Risk factors of end-stage renal disease and serum creatinine in a community-based mass screening

Graves' Disease and the Risk of End-Stage Renal Disease: A Korean Population-Based Study

BACKGROUND

Hyperthyroidism is associated with an increased glomerular filtration rate (GFR) in the hyperdynamic state, which is reversible after restoring euthyroidism. However, long-term follow-up of renal dysfunction in patients with hyperthyroidism has not been performed.

METHODS

This was a retrospective cohort study using the Korean National Health Insurance database and biannual health checkup data. We included 41,778 Graves' disease (GD) patients and 41,778 healthy controls, matched by age and sex. The incidences of end-stage renal disease (ESRD) were calculated in GD patients and controls. The cumulative dose and duration of antithyroid drugs (ATDs) were calculated for each patient and categorized into the highest, middle, and lowest tertiles.

RESULTS

Among 41,778 GD patients, 55 ESRD cases occurred during 268,552 person-years of follow-up. Relative to the controls, regardless of smoking, drinking, or comorbidities, including chronic kidney disease, GD patients had a 47% lower risk of developing ESRD (hazard ratio [HR], 0.53; 95% confidence interval [CI], 0.37 to 0.76). In particular, GD patients with a higher baseline GFR (≥90 mL/min/1.73 m2; HR, 0.33; 95% CI, 0.11 to 0.99), longer treatment duration (>33 months; HR, 0.31; 95% CI, 0.17 to 0.58) or higher cumulative dose (>16,463 mg; HR, 0.29; 95% CI, 0.15 to 0.57) of ATDs had a significantly reduced risk of ESRD.

CONCLUSION

This was the first epidemiological study on the effect of GD on ESRD, and we demonstrated that GD population had a reduced risk for developing ESRD.

Trend in creatinine determining methods: Conventional methods to molecular‐based methods

Renal failure (RF) disease is ranked as one of the most prevalent diseases with severe morbidity and mortality. Early diagnosis of RF leads to subsequent control of disease to reduce the poor prognosis. The level of sera creatinine is considered as a significant biomarker for kidney biofunction, which is routinely detected by the Jaffe reaction. The normal range for creatinine in the blood may be 0.84‐1.21 mg/dL. Low accuracy, insufficient sensitivity, explosive and toxicity of picric acid, and pseudo‐interaction with nonspecific elements such as ammonium ions in the Jaffe method lead to the development of various techniques for precise detection of creatinine such as spectroscopic, electrochemical, and chromatography approaches and sensors based on enzymes, molecular imprinted polymer and nanoparticles, etc. Based on previously established results, they are trying to construct sensors with high accuracy, optimum sensitivity, acceptable linear/calibration range, and limit of detection, which are small in size and applicable by the patient him/herself (point‐of‐care testing). By comparing the results of research, a molecularly imprinted electrochemiluminescence‐based sensor with linear/calibration range of 5‐1 mMconcentration of creatinine and the detection limit of 0.5 nM has the best detectable resolution with 2 million measurable points. In this paper, we will review the recently developed methods for measuring creatinine concentration and renal biofunction.

Effect of Fermentation on Nutritional Quality, Growth and Hematological Parameters of Rats Fed Sorghum-Soybean-Orange flesh Sweet Potato Complementary Diet

The protein quality of complementary foods developed from fermented and unfermented sorghum, soybeans, and orange-fleshed sweet potato (OFSP) flour blends was evaluated using rat model. The test diet was as follows: UF2: unfermented sorghum (56%), soybean (17%), and OFSP (27%); UF3: unfermented sorghum (59%), soybean (31%), and OFSP (10%); F2: fermented sorghum (56%), soybean (17%), and OFSP (27%); and F3: fermented sorghum (59%), soybean (31%), and OFSP (10%), while cerelac served as positive control, corn starch (basal diet), and ogi (negative control). Forty-nine Wistar albino rats were grouped and fed with diets for 28 days. The growth, hematological, serum parameters of animals, protein quality, and proximate composition of developed diet were determined. Fermentation significantly improved the protein content and nutritional indices of experimental animals. Moisture content ranged from 2.5% to 9.24%, protein (7.09%-25.29%), ash (1.09%-3.71%), fat (10.28%-15.24%), and fiber (0.85%-3.17%). The biological values (BV) ranged from 75.11% to 78.44%. The weight gained in rat fed the formulated diet ranged from 46.0 g to 77.3 g and was highest in F3. The packed cell volume (PCV), hemoglobin concentration (HBC), red blood cell (RBC), and lymphocytes were highest in F3. Urea nitrogen and creatinine of the rats fed with formulated diets ranged from 3.58 to 15.32 mg/dl and 1.56 to 6.15 mg/dl, respectively. Sample F3 is a protein-rich complementary food that is comparable to ogi and suitable to manage malnutrition and support growth in children. However, clinical trials on the formulated diet are needed to further substantiate its nutritional potentials.

An optimal method for measuring biomarkers: colorimetric optical image processing for determination of creatinine concentration using silver nanoparticles

Creatinine concentration is one of the important elements in the body for diagnosing kidney failure, muscular dystrophy, glomerular filtration rate, and diabetic nephropathy. The disadvantages of recently introduced analytical techniques, such as Jaffe's, spectroscopic, colorimetric, and chromatographic methods, for quantifying creatinine in urine involve toxicity, the high cost, interference, and the complexity of the design. In this paper, we designed and fabricated a new colorimetric assay for the measurement of creatinine concentration based on color differentiation generated by mixing different concentrations of creatinine with synthesized silver nanoparticles (AgNPs) coated with polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA). An isolated box is designed for the uniform optical imaging of solutions, the captured images are processed in real time, and the quantitative and qualitative results are displayed. For colorimetric processing, a variety of color systems, such as RGB (red, green, blue), CMYK (cyan, magenta, yellow, black), and grayscale (Gr), have been evaluated, indicating that the combination of green (G) and grayscale (Gr) provides the best results for this experiment. TEM analysis and spectroscopy were used to confirm the results of the experiment. Linear range and limit of detection (LOD) were obtained for AgNPs/PVP 0.03-1 mg/dl and 0.024 mg/dl and for AgNPs/PVA 0.01-1 mg/dl and 0.014 mg/dl, respectively, indicating the superiority of our proposed method over recently introduced methods. In this experiment, the detectable resolution with AgNPs/PVP is 40, while it is 71 with AgNPs/PVA. The designed system is simple to use, small in size, and cost-effective for measuring creatinine concentration, while it can be used as a portable system.

Nutritional, antioxidant, glycaemic index and Antihyperglycaemic properties of improved traditional plantain-based (Musa AAB) dough meal enriched with tigernut (Cyperus esculentus) and defatted soybean (Glycine max) flour for diabetic patients

The study aimed at determining nutritional, antioxidant and blood glucose lowering potentials of improved plantain-based dough meals enriched with defatted soybean and tigernut flour. The constituted dough meals [PSB (plantain 64.46, defatted soybean 35.54%), TNS (tigernut 59.83, defatted soybean 40.17%); PTS (plantain 51.07, tigernut, 11.50, defatted soybean, 37.43%); TNT (100% tigernuts); PLT (100% plantain) and CNT (a commercial flour)] were evaluated for nutritional, antioxidant and blood glucose concentration in streptozotocin-induced diabetics rats. The improved dough meals contained appreciable amount of protein, energy value, and high in antioxidative activity than PLT. Blood glucose reducing potential of improved plantain-based dough meals (60.5-71.9%) in streptozotocin-induced diabetic rats was higher than PLT, but comparable to acarbose (anti-diabetic drug) (69%). The present study established that improved traditional plantain-based dough meals (particularly PTS) was high in essential nutrients, antioxidative activities, and blood glucose reducing potentials. Hence, the dough-meals may be suitable for diabetes management.

Dipstick proteinuria and all-cause mortality among the general population

BACKGROUND

Dipstick proteinuria, but not albuminuria, is used for general health screening in Japan. How the results of dipstick proteinuria tests correlate with mortality and, however, is not known.

