Recent studies have reported that loss of bone mass is associated with renal function decline and increased fracture risks in chronic kidney disease (CKD) patients. The aim of this study was to investigate the best estimated glomerular filtration rate (eGFR) equation to detect osteopenia in CKD patients.

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common hereditary kidney diseases that frequently result in renal failure. In this cross-sectional observational cohort study, we evaluated urinary angiotensinogen (AGT) as a potential biomarker to assess renal function in ADPKD.

Serum creatinine (Cr) and cystatin C (CysC) can both be used to estimate glomerular filtration rate (eGFRCr and eGFRCysC). However, certain conditions may cause discrepancies between eGFR trends from Cr and CysC, and these remain undetermined in patients with chronic kidney disease (CKD).

Decreased kidney function is an important risk factor for cardiovascular disease (CVD). However, assessing risk of CVD may be difficult when there is a gap between creatinine- and cystatin C-based estimated glomerular filtration rate (eGFR). We studied the association of the difference in eGFRs with major adverse cardiovascular events (MACE) in patients with chronic kidney disease (CKD).

Anemia is a common complication among patients with chronic kidney disease (CKD), and it is associated with unfavorable clinical outcomes in patients with CKD independent of the estimated glomerular filtration rate (eGFR). We assessed the association of the urinary albumin-to-creatinine ratio (ACR) and eGFR with anemia in CKD patients.

High serum adiponectin is noted in several conditions of chronic kidney disease (CKD) and is a predictor for end stage renal disease. However, the relationship between adiponectin level and renal disease progression is not well established. This study aimed to determine the relationship between serum adiponectin levels and CKD progression. This prospective longitudinal study included 2238 patients from the Korean Cohort Study for Outcomes in Patients with Chronic Kidney Disease. Patients were divided into quartiles according to their serum adiponectin level. Composite renal outcome was defined as one or more of the following: initiation of dialysis or transplantation, a two-fold increase in baseline serum creatinine levels, or a 50% decline in the estimated glomerular filtration rate (eGFR) during the follow-up period. A cox proportional hazard ratio model was applied to analyze the relationship between composite renal outcome and serum adiponectin levels. Serum adiponectin level was inversely associated with eGFR (p < 0.001) and positively correlated with urine albumin-creatinine ratio. The highest quartile of serum adiponectin was associated with an increased risk of adverse renal outomes (HR, 1.39; 95%CI, 1.05-1.84; p=0.021). On time-dependent receiver operating characteristic curve analysis, predictive ability of adiponectin for renal outcomes disappeared after adjusting for eGFR. Therefore, serum adiponectin may be a biomarker of renal dysfunction rather than a true risk factor in CKD progression.

Studies on the effect of dietary protein intake (DPI) on chronic kidney disease (CKD) progression, along with the potential hazard of protein-energy wasting (PEW), are scarce. We evaluated the association between DPI and kidney function both cross-sectionally and longitudinally, particularly emphasizing the role of PEW, in a large-scale, observational, multicenter, prospective study. We enrolled 1572 patients with non-dialysis CKD between 2011 and 2016. CKD progression was defined by a >50% estimated glomerular filtration rate (eGFR) decrease, serum creatinine doubling, or dialysis initiation. A Cox proportional hazard regression analysis was conducted. During the mean follow-up period of 41.6 months, CKD progression was observed in 296 patients. Cross-sectionally, increased DPI was significantly associated with increased eGFR. Similarly, increased DPI tertile was significantly associated with increased renal survival in a Kaplan⁻Meier curve analysis. In the multivariate Cox proportional hazard regression analysis, the statistical significance of the DPI tertile group in CKD progression was lost when PEW-related variables were added as covariates. In penalized spline curve analysis, the adjusted odds ratio of PEW significantly increased as DPI decreased. DPI, per se was not a major determinant of CKD progression. An intimate association between reduced DPI and PEW may be a more important predictor of CKD progression than DPI.

The benefits and risks of aspirin therapy for patients with chronic kidney disease (CKD) who have a high burden of cardiovascular events (CVE) are controversial. To examine the effects of low-dose aspirin on major clinical outcomes in patients with CKD. As a prospective observational cohort study, using propensity score matching, 531 aspirin recipients and non-recipients were paired for analysis from 2070 patients and fulfilled the inclusion criteria among 2238 patients with CKD. The primary outcome was the first occurrence of major CVE. The secondary outcomes were kidney events defined as a > 50% reduction of estimated glomerular filtration rate from baseline, doubling of serum creatinine, or onset of kidney failure with replacement therapy, the all-cause mortality, and bleeding event. The incidence of CVE was significantly greater in low-dose aspirin users than in non-users (HR 1.798; P = 0.011). A significant association between aspirin use and an increased risk of CVE was observed only in the lowest quartile of body weight (HR 4.014; P = 0.019) (Q1 < 60.0 kg). Secondary outcomes were not significantly different between aspirin users and non-users. It needs to be individualized of prescribing low-dose aspirin for the prevention of cardiovascular events in patients with chronic kidney disease, particularly patients with low bodyweight (< 60 kg).

