KoreaN Cohort Study For Outcome Research Articles

Association between urine creatinine excretion and bone mineral density in chronic kidney disease: Results from the KNOW-CKD study.

Decreased lean body mass or muscle mass is associated with decreased bone mineral density in individuals with preserved renal function. However, the association between muscle mass and bone mineral density in chronic kidney disease (CKD) patients is not well known. The aim of this study was to assess the relationship between muscle mass estimated from urine creatinine (UCr) and bone mineral density in Korean CKD patients. This cross-sectional study analyzed 1872 participants from the Korean Cohort Study for Outcome in Patients With Chronic Kidney Disease (KNOW-CKD) cohort. Participants underwent UCr (g/day) and bone mineral density measurements, which were measured at the lumbar spine, total hip, and femoral neck by dual-energy X-ray absorptiometry. Patients were divided into three groups according to the tertiles of 24h UCr (T1-T3). The mean values for 24h urine creatinine of T1, T2, and T3 were 0.83 ± 0.23g, 1.18 ± 0.24g, and 1.55 ± 0.38g, respectively. A total of 172 patients were diagnosed withosteoporosis. The number of patients in each group was 92 (14.4%) in T1, 45 (7.3%) in T2, and 35 (5.7%) in T3. The odds ratio (95% confidence interval) for osteoporosis was 0.37 (0.20-0.69) for 1g/day increase of UCr. Compared with T1, the odds ratios (95% confidence interval) for osteoporosis were 0.58 (0.39-0.87) for T2 and 0.51 (0.32-0.80) for T3. Low 24-h UCr was associated with low bone mineral density. Low 24h UCr was significantly and independently associated with osteoporosis in Korean pre-dialysis CKD patients. Further research is warranted to verify the influence of muscle mass on bone health in CKD.

Baseline characteristics and associated factors for hypertension in children with chronic kidney disease: results from the Korean Cohort Study for Outcome in Patients with Pediatric Chronic Kidney Disease study.

Hypertension is one of the most important complications of chronic kidney disease (CKD) as it exacerbates disease progression in children. The aim of this study is to identify characteristics and factors associated with hypertension in children with CKD. This is a cross-sectional study using baseline data from the 10-year ongoing cohort study named KNOW-PedCKD (Korean Cohort Study for Outcome in Patients with Pediatric Chronic Kidney Disease). We enrolled finally 378 patients aged <18 years at seven major pediatric nephrology centers in Republic of Korea. Blood pressure was measured and samples and clinical data were collected during the patients' annual hospital visits. We found that 30.7% of the patients had hypertension (n = 116); specifically, 16.4% (n = 62) had systolic hypertension, and 22.8% (n = 86) had diastolic hypertension. Multiple logistic regression analysis indicated that older age (odds ratio [OR], 1.13; p < 0.001), female sex (OR, 2.32; p = 0.002), a high left ventricular mass index (OR, 1.05; p < 0.001), and a high urine protein/creatinine ratio (OR, 1.12; p = 0.02) were significant associated factors for systolic or diastolic hypertension. This study analyzed the associated factors for hypertension in children with CKD. Hypertension is associated with various factors, including age, sex, heart status, and proteinuria. Therefore, clinicians should consider these factors during patient evaluations to improve health outcomes.

Association of Handgrip Strength and Nutritional Status in Non-Dialysis-Dependent Chronic Kidney Disease Patients: Results from the KNOW-CKD Study.

Handgrip strength (HGS) is suggested as an indirect assessment of nutritional status in chronic kidney disease (CKD) patients, but evidence is limited for non-dialysis-dependent CKD (NDD-CKD) patients. This cross-sectional study included 404 patients from the Phase II KoreaN Cohort Study for Outcome in Patients With CKD. HGS, measured twice in each hand, was the exposure, and malnutrition status was defined by a malnutrition-inflammation score (MIS) of 6 or higher. A logistic regression analysis adjusted for age, sex, diabetes mellitus (DM), hypertension, CKD stages, smoking, overhydration, education, and income status was used to assess malnutrition risk. The predictability of HGS for malnutrition was evaluated using the area under the curve (AUC). Patients with lower HGS were older, had a higher prevalence of DM, and lower estimated glomerular filtration rate. Higher HGS was significantly associated with lower malnutrition risk after adjustment (per 1 standard deviation increase, adjusted odds ratio, 0.47 [0.30-0.75]). Subgroup analyses showed no significant interaction between HGS and malnutrition risk across age, sex, DM, and CKD stage. HGS showed fair predictability for malnutrition in men (AUC 0.64 [0.46-0.83]) and women (AUC 0.71 [0.55-0.86]). In conclusion, HGS is a useful diagnostic indicator of malnutrition in NDD-CKD patients.