METHODS

Subjects were participants of the 2008 Tokutei-Kenshin (Specific Health Check and Guidance program) in six districts in Japan. On the basis of the national database of death certificates from 2008 to 2012, we used a personal identifier in two computer registries to identify participants who might have died. The hazard ratio (95% confidence interval, CI) was calculated by Cox-proportional hazard analysis.

RESULTS

Among a total of 140,761 subjects, we identified 1641 mortalities that occurred by the end of 2012. The crude mortality rates were 1.1% for subjects who were proteinuria (-), 1.5% for those with proteinuria (+/-), 2.0% for those with proteinuria (1+), 3.5% for those with proteinuria (2+), and 3.7% for those with proteinuria (≥ 3+). After adjusting for sex, age, body mass index, estimated glomerular filtration rate, comorbid condition, past history, and lifestyle, the hazard ratio (95% CI) for dipstick proteinuria was 1.262 (1.079-1.467) for those with proteinuria (+/-), 1.437 (1.168-1.748) for those with proteinuria (1+), 2.201 (1.688-2.867) for those with proteinuria (2+), and 2.222 (1.418-3.301) for those with proteinuria (≥ 3+) compared with the reference of proteinuria (-).

CONCLUSION

Dipstick proteinuria is an independent predictor of death among Japanese community-based screening participants.

Chronic treatment with atrial natriuretic peptide in spontaneously hypertensive rats: beneficial renal effects and sex differences

Objective

The aim of this study was to investigate the effects of chronic treatment with atrial natriuretic peptide (ANP) on renal function, nitric oxide (NO) system, oxidative stress, collagen content and apoptosis in kidneys of spontaneously hypertensive rats (SHR), as well as sex-related differences in the response to the treatment.

Methods

10 week-old male and female SHR were infused with ANP (100 ng/h/rat) or saline (NaCl 0.9%) for 14 days (subcutaneous osmotic pumps). Systolic blood pressure (SBP) was recorded and diuresis and natriuresis were determined. After treatment, renal NO synthase (NOS) activity and eNOS expression were evaluated. Thiobarbituric acid-reactive substances (TBARS), glutathione concentration and glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities were determined in the kidney. Collagen was identified in renal slices by Sirius red staining and apoptosis by Tunel assay.

Results

Female SHR showed lower SBP, oxidative stress, collagen content and apoptosis in kidney, and higher renal NOS activity and eNOS protein content, than males. ANP lowered SBP, increased diuresis, natriuresis, renal NOS activity and eNOS expression in both sexes. Renal response to ANP was more marked in females than in males. In kidney, ANP reduced TBARS, renal collagen content and apoptosis, and increased glutathione concentration and activity of GPx and SOD enzymes in both sexes.

Conclusions

Female SHR exhibited less organ damage than males. Chronic ANP treatment would ameliorate hypertension and end-organ damage in the kidney by reducing oxidative stress, increasing NO-system activity, and diminishing collagen content and apoptosis, in both sexes.

Serum uric acid levels are associated with polymorphisms in the SLC2A9, SF1, and GCKR genes in a Chinese population

AIM

Genome-wide association studies have identified several novel loci associated with serum uric acid concentrations in individuals of European descent. In the current study, we aimed to evaluate the associations between these loci and serum uric acid concentrations in a Chinese population.

METHODS

Fourteen single nucleotide polymorphisms (SNPs) mapped in or near 11 loci (PDZK1, GCKR, LRP2, SLC2A9, ABCG2, LRRC16A, SLC17A1, SLC17A3, SLC22A11, SLC22A12 and SF1) were genotyped in 2329 Chinese subjects in Shanghai. Serum biochemical parameters including uric acid concentrations were determined. All the variants were analyzed for gender differences since uric acid metabolism differed between genders.

RESULTS

In males after adjustments for age and BMI, GCKR rs780094, SLC2A9 rs11722228 and SF1 rs606458 were associated with the uric acid concentrations, which were statistically significant (P=0.016, 0.001 and 0.03, respectively), whereas SLC2A9 rs3775948 was marginally associated with the uric acid concentrations (P=0.071). In females, SLC22A12 rs506338 was also marginally associated with the uric acid concentrations (P=0.057). The meta-analysis for combined data from both males and females revealed that rs3775948 and rs606458 were associated with the uric acid concentrations (P=0.036 and 0.043, respectively). Furthermore, the gender significantly affected the association of rs11722228 with serum uric acid levels (P=0.012).

CONCLUSION

The SLC2A9 rs11722228, SF1 rs606458 and GCKR rs780094 variants modulate uric acid concentrations in Chinese males, while SF1 rs606458 and SLC2A9 rs3775948 are associated with the uric acid concentrations in both Chinese males and females.

The effect of febuxostat to prevent a further reduction in renal function of patients with hyperuricemia who have never had gout and are complicated by chronic kidney disease stage 3: study protocol for a multicenter randomized controlled study

BACKGROUND

Hyperuricemia is a risk factor for the onset of chronic kidney disease (CKD) and is significantly associated with the progression of CKD. However, there is no sufficient evidence by interventional research supporting a cause-effect relationship. Hyperuricemic patients without gouty arthritis, whose serum urate (SUA) concentration is ≥8.0 mg/dL and who have a complication, are treated by pharmacotherapy in addition to lifestyle guidance. Nevertheless, there is no evidence that rationalizes pharmacotherapy for patients with hyperuricemia who have no complication and whose SUA concentration is below 9.0 mg/dL.

METHODS/DESIGN

The FEATHER (FEbuxostat versus placebo rAndomized controlled Trial regarding reduced renal function in patients with Hyperuricemia complicated by chRonic kidney disease stage 3) study is a prospective, multicenter, double-blind, randomized, placebo-controlled trial of febuxostat-a novel, nonpurine, selective, xanthine oxidase inhibitor. The present study will enroll, at 64 medical institutions in Japan, 400 Japanese patients aged 20 years or older who have hyperuricemia without gouty arthritis, who present CKD stage 3, and whose SUA concentration is 7.1-10.0 mg/dL. Patients are randomly assigned to either the febuxostat or the control group, in which febuxostat tablets and placebo are administered orally, respectively. The dosage of the study drugs should be one 10-mg tablet/day at weeks 1 to 4 after study initiation, increased to one 20-mg tablet/day at weeks 5 to 8, and elevated to one 40-mg tablet/day at week 9 and then maintained until week 108. The primary endpoint is estimated glomerular filtration rate (eGFR) slope. The secondary endpoints include the amount and percent rate of change in eGFR from baseline to week 108, the amount and percent rate of change in SUA concentration from baseline to week 108, the proportion of patients who achieved an SUA concentration≤6.0 mg/dL, and the incidence of renal function deterioration.

DISCUSSION

The present study aims to examine whether febuxostat prevents a further reduction in renal function as assessed with eGFR in subjects and will (1) provide evidence to indicate the inverse association between a reduction in SUA concentration and an improvement in renal function and (2) rationalize pharmacotherapy for subjects and clarify its clinical relevance.

TRIAL REGISTRATION

UMIN Identifier: UMIN000008343.

Long-term evolution of renal function in patients with type 2 diabetes mellitus: a registry-based retrospective cohort study

OBJECTIVES

To picture the 10-year evolution of renal function in patients with type 2 diabetes mellitus (T2DM) and chronic kidney disease (CKD) and to describe the risk factors for severe decline.

SETTING

Primary registration network with 97 general practitioners working in 55 practices sending routinely collected patient data.

PARTICIPANTS

From the database, we selected all patients aged 40 years or older with T2DM and at least two creatinine measurements in two different years with an interval of at least 3 months. Based on the last available value of estimated glomerular filtration rate calculated by the modification of diet in renal disease (MDRD) equation, patients were divided into grades of CKD. Severe decline (decline of >4 mL/min/year) and 'certain drop' (CD, year-to-year decline >10 mL/min) were determined in patients with CKD. Determinants of severe decline and CD were investigated with logistic regression and longitudinal logistic regression analysis, respectively.

PRIMARY OUTCOME MEASURE

Kidney function (MDRD).

