Hae Ryong Yun

High dietary phosphorus density is a risk factor for incident chronic kidney disease development in diabetic subjects: a community-based prospective cohort study

Background: High serum phosphorus concentrations are associated with an increased risk of cardiovascular disease and progression of chronic kidney disease (CKD). However, the relation between dietary phosphorus intake and CKD development has not been well evaluated.Objective: In this study, we investigated the impact of dietary phosphorus density on the development of incident CKD in a cohort of subjects with normal renal function.Design: Data were retrieved from the Korean Genome and Epidemiology Study, a prospective community-based cohort study. The study cohort consisted of subjects aged 40-69 y, who were followed up biennially from 2001 to 2014. A total of 873 subjects with diabetes mellitus (DM) and 5846 subjects without DM (non-DM) were included in the final analysis. The primary endpoint was incident CKD, defined as a composite of estimated glomerular filtration rate <60 mL · min-1 · 1.73 m-2 and/or the development of proteinuria.Results: In the DM and non-DM groups, the mean ages of the participants were 55.6 ± 8.7 and 51.4 ± 8.6 y, the numbers of male subjects were 454 (52.0%) and 2784 (47.6%), and the mean estimated glomerular filtration rates were 91.6 ± 14.0 and 94.5 ± 14.0 mL · min-1 · 1.73 m-2, respectively. The mean values of dietary phosphorus density, defined as the ratio of a single-day dietary phosphorus amount to the total daily calorie intake, were 0.51 ± 0.08 mg/kcal in the DM group and 0.51 ± 0.07 mg/kcal in the non-DM group. During the follow-up, CKD newly developed in 283 (32.4%) and 792 subjects (13.5%) in the DM and non-DM groups, respectively. When the subjects were divided into quartiles according to the dietary phosphorus density in each group, the highest quartile was significantly associated with the development of incident CKD by multiple Cox proportional hazard analysis in the DM group (P = 0.02) but not in the non-DM group (P = 0.72).Conclusions: High dietary phosphorus density is associated with an increased risk of CKD development in DM patients with normal renal function. The causality in this association needs to be tested in a randomized controlled trial.

Warfarin Use in Patients with Atrial Fibrillation Undergoing Hemodialysis: A Nationwide Population-Based Study

Background and Purpose— The aim of this study is to elucidate the effects of warfarin use in patients with atrial fibrillation undergoing dialysis using a population-based Korean registry. Methods— Data were extracted from the Health Insurance Review and Assessment Service, which is a nationwide, mandatory social insurance database of all Korean citizens enrolled in the National Health Information Service between 2009 and 2013. Thromboembolic and hemorrhagic outcomes were analyzed according to warfarin use. Overall and propensity score–matched cohorts were analyzed by Cox proportional hazards models. Results— Among 9974 hemodialysis patients with atrial fibrillation, the mean age was 66.6±12.2 years, 5806 (58.2%) were men, and 2921 (29.3%) used warfarin. After propensity score matching to adjust for all described baseline differences, 5548 subjects remained, and differences in baseline variables were distributed equally between warfarin users and nonusers. During a mean follow-up duration of 15.9±11.1 months, ischemic and hemorrhagic stroke occurred in 678 (6.8%) and 227 (2.3%) patients, respectively. In a multiple Cox model, warfarin use was significantly associated with an increased risk of hemorrhagic stroke (hazard ratio, 1.44; 95% confidence interval, 1.09–1.91; P=0.010) in the overall cohort. Furthermore, a significant relationship between warfarin use and hemorrhagic stroke was found in propensity-matched subjects (hazard ratio, 1.56; 95% confidence interval, 1.10–2.22; P=0.013). However, the ratios for ischemic stroke were not significantly different in either the propensity-matched (hazard ratio, 0.95; 95% confidence interval, 0.78–1.15; P=0.569) or overall cohort (hazard ratio, 1.06; 95% confidence interval, 0.90–1.26; P=0.470). Conclusions— Our findings suggest that warfarin should be used carefully in hemodialysis patients, given the higher risk of hemorrhagic events and the lack of ability to prevent thromboembolic complications.

