Predictive performance of the new race-free Chronic Kidney Disease Epidemiology Collaboration equations for kidney outcome in Korean patients with chronic kidney disease.

BACKGROUND: The new Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations without a race coefficient have gained recognition across the United States. We aimed to test whether these new equations performed well in Korean patients with chronic kidney disease (CKD). METHODS: This study included 2,149 patients with CKD G1-G5 without kidney replacement therapy from the Korean Cohort Study for Outcome in Patients with CKD (KNOW-CKD). The estimated glomerular filtration rate (eGFR) was calculated using the new CKD-EPI equations with serum creatinine and cystatin C. The primary outcome was 5-year risk of kidney failure with replacement therapy (KFRT). RESULTS: When we adopted the new creatinine equation [eGFRcr (NEW)], 81 patients (23.1%) with CKD G3a based on the current creatinine equation (eGFRcr) were reclassified as CKD G2. Accordingly, the number of patients with eGFR of <60 mL/min/1.73 m2 decreased from 1,393 (64.8%) to 1,312 (61.1%). The time-dependent area under the receiver operating characteristic curve for 5-year KFRT risk was comparable between the eGFRcr (NEW) (0.941; 95% confidence interval [CI], 0.922-0.960) and eGFRcr (0.941; 95% CI, 0.922-0.961). The eGFRcr (NEW) showed slightly better discrimination and reclassification than the eGFRcr. However, the new creatinine and cystatin C equation [eGFRcr-cys (NEW)] performed similarly to the current creatinine and cystatin C equation. Furthermore, eGFRcr-cys (NEW) did not show better performance for KFRT risk than eGFRcr (NEW). CONCLUSION: Both the current and the new CKD-EPI equations showed excellent predictive performance for 5-year KFRT risk in Korean patients with CKD. These new equations need to be further tested for other clinical outcomes in Koreans.

Association Between Proton Pump Inhibitor Exposure and Acute Kidney Injury After Cardiac Surgery.

OBJECTIVE: To evaluate the association of preoperative proton pump inhibitor (PPI) exposure with incident acute kidney injury (AKI) after cardiac surgery. PATIENTS AND METHODS: The Severance cardiac surgery cohort included 9860 cardiac surgery patients aged 18 years or older. The National Health Insurance Service-senior cohort included 2933 patients aged 60 years or older who underwent cardiac surgery. Preoperative PPI exposure was defined as a PPI prescription within 3 weeks prior to cardiac surgery. Primary outcomes were postoperative AKI and AKI requiring dialysis (AKI-dialysis). RESULTS: In the Severance cardiac surgery cohort after propensity score matching for PPI exposure, incident AKI (44.0% [472 of 1073] vs 40.5% [1304 of 3219]) and AKI-dialysis (5.8% [62 of 1073] vs 3.7% [119 of 3219]) were more common in patients exposed to PPI than in those who were not. Hospital and intensive care unit stay durations were longer among PPI-exposed than PPI-nonexposed patients. Multivariable conditional logistic analyses revealed that PPI exposure was significantly associated with incident AKI (adjusted odds ratio [AOR], 1.21; 95% CI, 1.03 to 1.42; P=.02) and AKI-dialysis (AOR, 1.74; 95% CI, 1.15 to 2.63; P=.009). The National Health Insurance Service-Senior cohort had similar results, revealing a significant association between PPI exposure and incident AKI-dialysis (AOR, 1.87; 95% CI, 1.25 to 2.81; P=.003). Discontinuation of PPI prior to operation was associated with a lower odds of AKI development in both cohorts. CONCLUSION: Preoperative PPI exposure may be a modifiable risk factor for AKI among patients undergoing cardiac surgery.

Exercise reduces the risk of chronic kidney disease in individuals with nonalcoholic fatty liver disease: A nationwide cohort study.