RESULTS

4041 patients, 1980 women, were included. The mean age was 71 years, mean diabetes duration was 7.7 years; 1514 (38%) suffered from CKD, 231 (15%) presented with severe decline and 18% of the patients with CKD presented with two or more CDs. Younger age, male gender, mean glycated haemoglobin and a higher number of CDs were significantly associated with the presence of severe decline (p<0.05); statins and higher diastolic blood pressure were significantly associated with the absence of severe decline (p<0.001). ACE inhibitors, other antihypertensive drugs and antidiabetic drugs including insulin therapy were specific determinants of CD.

CONCLUSIONS

CKD is highly prevalent in patients with T2DM; a minority of patients evolve into severe decline that is associated with younger age, male gender, 'CD' and manageable factors such as blood pressure, blood glucose, associated drugs prescriptions and statin therapy. Further prospective observational and experimental research is needed to clarify the nature of those associations.

Nephrology for the people: Presidential Address at the 42nd Regional Meeting of the Japanese Society of Nephrology in Okinawa 2012

The social and economic burdens of dialysis are growing worldwide as the number of patients increases. Dialysis is becoming a heavy burden even in developed countries. Thus, preventing end-stage kidney disease is of the utmost importance. Early detection and treatment is recommended because late referral is common, with most chronic kidney disease (CKD) patients remaining asymptomatic until a late stage. Three-quarters of dialysis patients initiated dialysis therapy within 1 year after referral to the facility. Since its introduction in 2002, the definition of CKD has been widely accepted not only by nephrologists but also by other medical specialties, such as cardiologists and general practitioners. Japan has a long history of general screening for school children, university students, and employees of companies and government offices, with everybody asked to participate. The urine test for proteinuria and hematuria is popular among Japanese people; however, the outcomes have not been well studied. We examined the effects of clinical and laboratory data from several sources on survival of dialysis patients and also predictors of developing dialysis from community-based screening (Okinawa Dialysis Study, OKIDS). At an early CKD stage, patients are usually asymptomatic; therefore, regular health checks using a urine dipstick and serum creatinine are recommended. The intervals for follow-up, however, are debatable due to the cost. CKD is a strong risk factor for developing cardiovascular disease and death and also plays an important role in infection and malignancies, particularly in elderly people. People can live longer with healthy kidneys.

Renal oxygenation measurement during partial nephrectomy using hyperspectral imaging may predict acute postoperative renal function

BACKGROUND AND PURPOSE

Digital Light Processing hyperspectral imaging (HsI) produces a highly sensitive, real-time tissue oxygenation map to monitor renal perfusion/oxygenation during partial nephrectomy (PN). Our initial experience with HsI revealed considerable variation in the baseline renal oxygenation, and we sought to correlate these differences with postoperative renal function.

PATIENTS AND METHODS

Hyperspectral images were collected intraoperatively in patients undergoing PN for cortical tumors. The kidney was illuminated with visible light (520-645 nm), the spectrum corresponding to that of oxyhemoglobin. Reflectance images were captured and digitally processed to determine the percentage of oxyhemoglobin (HbO2) at each image pixel. Images were taken before hilar occlusion; these %HbO2 values were used to categorize patients as high (>75% HbO2) or low (<75% HbO2) oxygenation, and postoperative eGFR was assessed.

RESULTS

There were 26 patients who underwent PN with ice cooling and HsI imaging. Nineteen patients had a "low" preclamp oxygenation (mean 69%) while the other 7 had a "high" HbO2 (mean 77%). There was no difference in tumor size, hematocrit value, clamp time, or preoperative eGFR between the two groups. Patients with a higher baseline %HbO2 had no significant postoperative change in their eGFR (mean 0 mL/min/1.73 m(2), +4%), while those with the lower baseline %HbO2 had a significant acute decline (mean 15 mL/min/1.73 m(2), -20%, P=0.02, 0.006).

CONCLUSIONS

Baseline renal oxygenation, as measured with HsI, may help predict risk of postoperative renal insufficiency and may distinguish between patients with otherwise similar baseline characteristics, such as eGFR. HsI may provide individualized assessment of renal function to influence intraoperative decision-making to help preserve renal function.

[Effect of coronary risk and of hypertension on renal risk in the general population]

INTRODUCTION

Abnormal albuminuria (≥ 30 mg/g) and low estimated glomerular filtration rate (eGFR<60 mL/min/1.73 m(2)) not only are renal risk factors, but also cardiovascular and coronarian risk factors. Though, the relation between coronary risk and renal risk, and its interaction with insufficiently controlled brachial pressure (BP) is poorly described in the literature.

SUBJECTS AND METHODS

We realised a cross-sectional study on subjects 40 and older, having attended a medical exam in 11 IRSA centers between 2006 and 2010. Every subject filled a questionnaire, underwent biological analysis, and a clinical examination. eGFR and albuminuria were measured, and the 10-year risk of coronarian event was calculated (Laurier's equation)

RESULTS

We analysed 118,314 subjects, amongst whom 96,400 had no personal cardiovascular history. Amongst those, 9.1% had a 10-year coronary risk over 10%. There was a continuous relationship between coronary risk and renal risk: subjects with a risk above 15% had a significative risk of pathological albuminuria (OR: 6.87 [5.58-8.44]), and of low eGFR (2.26 [1.82-2.78]) compared to those with a risk under 5%. There was a continuous relationship between BP and renal risk, with a significative risk of pathological albuminuria (OR=7.75 [6.69-8.96]) and of low eGFR (OR: 1.33 [1.09-1.60]) in subjects with BP greater than or equal to 180/110 mmHg, compared to those with normal BP.

CONCLUSION

In the French population, 9.1% of subjects have a 10-year coronary risk above 10%. This risk is associated to abnormalities of the renal function. The relation between coronary risk and renal risk is continuous and dose-dependent, as is the relation between BP and renal risk.

Worse renal disease in postmenopausal F2[Dahl S x R]-intercross rats: detection of novel QTLs affecting hypertensive kidney disease

The prevalence of hypertension increases after menopause with 75% of postmenopausal women developing hypertension in the United States, along with hypertensive end organ diseases. While human and animal model studies have indicated a protective role for estrogen against cardiovascular disease and glomerulosclerosis, clinical studies of hormone replacement therapy in postmenopausal women have shown polar results with some improvement in hypertension but worsening of hypertensive kidney disease, or no effect at all. These observations suggest that the pathogenesis of postmenopausal hypertension and its target organ complications is more complex than projected, and that loss of endogenous estrogens induces epigenetic changes that alter genetic susceptibility to end-organ complications per se resulting in pathogenetic mechanisms beyond correction by hormone replacement. We studied postmenopausal-induced changes in renal disease and performed a total genome scan for quantitative trait loci (QTLs) affecting kidney disease in postmenopausal 16m-old F2[Dahl S x R]-intercross female rats. We used glomerular injury score (GIS) as quantitative trait. We compared QTLs amongst premenopausal, ovariectomized and postmenopausal F2[Dahl S x R]-intercross rats using identical phenotype characterization. Postmenopausal F2[Dahl S x R]-intercross rats exhibited increased hypertensive glomerulosclerosis (P<0.01) and equivalent levels of kidney disease when compared to premenopausal and ovariectomized F2[Dahl S x R]-intercross rats respectively. We detected three significant to highly significant GIS-QTLs (GIS-pm1 on chromosome 4, LOD 3.54; GIS-pm2 on chromosome 3, LOD 2.72; GIS-pm3 on chromosome 5, LOD 2.37) and two suggestive GIS-QTLs (GIS-pm4 on chromosome 2, LOD 1.70; GIS-pm5 on chromosome 7, LOD 1.28), all of which were unique to this postmenopausal population. Detection of increased renal disease phenotype in postmenopausal and ovariectomized subjects suggests a protective role of ovarian hormones. Furthermore, the detection of distinct GIS-QTLs in postmenopausal intercross female rats suggests that distinct genetic mechanisms underlie hypertensive glomerulosclerosis in premenopausal and postmenopausal states.

