Predicting outcomes of continuous renal replacement therapy using body composition monitoring: a deep-learning approach

Fluid balance is a critical prognostic factor for patients with severe acute kidney injury (AKI) requiring continuous renal replacement therapy (CRRT). This study evaluated whether repeated fluid balance monitoring could improve prognosis in this clinical population. This was a multicenter retrospective study that included 784 patients (mean age, 67.8 years; males, 66.4%) with severe AKI requiring CRRT during 2017-2019 who were treated in eight tertiary hospitals in Korea. Sequential changes in total body water were compared between patients who died (event group) and those who survived (control group) using mixed-effects linear regression analyses. The performance of various machine learning methods, including recurrent neural networks, was compared to that of existing prognostic clinical scores. After adjusting for confounding factors, a marginal benefit of fluid balance was identified for the control group compared to that for the event group (p = 0.074). The deep-learning model using a recurrent neural network with an autoencoder and including fluid balance monitoring provided the best differentiation between the groups (area under the curve, 0.793) compared to 0.604 and 0.606 for SOFA and APACHE II scores, respectively. Our prognostic, deep-learning model underlines the importance of fluid balance monitoring for prognosis assessment among patients receiving CRRT.

Association between depressive symptoms and the risk of all-cause and cardiovascular mortality among US adults

Depression is a preventable and treatable mental health condition. Therefore, there are important clinical implications for identifying people with the highest mortality risk in a nationally representative sample. This study included 26,207 participants aged ≥18 years from the 2005-2014 National Health and Nutrition Examination Survey in USA. We investigated the association between depressive symptoms (defined as Patient Health Questionnaire 9 scores ≥10) and all-cause and cardiovascular disease (CVD) mortalities, adjusted for multiple factors (sociodemographic in Model 1, behavioral added in Model 2, and metabolic syndrome added in Model 3) and stratified by age and sex. During an average follow-up of 69.15 months (standard deviation [SD] 34.45), 1872 (7.3%) participants had died (person-years in the non-depressive and depressive groups, 12.12/1000 and 16.43/1000, respectively). Depressive symptoms increased all-cause (crude hazard ratio [HR] 1.37, 95% confidence interval [CI], 1.33-1.58) and CVD mortalities (crude HR 1.64, 95% CI, 1.20-2.24). Although the significance of all-cause mortality and CVD mortality was maintained in Models 1 (HR 1.58 and 2.08) and 2 (HR 1.48 and 1.79), it was not maintained in Model 3. Current smoking and lower physical activity were associated with reduced strength of the association between depression and all-cause mortality risk. The effect of depression on mortality risk was particularly pronounced in middle-aged men and older women. Our findings suggest that depressive symptoms increase mortality risk, even after adjusting for behavioral factors. Depression-induced mortality risk is particularly high among middle-aged men and older women.

Associations between greenness and kidney disease in Massachusetts: The US Medicare longitudinal cohort study

BACKGROUND

Recent studies have identified the association of environmental stressors with reduced kidney function and the development of kidney disease. While residential greenness has been linked to many health benefits, the association between residential greenness and the development of kidney disease is not clear. We aimed to investigate the association between residential greenness and the development of kidney disease.

METHODS

We performed a longitudinal population-based cohort study including all fee-for-service Medicare Part A beneficiaries (aged 65 years or older) in Massachusetts (2000-2016). We assessed greenness with the annual average Enhanced Vegetation Index (EVI) based on residential ZIP codes of beneficiaries. We applied Cox-equivalent Poisson models to estimate the association between EVI and first hospital admission for total kidney disease, chronic kidney disease (CKD), and acute kidney injury (AKI), separately.

RESULTS

Data for 1,462,949 beneficiaries who resided in a total of 644 ZIP codes were analyzed. The total person-years of follow-up for total kidney disease, CKD, and AKI were 9.8, 10.9, and 10.8 million person-years, respectively. For a 0.1 increase in annual EVI, the hazard ratios (HRs) were 0.95 (95% CI: 0.93 to 0.97) for the first hospital admission for total kidney disease, and the association was more prominent for AKI (HR: 0.94 with 95% CI: 0.92 to 0.97) than CKD (HR: 0.98 with 95% CI: 0.95-1.01]). The estimated effects of EVI on kidney disease were generally more evident in White beneficiaries and those residing in metropolitan areas compared to the overall population.

CONCLUSIONS

This study found that higher levels of annual residential greenness were associated with a lower risk of the first hospital admission for kidney diseases. Results are consistent with the hypothesis that higher residential greenness benefits kidney patients.