AIMS: Recent studies of individuals with nonalcoholic fatty liver disease (NAFLD) have indicated benefits of exercise in improving outcomes. We investigated whether exercise reduces the risk of chronic kidney disease (CKD) in individuals with NAFLD. METHODS: A total of 7275 participants from the Korea National Health and Nutrition Examination Survey (KNHANES) cohort, and 40,418 participants with NAFLD from the National Health Insurance Service (NHIS) cohort were included for the cross-sectional and longitudinal analyses, respectively. For the cross-sectional analysis, the primary outcome was prevalent CKD, defined as an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73m2. For the longitudinal analysis, the primary outcome was incident CKD, defined as the occurrence of eGFR <60 mL/min/1.73m2 or proteinuria (≥ trace) on two consecutive measurements during follow-up. RESULTS: In the KNHANES cohort, prevalent CKD was observed in 229 (6.1%), 48 (2.6%), and 36 (2.1%) participants in the 0, 1-2, and ≥ 3 exercise sessions/week groups, respectively. The likelihood of prevalent CKD was lowest in participants allocated to the ≥ 3 sessions/week group (adjusted OR 0.49; 95% CI, 0.33-0.71; P < 0.001). During a median follow-up of 5.0 years in the NHIS cohort, incident CKD occurred in 1,047 (9.7/1,000 person-years), 188 (7.3/1,000 person-years), and 478 (7.4/1,000 person-years) participants in the 0, 1-2, and ≥ 3 sessions/week groups, respectively. The risk of incident CKD was lowest in participants allocated to the ≥ 3 sessions/week group (adjusted HR 0.85; 95% CI, 0.76-0.95; P = 0.004). CONCLUSIONS: Exercise was significantly associated with a reduced risk of both prevalent and incident CKD in individuals with NAFLD.

Association of statin treatment with hepatocellular carcinoma risk in end-stage kidney disease patients with chronic viral hepatitis.

Statin use in end-stage kidney disease (ESKD) patients are not encouraged due to low cardioprotective effects. Although the risk of hepatocellular carcinoma (HCC), a frequently occurring cancer in East Asia, is elevated in ESKD patients, the relationship between statins and HCC is not known despite its possible chemopreventive effect. The relationship between statin use and HCC development in ESKD patients with chronic hepatitis was evaluated. In total, 6165 dialysis patients with chronic hepatitis B or C were selected from a national health insurance database. Patients prescribed with ≥ 28 cumulative defined daily doses of statins during the first 3 months after dialysis commencement were defined as statin users, while those not prescribed with statins were considered as non-users. Primary outcome was the first diagnosis of HCC. Sub-distribution hazard model with inverse probability of treatment weighting was used to estimate HCC risk considering death as competing risk. During a median follow-up of 2.8 years, HCC occurred in 114 (3.2%) statin non-users and 33 (1.2%) statin users. The HCC risk was 41% lower in statin users than in non-users (sub-distribution hazard ratio, 0.59; 95% confidence interval [CI], 0.42-0.81). The weighted incidence rate of HCC was lower in statin users than in statin non-users (incidence rate difference, - 3.7; 95% CI - 5.7 to - 1.7; P < 0.001). Incidence rate ratio (IRR) was also consistent with other analyses (IRR, 0.56; 95% CI, 0.41 to 0.78; P < 0.001). Statin use was associated with a lower risk of incident HCC in dialysis patients with chronic hepatitis B or C infection.

External validation of the international prediction tool in Korean patients with immunoglobulin A nephropathy.

BACKGROUND: The International IgA Nephropathy Prediction Tool has been recently developed to estimate the progression risk of immunoglobulin A nephropathy (IgAN). This study aimed to evaluate the clinical performance of this prediction tool in a large IgAN cohort in Korea. METHODS: The study cohort was comprised of 2,064 patients with biopsy-proven IgAN from four medical centers between March 2012 and September 2021. We calculated the predicted risk for each patient. The primary outcome was occurrence of a 50% decline in estimated glomerular filtration rate (eGFR) from the time of biopsy or end-stage kidney disease. The model performance was evaluated for discrimination, calibration, and reclassification. We also constructed and tested an additional model with a new coefficient for the Korean race. RESULTS: During a median follow-up period of 3.8 years (interquartile range, 1.8-6.6 years), 363 patients developed the primary outcome. The two prediction models exhibited good discrimination power, with a C-statistic of 0.81. The two models generally underestimated the risk of the primary outcome, with lesser underestimation for the model with race. The model with race showed better performance in reclassification compared to the model without race (net reclassification index, 0.13). The updated model with the Korean coefficient showed good agreement between predicted risk and observed outcome. CONCLUSION: In Korean IgAN patients, International IgA Nephropathy Prediction Tool had good discrimination power but underestimated the risk of progression. The updated model with the Korean coefficient showed acceptable calibration and warrants external validation.

Metabolic dysfunction-associated fatty liver disease and risk of incident chronic kidney disease: A nationwide cohort study.

