimated renal function in apparently healthy men without history of cardiovascular disease.