High and low sodium intakes are associated with incident chronic kidney disease in patients with normal renal function and hypertension

The association between salt intake and renal outcome in subjects with preserved kidney function remains unclear. Here we evaluated the effect of sodium intake on the development of chronic kidney disease (CKD) in a prospective cohort of people with normal renal function. Data were obtained from the Korean Genome and Epidemiology Study, a prospective community-based cohort study while sodium intake was estimated by a 24-hour dietary recall Food Frequency Questionnaire. A total of 3,106 individuals with and 4,871 patients without hypertension were analyzed with a primary end point of CKD development [a composite of estimated glomerular filtration rate (eGFR) under 60 mL/min/1.73 m2 and/or development of proteinuria during follow-up]. The median ages were 55 and 47 years, the proportions of males 50.9% and 46.3%, and the median eGFR 92 and 96 mL/min/1.73 m2 in individuals with and without hypertension, respectively. During a median follow-up of 123 months in individuals with hypertension and 140 months in those without hypertension, CKD developed in 27.8% and 16.5%, respectively. After adjusting for confounders, multiple Cox models indicated that the risk of CKD development was significantly higher in people with hypertension who consumed less than 2.08 g/day or over 4.03 g/day sodium than in those who consumed between 2.93-4.03 g/day sodium. However, there was no significant difference in the incident CKD risk among each quartile of people without hypertension. Thus, both high and low sodium intakes were associated with increased risk for CKD, but this relationship was only observed in people with hypertension.

Vitamin D deficiency is significantly associated with depression in patients with chronic kidney disease

Background Depression is reported to be the most common psychological problem in patients with chronic kidney disease (CKD). Several studies have reported that lower levels of serum vitamin D are significantly associated with depression. Both vitamin D deficiency and depression are prevalent in patients with CKD, yet the relationship between these two factors remains poorly understood. This study aimed to investigate the association between vitamin D levels and depression among CKD patients. Methods Totally, 21,257 individuals who participated in the Korean National Health and Nutrition Examination Survey (KNHANES V, VI) from 2010–2014 were screened for the study; 533 CKD patients were included. Vitamin D deficiency was defined as serum 25-hydroxyvitamin D3 [25(OH)D3] ≤10 ng/mL. Patients were divided into vitamin D deficient or sufficient groups. Depression was screened for using the Korean version of the WHO Composite International Diagnostic Interview-Short Form. The association between vitamin D deficiency and depression was evaluated by multivariate logistic regression analysis. Results The mean participant age was 70.1±9.4 years; 262 patients (49.2%) were male. The median 25(OH)D3 level was 19.1±6.9 ng/mL. The prevalence of depression was higher in CKD patients than in the general population (14.3 vs. 11.1%, P = 0.03). Additionally, the prevalence of depression was significantly higher in CKD patients with (vs. without) vitamin D deficiency (32.5% vs. 50.0%, P<0.001). Multivariate logistic regression analysis showed that vitamin D deficiency was a significant independent predictor of depression after adjusting for confounding factors (adjusted odds ratio, 6.15; 95% confidence interval, 2.02–8.75; P = 0.001). Conclusion Depression was highly prevalent in CKD patients, in whom vitamin D deficiency was a significant independent predictor of depression. Therefore, management of vitamin D deficiency might help prevent depression in CKD patients.