AIMS: The recently proposed metabolic dysfunction-associated fatty liver disease (MAFLD) has been suggested to better reflect the metabolic components of fatty liver disease (FLD), compared to nonalcoholic fatty liver disease (NAFLD). This study investigated whether MAFLD identifies a higher proportion of individuals at risk of developing chronic kidney disease (CKD). METHODS: 268,946 participants aged 40-64 years, who underwent National Health Insurance Service health examinations between 2009 and 2015 were included. Participants were categorized by presence of FLD, according to MAFLD or NAFLD. In participants with FLD, participants were categorized into three groups: non-metabolic risk (non-MR) NAFLD, MAFLD but not NAFLD, and overlapping FLD. Incident CKD was defined as the occurrence of eGFR < 60 mL/min/1.73m2 or proteinuria (≥ trace) on two consecutive health examinations. RESULTS: 73,726 (27.4%) and 88,762 (33.0%) participants had NAFLD and MAFLD, respectively. During a median follow-up of 5.1 years, CKD occurred in 8,335 (6.2/1,000 person-years) participants. Compared to non-NAFLD participants, the adjusted hazard ratio (aHR) for incident CKD was 1.33 (95% CI, 1.27-1.39; P < 0.001) for participants with NAFLD. Compared to non-MAFLD participants, the aHR for participants with MAFLD was 1.39 (95% CI, 1.33-1.46; P < 0.001). When the analysis was confined to participants with FLD, compared to non-MR NAFLD participants, the aHRs for participants with MAFLD but not NAFLD, and those with overlapping FLD were 1.18 (95% CI, 1.01-1.39; P = 0.040) and 1.36 (95% CI, 1.19-1.54; P < 0.001), respectively. CONCLUSION: MAFLD identified a higher proportion of individuals at risk of developing CKD than NAFLD.

Erythropoiesis stimulating agent recommendation model using recurrent neural networks for patient with kidney failure with replacement therapy.

In patients with kidney failure with replacement therapy (KFRT), optimizing anemia management in these patients is a challenging problem because of the complexities of the underlying diseases and heterogeneous responses to erythropoiesis-stimulating agents (ESAs). Therefore, we propose a ESA dose recommendation model based on sequential awareness neural networks. Data from 466 KFRT patients (12,907 dialysis sessions) in seven tertiary-care general hospitals were included in the experiment. First, a Hb prediction model was developed to simulate longitudinal heterogeneous ESA and Hb interactions. Based on the prediction model as a prospective study simulator, we built an ESA dose recommendation model to predict the required amount of ESA dose to reach a target hemoglobin level after 30 days. Each model's performance was evaluated in the mean absolute error (MAE). The MAEs presenting the best results of the prediction and recommendation model were 0.59 (95% confidence interval: 0.56-0.62) g/dL and 43.2 µg (ESAs dose), respectively. Compared to the results in the real-world clinical data, the recommendation model achieved a reduction of ESA dose (Algorithm: 140 vs. Human: 150 µg/month, P < 0.001), a more stable monthly Hb difference (Algorithm: 0.6 vs. Human: 0.8 g/dL, P < 0.001), and an improved target Hb success rate (Algorithm: 79.5% vs. Human: 62.9% for previous month's Hb < 10.0 g/dL; Algorithm: 95.7% vs. Human:73.0% for previous month's Hb 10.0-12.0 g/dL). We developed an ESA dose recommendation model for optimizing anemia management in patients with KFRT and showed its potential effectiveness in a simulated prospective study.

Synergic association of diabetes mellitus and chronic kidney disease with muscle loss and cachexia: results of a 16-year longitudinal follow-up of a community-based prospective cohort study.

Muscle loss is a serious complication in patients with diabetes mellitus (DM) and chronic kidney disease (CKD). However, studies on a long-term change in muscle mass presence or absence of DM and CKD are scarce. We included 6247 middle-aged adults from the Korean Genome and Epidemiology Study (KoGES) between 2001 and 2016. Bioimpedance analysis (BIA) was performed biennially. Patients were classified into four groups according to the presence or absence of DM and CKD. The primary outcome was muscle depletion, which was defined as a decline in fat-free mass index (FFMI) below the 10th percentile of all subjects. The secondary outcomes included the occurrence of cachexia, all-cause mortality, and the slopes of changes in fat-free mass and weight. During 73,059 person-years of follow-up, muscle depletion and cachexia occurred in 460 (7.4%) and 210 (3.4%), respectively. In the multivariable cause-specific hazards model, the risk of muscle depletion was significantly higher in subjects with DM alone than in those without DM and CKD (HR, 1.37; 95% CI, 1.04-1.80) and was strongly pronounced in subjects with both conditions (HR, 3.38; 95% CI, 1.30-8.75). The secondary outcome analysis showed consistent results. The annual decline rates in FFMI, fat mass, and body mass index (BMI) were the steepest in subjects with DM and CKD among the four groups. DM and CKD are synergically associated with muscle loss over time. In addition, the mortality risk is higher in individuals with muscle loss.