Hospitalization among adults with chronic kidney disease: results from the KoreaN cohort study for Outcomes in patients With Chronic Kidney Disease (KNOW-CKD) study.

Chronic kidney disease (CKD) patients are hospitalized for various conditions. Hospitalization increases the readmission rate and mortality rate, seriously deteriorating patients' quality of life. Consequently, it is crucial to analyze the reasons for hospitalization in CKD patients from a broader perspective according to CKD grade. This is a prospective cohort study of CKD patients entitled the KoreaN Cohort Study for Outcomes in Patients With Chronic Kidney Disease (KNOW-CKD). A total of 2,238 patients were examined, and the reasons for hospitalization were classified into 16 disease categories. The incidence rate ratio (IRR) according to CKD stage was compared using negative bimodal regression analysis. The all-cause hospitalization incidence was 184.96 per 1,000 person-years. The most common reason for hospitalization was circulatory system disease, followed by infection and digestive system disease. Among hospitalizations for acute kidney injury, endocrine-nutrition-metabolic-related illness, blood-related disease, and diseases of the nervous system and sensory organs, IRR increased as CKD grade advanced. The incidence of ophthalmologic surgery during hospitalization increased according to the CKD stage. The IRR of KNOW-CKD patients was 6.19 (95% confidence interval, 5.92-6.48; p < 0.001) compared with the general population. This in-depth analysis of hospitalizations among CKD patients confirmed that CKD patients were hospitalized for various reasons, such as metabolic, ophthalmic, and hematologic diseases. Early detection and intervention regarding causative diseases of CKD are important to reduce the hospitalization burden and improve patients' quality of life.

The association between transferrin saturation and all-cause mortality in chronic kidney disease: findings from Korean Cohort Study for Outcome in Patients with Chronic Kidney Disease.

Transferrin saturation (TSAT) has been used as an indicator of iron deficiency. However, there is no consensus regarding its optimal range for patient with chronic kidney disease (CKD). We aimed to analyze the effect of TSAT on the prognosis of patients with non-dialysis CKD (NDCKD). From 2011 to 2016, 2157 NDCKD patients with baseline TSAT measurements were followed for 10 years. Patients were divided into three groups based on baseline TSAT values: <25%, ≥25% and <45%, and ≥45%. All-cause mortality and 4-point major adverse cardiovascular events (MACE) were analyzed using multivariable Cox regression analysis. Other iron biomarkers and mortality were also analyzed. During a mean follow-up of 7.1 ± 2.9 years, 182 of a total of 2,157 patients (8.4%) died. Compared with the TSAT ≥25% and <45% group, the TSAT <25% group showed significantly increased all-cause mortality (hazard ratio [HR], 1.44; 95% confidence interval (CI), 1.02-2.03; p = 0.04). The occurrence of 4-point MACE was significantly increased in univariable analysis in the TSAT <25% group (HR, 1.48; 95% CI, 1.02-2.15; p = 0.04), but it was not significant in the multivariable analysis (HR, 1.38; 95% CI, 0.89-2.15; p = 0.15). Tertile comparisons of the iron-to-log-ferritin ratio showed increased mortality in the first tertile group. TSAT <25% is an independent risk factor for all-cause mortality in patients with NDCKD and care should be taken to prevent TSAT values of <25%. Other indicators, such as serum iron and iron-to-log-ferritin ratio, may also be used to assess iron deficiency.