Causal linkage of tobacco smoking with ageing: Mendelian randomization analysis towards telomere attrition and sarcopenia

BACKGROUND

Ageing traits and frailty are important health issues in modern medicine. Evidence supporting the causal effects of tobacco smoking on various ageing traits is required.

METHODS

This study performed Mendelian randomization (MR) analysis instrumenting 377 genetic variants associated with being an ever-smoker at a genome-wide significance level to test the causal estimates from tobacco smoking. The outcome data were obtained from 337 138 white British ancestry participants from the UK Biobank. Leucocyte telomere length, appendicular lean mass index, subjective walking pace, handgrip strength, and wristband accelerometry-determined physical activity degree were collected as ageing-related outcomes. Summary-level MR analysis was performed using the inverse variance-weighted method and pleiotropy-robust MR methods, including weighted median and MR-Egger. Observational association between the outcome traits and phenotypically being an ever-smoker was also investigated.

RESULTS

Summary-level MR analysis indicated that a higher genetic predisposition for tobacco smoking was significantly associated with shorter leucocyte telomere length (twofold increase in prevalence of smoking towards standardized Z-score, -0.041 [-0.054, -0.028]), lower appendicular lean mass index (-0.007 [-0.010, -0.005]), slower walking pace (ordinal category, -0.047 [-0.054, -0.033]) and lower time spent on moderate-to-vigorous physical activity (hours per week, -0.39 [-0.56, -0.23]). The causal estimates were non-significant towards handgrip strength phenotype (kg, 0.074 [-0.055, 0.204]). Pleiotropy-robust MR results generally supported the main causal estimates. The observational findings also showed significant association between being an ever-smoker and the ageing traits.

CONCLUSIONS

Genetically predicted and observational tobacco smoking status are significantly associated with poor ageing phenotypes. Healthcare providers may continue to reduce tobacco use, which may be helpful in reducing the burden of ageing and frailty.

Genetically predicted body selenium concentration and eGFR: A Mendelian randomization study

Introduction

Selenium is a trace mineral that is commonly included in micronutrient supplements. The effect of selenium on kidney function remains unclear. A genetically predicted micronutrient and its association with estimated glomerular filtration rate (eGFR) can be used to assess the causal estimates by Mendelian randomization (MR).

Methods

In this MR study, we instrumented 11 genetic variants associated with blood or total selenium levels from a previous genome-wide association study (GWAS). The association between genetically predicted selenium concentration and eGFR was first assessed by summary-level MR in the chronic kidney disease(CKDGen) GWAS meta-analysis summary statistics, including 567,460 European samples. Inverse-variance weighted and pleiotropy-robust MR analyses were performed, in addition to multivariable MR adjusted for the effects of type 2 diabetes mellitus. Replication analysis was performed with individual-level UK Biobank data, including 337,318 White individuals of British ancestry.

Results

Summary-level MR analysis indicated that a genetically predicted 1 SD increase in selenium concentration was significantly associated with lower eGFR (-1.05 [-1.28, -0.82] %). The results were similarly reproduced by pleiotropy-robust MR analysis, including MR-Egger and weighted-median methods, and consistent even in the multivariable MR adjusted for diabetes. In the UK Biobank data, genetically predicted higher selenium concentration was also significantly associated with lower eGFR (- 0.36 [-0.52, -0.20] %), and the results were similar when body mass index, waist circumference, hypertension, and diabetes mellitus covariates were adjusted (-0.33 [-0.50, -0.17] %).

Conclusion

This MR study supports the hypothesis that higher genetically predicted body selenium is causally associated with lower eGFR.

Excess mortality and the COVID-19 pandemic: causes of death and social inequalities

BACKGROUND

During the coronavirus diseases 2019 (COVID-19) pandemic, population's mortality has been affected not only by the risk of infection itself, but also through deferred care for other causes and changes in lifestyle. This study aims to investigate excess mortality by cause of death and socio-demographic context during the COVID-19 pandemic in South Korea.  METHODS: Mortality data within the period 2015-2020 were obtained from Statistics Korea, and deaths from COVID-19 were excluded. We estimated 2020 daily excess deaths for all causes, the eight leading causes of death, and according to individual characteristics, using a two-stage interrupted time series design accounting for temporal trends and variations in other risk factors.