Background Few studies have examined the association between the early diastolic mitral inflow velocity/early diastolic mitral annulus velocity ratio (E/e') and chronic kidney disease progression. Methods and Results We reviewed data from 2238 patients with nondialysis chronic kidney disease from the KNOW-CKD (Korean Cohort Study for Outcome in Patients With Chronic Kidney Disease); data from 163 patients were excluded because of missing content. A >50% decrease in estimated glomerular filtration rate from baseline, doubling of serum creatinine, or dialysis initiation and/or kidney transplantation were considered renal events. At baseline, median (interquartile range) ejection fraction and E/e' were 64.0% (60.0%-68.0%) and 9.1 (7.4-11.9), respectively. Proportions of ejection fraction <50% and E/e' ≥15 were 1.3% and 9.6%, respectively. More than one quarter of patients (27.2%) had an estimated glomerular filtration rate <30 mL/min per 1.73 m2. During the mean 59.1-month follow-up period, 724 patients (34.9%) experienced renal events. In multivariable Cox proportional hazard regression analysis, the hazard ratio with 95% CI per 1-unit increase in E/e' was 1.027 (1.005-1.050; P=0.016). Penalized spline curve analysis yielded a suggested threshold of E/e' for renal events of 12; in our data set, the proportion of E/e' ≥12 was 4.1%. Conclusions Increased E/e' was associated with an increased hazard of renal events, suggesting that diastolic heart dysfunction is a novel risk factor for chronic kidney disease progression.

The prevalence of hyperuricemia and chronic kidney disease (CKD) has been steadily increasing. The role of hyperuricemia and efficacy of uric acid-lowering agents against CKD progression remain controversial. This study aimed to evaluate the effect of hyperuricemia and uric acid-lowering agents on the progression of CKD. A total 2042 patients with CKD were analyzed in the KoreaN cohort Study for Outcomes in patients With Chronic Kidney Disease (KNOW-CKD), a prospective cohort study. Patients were classified into quartiles on the basis of their serum uric acid level and the prevalence of advanced CKD was higher in patients with a high uric acid level. A composite renal outcome was defined as one or more of the following: initiation of dialysis or transplantation, a two-fold increase in baseline serum creatinine levels, or a 50% decline in the estimated glomerular filtration rate during the follow-up period. A Cox proportional hazard ratio model was applied to analyze the relationship between composite renal outcome and uric acid levels. The risk of progression to renal failure increased by 28% (hazard ratio [HR], 1.277; 95% confidence interval [CI], 1.212-1.345) for each 1 mg/dl increase in the baseline uric acid level. In multivariate models, an association was found between the highest quartile of uric acid and increased risk of composite renal outcome (HR, 3.590; 95% CI, 2.546-5.063). A propensity score matching analysis was performed to survey the effect of uric acid lowering agent. Both allopurinol and febuxostat did not affect the renal outcome. In conclusion, hyperuricemia appears to be an independent risk factor for composite renal outcome, but allopurinol and febuxostat did not show reno-protective effect.

Background The function of high-density lipoprotein can change from protective to proatherosclerotic under inflammatory conditions. Herein, we studied whether inflammation could modify the relationship between high-density lipoprotein level and risk of adverse outcomes in patients with chronic kidney disease . Methods and Results In total, 1864 patients from the prospective KNOW-CKD (Korean Cohort Study for Outcome in Patients With Chronic Kidney Disease) were enrolled. The main predictor was high-density lipoprotein cholesterol (HDL-C) level. Presence of inflammation was defined by hs-CRP (high-sensitivity C-reactive protein) level of ≥1.0 mg/L. The primary outcome was extended major adverse cardiovascular events. During 9231.2 person-years of follow-up, overall incidence of the primary outcome was 15.8 per 1000 person-years. In multivariable Cox analysis after adjusting for confounders, HDL-C level was not associated with the primary outcome. There was a significant interaction between the inflammatory status and HDL-C for risk of extended major adverse cardiovascular events (P=0.003). In patients without inflammation, the hazard ratios (HRs) (95% CIs) for HDL-C levels <40, 50 to 59, and ≥60 mg/dL were 1.10 (0.50-1.82), 0.95 (0.50-1.82), and 0.42 (0.19-0.95), respectively, compared with HDL-C of 40 to 49 mg/dL. However, the significant association for HDL-C ≥60 mg/dL was not seen after Bonferroni correction. In patients with inflammation, we observed a trend toward increased risk of extended major adverse cardiovascular events in higher HDL-C groups (HRs [95% CIs], 0.73 [0.37-1.43], 1.24 [0.59-2.61], and 1.56 [0.71-3.45], respectively), but without statistical significance. Conclusions The association between HDL-C level and adverse cardiovascular outcomes showed reverse trends based on inflammation status in Korean patients with chronic kidney disease. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT01630486.