#1688 Association of baseline serum activin levels with left atrial diameter at 5 years post-kidney transplantation: results from the KNOW-KT

Abstract Background and Aims Serum activin A inhibits muscle growth, promotes apoptosis, and impairs heart function. However, the role of serum activin remains unclear in kidney transplant patients, where cardiovascular complications are a significant cause of morbidity and mortality. In this multicenter, observational cohort study, we investigated a potential association of pre-transplant serum activin levels with the left atrial (LA) diameter, an indicator of diastolic burden and a predictor of cardiovascular complications, to indirectly assess the impact of pre-transplant activin levels on heart function in kidney transplant patients. Method Overall, 602 kidney transplant patients from KNOW-KT (Korean cohort study for outcome in patients with kidney transplantation) were analyzed. Activin levels were measured at baseline immediately before kidney transplantation (KT). The primary outcome was the LA diameter that was measured by transthoracic echocardiography at 5 years after KT. Results The mean age of study population was 45.4 years and 221 (46.7%) patients were men. Pre-transplant serum activin levels were 718.4 ± 363.2 (mean ± standard deviation). When activin levels were divided into categorical variables according to the median value, the ejection fraction of LV showed a lower tendency in the high-activin group (64.3 ± 7.0) compared to the low-activin group (65.3 ± 6.2); however, there was no statistical significance (P=0.069). LV diastolic dimension was significantly higher in the high-activin group (47.3 ± 5.3) compared to the low-activin group (46.3 ± 5.5) (P=0.021). Notably, the post-transplant LA diameter was 37.0 ± 7.0 mm in the low-activin group and 39.1 ± 6.5 mm in the high-activin group, showing a significant difference (P&amp;lt;0.001). The multivariate linear regression coefficient for association between activin groups and LA diameter was 1.08 (95% confidence interval [CI], 0.67-2.10, P=0.037). In an additional logistic regression analysis of LA diameter groups, the high activin group was significantly associated with the high LA diameters compared to the low-activin group in multivariate analysis (adjusted odds ratio [OR], 2.04; 95% CI, 1.34-3.09, P=0.001). When activin levels were used as a continuous variable, adjusted ORs of activin for high LA diameters were 1.29 (95% CI, 1.04-1.60, P=0.018). Conclusion Pre-transplant serum activin levels were independently associated with a higher post-transplant LA diameter, suggesting that activin may negatively affect heart functions in kidney transplant patients. Therefore, activin may be a potential prognostic and therapeutic target in kidney transplant patients.

#210 Effects of serum magnesium level on kidney disease progression and major cardiovascular outcome in patients with chronic kidney disease

Abstract Background and Aims Magnesium is known for its anti-inflammatory, anti-apoptotic, and anti-oxidative effects, potentially inhibiting renal fibrosis. Additionally, it is believed that magnesium can inhibit vascular calcification, potentially improving cardiovascular outcomes. However, this remains a topic of controversy. This study aims to investigate the association between serum magnesium levels and CKD progression as well as cardiovascular outcomes. Method We analyzed 1,893 patients from The KoreaN Cohort Study for Outcomes in Patients With Chronic Kidney Disease (KNOW-CKD), which is a prospective cohort study. These patients were categorized into three groups based on their baseline magnesium levels: Mg1 (hypomagnesemia, &amp;lt;1.8 mg/dL), Mg2 (normomagnesemia, 1.8-2.4 mg/dL), and Mg3 (hypermagnesemia, &amp;gt;2.4 mg/dL). The primary outcome was defined as meeting one or more of the following criteria during the follow-up period: initiation of dialysis or transplantation, a two-fold increase in baseline serum creatinine levels, or a 50% decline in the estimated glomerular filtration rate. The secondary outcome was a composite of major adverse cardiovascular events (MACEs). We used Cox proportional hazard regression model. Results A total of 673 patients (35.6%) experienced the composite renal outcome. The Mg1 group showed significantly increased adverse renal outcomes compared to the Mg2 group (HR, 1.885; 95% CI, 1.137-3.124; p = 0.013), however, Mg3 group did not show a significant difference (HR, 0.927; 95% CI, 0.783-1.097; p = 0.379). The composite cardiovascular outcome occurred in 138 patients (7.3%). The risk of composite cardiovascular outcomes significantly increased in the Mg1 group compared to the Mg2 group (HR 3.472; 95% CI, 1.492-8.076; p = 0.003). However, we observed no statistically significant differences in the Mg3 group (HR 1.021; 95% CI, 0.689; p = 0.913). The cubic spline curves demonstrated a U-shaped association between serum magnesium levels and both renal and cardiovascular outcomes. Conclusion Hypomagnesemia is associated with the progression of renal disease and a significant increase in MACEs. Beyond a certain level, hypermagnesemia may also be associated with worsening renal and cardiovascular outcomes.