RESULTS

During the pandemic period (February 18 to December 31, 2020), an estimated 663 (95% empirical confidence interval [eCI]: -2356-3584) excess deaths occurred in South Korea. Mortality related to respiratory diseases decreased by 4371 (3452-5480), whereas deaths due to metabolic diseases and ill-defined causes increased by 808 (456-1080) and 2756 (2021-3378), respectively. The increase in all-cause deaths was prominent in those aged 65-79 years (941, 88-1795), with an elementary school education or below (1757, 371-3030), or who were single (785, 384-1174), while a decrease in deaths was pronounced in those with a college-level or higher educational attainment (1471, 589-2328).

CONCLUSION

No evidence of a substantial increase in all-cause mortality was found during the 2020 pandemic period in South Korea, as a result of a large decrease in deaths related to respiratory diseases that offset increased mortality from metabolic disease and diseases of ill-defined cause. The COVID-19 pandemic has disproportionately affected those of lower socioeconomic status and has exacerbated inequalities in mortality.

Plasma Circulating Tumor Necrosis Factor Receptors at Multiple Time Points Can Predict the Outcome of Severe Acute Kidney Injury

INTRODUCTION

This prospective cohort study investigated the clinical role of circulating tumor necrosis factor receptor (cTNFR) levels as prognostic biomarkers in severe acute kidney injury (AKI) patients requiring continuous renal replacement therapy (CRRT).

METHODS

We enrolled 136 patients from 7 hospitals participating in the VENUS (VolumE maNagement Under body composition monitoring in critically ill patientS on CRRT) trial from July 2017 to October 2019. The levels of cTNFR1 and cTNFR2 were measured using plasma samples collected on days 0 (D0), 2 (D2), and 7 (D7). Patients were divided into high- and low-cTNFR groups based on their receptor concentrations.

RESULTS

D0 concentrations of cTNFR1 and cTNFR2 were positively correlated with one another (R2 = 0.37, p < 0.001). The high-cTNFR1 group displayed a higher in-hospital mortality rate than the low-TNFR1 group (p = 0.002). Moreover, the mortality rate was significantly higher in the high-TNFR1 group than in the low-TNFR1 group after adjusting for age, sex, and acute physiology, and chronic health evaluation II scores (hazard ratio 1.82, 95% confidence interval 1.09-3.03, p = 0.025). D2 and D7 cTNFR1 levels were also associated with in-hospital mortality; contrastingly, cTNFR2 levels were not associated with this outcome. Additionally, patients were divided into three groups according to the change in cTNFR levels from D0 to D2 (ΔcTNFR). Those in the highest ΔcTNFR tertile had a higher mortality rate than the remaining patients (p = 0.033 for ΔcTNFR1; p = 0.025 for ΔcTNFR2). Patients who underwent AKI-to-chronic kidney disease transition had higher concentrations of cTNFR1 (p = 0.014).

DISCUSSION/CONCLUSION

Plasma cTNFR1 concentrations at CRRT initiation and changes in cTNFR1 and 2 levels immediately following CRRT initiation are significant biomarkers for predicting the outcomes of patients with severe AKI.

Development of New Equations Predicting the Mortality Risk of Patients on Continuous RRT

Background

Predicting the risk of death in patients admitted to the critical care unit facilitates appropriate management. In particular, among patients who are critically ill, patients with continuous RRT (CRRT) have high mortality, and predicting the mortality risk of these patients is difficult. The purpose of this study was to develop models for predicting the mortality risk of patients on CRRT and to validate the models externally.

Methods

A total of 699 adult patients with CRRT who participated in the VolumE maNagement Under body composition monitoring in critically ill patientS on CRRT (VENUS) trial and 1515 adult patients with CRRT in Seoul National University Hospital were selected as the development and validation cohorts, respectively. Using 11 predictor variables selected by the Cox proportional hazards model and clinical importance, equations predicting mortality within 7, 14, and 28 days were developed with development cohort data.

Results

The equation using 11 variables had area under the time-dependent receiver operating characteristic curve (AUROC) values of 0.75, 0.74, and 0.73 for predicting 7-, 14-, and 28-day mortality, respectively. All equations had significantly higher AUROCs than the Sequential Organ Failure Assessment (SOFA) and Acute Physiology and Chronic Health Evaluation II (APACHE II) scores. The 11-variable equation was superior to the SOFA and APACHE II scores in the integrated discrimination index and net reclassification improvement analyses.

Conclusions

The newly developed equations for predicting CRRT patient mortality showed superior performance to the previous scoring systems, and they can help physicians manage patients.