Dietary intake and the risk of hyperuricemia, gout and chronic kidney disease in elderly Taiwanese men

INTRODUCTION

This study was conducted to examine the relationship between dietary intake and the risk of chronic kidney disease (CKD), treated hyperuricemia (or gout) without CKD, and untreated hyperuricemia without CKD in elderly men.

METHODS

The study population comprised 752 men aged 65 or older who had been included in the Elderly Nutrition and Health Survey (1999-2000) (Elderly NAHSIT).

RESULTS

Statistical analysis using a polychotomous logistic regression model revealed that compared with the individuals in the normouricemic group, the individuals in the other groups exhibited a significant association between a higher prevalence of CKD and the following factors: advanced age, drug use for hypertension, egg and shellfish consumption and consumption of poultry with the skin and meat with fat. The significant risk factors for the patients who did not have CKD and were undergoing treatment for hyperuricemia were as follows: BMI ≥ 25 kg/m(2); drug use for hypertension; intake of poultry with skin; increased daily consumption of shellfish, fried food, sugar and juice.

CONCLUSIONS

Men who use anti-hypertensive drugs and who consume fewer soy products and more shellfish may be at a higher risk of developing hyperuricemia or CKD.

Risk factors for chronic kidney disease in adults with cystic fibrosis

RATIONALE

Adults with cystic fibrosis (CF) possess multiple potential risk factors for chronic kidney disease, including CF-related diabetes (CFRD) and lifetime nephrotoxic drug exposure.

OBJECTIVES

To determine whether cumulative intravenous (IV) aminoglycoside exposure and CFRD increase the risk of chronic kidney disease in adults with CF.

METHODS

This was a cohort study using adults (≥ 18 yr) in the CF Foundation registry from 2001-2008. Chronic kidney disease (stage 3 or greater) was defined by an estimated glomerular filtration rate of less than 60 ml/min/1.73 m(2). Time-dependent multivariable Cox proportional hazards models were used to determine whether cumulative number of acute pulmonary exacerbations (surrogate for IV aminoglycoside exposure) and CFRD requiring insulin increase the risk of chronic kidney disease, adjusting for confounders.

MEASUREMENTS AND MAIN RESULTS

The study cohort included 11,912 adults with a median follow-up of 4 years. During the study period, 204 subjects had chronic kidney disease, with an annual disease prevalence of 2.3%. Disease prevalence doubled with every 10-year increase in age. CFRD requiring insulin therapy substantially increased the risk of chronic kidney disease (1-4 yr of CFRD requiring insulin vs. no CFRD, hazard ratio [HR] = 2.40, 95% confidence interval [CI] 1.74-3.32; ≥ 5 yr, HR = 4.56, 95% CI 2.84-7.31). Pulmonary exacerbations did not significantly increase the risk of chronic kidney disease (one to five exacerbations vs. none, HR = 0.79, 95% CI 0.56-1.11; six to nine exacerbations, HR = 0.92, 95% CI 0.58-1.46; ≥ 10 exacerbations, HR = 1.16, 95% CI 0.75-1.81).

CONCLUSIONS

CF-related diabetes is a significant risk factor for chronic kidney disease in adults with CF, but additional studies examining IV aminoglycoside exposure directly are required.

Relationship between chronic kidney disease and risk of coronary heart disease in Korean men

There have been many epidemiological researches of chronic kidney disease (CKD), accompanied by an increase in the incidence of coronary heart disease (CHD). However, as far as we know, little research has been done to examine the extent of the relationship between CKD and CHD as estimated by Framingham risk score (FRS) in Korean men. CKD was defined as either proteinuria or an eGFR of < 60 mL/min per 1.73 m(2). The FRS has been used to predict the 10-yr risk of coronary events and usually divided into three levels of risk < 10% (low), 10%-19% (intermediate) and ≥ 20% (high). We defined FRS ≥ 10% as more-than-a-moderate CHD risk group and FRS ≥ 20% as a high CHD risk group, respectively. After adjusting for covariates, multivariable-adjusted logistic regression analyses showed a strong statistical significant relationship between CKD and high risk of CHD (adjusted OR, 1.95 [95% CI, 1.32-2.87]). Dipstick urinalysis and eGFR can be readily measured in most clinical settings. The measurement of kidney function may represent a relatively inexpensive and efficient way to identify individuals at higher risk for CHD.

Underestimation of impaired kidney function with serum creatinine

Serum creatinine (SCr) levels are frequently used as a screening test to assess impaired renal function; however, patients can have significantly decreased glomerular filtration rate (GFR) with normal SCr values and making the recognition of kidney dysfunction more difficult. Hence, this study was designed to determine the extent of misclassification of the patients who have significantly reduced GFR as calculated by reexpressed four variable modification of diet in renal disease (MDRD) equation but, normal range of SCr. The study included 1040 in and out patients referred by physicians for serum creatinine measurement. When an exclusion criterion was applied 928 patients were qualified for the study. SCr was measured in 928 patients by a Roche kinetic compensated Jaffe's assay. GFR was calculated using reexpressed four variable MDRD study equation. Of the 928 patients 270 (29.1%) had renal dysfunction on the basis of eGFR (<60 ml/min/1.73 m(2)). However, with SCr only 162 (17.5%) patients had abnormal renal function (>1.5 mg/dl) and SCr values misrepresented (108) 11.6% patients with impaired kidney function. In addition, more females, about 15% were failed to detect by SCr method in contrast to males of 9%. This study documented that, a large proportion of patients with impaired renal function are not diagnosed if clinicians rely solely on normal SCr as evidence of normal renal function. Inclusion of eGFR calculated by re-expressed 4 variable MDRD equation may facilitates the early identification and intervention of patients with renal impairment.

The state of U.S. living kidney donors

BACKGROUND AND OBJECTIVES

Increasing living kidney donation mandates ongoing assessment of living donors for future health risks and revision of national health policy.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Living kidney donors as reported to the Organ Procurement and Transplant Network database from January 1988 through December 2008 were reviewed for minor medical abnormalities, presence of donor health care coverage, and occurrence of surgical complications and death.

RESULTS

At donation in 2008, 19.5% were obese, 2.0% had a history of hypertension, and 3.5% had proteinuria. The median estimated GFR of living donors was 92.2 ml/min. Additionally, 12.2% of donors were reported not to have health insurance at the time of donation. By racial background, 14.9% of black and 17.0% of Hispanic donors did not have insurance at donation. Perioperative complications included blood transfusion (0.4%), reoperation (0.5%), and vascular complications (0.2%). Death occurred within 30 days of donation in 0.03% donating between October 1999 and December 2008. During those same years, overall donor death was 2.8%.

CONCLUSIONS

Almost one quarter of living donors have medical conditions that may be associated with future health risk. Close follow-up and a registry of these donors are necessary. Only then will we be able to inform prospective living donors most accurately of the real risk of donation on their health and survival. Additionally, these data speak to the need for a national discussion on the provision of health insurance for living donors.