#1200 Coronary artery calcium modifies the relationship between blood pressure and adverse kidney outcome: results from KNOW-CKD

Abstract Background and Aims Previous studies evidenced that elevated coronary artery calcium (CAC) score is associated with higher chronic kidney disease (CKD) progression. However, the use of CAC score to guide CKD management has not been adequately evaluated. Here, we evaluated whether presence of CAC modify the association between systolic blood pressure (SBP) and CKD progression in patients with CKD. Method We analyzed 1693 participants with CKD stages G1 to G5 from the KoreaN cohort study for Outcome in patients With Chronic Kidney Disease (KNOW-CKD). Key exclusion criteria were kidney failure with replacement therapy (KFRT) and missing data for CAC and SBP information. We categorized participants according to baseline SBP and CAC score (Controlled BP, SBP &amp;lt; 120 mmHg; Elevated BP without CAC, SBP 120-140 mmHg and CAC score = 0; Elevated BP with CAC, SBP 120-140 mmHg and CAC score &amp;gt;0; Uncontrolled BP, SBP &amp;gt;140 mmHg) and compared the CKD progression. The CKD progression was defined as a composite of halving eGFR from baseline value or onset of KFRT. Results During 10,023 person-years of follow-up (median 6.2 years), the composite outcome occurred in 689 (40.7%) participants, and 108 (6.4%) participants died among the KNOW-CKD participants. There was significant interaction between CAC score and SBP for CKD progression (P &amp;lt; 0.001). There were 181/568 (31.9%), 167/424 (39.4%), 128/314 (40.8%) 213/387 (55.0%), composite outcomes in controlled BP, elevated BP without CAC, elevated BP with CAC, uncontrolled BP group, respectively. In crude Cox regression, compared to controlled BP, elevated BP with CAC group showed similar CKD progression risk (Hazard ratio [HR], 1.17; 95% confidence interval [CI], 0.95-1.44), whereas other strata group showed increased risk of CKD progression (elevated BP with CAC; HR, 1.59; 95% CI 1.31-1.94 and uncontrolled BP, HR, 1.94; 95% CI 1.56-2.41). Similar elevated risk in elevated BP with CAC was observed even after adjustment of age, sex, diabetes mellitus, estimated glomerular filtration ratio, and proteinuria (HR, 1.26; 95% CI, 1.02-1.56). However, the risk of CKD progression in elevated BP without CAC group was comparable to controlled BP group (HR, 1.20; 95% CI, 0.87-1.66). Conclusion Elevated SBP was more strongly associated with an increased risk of adverse kidney outcomes in patients with coronary calcification.

Association between progression of coronary artery calcification and development of kidney failure with replacement therapy: Findings from KNOW-CKD study

Background and aimsHigh coronary artery calcification (CAC) burden is a significant risk factor for adverse cardiovascular and kidney outcomes. However, it is unknown whether changes in the coronary atherosclerotic burden can accompany changes in kidney disease progression. Here, we evaluated the relationship between CAC progression and the risk of kidney failure with replacement therapy (KFRT). MethodsWe analyzed 1173 participants with chronic kidney disease (CKD) G1 to G5 without kidney replacement therapy from the KoreaN Cohort Study for Outcomes in Patients With Chronic Kidney Disease (KNOW-CKD). Participants were categorized into three groups according to the change in the CAC score between enrollment and year 4 (non-progressors, ≤0 AU; moderate progressors, 1–199 AU; and severe progressors, ≥200 AU). The primary outcome was the development of KFRT. ResultsDuring a follow-up period of 4690 person-years (median, 4.2 years), the primary outcome occurred in 230 (19.6 %) participants. The incidence of KFRT was 37.6, 54.3, and 80.9 per 1000 person-years in the non-, moderate, and severe progressors, respectively. In the multivariable cause-specific hazard model, the hazard ratios (HRs) for the moderate and severe progressors were 1.71 (95 % confidence interval [CI], 1.02–2.87) and 2.55 (95 % CI, 1.07–6.06), respectively, compared with non-progressors. A different definition of CAC progression with a threshold of 100 AU yielded similar results in a sensitivity analysis. ConclusionsCAC progression is associated with an increased risk of KFRT in patients with CKD. Our findings suggest that coronary atherosclerosis changes increase the risk of CKD progression.