The FimAsartaN proTeinuriA SusTaIned reduCtion in comparison with losartan in diabetic chronic kidney disease (FANTASTIC) trial

As angiotensin II type 1 receptor blockers (ARBs) may have different antiproteinuric effects in diabetic kidney disease (DKD), we ascertained the albuminuria-reducing effect of fimasartan and losartan in patients with DKD. This was a randomized, multicenter, double-blind, 4-parallel-group, dose-titration, phase III study designed to compare the efficacy of fimasartan and losartan in reducing albuminuria in patients with DKD (NCT02620306). The primary endpoint was the rate of change in albuminuria from baseline to week 24. A total of 341 patients were randomized to different groups. The urinary albumin-to-creatinine ratio (ACR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were not different between the fimasartan and losartan groups at baseline (ACR: 1376.84 vs. 1521.07 mg/gCr, SBP: 154.69 vs. 154.47 mmHg, DBP: 83.96 vs. 83.83 mmHg). However, ACR reduction was significantly larger in the fimasartan group than in the losartan group during the entire study period (% changes in the ACR at 4, 8, 12, and 24 weeks were -23.58, -33.06, -35.00, and -38.13 in the fimasartan group vs. -8.74, -10.17, -14.91, and -19.71 in the losartan group, p < 0.01, respectively). The superior antiproteinuric effect of fimasartan compared to losartan was still significant after adjustment for SBP levels. There were no significant differences in adverse events, including the incidences of estimated glomerular filtration decline and hyperkalemia. This study demonstrates that compared to losartan, fimasartan significantly reduces albuminuria in patients with DKD, even after adjustment for SBP and DBP.

Association between homocysteinemia and mortality in CKD: A propensity-score matched analysis using NHANES-National Death Index

Hyperhomocysteinemia (HHcy) is considered a risk factor for cardiovascular disease (CVD), including chronic kidney disease (CKD). In this study, we investigated the association between levels of serum homocysteine (Hcy) and mortality, inferred from the presence of CKD. Our study included data of 9895 participants from the 1999 to 2016 National Health and Nutrition Examination Surveys (NHANES). Multivariable-adjusted Cox proportional hazard models using propensity-score, were used to examine dose-response associations between Hcy level and mortality. A total of 9895 participants, 1025 (10.3%) participants were diagnosed with CKD. In a multivariate Cox regression analysis including all participants, Hcy level was significantly associated with all-cause mortality in the nonCKD group, compared to the 1st quartile in the fully adjusted model (2nd quartile: hazard ratio (HR) 1.75, 95% confidence interval (CI) 1.348-2.274, P < .001; 3rd quartile: HR 2.22, 95% CI 1.726-2.855, P < .001; 4th quartile: HR 3.77, 95% CI 2.952-4.830, P < .001). However, this finding was not observed in the CKD group. The observed pattern was similar after propensity score matching. In the nonCKD group, overall mortality increased in proportion to Hcy concentration (2nd quartile: HR 2.19, 95% CI 1.299-3.709, P = .003; 3rd quartile: HR 2.60, 95% CI 1.570-4.332, P < .001; 4th quartile: HR 3.72, 95% CI 2.254-6.139, P < .001). However, the risk of all-cause mortality according to the quartile of Hcy level, did not increase in the CKD group. This study found a correlation between the Hcy level and mortality rate only in the nonCKD group. These altered risk factor patterns may be attributed to protein-energy wasting or chronic inflammation status, that is accompanied by CKD.

Insufficient early renal recovery and progression to subsequent chronic kidney disease in living kidney donors

BACKGROUND/AIMS

Renal recovery of a kidney donor after undergoing nephrectomy though challenging is essential. We aimed to examine the effect of estimated glomerular filtration rate (eGFR) percent change at 1-month post-donation on insufficient kidney function after kidney donation.

METHODS

A total of 3,952 living kidney donors who underwent donor nephrectomy from 1982 to 2019 from eight different tertiary hospitals in Korea were initially screened. Percent changes in the eGFR from baseline to 1-month post-donation were calculated. The degree of percent changes was categorized by quartile, and the 1st quartile was regarded as the group with the lowest decreased eGFR at 1-month after donation. The remaining eGFR less than 60 mL/min/1.73 m2 was the end-point. The Cox proportional hazard model was used for evaluating the impact of initial eGFR and eGFR percent change at 1-month post-donation on the condition with remaining eGFR &lt; 60 mL/ min/1.73 m2. In the multivariate analysis, we used variables with a p &lt; 0.1 in the univariate analysis.