Smoking Cessation and Coronary Artery Calcification in CKD.

BACKGROUND AND OBJECTIVES: Smoking is associated with vascular calcification and a higher risk of cardiovascular disease. In this study, we investigated the association of smoking dose and cessation with coronary artery calcification (CAC) in patients with CKD. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: From a nationwide, prospective cohort of Korean patients with CKD, 1914 participants were included. Prevalent CAC was defined as an Agatston score >0, using computed tomography. CAC progression was defined as ≥30%/yr increase in Agatston score at the 4-year follow-up examination in patients with baseline CAC. RESULTS: Prevalent CAC was observed in 952 (50%) patients. Compared with never smokers, former smokers had a similar prevalence ratio for CAC, but current smokers had a 1.25-fold higher prevalence ratio (95% confidence interval [95% CI], 1.10 to 1.42). Among former smokers, a lower smoking load of <10 pack-years (prevalence ratio, 0.77; 95% CI, 0.65 to 0.90) and longer duration of smoking cessation (prevalence ratio for 10 to <20 years, 0.85; 95% CI, 0.73 to 0.98: prevalence ratio for ≥20 years, 0.83; 95% CI, 0.73 to 0.96) were associated with lower risk of prevalent CAC compared with current smoking. The prevalence ratios did not differ between never smoking and long-term cessation. However, short-term cessation with heavy smoking load was associated with a higher risk of prevalent CAC (prevalence ratio, 1.21; 95% CI, 1.03 to 1.40) compared with never smoking. CAC progression was observed in 111 (33%) patients with baseline CAC. Compared with never smokers, former smokers showed a similar risk of CAC progression, but current smokers had a higher risk (relative risk, 1.92; 95% CI, 1.30 to 2.86). CONCLUSIONS: In CKD, former smoking with a lower smoking load and long-term cessation were associated with a lower risk of prevalent CAC than current smoking. CAC progression was more pronounced in current smokers.

Association between the transtubular potassium gradient and progression of chronic kidney disease: results from KNOW-CKD.

BACKGROUND: The transtubular potassium gradient which reflects potassium secretion by the kidney through the cortical collecting duct, has not yet been tested as a surrogate marker of kidney function decline. Here, we investigate the relationship between the transtubular potassium gradient and chronic kidney disease (CKD) progression. METHODS: We studied 1672 patients from the KoreaN Cohort Study for Outcome in Patients With Chronic Kidney Disease (KNOW-CKD) cohort. The transtubular potassium gradient was calculated using a standard equation. The study endpoint was CKD progression, defined as a composite of a ≥ 50% decrease in estimated glomerular filtration rate (eGFR) from baseline values or end-stage kidney disease. RESULTS: During a median follow-up of 4.1 years (7149 person-years), 441 participants reached the endpoint. In cause-specific competing risk analysis, the highest tertile was associated with a significantly lower risk of an adverse kidney outcome compared with the lowest tertile [hazard ratio (HR), 0.73; 95% confidence interval (CI), 0.55-0.97]. When the transtubular potassium gradient was treated as a continuous variable, an increase of 1 in the transtubular potassium gradient was associated with a 6% lower risk of CKD progression (95% CI, 0.90-0.99). This association was particularly evident in patients with an eGFR ≥ 45 mL/min/1.73 m2. A time-updated transtubular potassium gradient model showed similar results. The predictive performance of the transtubular potassium gradient was significantly less than that of the eGFR, but similar to that of proteinuria, serum bicarbonate, and urine osmolality. CONCLUSIONS: A higher transtubular potassium gradient is associated with a significantly lower risk of CKD progression, suggesting that it may offer insights into the prognosis of CKD.

Systolic blood pressure and chronic kidney disease progression in patients with primary glomerular disease.