Phosphate is a potential biomarker of disease severity and predicts adverse outcomes in acute kidney injury patients undergoing continuous renal replacement therapy

Hyperphosphatemia is associated with mortality in patients with chronic kidney disease, and is common in critically ill patients with acute kidney injury (AKI); however, its clinical implication in these patients is unknown. We conducted an observational study in 1144 patients (mean age, 63.2 years; male, 705 [61.6%]) with AKI who received continuous renal replacement therapy (CRRT) between January 2009 and September 2016. Phosphate levels were measured before (0 h) and 24 h after CRRT initiation. We assessed disease severity using various clinical parameters. Phosphate at 0 h positively correlated with the Acute Physiology and Chronic Health Evaluation II (APACHE II; P < 0.001) and Sequential Organ Failure Assessment (SOFA; P < 0.001) scores, and inversely with mean arterial pressure (MAP; P = 0.02) and urine output (UO; P = 0.01). In a fully adjusted linear regression analysis for age, sex, Charlson comorbidity index (CCI), MAP, and estimated glomerular filtration rate (eGFR), higher 0 h phosphate level was significantly associated with high APACHE II (P < 0.001) and SOFA (P = 0.04) scores, suggesting that phosphate represents disease severity. A multivariable Cox model also showed that hyperphosphatemia was significantly associated with increased 28-day (HR 1.05, 95% CI 1.02–1.08, P = 0.001) and 90-day (HR 1.05, 95% CI 1.02–1.08, P = 0.001) mortality. Furthermore, patients with increased phosphate level during 24 h were at higher risk of death than those with stable or decreased phosphate levels. Finally, c-statistics significantly increased when phosphate was added to a model that included age, sex, CCI, body mass index, eGFR, MAP, hemoglobin, serum albumin, C-reactive protein, and APACHE II score. This study shows that phosphate is a potential biomarker that can reflect disease severity and predict mortality in critically ill patients receiving CRRT.

Extracellular Fluid Excess Is Significantly Associated With Coronary Artery Calcification in Patients With Chronic Kidney Disease

Background Extracellular fluid (ECF) excess is an independent predictor of cardiovascular morbidity in patients undergoing dialysis. This study aimed to investigate the relationship between ECF status, which is affected by renal function, and coronary artery calcification (CAC), which is a marker of cardiovascular disease, in patients with chronic kidney disease (CKD). Methods and Results A total of 1741 patients at all stages of pre‐dialysis CKD from the prospective observational cohort of CMERC‐HI (Cardiovascular and Metabolic Disease Etiology Research Center‐High Risk) were analyzed for the association between ECF status and CAC. ECF status was defined as extracellular water‐to‐total body water ratio (ECW/TBW) measured using bioelectrical impedance analysis. ECF excess was defined as ECW/TBW ≥0.390 or ≥0.400 depending on its severity. To define CAC, Agatston coronary artery calcium scores were measured. A total coronary artery calcium score of ≥400 was defined as CAC. The CKD stages were defined according to estimated glomerular filtration rate calculated using the CKD Epidemiology Collaboration equation. ECW/TBW and the proportion of ECF excess increased with progressing CKD stages. Multivariable logistic regression analyses showed that ECW/TBW was independently associated with CAC (per 0.01 increase of ECW/TBW, odds ratio 1.168, 95% confidence interval, 1.079–1.264, P<0.001). The adjusted R 2 for predicting higher coronary artery calcium scores and CAC significantly improved after ECW/TBW was added to conventional factors. This association was further confirmed by net reclassification and integrated discriminant improvements, sensitivity analysis, and subgroup analysis. Conclusions ECF status is independently associated with a high risk of CAC in patients with CKD. Study Registration URL: https://www.clinicaltrials.gov/. Unique identifier: NCT02003781.

THYROID HORMONE REPLACEMENT REDUCES the RISK of CARDIOVASCULAR DISEASES in DIABETIC NEPHROPATHY PATIENTS with SUBCLINICAL HYPOTHYROIDISM