Impact of Arterial Calcification on Cardiovascular and Renal Outcomes in Kidney Transplant Patients

Plain Language SummaryArterial calcification, accumulation of calcium in the arterial walls, vascular stiffness, and loss of elasticity of blood vessels can contribute to the development of cardiovascular diseases. Patients with chronic kidney disease and those undergoing dialysis have a considerably increased risk of vascular calcification. Even after kidney transplantation when kidney function has been restored, the prevalence of vascular calcification and subsequent cardiovascular disease remains high. Coronary artery calcification score and abdominal aortic calcification score are both well-established markers of vascular calcification. However, the impact of pretransplant vascular calcification scores on cardiovascular and renal outcomes in kidney transplant patients has not been established. When we analyzed 944 Korean kidney transplant patients, both vascular calcification scores were significantly associated with cardiovascular outcomes after kidney transplantation, but were not associated with renal outcomes. We also demonstrated that the addition of coronary artery calcification scores led to a modest improvement in the prediction performance for kidney transplant outcomes. Our findings suggest a potential role of pretransplant screening of coronary calcification scores and aortic calcification scores in risk stratification for post-kidney transplant outcomes.

Triglyceride-glucose index is an independent predictor of coronary artery calcification progression in patients with chronic kidney disease.

Coronary artery calcification (CAC) is highly prevalent in patients with chronic kidney disease (CKD) and is associated with major adverse cardiovascular events and metabolic disturbances. The triglyceride-glucose index (TyGI), a novel surrogate marker of metabolic syndrome and insulin resistance, is associated with CAC in the general population and in patients with diabetes. This study investigated the association between the TyGI and CAC progression in patients with CKD, which is unknown. A total of 1,154 patients with CKD (grades 1-5; age, 52.8 ± 11.9 years; male, 688 [59.6%]) were enrolled from the KNOWCKD (KoreaN Cohort Study for Outcomes in Patients With Chronic Kidney Disease). The TyGI was calculated as follows: ln (fasting triglycerides × fasting glucose/2). Patients were classified into tertiles (low, intermediate, high) based on the TyGI. The primary outcome was annualized percentage change in CAC score [(percent change in CAC score + 1)12/follow-up months - 1] of ≥15%, defined as CAC progression. During the 4-year follow-up, the percentage of patients with CAC progression increased across TyGI groups (28.6%, 37.5%, and 46.2% in low, intermediate, and high groups, respectively; p < 0.001). A high TyGI was associated with an increased risk of CAC progression (odds ratio [OR], 2.11; 95% confidence interval [CI], 1.14-3.88; p = 0.02) compared to the low group. Moreover, a 1-point increase in the TyGI was related to increased risk of CAC progression (OR, 1.55; 95% CI, 1.06-1.76; p = 0.02) after adjustment. A high TyGI may be a useful predictor of CAC progression in CKD.

Longitudinal progression trajectory of estimated glomerular filtration rate in children with chronic kidney disease: results from the KNOW-Ped CKD (KoreaN cohort study for Outcomes in patients With Pediatric Chronic Kidney Disease).

The natural course of chronic kidney disease (CKD) progression in children varies according to their underlying conditions. This study aims to identify different patterns of subsequent decline in kidney function and investigate factors associated with different patterns of estimated glomerular filtration rate (eGFR) trajectories. We analyzed data from the KNOW-Ped CKD (KoreaN cohort study for Outcomes in patients With Pediatric Chronic Kidney Disease), which is a longitudinal, prospective cohort study. A latent class linear mixed model was applied to identify the trajectory groups. In a total of 287 patients, the median baseline eGFR (mL/min/1.73 m2) was 63.3, and the median age was 11.5 years. The eGFR decline rate was -1.54 during a 6.0-year follow-up. The eGFR trajectory over time was classified into four groups. Classes 1 (n = 103) and 2 (n = 11) had a slightly reduced eGFR at enrollment with a stable trend (ΔeGFR, 0.2/year) and a rapid decline eGFR over time (ΔeGFR, -10.5/year), respectively. Class 3 had a normal eGFR (n = 16), and class 4 had a moderately reduced eGFR (n = 157); both these chasses showed a linear decline in eGFR over time (ΔeGFR, -4.1 and -2.4/year). In comparison with classes 1 and 2, after adjusting for age, causes of primary renal disease, and baseline eGFR, nephrotic-range proteinuria was associated with a rapid decline in eGFR (odds ratio, 8.13). We identified four clinically relevant subgroups of kidney function trajectories in children with CKD. Most children showed a linear decline in eGFR; however, there are different patterns of eGFR trajectories.