INTRODUCTION: Many current guidelines on optimal target blood pressure (BP) for chronic kidney disease (CKD) patients are largely based on studies in diabetic and hypertensive patients. However, there have been few studies in patients with glomerular diseases. METHODS: We retrospectively studied the longitudinal association between BP and CKD progression in 1,066 biopsy-proven patients diagnosed with primary glomerular diseases, including IgA nephropathy, membranous nephropathy (MN), and focal segmental glomerulosclerosis (FSGS), between 2005 and 2017. The main predictor was time-updated systolic blood pressure (SBP) at every clinic visit. The primary outcome was a composite one including ≥ 50% decrease in estimated glomerular filtration rate (eGFR) from the baseline, and end-stage kidney disease (ESKD). RESULTS: During 5009 person-years of follow-up, the primary outcome occurred in 157 (14.7%) patients. In time-varying Cox model, the adjusted hazard ratios (HRs) (95% confidence interval (CI)) for the primary outcome were 1.48 (0.96-2.29), 2.07 (1.22-3.52), and 2.53 (1.13-5.65) for SBP of 120-129, 130-139, and ≥ 140 mmHg, respectively, compared with SBP < 120 mmHg. This association was particularly evident in patients with elevated proteinuria. However, there was no association between baseline SBP and adverse kidney outcomes. Finally, prediction models failed to show the improvement of predictive performance of SBP compared with that of remission status. Moreover, patients with remission and less controlled SBP had better kidney outcomes than those with non-remission and well-controlled SBP. CONCLUSION: Among patients with glomerular disease, higher time-updated SBP was significantly associated with higher risk of CKD progression. However, the clinical significance of blood pressure was less powerful than remission status.

Smoking, Smoking Cessation, and Progression of Chronic Kidney Disease: Results From KNOW-CKD Study.

INTRODUCTION: In patients with chronic kidney disease (CKD), studies investigating the association between smoking and deterioration of kidney function are scarce. AIMS AND METHODS: We analyzed data for 1,951 patients with an estimated glomerular filtration rate (eGFR) ≥15 mL/min/1.73 m2 enrolled in the KoreaN cohort study for Outcome in patients With Chronic Kidney Disease (KNOW-CKD) from 2011 to 2016. Patients were categorized by smoking load. Primary outcome was a composite of a ≥50% reduction in eGFR, initiation of dialysis, or kidney transplantation. RESULTS: There were 967 never-smokers and 369, 276, and 339 smokers who smoked <15, 15 to 29, ≥30 pack-years, respectively. During a mean follow-up of 3.0 years, the incidence rates (95% confidence interval [CI]) of the primary outcome were 54.3 (46.4-63.5), 46.9 (35.9-61.4), 69.2 (52.9-90.6), and 76.3 (60.7-96.0) events per 1,000 person-yr in never-, <15, 15 to 29, and ≥30 pack-year smokers. In cause-specific hazard model after adjustment of confounding factors, smokers were associated with 1.09 (0.73-1.63), 1.48 (1.00-2.18), and 1.94 (1.35-2.77) fold increased risk (95% CI) of primary outcome in <15, 15-29, and ≥30 pack-year smokers compared with never-smokers. The association of longer smoking duration with higher risk of CKD progression was evident particularly in patients with eGFR < 45 mL/min/1.73 m2 and proteinuria ≥ 1.0 g/g. In contrast, the risk of adverse kidney outcome decreased with longer smoking-free periods among former-smokers. CONCLUSIONS: These findings suggest potentially harmful effects of the degree of exposure to smoking on the progression of CKD. IMPLICATIONS: Among patients with CKD, there has been lack of studies on the association between smoking and CKD progression and studies to date have yielded conflicting results. In this prospective cohort study involving Korean CKD patients, smoking was associated with significantly higher risk of worsening kidney function. Furthermore, the risk of adverse kidney outcome was incrementally higher as smoking pack-years were higher. As the duration of smoking cessation increased, the hazard ratios for adverse kidney outcome were attenuated, suggesting that quitting smoking may be a modifiable factor to delay CKD progression.

Creatinine-Cystatin C Ratio and Mortality in Patients Receiving Intensive Care and Continuous Kidney Replacement Therapy: A Retrospective Cohort Study.