RESULTS

A total of 1,585 donors were included in the analysis. During 62.2 ± 49.3 months, 13.7% of donors showed renal insufficiency. The 4th (adjusted hazard ratio [aHR], 10.41; 95% confidence interval [CI], 5.15 to 21.04) and the 3rd (aHR, 4.29; 95% CI, 2.15 to 8.56) quartiles of percent change in eGFR and the pre-donation eGFR (aHR, 0.90; 95% CI, 0.88 to 0.92) were associated with the development of renal insufficiency.

CONCLUSION

The impact of worse initial renal recovery on renal insufficiency was pronounced in donors with lower pre-donation eGFRs. Additionally, worse initial renal recovery of remaining kidney affected the long-term development of renal insufficiency in kidney donors.

Serum bilirubin and kidney function: a Mendelian randomization study

Background

Further investigation is needed to determine the causal effects of serum bilirubin on the risk of chronic kidney disease (CKD).

Methods

This study is a Mendelian randomization (MR) analysis. Among the well-known single-nucleotide polymorphisms (SNPs) related to serum bilirubin levels, rs4149056 in the SLCO1B1 gene was selected as the genetic instrument for single-variant MR analysis, as it was found to be less related to possible confounders than other SNPs. The association between genetic predisposition for bilirubin levels and estimated glomerular filtration rate (eGFR) or CKD was assessed in 337 129 individuals of white British ancestry from the UK Biobank cohort. Two-sample MR based on summary-level data was also performed. SNPs related to total or direct bilirubin levels were collected from a previous genome-wide association study and confounder-associated SNPs were discarded. The independent CKDGen meta-analysis data for CKD were employed as the outcome summary statistics.

Results

The alleles of rs4149056 associated with higher bilirubin levels were associated with better kidney function in the UK Biobank data. In the summary-level MR, both of the genetically predicted total bilirubin {per 5 µmol/L increase; odds ratio [OR] 0.931 [95% confidence interval (CI) 0.871-0.995]} and direct bilirubin [per 1 µmol/L increase; OR 0.910 (95% CI 0.834-0.993)] levels were significantly associated with a lower risk of CKD, supported by the causal estimates from various MR sensitivity analyses.

Conclusion

Genetic predisposition for higher serum bilirubin levels is associated with better kidney function. This result suggests that higher serum bilirubin levels may have causal protective effects against kidney function impairment.

Exposure to several polychlorinated biphenyls (PCBs) is associated with chronic kidney disease among general adults: Korean National Environmental Health Survey (KoNEHS) 2015-2017

We investigated the association between major persistent organic pollutants (POPs) exposure and chronic kidney disease (CKD) among general adult population of Korea. For this purpose, a subset of the adult population (n = 1276) participated in Korean National Environmental Health Survey (KoNEHS) Cycle 3 (2015-2017) were analyzed for twenty-four POPs in serum, including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs), and were derived for estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (uACR). Multivariable linear regression was conducted to assess the association between POPs exposure and CKD-related parameters including eGFR and uACR. As sensitivity analyses, principal component analysis was conducted. Moreover, the U.S. National Health and Nutrition Examination Survey (NHANES) 1999-2004 data were chosen to compare with the observations of the Korean adults. Approximately 7.7% of the Korean adult population possessed CKD based on either eGFR (<60 ml/min/1.73 m²) or uACR (≥30 mg/g) criteria. Among the POPs that were detected in ≥70% of the subjects, PCB153 (β = -1.61, 95% CI: -2.55, -0.67, P = 0.001) and PCB180 (β = -1.47, 95% CI: -2.53, -0.40, P = 0.007) exhibited significant associations with decreased eGFR, especially in females. In male participants, hexachlorobenzene (HCB) was associated with eGFR (β = -0.79, 95% CI: -1.53, -0.04, P = 0.040). Sex-dependent associations with eGFR were also shown in the PCA model. Moreover, the sex-dependent associations of PCBs were similarly observed in the adult populations of the US NHANES. However, POPs exposure was not associated with uACR, regardless of association model or population. The observed associations of PCBs are supported by several experimental studies reported elsewhere. To our knowledge, it is the first report that suggests significant associations of PCBs and HCB with eGFR among general population, and further validations in other populations are warranted.