OBJECTIVEnPatients with diabetic nephropathy (DMN) have an increased risk of cardiovascular disease (CVD). However, strategies to reduce this risk are limited. Thyroid hormone replacement therapy (THRT) in patients with hypothyroidism has been shown to reduce several surrogate markers of CVD. Therefore, we performed a study to determine if THRT would reduce CVD risk in patients with subclinical hypothyroidism (SCH) and DMN.nnnMETHODSnThis was a retrospective, nonrandomized study of patients with type 2 diabetes, DMN, and SCH. Those with known thyroid dysfunction or taking THRT at baseline were excluded. Patients receiving THRT for at least 180 days were included in the THRT group, while the remaining patients were assigned to the non-THRT group. The primary outcome was CVD events, which included coronary syndrome, cerebrovascular events, and peripheral artery diseases.nnnRESULTSnAmong the 257 patients, 83 (32.3%) were in the THRT group. The mean ages were 62.7 ± 12.3 and 66.8 ± 12.4 years in the THRT and non-THRT groups, respectively. The corresponding numbers of male patients were 32 (40.0%) and 94 (53.1%). During a mean follow-up of 38.0 ± 29.2 months, 98 CVD events were observed. Acute coronary syndrome and cerebrovascular event prevalence rates were lower in the THRT group than the non-THRT group, but there was no difference for peripheral artery diseases. Multivariate Cox analysis revealed that THRT was independently associated with a decreased CVD event risk.nnnCONCLUSIONnTHRT may decrease the risk of CVD in DMN patients with SCH. Randomized trials are needed to verify this finding.nnnABBREVIATIONSnCV = cardiovascular DMN = diabetic nephropathy eGFR = estimated glomerular filtration rate fT4 = free thyroxine HbA1c = glycosylated hemoglobin HR = hazard ratio hs-CRP = high-sensitivity C-reactive protein LDL-C = low-density lipoprotein cholesterol SCH = subclinical hypothyroidism T2DM = type 2 diabetes THRT = thyroid hormone replacement therapy TSH = thyroid-stimulating hormone.

High serum adiponectin is associated with anemia development in chronic kidney disease: The results from the KNOW-CKD study

Background Adiponectin is an adipokine secreted by adipocytes. A low adiponectin level is a significant risk factor of diabetes mellitus and cardiovascular disease. Recent studies have shown that adiponectin is negatively associated with hematopoiesis and predicts the development of anemia in the general population. In chronic kidney disease (CKD) patients, circulating adiponectin level is paradoxically elevated and the role of adiponectin is complex. Therefore, we evaluated the relationship between adiponectin and anemia in these patients. Methods This prospective longitudinal study included 2113 patients from the KNOW‐CKD study (KoreaN cohort study for Outcome in patients With CKD), after excluding 125 without data on adiponectin levels. Hemoglobin levels were measured yearly during a mean follow‐up period of 23.7 months. Anemia was defined as hemoglobin levels of <13.0 and 12.0 g/dL for men and women, respectively. Results Mean patient age was 53.6 ± 12.2 years, and 1289 (61%) were men. The mean estimated glomerular filtration rate (eGFR) was 50.4 ± 30.2 mL min−1 1.73 m−2. Serum adiponectin level was inversely associated with body mass index, eGFR, log‐transformed C‐reactive protein, and positively with Charlson comorbidity index, urine protein to creatinine ratio, and high density lipoprotein cholesterol. In addition, serum adiponectin level was also negatively correlated with hemoglobin level and reticulocyte production index in both men and women. In multivariable linear regression analysis after adjustment of multiple confounders, adiponectin was negatively associated with hemoglobin (men, &bgr; = −0.219, P < .001; women, &bgr; = −0.09, P = .025). Among 1227 patients without anemia at baseline, 307 newly developed anemia during the follow‐up period. In multivariable Cox regression analysis after adjustment of confounders, high adiponectin level was significantly associated with an increased risk of incident anemia (per 1 &mgr;g/mL increase, hazard ratio, 1.02; 95% confidence interval 1.01–1.04; P = .001). Conclusions A high serum adiponectin level is independently associated with a low hemoglobin level and predicts the development of anemia in patients with CKD. These findings reveal the potential role of adiponectin in CKD‐related anemia. HighlightsAdiponectin is negatively associated with hemoglobin in general population.The role of adiponectin is complex in patients with chronic kidney disease.Serum adiponectin is a predictive marker of anemia development in patients with chronic kidney disease.