RATIONALE & OBJECTIVE: Studies have suggested associations between lower ratios of serum creatinine to cystatin C with both lower muscle mass and adverse clinical outcomes in multiple disease conditions. Identifying risk factors for mortality among patients with acute kidney injury (AKI) undergoing continuous kidney replacement therapy (CKRT) may improve assessment of prognosis. We sought to evaluate the association of creatinine-cystatin C ratio with outcomes in patients with AKI undergoing CKRT. STUDY DESIGN: Retrospective cohort study. SETTING & PARTICIPANTS: 1,588 patients treated with intensive care and CKRT for AKI at a tertiary Korean medical center. PREDICTOR: Baseline serum creatinine-cystatin C ratio at the time of CKRT initiation. OUTCOMES: Age- and sex-adjusted 90-day mortality after CKRT initiation. ANALYTICAL APPROACH: Cox proportional hazard models to estimate the association between creatinine-cystatin C ratio and outcome. RESULTS: Mean age was 64.7 ± 14.5 years and 635 patients (40.0%) were women. The range of creatinine-cystatin C ratios was 0.08 to 10.48. The 30- and 90-day mortality rates were significantly lower for the higher creatinine-cystatin C ratio groups. Multivariable Cox proportional hazards regression analyses revealed that mortality risk became successively lower across quartiles of greater creatinine-cystatin C ratio. When creatinine-cystatin C ratio was evaluated using cubic spline analyses, risks for both 30- and 90-day mortality were lower with higher creatinine-cystatin C ratios. These associations remained significant even after adjustment for confounding variables. LIMITATIONS: Retrospective analysis, serum creatinine and cystatin C may not be in steady state in the setting of AKI. CONCLUSIONS: Higher serum creatinine-cystatin C ratios were associated with better survival in patients receiving intensive care and CKRT.

Dietary zinc intake and incident chronic kidney disease.

BACKGROUND & AIMS: Previous studies have shown that dietary zinc intake is closely related to cardiovascular complications and metabolic derangements. However, the effect of dietary zinc intake on renal function is not fully elucidated. METHODS: Data from the Korean Genome and Epidemiology Study were used. Dietary zinc intake was assessed by a Food Frequency Questionnaire and dietary zinc density was calculated as absolute zinc intake amount per daily energy intake (mg/1000 kcal day). The participants were categorized into quartiles according to dietary zinc density. The primary end point was incident chronic kidney disease (CKD), defined as estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m2. RESULTS: A total of 7735 participants with normal renal function was included in the final analysis. The mean age was 52.0 ± 8.8 years, 47.5% were male, and mean eGFR was 92.1 ± 16.1 ml/min/1.73 m2. The mean daily zinc intake and zinc intake density were 8.6 ± 3.4 mg and 4.4 ± 0.9 mg/1000 kcal, respectively. During a median follow up of 11.5 (1.7-12.5) years and 70,617 person-years of observation, CKD developed in 1409 (18.2%) participants. Multivariable cox hazard analysis revealed that risk for CKD development was significantly higher in the quartile with a mean zinc intake density of 3.6 ± 0.2 mg/1000 kcal compared with the quartile with a mean zinc intake density of 5.6 ± 1.0 mg/1000 kcal (Hazard ratio; 1.36; 95% Confidence Interval 1.18-1.58; P < 0.001). This relationship remained significant even after adjustments for confounding factors. CONCLUSION: Low dietary zinc intake may increase the risk of CKD development in individuals with normal renal function.

Association of Reproductive Lifespan Duration and Chronic Kidney Disease in Postmenopausal Women.

OBJECTIVE: To investigate the relationship between endogenous estrogen exposure and renal function, the association of female reproductive life span duration (RLD) and chronic kidney disease (CKD) was analyzed in postmenopausal women. PATIENTS AND METHODS: Data were retrieved from the Korean Genome and Epidemiology Study, which was constructed from May 1, 2001, through December 25, 2017. A total of 50,338 and 3155 postmenopausal women were each included in the cross-sectional and longitudinal analyses. The RLD was determined by subtracting the age at menarche from the age at menopause. Participants were grouped into RLD quartiles. Participants with estimated glomerular filtration rates less than 60 mL/min/1.73 m2 were regarded to have CKD. RESULTS: In the cross-sectional analysis, mean ± SD age and estimated glomerular filtration rate were 56.3±4.9 years and 93.1±13.6 mL/min/1.73 m2, respectively. Mean ± SD RLD was 34.2±4.0 years. A total of 765 of 50,338 (1.52%) women were found to have CKD. Logistic regression analysis revealed that the odds ratio for CKD was lower in groups with longer RLDs as compared with the shortest RLD group. In longitudinal analysis, postmenopausal women with normal kidney function were followed up for 9.7 years and incident CKD occurred in 221 of 3155 (7.00%) participants. Cox analysis revealed that the risk for CKD development was significantly lower in longer RLD groups. This finding was significant even after adjustments for confounding factors. CONCLUSION: The risk for CKD was lower in women with longer RLDs. The amount of endogenous estrogen exposure could be a determining factor for renal function in postmenopausal women.