Cisplatin causes acute kidney injury (AKI) through proximal tubular injury. We investigated the protective effect of the adenosine monophosphate protein kinase (AMPK) activator 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) against cisplatin-induced AKI. We investigated whether the AMP-kinase activator AICAR ameliorates cisplatin-induced AKI through the JAK/STAT/SOCS pathway. Male Sprague-Dawley (SD) rats were randomly divided into four groups: control, AICAR, cisplatin, and cisplatin + AICAR. As appropriate to their treatment group, the rats were injected with a single dose of cisplatin (7 mg/kg, i.p.). AICAR was administered to the rats at 100 mg/kg i.p. daily. Blood urea nitrogen (BUN) and serum creatinine were measured. Renal damage was analyzed in sections stained with hematoxylin and eosin (H&E). Renal tissues were also examined by immunohistochemistry and western blot for p-AMPK, Kim-1, cleaved caspase 3, and JAK/STAT/SOCS. For in vitro studies, NRK-52E normal rat kidney cells were treated with cisplatin and/or AICAR. By western blot, we confirmed the expression of p-AMPK and the JAK/STAT/SOCS pathway in NRK-52E cells. AICAR was protective against cisplatin-induced acute tubular injury by up-regulating p-AMPK expression in NRK-52E cells. Protein expression levels of JAK2/STAT1 were markedly ameliorated in NRK-52E cells by AICAR. The protective mechanism of AICAR may be associated with suppression of the JAK2/STAT1 pathway and up-regulation of SOCS1, an inhibitor of the JAK2/STAT1 pathway. The present study demonstrates the protective effects of AICAR against cisplatin-induced AKI and shows a new renoprotective mechanism through the JAK2/STAT1/SOCS1 pathway and apoptosis inhibition. This study suggests that activation of the AMPK activator AICAR might ameliorate cisplatin-induced AKI.

Background: We aimed to evaluate serum bicarbonate as a risk factor for renal progression, cardiovascular events, and mortality in Korean CKD patients. Methods: We analyzed 1,808 participants from a Korean CKD cohort whose serum bicarbonate levels were measured at enrollment. Serum bicarbonate levels were categorized as low, lower normal, higher normal, and high (total carbon dioxide <22, 22-26, 26.1-29.9, and ≥30 mmol/L, respectively) groups. Metabolic acidosis was defined as a serum bicarbonate level <22 mmol/L. The primary outcome was renal events defined as doubling of serum creatinine, 50% reduction of eGFR from the baseline values, or development of end-stage kidney disease. The secondary outcome consisted of cardiovascular events and death. In addition, patients whose eGFR values were measured more than three times during the follow-up period were analyzed for eGFR decline. The rapid decline in eGFR was defined as lower than the median value of the eGFR slope. Results: The mean serum bicarbonate level was 25.7 ± 3.7 mmol/L and 240 (13.2%) patients had metabolic acidosis. During the follow-up period of 55.2 ± 24.1 months, 545 (30.9%) patients developed renal events and 187 (10.6%) patients developed a composite of cardiovascular events and death. After adjustment, the low serum bicarbonate group experienced 1.27 times more renal events than the lower normal bicarbonate group [hazard ratio (HR): 1.27; 95% CI: 1.01-1.60, P = 0.043]. There was no significant association between the bicarbonate groups and the composite outcome of cardiovascular events and death. The low bicarbonate group showed a significantly rapid decline in eGFR [odds ratio (OR): 2.12; 95% CI: 1.39-3.22, P < 0.001] compared to the lower normal bicarbonate group. Conclusions: Metabolic acidosis was significantly associated with increased renal events and a rapid decline in renal function in Korean predialysis CKD patients.