Effects ofFicus thonningii(Blume) [Morarceae] Stem-Bark Ethanolic Extract on Blood Glucose, Cardiovascular and Kidney Functions of Rats, and on Kidney Cell Lines of the Proximal (LLC-PK1) and Distal Tubules (MDBK)

Previous observations indicate that Ficus thonningii (Blume) [Moraceae] stem-bark extracts may be useful in the control of diabetes mellitus. Accordingly, we investigated in some experimental animal paradigms the effects of F. thonningii stem-bark ethanolic extract (FTE) on renal and cardiovascular functions as complications of diabetes. Oral glucose tolerance tests were conducted in separate groups of non-diabetic and STZ-treated diabetic rats given glucose load (0.86 g x kg(-1), p.o.) after 18-h fast, followed by various FTE doses (60, 120, and 240 mg x kg(-1)). Rats treated with deionized water (3 mL x kg(-1) p.o.), or metformin (500 mg x kg(-1) p.o.) acted as untreated and treated positive controls, respectively. Blood glucose was monitored at 15-min intervals for the first hour, and hourly thereafter for 3 h. Acute effects of FTE on kidney function and mean arterial blood pressure (MAP) were investigated in anaesthetized rats challenged with hypotonic saline after a 3.5-h equilibration for 4 h of 1 h control, 1.5 h treatment, and 1.5 h recovery periods. FTE was added to the infusate during the treatment period. Chronic effects of FTE were studied in individually caged rats treated daily with FTE (120 mg x kg(-1), p.o.) for five weeks. Cytotoxicity of FTE was assessed by dye-reduction colorimetric (MTT) assay on MDBK and LLCPK1 kidney cell lines exposed for 24 h, 48 h, and 72 h to graded concentrations of the extract. Myocardial contractile performance was evaluated on rat isolated atrial muscle strips. FTE, like metformin, decreased blood glucose levels in non-diabetic and STZ-diabetic rats. Both acute and chronic FTE treatments did not affect renal function. In vitro studies demonstrated that FTE increased MDBK cell metabolic activity by an average of 15% (72 h), and LLCPK1 mirrored the controls. Acute intravenous infusion of FTE reduced the MAP from 119 +/- 1 mmHg to 98 +/- 4 mmHg. The MAP also was reduced throughout the five-week experimental study period. FTE also produced concentration-dependent, negative inotropic and chronotropic effects on rat isolated, electrically driven left-, and spontaneously beating right-, atrial muscle preparations. Our experimental findings suggest that FTE possesses reno- and cardio-protective effects in diabetes mellitus.

Prehypertension, obesity, and risk of kidney disease: 20-year follow-up of the HUNT I study in Norway

BACKGROUND

The combined effect of blood pressure (BP) and body weight on risk of kidney disease has not been previously studied. To improve risk stratification in prehypertensive individuals (ie, BP, 120 to 139/80 to 89 mm Hg), we examined the interaction between BP and body weight on the risk of end-stage renal disease or chronic kidney disease (CKD)-related death.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

74,986 adults participating in the first Health Study in Nord-Trøndelag (88% participation rate) were linked to the Norwegian Renal Registry and Cause of Death Registry.

PREDICTORS

BP and body weight were measured by using standard procedures, and other relevant covariates were obtained from an extensive questionnaire.

OUTCOME & MEASUREMENTS

Hazard ratios for treated end-stage renal disease and CKD-related death were calculated.

RESULTS

Mean systolic BP and body mass index (BMI) were 136.8 +/- 23.3 (SD) mm Hg and 25.2 +/- 3.9 kg/m(2), whereas 12.9% had treated hypertension at baseline, respectively. During a median follow-up of 21 years (1,345,882 person-years), 507 men (1.4%) and 319 women (0.8%) initiated renal replacement therapy (n = 157) or died of CKD (n = 669). Multiadjusted risk of these kidney outcomes increased continuously with no lower threshold for BP. The risk associated with body weight started to increase from a BMI of 25.0 kg/m(2). In participants with BP less than 120/80 mm Hg, risk did not increase with increasing BMI. In prehypertensive participants, multivariate adjusted hazard ratios in the BMI categories 18.5 to 24.9, 25.0 to 29.9, 30.0 to 34.9, and 35.0 kg/m(2) or greater were 1.21 (95% confidence interval [CI], 0.67 to 2.17), 1.10 (95% CI, 59 to 2.00), 2.66 (95% CI, 1.28 to 5.53), and 5.94 (95% CI, 1.94 to 18.20) compared with BP less than 120/80 mm Hg and BMI of 18.5 to 24.9 kg/m(2), respectively (P = 0.02 for trend). Corresponding risks in hypertensive participants were 2.13 (95% CI, 1.23 to 3.70), 2.40 (95% CI, 1.40 to 4.15), 3.32 (95% CI, 1.89 to 5.81), and 5.53 (95% CI, 3.01 to 10.20), respectively (P < 0.001 for trend).

LIMITATIONS

Baseline creatinine measurements were not available; hence, a secondary analysis was performed that excluded all individuals who experienced outcomes in the 5 years after the study start.

CONCLUSIONS

Participants with prehypertension are not at increased risk of serious kidney outcomes if BMI is less than 30.0 kg/m(2). However, the risk of kidney disease increases substantially if prehypertension is present in obese participants.

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

BACKGROUND

Few cohort studies have focused on risk factors for end-stage renal disease (ESRD). This investigation evaluated the prognostic value of several potential novel risk factors for ESRD after considering established risk factors.

METHODS

We studied 177 570 individuals from a large integrated health care delivery system in northern California who volunteered for health checkups between June 1, 1964, and August 31, 1973. Initiation of ESRD treatment was ascertained using US Renal Data System registry data through December 31, 2000.

RESULTS

A total of 842 cases of ESRD were observed during 5 275 957 person-years of follow-up. This comprehensive evaluation confirmed the importance of established risk factors, including the following: male sex, older age, proteinuria, diabetes mellitus, lower educational attainment, and African American race, as well as higher blood pressure, body mass index, and serum creatinine level. The 2 most potent risk factors were proteinuria and excess weight. For proteinuria, the adjusted hazard ratios (HRs) were 7.90 (95% confidence interval [CI], 5.35-11.67) for 3 to 4+ on urine dipstick, 3.59 (2.82-4.57) for 1 to 2+ on urine dipstick, and 2.37 (1.79-3.14) for trace vs negative on urine dipstick. For excess weight, the HRs were 4.39 (95% CI, 3.38-5.70) for class 2 to class 3 obesity, 3.11 (2.51-3.84) for class 1 obesity, and 1.65 (1.39-1.97) for overweight vs normal weight. Furthermore, several independent novel risk factors for ESRD were identified, including lower hemoglobin level (1.33 [1.08-1.63] for lowest vs highest quartile), higher serum uric acid level (2.14 [1.65-2.77] for highest vs lowest quartile), self-reported history of nocturia (1.36 [1.17-1.58]), and family history of kidney disease (HR, 1.40 [95% CI, 1.02-1.90]).

CONCLUSIONS

We confirmed the importance of established ESRD risk factors in this large cohort with broad sex and racial/ethnic representation. Lower hemoglobin level, higher serum uric acid level, self-reported history of nocturia, and family history of kidney disease are independent risk factors for ESRD.

Time-dependent association between metabolic syndrome and risk of CKD in Korean men without hypertension or diabetes

BACKGROUND

The time-dependent association between metabolic syndrome and risk of chronic kidney disease (CKD) is not clear.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

The study cohort was composed of 10,685 healthy men without CKD, hypertension, or diabetes who participated in a health-checkup program at a large work site.

PREDICTOR

Metabolic syndrome.

OUTCOMES & MEASUREMENTS

CKD was defined as an estimated glomerular filtration rate (GFR) less than 60 mL/min/1.73 m(2). A standard Cox proportional hazards model and a time-dependent Cox model were used to calculate adjusted hazard ratios (HRs) in the CKD model.

RESULTS

During 40,616.8 person-years of follow-up, 291 incident cases of CKD developed; 787 patients (7.4%) had metabolic syndrome at baseline and 1,444 (14.4%) developed incident metabolic syndrome during follow-up. After adjustment for age, baseline GFR, gamma-glutamyltransferase level, and uric acid level, metabolic syndrome at baseline was associated with a significantly increased risk of CKD (HR, 1.99; 95% confidence interval, 1.46 to 2.73). Metabolic syndrome over time as a time-dependent variable also predicted the development of CKD (HR, 1.83; [corrected] 95% confidence interval, 1.34 to 2.49) [corrected] The relationship between metabolic syndrome and incident CKD remained significant, even after further adjustment for the homeostasis model assessment of insulin resistance, high-sensitivity C-reactive protein level, current smoking, alcohol consumption, or regular exercise. In addition, there were graded relationships between number of metabolic syndrome traits or quintile of homeostasis model assessment of insulin resistance over time as a time-dependent variable and risk of CKD. Both increased triglyceride and low high-density lipoprotein cholesterol levels among metabolic syndrome traits were associated with significantly increased risk of CKD. These results were effectively unchanged, even after additional adjustment for incident hypertension and incident diabetes.