Association of smoking with incident CKD risk in the general population: A community-based cohort study.

BACKGROUND: Chronic kidney disease (CKD) is a public health problem, and an unfavorable lifestyle has been suggested as a modifiable risk factor for CKD. Cigarette smoking is closely associated with cardiovascular disease and cancers; however, there is a lack of evidence to prove that smoking is harmful for kidney health. Therefore, we aimed to determine the relationship between cigarette smoking and CKD among healthy middle-aged adults. METHODS: Using the database from the Korean Genome and Epidemiology Study, we analyzed 8,661 participants after excluding those with baseline estimated glomerular filtration rate (eGFR)<60 ml/min/1.72 m2 or proteinuria. Exposure of interest was smoking status: never-, former-, and current-smokers. Primary outcome was incident CKD defined as eGFR <60 ml/min/1.73 m2 or newly developed proteinuria. RESULTS: The mean age of the subjects was 52 years, and 47.6% of them were males. There were 551 (6.4%) and 1,255 (14.5%) subjects with diabetes and hypertension, respectively. The mean eGFR was 93.0 ml/min/1.73 m2. Among the participants, 5,140 (59.3%), 1,336 (15.4%), and 2,185 (25.2%) were never-smokers, former-smokers, and current-smokers, respectively. During a median follow-up of 11.6 years, incident CKD developed in 1,941 (22.4%) subjects with a crude incidence rate of 25.1 (24.0-26.2) per 1,000 person-years. The multivariable Cox regression analysis after adjustment of confounding factors showed hazard ratios (95% confidence interval) of 1.13 (0.95-1.35) and 1.26 (1.07-1.48) for CKD development in the former- and current-smokers, compared with never-smokers. CONCLUSION: This study showed that smoking was associated with a higher risk of incident CKD among healthy middle-aged adults.

High muscle-to-fat ratio is associated with lower risk of chronic kidney disease development.

BACKGROUND: Obesity, a known risk factor for chronic kidney disease (CKD), is generally assessed using body mass index (BMI). However, BMI may not effectively reflect body composition, and the impact of muscle-to-fat (MF) mass balance on kidney function has not been elucidated. This study evaluated the association between body muscle and fat mass balance, represented as the MF ratio, and incident CKD development. METHODS: Data were retrieved from a prospective community-based cohort study (Korean Genome and Epidemiology Study). Muscle and fat mass were measured using multifrequency bioelectrical impedance analysis. The study endpoint was incident CKD (estimated glomerular filtration rate <60 mL/min/1.73 m2 in at least two or more consecutive measurements during the follow-up period). RESULTS: Totally, 7682 participants were evaluated. Their mean age was 51.7 ± 8.7 years, and 48% of the subjects were men. During a median follow-up of 140.0 (70.0-143.0) months, 633 (8.2%) subjects developed incident CKD. When the association between body composition and incident CKD was investigated, multivariable Cox proportional hazard analysis revealed that increase in MF ratio was related with a decreased risk of CKD development [per 1 increase in MF ratio: hazard ratio (HR), 0.86; 95% confidence interval (CI), 0.77-0.96; P = 0.008]. This association was also maintained when MF ratio was dichotomized according to sex-specific median values (high vs. low: HR, 0.83; 95% CI, 0.70-0.98; P = 0.031). Analyses preformed in a propensity score matched group also revealed a similar decreased risk of incident CKD in high MF ratio participants (high vs. low: HR, 0.84; 95% CI, 0.71-0.98; P = 0.037). This relationship between MF ratio and incident CKD risk was consistently significant across subgroups stratified by age, sex, hypertension, estimated glomerular filtration rate categories, and proteinuria. Among different BMI groups (normal, overweight, and obese), the relationship between high MF ratio and lower incident CKD risk was significant only in overweight and obese subjects. CONCLUSIONS: Lower fat mass relative to muscle mass may lower the risk of CKD development in individuals with normal renal function. This relationship seems more prominent in overweight and obese subjects than in normal weight subjects.

Predictive value of mesangial C3 and C4d deposition in IgA nephropathy.