Association of Serum Osteoprotegerin With Vascular Calcification, and Cardiovascular and Graft Outcomes in Kidney Transplant Patients: Results From the KNOW-KT.

Vascular calcification and stiffness contribute to increased cardiovascular morbidity in patients with chronic kidney disease. This study investigated associations between serum osteoprotegerin (OPG) levels and vascular calcification or stiffness to assess cardiovascular and graft outcomes in kidney transplant patients. The KoreaN cohort study for Outcome in patients With Kidney Transplantation was a prospective multicenter cohort study. Serum OPG levels were measured at baseline and 3 y after transplantation in 1018 patients. Patients were classified into high and low OPG groups according to median serum OPG levels. The median follow-up duration was 93.5 mo. The mean age was 45.8 ± 11.7 y and 62.9% were men. Patients with high OPG had significantly higher coronary artery calcium scores, abdominal aortic calcification scores, and brachial-ankle pulse wave velocities than those with lower OPG; these parameters remained significant for 5 y after transplantation. The 3-y OPG levels were lower than baseline values ( P < 0.001) and were positively correlated ( r = 0.42, P < 0.001). Multivariate Cox regression analysis showed that high OPG levels were significantly associated with posttransplant cardiovascular events ( P = 0.008) and death-censored graft loss ( P = 0.004). Similar findings regarding posttransplant cardiovascular events ( P = 0.012) and death-censored graft loss ( P = 0.037) were noted in patients with high OPG at the 3-y follow-up. Mediation analyses revealed that coronary artery calcium scores, abdominal aortic calcification scores, and brachial-ankle pulse wave velocities could act as mediators between serum OPG levels and posttransplant cardiovascular events. Serum OPG concentration is associated with vascular calcification and stiffness and could be a significant risk factor for cardiovascular outcomes and graft loss in patients undergoing kidney transplantation.

Benefits of statin therapy within a year after kidney transplantation

Cardiovascular disease remains a leading cause of morbidity and mortality after kidney transplantation (KT). Although statins reduce cardiovascular risk and have renal benefits in the general population, their effects on KT recipients are not well-established. We studied the effects of early statin use (within 1-year post-transplantation) on long-term outcomes in 714 KT recipients from the Korean cohort study for outcome in patients with KT. Compared with the control group, statin group recipients were significantly older, had a higher body mass index, and had a higher prevalence of diabetes mellitus. During a median follow-up of 85 months, 74 graft losses occurred (54 death-censored graft losses and 20 deaths). Early statin use was independently associated with lower mortality (hazard ratio, 0.280; 95% confidence interval 0.111–0.703) and lower death-censored graft loss (hazard ratio, 0.350; 95% confidence interval 0.198–0.616). Statin therapy significantly reduced low-density lipoprotein cholesterol levels but did not decrease the risk of major adverse cardiovascular events. Biopsy-proven rejection and graft renal function were not significantly different between statin and control groups. Our findings suggest that early statin use is an effective strategy for reducing low-density lipoprotein cholesterol and improving patient and graft survival after KT.

Association of Serum Activin Levels with Allograft Outcomes in Patients with Kidney Transplant: Results from the KNOW-KT.

Serum activin A has been reported to contribute to vascular calcification and kidney fibrosis in chronic kidney disease. We aimed to investigate whether higher serum activin levels were associated with poor allograft outcomes in patients with kidney transplantation (KT). A total of 860 KT patients from KNOW-KT (Korean Cohort Study for Outcome in Patients with Kidney Transplantation) were analyzed. We measured serum activin levels pre-KT and 1 year after KT. The primary outcome was the composite of a ≥50% decline in estimated glomerular filtration rate and graft failure. Multivariable cause-specific hazard model was used to analyze association of 1-year activin levels with the primary outcome. The secondary outcome was coronary artery calcification score (CACS) at 5 years after KT. During the median follow-up of 6.7 years, the primary outcome occurred in 109 (12.7%) patients. The serum activin levels at 1 year were significantly lower than those at pre-KT (488.2 ± 247.3 vs. 704.0 ± 349.6). When patients were grouped based on the median activin level at 1 year, the high-activin group had a 1.91-fold higher risk (95% CI, 1.25-2.91) for the primary outcome compared to the low-activin group. A one-standard deviation increase in activin levels as a continuous variable was associated with a 1.36-fold higher risk (95% CI, 1.16-1.60) for the primary outcome. Moreover, high activin levels were significantly associated with 1.56-fold higher CACS (95% CI, 1.12-2.18). Post-transplant activin levels were independently associated with allograft functions as well as coronary artery calcification in KT patients.

