The progression and complications of chronic kidney disease should differ depending on the cause (C), glomerular filtration rate category (G), and albuminuria (A). The KNOW-CKD (KoreaN Cohort Study for Outcome in Patients With Chronic Kidney Disease), which is a prospective cohort study, enrolls subjects with chronic kidney disease stages 1 to 5 (predialysis). Nine nephrology centers in major university hospitals throughout Korea will enroll approximately 2,450 adults with chronic kidney disease over a 5-year period from 2011 to 2015. The participating individuals will be monitored for approximately 10 years until death or until end-stage renal disease occurs. The subjects will be classified into subgroups based on the following specific causes of chronic kidney disease: glomerulonephritis, diabetic nephropathy, hypertensive nephropathy, polycystic kidney disease, and others. The eligible subjects will be evaluated at baseline for socio-demographic information, detailed personal/family history, office BP, quality of life, and health behaviors. After enrollment in the study, thorough assessments, including laboratory tests, cardiac evaluation and radiologic imaging, will be performed according to the standardized protocol. The biospecimen samples will be collected regularly. A renal event is defined by >50% decrease in estimated GFR (eGFR) from the baseline values, doubling of serum creatinine, or end-stage renal disease. The primary composite outcome consists of renal events, cardiovascular events, and death. As of September 2013, 1,470 adult chronic kidney disease subjects were enrolled in the study, including 543 subjects with glomerulonephritis, 317 with diabetic nephropathy, 294 with hypertensive nephropathy and 249 with polycystic kidney disease. As the first large-scale chronic kidney disease cohort study to be established and maintained longitudinally for up to 10 years, the KNOW-CKD will help to clarify the natural course, complication profiles, and risk factors of Asian populations with chronic kidney disease. No. NCT01630486 at http://www.clinicaltrials.gov .

Kim S, et al. J Korean Med Sci. 2009 Jan;24(Suppl 1):S11-S21. https://doi.org/10.3346/jkms.2009.24.S1.S11

Background. The incidence of chronic kidney disease (CKD) is increasing in Korea, especially in the aged population. The health-related quality of life (HRQOL) of patients with chronic renal insufficiency is lower than that for the general population and a lower HRQOL is a predictor of adverse events. We report the impact of kidney function on the HRQOL and the risk factors for poor HRQOL in an elderly population living in one Korean city. Methods. This study was conducted as a part of the Korean Longitudinal Study on Health and Aging (KLoSHA) that was designed as a population-based, prospective cohort-study in a population aged >65 years living in a satellite city of Seoul in Korea. Among 1 000 randomly selected subjects, 944 were able to complete the SF-36 questionnaires to measure HRQOL. We categorized the participants into five GFR groups: group 1: 90 mL/min/1.73 m ² or more, group 2: 89–75 mL/ min/1.73 m ² , group 3: 60–74 mL/min/1.73 m ² , group 4: 45–59 mL/min/1.73 m ² and group 5: less than 45 mL/min/ 1.73 m ² . Results. Except for the general health perception and mental health scale, all the other scores of the SF-36 scales showed differences among five groups categorized according to GFR. However, the scores were significantly decreased only among participants with a GFR value of <45 mL/min/1.73 m ² , compared to the other four GFR groups. After adjustment, the physical component summary score was the lowest in participants with GFR values <45 mL/min/1.73 m ² . The dichotomized GFR factor with the criterion of 45 mL/min/1.73 m ² was an independent predictor of poor physical HRQOL. Other factors, such as age, gender, duration of education, regular exercising habits, depression and a history of cardiovascular accident, were also predictors of HRQOL. A lower haemoglobin level was related to the mental component summary. Conclusion. The renal function deduced to be an important predictor of HRQOL, even in the old age group. The moderately decreased renal function of 45 mL/min/1.73 m ² GFR was the level at which HRQOL decreased in the elderly Korean population.

Sodium intake was reported to be related to metabolic syndrome (MS). Although a strong association between sodium intake and blood pressure (BP) has been reported, the relationship between sodium intake and other components of MS is unknown. An observational study of 18,146 adults in the Korea National Health and Nutrition Examination Survey IV-V databases (2008-2011) was performed. Estimates of 24-h sodium excretion were made from a single fasting urine sample. A significant positive association was found between sodium excretion and systolic BP and between sodium excretion and diastolic BP in participants with and without hypertension after adjusting for multiple covariates (P < 0.001 for trend). The relationship between triglyceride or glucose levels and sodium excretion was linear (P < 0.005). In both men and women, a positive relationship between sodium excretion and waist circumference and an inverse relationship between sodium excretion and high-density lipoprotein were found (P ≤ 0.001). Body fat percentage, body fat mass, and insulin level were positively related to sodium excretion (P ≤ 0.001), and HOMA-IR was significantly associated with sodium excretion (P < 0.05). The risk of MS was elevated 1.279-fold in the second quartile of sodium excretion (95% CI, 1.088-1.504, P = 0.003), 1.479-fold in the third quartile (95% CI, 1.262-1.734; P < 0.001), and 1.929-fold in the highest quartile (95% CI 1.654-2.249, P < .001) compared with the lowest quartile. Sodium intake is significantly associated with all components of MS, body fat, and insulin resistance. Therefore, a high-salt diet is a significant risk factor for MS.

Background: The inhibition of dipeptidyl peptidase (DPP) IV shows protective effects on tissue injury of the heart, lung, and kidney. Forkhead box O (FoxO) transcriptional factors regulate cellular differentiation, growth, survival, the cell cycle, metabolism, and oxidative stress. The aims of this study were to investigate whether the DPP IV inhibitor sitagliptin could attenuate kidney injury and to evaluate the status of FoxO3a signaling in the rat remnant kidney model. Methods: Rats were received two-step surgery of 5/6 renal mass reduction and fed on an oral dose of 200 mg/kg/day sitagliptin for 8 weeks. Before and after the administration of sitagliptin, physiologic parameters were measured. After 8 weeks of treatment, the kidneys were harvested. Results: The sitagliptin treatment attenuated renal dysfunction. A histological evaluation revealed that glomerulosclerosis and tubulointerstitial injury were significantly decreased by sitagliptin. Sitagliptin decreased DPP IV activity and increased the renal expression of glucagon-like peptide-1 receptor (GLP-1R). The subtotal nephrectomy led to the activation of phosphatidylinositol 3-kinase (PI3K)-Akt and FoxO3a phosphorylation, whereas sitagliptin treatment reversed these changes, resulting in PI3K-Akt pathway inactivation and FoxO3a dephosphorylation. The renal expression of catalase was increased and the phosphorylation of c-Jun N-terminal kinase (JNK) was decreased by sitagliptin. Sitagliptin treatment reduced apoptosis by decreasing cleaved caspase-3 and −9 and Bax levels and decreased macrophage infiltration. Conclusions: In rat remnant kidneys, DPP IV inhibitor attenuated renal dysfunction and structural damage. A reduction of apoptosis, inflammation and an increase of antioxidant could be suggested as a renoprotective mechanism together with the activation of FoxO3a signaling. Therefore, DPP IV inhibitors might provide a promising approach for treating CKD, but their application in clinical practice remains to be investigated.