LIMITATIONS

Estimated GFR was used instead of a directly measured GFR to define CKD.

CONCLUSION

Metabolic syndrome is an independent risk factor for the development of CKD in Korean men without hypertension or diabetes, even with changes in status of metabolic syndrome over time.

Oral estrogen therapy in postmenopausal women is associated with loss of kidney function

Women are generally protected against progressive loss of kidney function; however, this advantage seems to diminish with menopause. Because of conflicting reports on the association between use of hormone therapy and kidney function we studied 5845 women (1459 on hormone therapy and 4386 non-users) who were over 66 years of age and had at least 2 serum creatinine measurements during the 2 year study period. After adjustment for covariates, hormone use (estrogen-only, progestin-only, or both) was associated with a significant loss of estimated GFR as the primary outcome along with an increased risk of rapid loss of kidney function as the secondary outcome compared to non-users. This increased rate of loss was associated with oral but not transvaginal estrogen use. An increased cumulative dose of estrogen was also associated with a greater decline in estimated GFR. Our study shows an independent association in a dose-dependent manner of estrogen use and loss of kidney function in this elderly population.

High prevalence of chronic kidney disease in population-based patients diagnosed with type 2 diabetes in downtown Shanghai

OBJECTIVE

This study aimed to evaluate the prevalence of chronic kidney disease (CKD) and the risk factors associated with CKD among Chinese patients diagnosed with type 2 diabetes aged over 30 in downtown Shanghai and to assess the relationship between CKD and diabetic retinopathy (DR).

METHODS

We investigated 1039 Chinese patients diagnosed with type 2 diabetes aged over 30 by randomized cluster sampling in downtown Shanghai, and 1009 patients in this study were analyzed based on data integrity. Body measurements including height, weight, waist circumference and hip circumference, resting blood pressure, fasting blood measures, and urinary albumin-to-creatinine ratio (ACR), as well as the digitally stored fundus images, were investigated. Glomerular filtration rate (GFR) was estimated using the Cockcroft-Gault equation. The prevalence of CKD was calculated, and the risk factors associated with CKD were evaluated using stepwise logistic regression. The relationship between CKD and DR was evaluated using Spearman correlation and the chi-square test.

RESULTS

The following were the results found in this study: (a) The prevalence rate of CKD (Stages 1-5) was 63.9% in Chinese patients diagnosed with type 2 diabetes, 8.8% in those with CKD Stage 1, 22.3% in those with CKD Stage 2, and 32.8% in those with CKD Stages 3-5 (GFR<60 ml/min/1.73 m(2)). The prevalence of CKD increased with age. (b) CKD patients were older and had higher duration of diabetes, systolic blood pressure, urea nitrogen, uric acid, creatinine, and ACR of the first urine than those without CKD. (c) Male patients had a higher percentage of CKD Stages 3-5, and female patients had a higher percentage of CKD Stages 1-2. (d) CKD was significantly associated with duration of diabetes, older age, systolic blood pressure, and serum urea nitrogen based on logistic regression analysis. (e) Of the patients without CKD, 15.6% had DR, and of those with CKD, 27.6% had DR. The decrease in GFR was significantly correlated with DR after controlling for sex, age, and albuminuria staging.

CONCLUSION

The high prevalence of CKD observed in Chinese patients diagnosed with type 2 diabetes aged over 30 in downtown Shanghai was similar to that in Western patients, and the cause of CKD is likely to be any of the following: type 2 diabetes, IgA nephropathy, hypertension, or any combination of these. The screening program for GFR in type 2 diabetic patients should be performed even on those with normoalbuminuria. The decrease in GFR might predict the occurrence of DR among patients diagnosed with type 2 diabetes.

In chronic kidney disease staging the use of the chronicity criterion affects prognosis and the rate of progression

The Kidney Disease Outcomes Quality Initiative definition and staging of chronic kidney disease (CKD) have been adopted by most nephrologists but include a criterion of chronicity that has not been investigated. This criterion specifies that renal structural damage and/or reduction in glomerular filtration rate (GFR) should be present for periods lasting longer than 3 months. We examined the effects of changing this criterion to 6, 9, or 12 months on the prognosis and the rate of progression in population-based cohorts with CKD stages 3 and 4. A 12-month chronicity criterion significantly reduced the number of CKD patients relative to the 3-month criterion for both stages 3 and 4. For both stages, there were statistically significant differences in 5-year mortality between the 6- and 9-month cohorts. For stage 4, the 5-year cumulative incidence of renal failure significantly increased from 6 to 9 months, and the rate of change in GFR significantly decreased between the same two cohorts. The 5-year cumulative incidence of improvement in GFR lasting 1 year or more was significantly higher for the 3-month cohort than for the 12-month cohort in the stage 3 group. Hence, we suggest that the chronicity criterion is an important determinant of the characteristics of the population of patients with CKD stages 3 and 4. This may have practical consequences in both research and clinical work.

Risk of developing low glomerular filtration rate or elevated serum creatinine in a screened cohort in Okinawa, Japan

There are no known predictors of renal dysfunction, particularly for a community-based screening. We evaluated the changes in serum creatinine (SCr) and glomerular filtration rate (GFR) among screenees who participated in the screening program of the Okinawa General Health Maintenance Association both in 1983 and 1993. A total of 4,662 screenees at least 30 years of age at the 1983 screening were analyzed to examine whether they developed high SCr (>or=1.4 mg/dl for men, >or=1.2 mg/dl for women) or low GFR (<60 ml/min/1.73 m2). Overall, mean GFR (mean+/-SD) decreased slightly from 72.7+/-11.7 ml/min/1.73 m2 to 70.8+/-15.0 ml/min/1.73 m2. In 1983, the prevalences of high SCr and low GFR were 3.6% and 13.2%, respectively, and in 1993, they were 8.1% and 24.2%, respectively. Among the variables studied, dipstick proteinuria was the strongest predictor: the adjusted odds ratio (95% CI) was 1.282 (1.076-1.527, p<0.01) for high SCr and 1.215 (1.116-1.322, p<0.01) for low GFR. Dipstick proteinuria was best for detecting subjects who might develop low GFR in a screening setting. In subjects without proteinuria, systolic blood pressure was a significant predictor for low GFR (the adjusted odds ratio [95% CI] was 1.015 [1.009-1.020, p<0.01]) and for high SCr (the adjusted odds ratio [95% CI] was 1.028 [1.016-1.040, p<0.01]). In conclusion, the present study suggests that a dipstick urine test for proteinuria and both systolic and diastolic blood pressure are useful to identify those who are at risk of developing high SCr and low GFR and consequently end-stage renal disease.

Epidemiologic and clinical factors associated with chronic kidney disease among Asian Americans and Native Hawaiians

OBJECTIVE

To examine the association between key susceptibility factors and measures of chronic kidney disease in Asian American and Native Hawaiian participants enrolled in the Hawai'i site of the national Kidney Early Evaluation Program (KEEP-2) study community screening program.

DESIGN

In 2001-2003, 793 participants from five ethnic groups (Japanese, Native Hawaii an, Chinese, Filipino and Caucasian) were enrolled in the Hawai'i KEEP-2 program. Odds ratios were used as the measure of association and were computed using unconditional logistic regression. Renal susceptibility factors for chronic kidney disease were included in a multivariable model if found to be statistically significant in univariate analysis. The proportion of Hawai'i KEEP-2 study participants manifesting various clinical characteristics were compared by ethnicity with Japanese as the referent group.

RESULTS

Significant ethnic differences in the occurrence of chronic kidney disease were found, with Japanese having the lowest occurrence of chronic kidney disease (18%) and Native Hawaiians the highest (40%). Within each ethnic group, the occurrence of chronic kidney disease was associated with a different ethnic-specific clustering of susceptibility factors. Hypertension was associated with chronic kidney disease among four of the five ethnic groups: Japanese, Caucasian, Native Hawaiian and Filipino. Overweight was associated with a decreased occurrence of chronic kidney disease among Caucasians, while diabetes and lower educational attainment were associated with increased occurrence of chronic kidney disease among Native Hawaiians. For Filipinos, diabetes and age 65 years and older were both associated with an increased occurrence for chronic kidney disease while lower educational attainment was associated with a reduced occurrence of chronic kidney disease. Among Chinese, no factors were significantly associated with chronic kidney disease, although trends for all factors paralleled those of the overall study group.