Findings from the KNOW-CKD Study indicate that higher systolic blood pressure time in target range is associated with a lower risk of chronic kidney disease progression

Time-in-target range (TTR) of systolic blood pressure (SBP) is determined by the proportion of time during which SBP remains within a defined optimal range. TTR has emerged as a useful metric for assessing SBP control over time. However, it is uncertain if SBP-TTR can predict the progression of chronic kidney disease (CKD). Here, we investigated the association between SBP-TTR during the first year of enrollment and CKD progression among 1758 participants from the KNOW-CKD (KoreaN Cohort Study for Outcomes in Patients With Chronic Kidney Disease). Baseline median estimated glomerular filtration rate (eGFR) was 51.7 ml/min per 1.73 m2. Participants were categorized into four SBP-TTR groups (0%, 1–50%, 51–99%, and 100%). The primary outcome was CKD progression defined as 50% or more decline in eGFR from baseline measurement or the initiation of kidney replacement therapy. During the follow-up period (9212 person-years over a median 5.4 years), the composite outcome occurred in 710 participants. In the multivariate cause-specific hazard model, a one-standard deviation increase in SBP-TTR was associated with an 11% lower risk of the composite outcome with hazard ratio, 0.89 (95% confidence interval, 0.82–0.97). Additionally, compared to patients with SBP-TTR 0%, the respective hazard ratios for those with SBP-TTR 1–50%, 51–99%, and 100% were 0.85 (0.68–1.07), 0.76 (0.60–0.96), and 0.72 (0.55–0.94), and the respective corresponding slopes of eGFR decline were –3.17 (–3.66 to –2.69), –3.02 (–3.35 to –2.68), –2.62 (–2.89 to – 2.36), and –2.33 (–2.62 to –2.04) ml/min/1.73 m2 . Thus, higher SBP-TTR was associated with a decreased risk of CKD progression in patients with CKD.

High pretransplant FGF23 level is associated with persistent vitamin D insufficiency and poor graft survival in kidney transplant patients

Vitamin D3 (25[OH]D3) insufficiency and fibroblast growth factor 23 (FGF23) elevation are usually attenuated after kidney transplantation (KT). However, elevated FGF23 may be associated with poor graft outcomes and vitamin D insufficiency after KT. This study investigated the effect of pretransplant FGF23 levels on post-KT 25(OH)D3 status and graft outcomes. Serum FGF23 levels from 400 participants of the KoreaN Cohort Study for Outcome in Patients With Kidney Transplantation were measured. Annual serum 25(OH)D3 levels, all-cause mortality, cardiovascular event, and graft survival were assessed according to baseline FGF23 levels. Serum 25(OH)D3 levels were initially increased 1 year after KT (12.6 ± 7.4 vs. 22.6 ± 6.4 ng/mL). However, the prevalence of post-KT vitamin D deficiency increased again after post-KT 3 years (79.1% at baseline, 30.8% and 37.8% at 3 and 6 years, respectively). Serum FGF23 level was decreased 3 years post-KT. When participants were categorized into tertiles according to baseline FGF23 level (low, middle, high), 25(OH)D3 level in the low FGF23 group was persistently low at a median follow-up of 8.3 years. Furthermore, high baseline FGF23 level was a risk factor for poor graft survival (HR 5.882, 95% C.I.; 1.443–23.976, P = 0.013). Elevated FGF23 levels are associated with persistently low post-transplant vitamin D levels and poor graft survival.

Measured sodium excretion is associated with cardiovascular outcomes in non-dialysis CKD patients: results from the KNOW-CKD study.