The impact of disease severity on paradoxical association between body mass index and mortality in patients with acute kidney injury undergoing continuous renal replacement therapy

BackgroundAssociation between high body mass index (BMI) and survival benefit is confounded by comorbid conditions such as nutritional status and inflammation. Patients with acute kidney injury (AKI), particularly those receiving continuous renal replacement therapy (CRRT), are highly catabolic and more susceptible to loss of energy. Herein, we evaluated whether disease severity can modify the relationship between BMI and mortality.MethodsWe conducted an observational study in 1144 patients who had undergone CRRT owing to various causes of AKI between 2010 and 2014. Patients were categorized into four groups; underweight (<u200918.5xa0kg/m2), normal (18.5–22.99xa0kg/m2), overweight (23.0–24.99xa0kg/m2), and obesity (≥25xa0kg/m2) according to BMI classification by the Committee of Clinical Practice Guidelines and Korean Society for the Study of Obesity. More severe disease was defined as sepsis-related organ failure assessment (SOFA) score of ≥ a median value of 12. The study endpoint was death that occurred within 30xa0days after the initiation of CRRT.ResultsThe mean age was 63.2xa0years and 439 (38.4%) were females. The median BMI was 23.6 (20.9–26.2) kg/m2. The obese group were younger and higher SOFA score than normal BMI group. In a multivariable Cox regression analysis, we found a significant interaction between BMI and SOFA score (Pu2009<u2009xa00.001). Furthermore, obese patients were significantly associated with a lower risk of death as compared to normal BMI group after adjusting confounding factors [hazard ratio (HR), 0.81; 95% confidence interval (CI), 0.68–0.97; Pu2009=u20090.03]. This association was only evident among patients with high severity (HR, 0.61; 95% CI, 0.48–0.76, Pu2009<u2009xa00.001). In contrast, in those with low severity, survival benefit of high BMI was lost, whereas underweight was associated with an increased risk of death (HR, 1.74; 95% CI, 1.16–2.60; Pu2009=u20090.007).ConclusionIn this study, we found a survival benefit of high BMI in AKI patients undergoing CRRT, particularly in those with more disease severity; the effect was not observed in those with less disease severity.

Characteristics and Clinical Outcomes of End-Stage Renal Disease Patients on Peritoneal Dialysis for Over 15 Years: A Single-Center Experience

Background: Maintaining peritoneal dialysis (PD) for a long time is problematic owing to a number of factors. This study aimed to clarify the characteristics and examine the clinical outcomes of patients who received PD as a long-term dialysis modality. Methods: All end-stage renal disease (ESRD) patients who initiated PD at Yonsei University Health System between 1987 and 2000 were screened. Patients who maintained PD for over 15 years were classified as the long-term PD group and those who were treated with PD for less than 5 years were included in the short-term PD group. Demographic and biochemical data and clinical outcomes were compared between the groups. Independent factors associated with long-term PD maintenance were ascertained using multivariate logistic regression analysis. Results: Among 1,116 study patients, 87 (7.8%) were included in the long-term group and 293 (26.3%) were included in the short-term group. In the long-term group, the mean patient age at PD initiation was 39.6 ± 11.5 years, 35 patients (40.2%) were male, and the mean PD duration was 205.3 ± 32.7 months. Patients were younger, body weight was lower, the proportion of patients with diabetes or cardiovascular diseases was lower, and the proportion of low to low-average transporters was higher in the long-term group than in the short-term group (p < 0.001). Multiple logistic regression analysis revealed that age, body mass index (BMI), serum creatinine, type of PD solution, and diabetes were significant independent factors associated with long-term PD maintenance. Conclusion: Peritoneal dialysis can be considered as a long-term renal replacement therapy option, especially in non-diabetic, not overweight, and young ESRD patients.