CONCLUSIONS

The occurrence of chronic kidney disease in the Hawai'i KEEP-2 study was nearly fourfold greater compared with the general US population. The clustering of susceptibility factors for chronic kidney disease occurrence was found to differ for all five ethnic groups.

Changes in the Demographics and Prevalence of Chronic Kidney Disease in Okinawa, Japan (1993 to 2003)

To compare the risk factor demographics and the prevalence of chronic kidney disease (CKD), we analyzed two databases from the 1993 (N=143,948) and 2003 (N=154,019) mass screenings in Okinawa, Japan (Okinawa General Health Maintenance Association registry). We estimated the glomerular filtration rate (GFR) using serum creatinine (SCr) levels. SCr was measured by the modified Jaffe method in 1993 and by enzyme assay in 2003; the relation between the two methods was: SCr (Jaffe) = 0.194 + 1.079 x SCr (enzyme). CKD prevalence was compared using the estimated GFR calculated by the abbreviated Modification of Diet in Renal Disease (MDRD) equation. SCr was measured in 66.2% (1993) and 69.8% (2003) of the total screenees. Proteinuria was present in 3.4% (1993) and 4.3% (2003) of the total screened population, respectively. The prevalence of CKD (GFR<60 ml/min/1.73 m(2)) was similar between the two databases, being 15.7% in 1993 and 15.1% in 2003. However, the demographics of the CKD risk factors changed during the study period. The mean level of systolic blood pressure decreased, whereas the prevalence of obesity and the mean levels of serum cholesterol and fasting plasma glucose increased. In 2003, the estimated prevalence of metabolic syndrome in the general population of Japan calculated using the modified National Cholesterol Education Program (NCEP) criteria was 19.1%. The prevalence of CKD was significantly associated with that of metabolic syndrome: the age- and sex-adjusted odds ratio was 1.332 (95% confidence interval [CI], 1.277-1.389; p<0.0001). In conclusion, the demographics of the participants of the general screenings in Okinawa, Japan differed between the 1993 and 2003 screenings, but the prevalence of CKD seemed to be similar, or at least did not increase substantially, between the two databases.

Exploring Secular Trends in the Likelihood of Receiving Treatment for End-Stage Renal Disease

There is a limited understanding of the forces that drive the steady rise in the number of patients who receive treatment for ESRD. It was hypothesized that this is not simply due to increasing prevalence of chronic kidney disease (CKD) or changes in renal failure risk factors in the population from which ESRD cases develop. A noncurrent cohort study was conducted to quantify the change over time (per year) in the likelihood of receiving ESRD therapy in a cohort of 320,252 individuals who volunteered for health check-ups between 1964 and 1985. Initiation of ESRD treatment was ascertained using the US Renal Data System registry through 2000. A total of 1471 cases of ESRD were observed during 8,347,955 person-years of observation, with ESRD cases developing between 1973 and 2000. In unadjusted Cox proportional hazards analysis, individuals who were examined later in time had an 8% per year higher risk for progressing to receive treatment for ESRD (relative risk 1.08; 95% confidence interval 1.05 to 1.11). This temporal trend in risk for future ESRD associated with year of cohort entry (baseline examination) was not explained by increases over time in the prevalence of CKD or risk factors for renal failure. After adjustment for age, gender, race, diabetes, BP, body mass index, education level, smoking status, history of myocardial infarction, serum cholesterol, proteinuria, hematuria, and serum creatinine level, there remained an 8% per year increase in risk (relative risk 1.08; 95% confidence interval 1.06 to 1.11). Among individuals who were examined from the 1960s through the 1980s, those who were examined later were more likely to receive treatment for ESRD. This trend was not accounted for by increasing prevalence of baseline CKD or risk factors for renal failure. These findings should spur further research into other forces that drive the rise in treated ESRD.

gamma-Glutamyltransferase as a predictor of chronic kidney disease in nonhypertensive and nondiabetic Korean men

BACKGROUND

Little research has been done to examine whether gamma-glutamyltransferase (GGT) is prospectively associated with the development of chronic kidney disease (CKD). We performed a prospective study to examine the association between GGT and the risk for the development of CKD.

METHODS

The study cohort included a total of 10 337 healthy males with normal baseline kidney functions and no proteinuria. Participants were workers in a semiconductor manufacturing company and its 13 affiliates. CKD was defined as either the presence of proteinuria or a glomerular filtration rate (GFR) of < 60 mL x min(-1) x (1.73(2))(-1). Cox proportional hazards models were used to calculate the adjusted hazard ratios in separate models for CKD.

RESULTS

During a follow-up period of 25,774.4 person-years, 366 men developed CKD. After adjustments were made for age, baseline GFR, triglyceride, and HDL-C, the risk for CKD increased with an increasing quartile of serum GGT (p for trend <0.001). The top one fourth of serum GGT vs the bottom one fourth of relative risks for CKD was 1.90 (95% confidence interval, 1.37-2.63). These associations were also apparent in participants who consumed < or = 20 g/day of alcohol and those with normal weight, with values of alanine aminotransferase within reference intervals, or with C-reactive protein < 3.0 mg/L, and participants without metabolic syndrome.

CONCLUSIONS

Our findings, which were obtained from a large work-site cohort and excluded individuals with diabetes and hypertension, indicated that serum GGT may be an early predictor for the development of CKD, independent of baseline confounding factors.

Sex differences and the role of sex steroids in renal injury

PURPOSE

There is growing evidence that significant sex differences exist in the response of the kidney to injury. In this review we explored the cumulative clinical knowledge and experimental evidence of this phenomenon.

MATERIALS AND METHODS

The current clinical evidence of increased male susceptibility to acute and chronic renal injury, and experimental data elucidating potential mechanisms of this phenomenon were reviewed.

RESULTS

Renal damage induced by nephron reduction, patient age and renal ischemia is tolerated differently by the sexes. Sex differences in disease susceptibility have historically been attributed to the protective effects of estrogen but recent evidence suggests that male hormones also have an important role in these differences. Vascular mediators, such as endothelin, nitric oxide and angiotensin II, appear to be influenced by sex and sex steroids. Additionally, inflammatory mediators, such as transforming growth factor-beta1, tumor necrosis factor-alpha and p38 mitogen activating protein kinase, similarly show differential expression and activity based on sex and the presence of sex steroids. These mediators have a significant impact on the kidney response to inflammation and injury.

CONCLUSIONS

Greater understanding of the specific role of sex steroids in renal injury may provide new therapeutic strategies to protect against inflammatory injury and renal damage in the future.

Evaluation of GFR Estimating Equations in the General Community: Implications for Screening

The Kidney Disease Outcomes Quality Initiative has recommended the use of GFR estimating equations to detect silent chronic kidney disease (CKD) in the community. The benefit of general reporting of CKD must be balanced with the harm of mislabeling people who do not have CKD. The popular Cockcroft-Gault (CG) and Modification of Diet in Renal Disease (MDRD) GFR estimating equations were compared with the recently devised Rule equation in a representative community population sample (2166) divided into subsamples with (385) and without (1781) previous renal impairment. The prevalence of CKD was CG > MDRD >> Rule estimates. The magnitude of difference in prevalence of CKD as detected by the MDRD and CG versus the Rule equation increases markedly when the subsamples with (30.8 and 29.7 versus 17.5%) and without (12 and 11.3 versus 3.0%) previous kidney impairment are compared. General demographic and potential or known risk factors were used in a logistic regression model to assess the association with CKD. The MDRD estimates note female gender (odds ratio 2.19; 95% confidence interval 1.63 to 2.95) and both MDRD and the Rule equations identify hypertension and diabetes as significant CKD risk factors. All estimating equations identify age to be associated with CKD. The annualized serial decline in GFR was CG > MDRD > Rule estimates. Only the Rule GFR estimates detected a greater decline in renal impaired versus unimpaired populations. The calibrated Rule equation seems to perform better than CG and MDRD (CKD 3 versus 11.3 to 12%) but lacks validation against gold standards for community-based screening.