There are insufficient studies on the effect of dietary salt intake on cardiovascular (CV) outcomes in chronic kidney disease (CKD) patients, and there is no consensus on the sodium (Na) intake level that increases the risk of CV disease in CKD patients. Therefore, we investigated the association between dietary salt intake and CV outcomes in CKD patients. In the Korean cohort study for Outcome in patients with CKD (KNOW-CKD), 1,937 patients were eligible for the study, and their dietary Na intake was estimated using measured 24h urinary Na excretion. The primary outcome was a composite of CV events and/or all-cause death. The secondary outcome was a major adverse cardiac event (MACE). Among 1,937 subjects, there were 205 (10.5%) events for the composite outcome and 110 (5.6%) events for MACE. Compared to the reference group (urinary Na excretion< 2.0g/day), the group with the highest measured 24h urinary Na excretion (urinary Na excretion ≥ 8.0g/day) was associated with increased risk of both the composite outcome (hazard ratio 3.29 [95% confidence interval 1.00-10.81]; P = 0.049) and MACE (hazard ratio 6.28 [95% confidence interval 1.45-27.20]; P = 0.013) in a cause-specific hazard model. Subgroup analysis also showed a pronounced association between dietary salt intake and the composite outcome in subgroups of patients with abdominal obesity, female, lower estimated glomerular filtration rate (< 60 ml/min per 1.73m2), no overt proteinuria, or a lower urinary potassium-to-creatinine ratio (< 46 mmol/g). A high-salt diet is associated with CV outcomes in non-dialysis CKD patients.

The 2021 KDIGO blood pressure target and the progression of chronic kidney disease: Findings from KNOW-CKD.

The 2021 Kidney Disease: Improving Global Outcomes (KDIGO) clinical practice guideline for the management of blood pressure (BP) in chronic kidney disease (CKD) recommends a target systolic BP of <120mmHg as this target can provide cardiovascular benefits. However, it remains unclear whether implementing the new BP target could improve kidney outcomes. The association between the 2021 KDIGO BP target and CKD progression was examined and compared with the 2012 KDIGO BP target among 1724 participants included in the KoreaN Cohort Study for Outcomes in Patients With CKD. The main exposure was the BP status categorized according to the 2012 or 2021 KDIGO guideline: (1) controlled within the 2021 target, (2) controlled within the 2012 target only, and (3) above both targets. The primary outcome was a composite kidney outcome of ≥50% decline in the estimated glomerular filtration rate from baseline or the initiation of kidney replacement therapy during the follow-up period. Composite kidney outcomes occurred in 650 (37.7%) participants during the 8078 person-years of follow-up (median, 4.9 years). The incidence rates of this outcome were 55, 66.5, and 116.4 per 1000 person-years in BP controlled within the 2021 and 2012 KDIGO targets, and BP above both targets, respectively. In the multivariable cause-specific hazard model, hazard ratios for the composite outcome were 0.76 (95% confidence interval (CI), 0.60-0.95) for BP controlled within the 2021 target and 1.36 (95% CI, 1.13-1.64) for BP above both targets, compared with BP controlled within 2012 target only. The newly lowered BP target by the 2021 KDIGO guideline was associated with improved kidney outcome compared with BP target by the 2012 KDIGO guideline.

Association between serum total cholesterol and chronic kidney disease progression in children: results from the KNOW-PedCKD.

Dyslipidemia can cause cardiovascular disease and increase the fatality rate among children with chronic kidney disease (CKD); this makes early screening and treatment of dyslipidemia crucial. This study aimed to assess the association between the changes in serum total cholesterol levels over time and the degree of CKD progression in children. From April 2011 to August 2021, 379 of the 432 participants enrolled in the KoreaN cohort study for Outcomes in patients With Pediatric CKD (KNOW-PedCKD) were included and divided into 4 categories based on total cholesterol levels (< 170mg/dL, acceptable; 170-199, borderline; 200-239, high; and ≥ 240, very high). Survival analysis using conventional and time-dependent Cox proportional hazards model were performed for a composite event of CKD progression (≥ 50% decrease in estimated glomerular filtration rate from baseline, a twofold increase in creatinine, or the occurrence of dialysis or kidney transplantation). The incidence of composite event of CKD progression was 96.3, 90.4, 87.3, and 270.6 cases per 1000 person-years in the acceptable, borderline, high, and very high categories, respectively. On using the time-dependent Cox proportional hazards model, the hazard ratio of the very high category was significantly higher than that of the acceptable category by 3.13 times as per univariate analysis and 2.37 times as per multivariate analysis. Very high serum total cholesterol is a significant risk factor for CKD progression in children. Lowering total cholesterol levels below the very high category in children with CKD may delay the progression of CKD. A higher resolution version of the Graphical abstract is available as Supplementary information.