We aimed to determine the relative contribution of each complement (C3 and C4d) deposition to the progression of IgA nephropathy (IgAN). We enrolled a total of 380 patients with biopsy-confirmed IgAN. Mesangial deposition of C3(<2+ vs. ≥2+) and C4d(positive vs. negative) was evaluated by immunofluorescence staining and immunohistochemistry, respectively. Study endpoint was the composite of a 30% decline in eGFR or ESRD. The risk of reaching the primary outcome was significantly higher in patients having C3 ≥ 2+ and C4d(+) than in corresponding counterparts. Adding C3 deposition to clinical data acquired at kidney biopsy modestly increased the area under the receiver-operating characteristic curve, net reclassification improvement, and integrated discrimination improvement (IDI); adding C4d increased IDI only. In conclusion, mesangial C3 and C4d deposition was an independent risk factor for progression of IgAN. C3 showed better predictability than C4d, suggesting that lectin pathway alone has limited clinical prognostic value.

Secondhand Smoke and CKD.

BACKGROUND AND OBJECTIVES: Active smoking is associated with higher risk of various diseases. However, the risk of CKD development in nonsmokers exposed to secondhand smoke is not well elucidated. We aimed to investigate the association between secondhand smoke exposure and the risk of CKD development among never-smokers. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: A total of 131,196 never-smokers with normal kidney function, who participated in the Korean Genome and Epidemiology Study from 2001 to 2014, were analyzed. The participants were classified into three groups on the basis of frequency of secondhand smoke exposure, assessed with survey questionnaires; no exposure, <3 days per week, and ≥3 days per week. The association between secondhand smoke and CKD, defined as eGFR<60 ml/min per 1.73 m2, was examined in the cross-sectional analysis. In addition, the risk of incident CKD development was analyzed in a longitudinal cohort of 1948 participants without CKD at baseline, which was a subset of the main cohort. RESULTS: The mean age of participants was 53 years, and 75% were women. Prevalent CKD was observed in 231 (1.8%), 64 (1.7%), and 2280 (2.0%) participants in the ≥3 days per week, <3 days per week, and no exposure groups. The odds ratio (OR) of prevalent CKD was significantly higher in the groups exposed to secondhand smoke than the no exposure group (<3 days per week: OR, 1.72; 95% confidence interval [95% CI], 1.30 to 2.27; and ≥3 days per week: OR, 1.44; 95% CI, 1.22 to 1.70). During a mean follow-up of 104 months, CKD occurred in 319 (16%) participants. Multivariable Cox analysis revealed that the risk for CKD development was higher in participants exposed to secondhand smoke than the no exposure group (<3 days per week: hazard ratio, 1.59; 95% CI, 0.96 to 2.65; and ≥3 days per week: hazard ratio, 1.66; 95% CI, 1.03 to 2.67). CONCLUSIONS: Exposure to secondhand smoke was associated with a higher prevalence of CKD as well as development of incident CKD.

Incidence of Acute Kidney Injury after Adrenalectomy in Patients with Primary Aldosteronism.

BACKGROUND: Aldosterone-induced glomerular hyperfiltration can lead to masked preoperative renal dysfunction in primary aldosteronism(PA) patients. We evaluated whether PA patients had a higher prevalence of acute kidney injury (AKI) after unilateral adrenalectomy. In addition, we identified risk factors for AKI in these subjects. METHODS: This retrospective study included 107 PA patients, and 186 pheochromocytoma patients as a control group, all of whom underwent adrenalectomy between January 2006 and November 2017 at Yonsei University Severance Hospital. The primary outcome was AKI within 48 hours after adrenalectomy. Univariate and multivariate logistic regression analyses were performed to identify predictors of AKI after adrenalectomy. RESULTS: Overall incidence of AKI was 49/293 (16.7%). In PA patients, the incidence of AKI was 29/107 (27.1%). In contrast, incidence of AKI was 20/186 (10.7%) in pheochromocytoma patients. Univariate and multivariate logistic regression analysis both showed a higher risk of postoperative AKI in PA patients compared to pheochromocytoma patients. In addition, old age, diabetes, longer duration of hypertension, lower preoperative estimated glomerular filtration rate, high aldosterone-cortisol ratio (ACR) and lateralization index (LI) were identified as independent risk factors for postoperative AKI in PA patients after unilateral adrenalectomy. CONCLUSION: Incidence and risk of postoperative AKI were significantly higher in PA patients after surgical treatment. High ACR on the tumor side and high LI were associated with higher risk of AKI in PA patients compared to pheochromocytoma patients.