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

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

Chronic kidney disease: A European perspective

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

Prevalence of chronic kidney disease based on estimated glomerular filtration rate and proteinuria in Icelandic adults

BACKGROUND

The purpose of this study was to compare three different equations to calculate estimated glomerular filtration rate (eGFR) based on serum creatinine (SCr) and to estimate the prevalence of chronic kidney disease (CKD) in the Icelandic population.

METHODS

This was a cross-sectional study using data from the Reykjavik Heart Study. GFR was estimated with three equations: Equation I was based on 1/SCr; Equation II based on the Cockcroft-Gault equation; and Equation III was the modified MDRD equation. The eGFR calculated with Equation III and proteinuria were used to estimate the prevalence of CKD. The prevalence was age-standardized to the truncated world population. We used chi-square and ANCOVA to compare the group with low eGFR to age-matched controls.

RESULTS

The subjects consisted of 9229 males and 10,027 females, aged 33-85 years. The equations performed very differently. Equation I showed women with higher eGFR than men and little change with age. Equation II showed men with higher eGFR than women and marked decline in eGFR with age. Equation III was similar to Equation II but the decline in eGFR with age was not as great. Regardless of the equation used, most subjects (63.7-80.7%) had an eGFR in the range of 60-89 ml/min/1.73 m2. Using Equation III, age-standardized prevalence of low eGFR for the population aged 35-80+ years was estimated to be 4.7 and 11.6% for men and women, respectively. The proportion of subjects with eGFR <60 ml/min/1.73 m2 increased with advancing age. An additional 2.39% of men and 0.89% of women had proteinuria. The prevalence of renal and cardiovascular risk factors including proteinuria, hypertension, lipid abnormalities and markers of inflammation was higher among those with low eGFR than age-matched controls.

CONCLUSIONS

GFR estimates and the prevalence of CKD are dependent on the equation used to calculate eGFR. Unexpectedly, a low proportion of the Icelandic population had normal kidney function according to the eGFR regardless of the equation used. These equations may not be useful in epidemiological research.

The influence of obesity on the development and survival outcomes of chronic kidney disease

The prevalence of obesity, defined as a body mass index (BMI) greater than 30 kg/m2 , has more than doubled in many Western countries over the past 2 decades and has become a major public health challenge. This epidemic of obesity in developed countries has been matched closely by alarming increases in the incidence of diabetes mellitus, hypertension, chronic kidney disease (CKD), and cardiovascular disease. However, the exact role that increased body size plays in the development of nephropathy and its subsequent contribution to cardiovascular morbidity and mortality remain unclear. For example, whether obesity per se is a risk factor for CKD independent of diabetes mellitus and hypertension is uncertain. Moreover, in patients with end-stage kidney disease, strong evidence suggests that obesity may paradoxically enhance patient survival. This review will focus on the evidence for obesity as an independent risk factor for the development and progression of CKD and as a paradoxical survival factor in patients with end-stage kidney failure. Possible mechanisms underlying these observed associations will be discussed.

Body mass index and the risk of development of end-stage renal disease in a screened cohort

BACKGROUND

Obesity is associated with proteinuria and could be a risk factor for end-stage renal disease (ESRD). However, few studies have examined the significance of body mass index (BMI) as a risk factor for the development of ESRD in the general population.

METHODS

We examined the relationship between BMI and the development of ESRD using data from a 1983 community-based screening in Okinawa, Japan. Screenees who developed ESRD by the end of 2000 were identified through the Okinawa Dialysis Study registry. BMI data were available for 100,753 screenees (47,504 men and 53,249 women) aged >/=20 years. The cumulative incidence of ESRD was analyzed according to the quartile of BMI: <21.0, 21.0 to 23.1, 23.2 to 25.4, and >/=25.5 kg/m(2).

RESULTS

The mean (SD) BMI of the screenees was 23.4 (3.3) kg/m(2) (range 7.9 to 59.1 kg/m(2)); the mean was 23.4 kg/m(2) for both men and women. During the follow-up period, 404 screenees (232 men and 172 women) developed ESRD. The cumulative incidences of ESRD per 1000 screenees were, from the lowest to highest BMI quartile, 2.48, 3.79, 3.86, and 5.81. The odds ratio (95% CI) of BMI for developing ESRD, after adjustment for age, sex, systolic blood pressure, and proteinuria, was 1.273 (1.121-1.446, P= 0.0002) for men and 0.950 (0.825-1.094, not significant) for women.

CONCLUSION

We found that BMI was associated with an increased risk of the development of ESRD in men in the general population in Okinawa. The maintenance of optimal body weight may reduce the risk of ESRD.

Atherosclerotic risk factors and renal function in the elderly: the role of hyperfibrinogenaemia and smoking. Results from the Italian Longitudinal Study on Ageing (ILSA)

BACKGROUND

We examined associations between cardiovascular diseases and risk factors with pathological levels of and significant changes in serum creatinine (SCr) in a large prevalence phase and longitudinal phase community-based sample of an elderly Italian population (ILSA Study) showing no clinical evidence of renal impairment.

METHODS

The prevalence phase was performed on 2981 subjects, aged 65-84 years, who were negative for renal diseases, had available SCr values and had complete clinical information on their cardiovascular risk factors. Of these, 371 were considered 'healthy' since they were not affected by cardiovascular diseases or diabetes, whereas 2610 tested positive for cardiovascular diseases and were considered 'diseased'. The sex-specific 95th percentiles for SCr (cut-off points) were calculated in the healthy reference sample to define the upper limit for normal SCr values. The distribution and prevalence of diseased subjects having values over the cut-off point values were then estimated. Associations between values over the cut-off point levels and pathological or clinical conditions were analysed from the diseased sample. The longitudinal phase was carried out on 1906 subjects who had SCr values and sufficient clinical information for our investigation. The incidence of an increase of >26.5 micromol/l of SCr was evaluated in the longitudinal cohort.

RESULTS

In healthy subjects, the 95th SCr percentiles (cut-off points) were 123.8 micromol/l in men and 97.2 micromol/l in women. In diseased subjects, the prevalence of SCr values over the cut-off point was 4.6% in men and 9.3% in women. In logistic regression analysis, independent variables that correlated with over the cut-off point SCr values were: age >75 years [odds ratio (OR) = 2.2; 95% confidence interval (CI) = 1.5-3.4], atherosclerosis of the lower limbs (OR = 2.0; 95% CI = 1.2-3.3), cerebrovascular disease (OR = 1.9; 95% CI = 1.2-3.3), angiotensin-converting enzyme (ACE) inhibitor medication (OR = 1.8; 95% CI = 1.2-2.8), fibrinogen values >3.5 g/l (OR = 1.2; 95% CI = 1.2-2.7) and diuretic treatment (OR = 1.6; 95% CI = 1.1-2.4). After a mean 3.6 years follow-up, multiple logistic regression analysis showed that risk factors for pathological loss of renal function (rise of SCr >26.5 micromol/l) were: current smokers >20 cigarettes/day (OR = 2.3; 95% CI = 1.0-5.3), fibrinogen values >3.5 g/l (OR = 2.2; 95% CI = 1.6-3.3), diabetes (OR = 1.8; 95% CI = 1.1-2.8), age >75 years (OR = 1.7; 95% CI = 1.2-2.4) and isolated systolic hypertension (OR = 1.6; 95% CI = 1.0-2.6). The loss of renal function examined during the longitudinal phase appeared to be independent of baseline SCr levels.

CONCLUSION

The present prevalence and longitudinal studies show that age-associated decline in renal function in elderly subjects is associated with co-existing cardiovascular diseases and risk factors. These observations should be incorporated into clinical practice since some of the factors detrimental to kidney function, such as smoking, altered fibrinogen levels and elevated systolic blood pressure, can be prevented and/or modified when appropriate measures are taken.