Zebrafish (Danio rerio) as a model organism for screening nephrotoxic chemicals and related mechanisms

Because of essential role in homeostasis of the body fluid and excretion of wastes, kidney damage can lead to severe impacts on health and survival of humans. For most chemicals, nephrotoxic potentials and associated mechanisms are unclear. Hence, fast and sensitive screening measures for nephrotoxic chemicals are required. In this study, the utility of zebrafish (Danio rerio) was evaluated for the investigation of chemical-induced kidney toxicity and associated modes of toxicity, based on the literature review. Zebrafish has a well-understood biology, and many overlapping physiological characteristics with mammals. One such characteristic is its kidneys, of which histology and functions are similar to those of mammals, although unique differences of zebrafish kidneys, such as kidney marrow, should be noted. Moreover, the zebrafish kidney is simpler in structure and easy to observe. For these advantages, zebrafish has been increasingly used as an experimental model for screening nephrotoxicity of chemicals and for understanding related mechanisms. Multiple endpoints of zebrafish model, from functional level, i.e., glomerular filtration, to transcriptional changes of key genes, have been assessed to identify chemical-induced kidney toxicities, and to elucidate underlying mechanisms. The most frequently studied mechanisms of chemical-induced nephrotoxicity in zebrafish include oxidative stress, inflammation, DNA damage, apoptosis, fibrosis, and cell death. To date, several pharmaceuticals, oxidizing agents, natural products, biocides, alcohols, and consumer chemicals have been demonstrated to exert different types of kidney toxicities in zebrafish. The present review shows that zebrafish model can be efficiently employed for quick and reliable assessment of kidney damage potentials of chemicals, and related toxic mechanisms. The toxicological information obtained from this model can be utilized for identification of nephrotoxic chemicals and hence for protection of public health.

Mendelian randomization reveals causal effects of kidney function on various biochemical parameters

The kidney is a vital organ with diverse biological effects and the burden of kidney function impairment is increasing in modern medicine. As the effects from kidney function on diverse biochemical parameters are yet fully understood, additional investigation to reveal the causal effects is warranted. Here we show the causal estimates from kidney function parameter, estimated glomerular filtration rate (eGFR), on 60 biochemical parameters by performing two-sample Mendelian randomization (MR) study in 337,138 white British UK Biobank participants. A higher genetically predicted eGFR was significantly associated with higher lymphocyte percentage, HDL cholesterol, and alanine aminotransferase. The causal estimates indicated that a higher genetically predicted eGFR was associated with lower urea, urate, insulin growth factor-1, and triglycerides levels. The parameters with significant but non-linear causal estimates were hemoglobin concentration, calcium, vitamin D, and urine creatinine values, identified by non-linear MR. Healthcare providers should understand that changes in eGFR may affect the identified biochemical parameters in diverse patterns. Future study is warranted to expand the knowledge of the mechanisms and clinical implications of the causal effects of eGFR on various biochemical parameters.

Ambient carbon monoxide correlates with mortality risk of hemodialysis patients: comparing results of control selection in the case-crossover designs

Background

Growing evidence suggests that environmental air pollution adversely affects kidney health. To date, the association between carbon monoxide (CO) and mortality in patients with end-stage renal disease (ESRD) has not been examined.

Methods

Among 134,478 dialysis patients in the Korean ESRD cohort between 2001 and 2014, 8,130 deceased hemodialysis patients were enrolled, and data were analyzed using bidirectional, unidirectional, and time-stratified case-crossover design. We examined the association between short-term CO concentration and mortality in patients with ESRD. We used a two-pollutant model, adjusted for temperature as a climate factor and for nitrogen dioxide (NO₂), sulfur dioxide (SO₂), ozone (O₃), and particulate matter less than 10 μm in diameter as air pollution variables other than CO.

Results

Characteristics of the study population included age (66.2 ± 12.1 years), sex (male, 59.1%; female, 40.9%), and comorbidities (diabetes, 55.6%; hypertension, 14.4%). Concentration of CO was significantly associated with all-cause mortality in the three case-crossover designs using the two-pollutant model adjusted for SO₂. Patients with diabetes or age older than 75 years had a higher risk of mortality than patients without diabetes or those younger than 75 years.

Conclusion

Findings presented here suggest that higher CO concentration is correlated with increased all-cause mortality in hemodialysis patients, especially in older high-risk patients.

Superior effect of allopurinol compared to febuxostat on the retardation of chronic kidney disease progression

Background

Although hyperuricemia is associated with chronic kidney disease, whether and how it should be managed for renoprotection remains debatable. Thus, we investigated whether allopurinol and febuxostat, the most frequently used urate-lowering treatments, have differential renoprotective effects on chronic kidney disease.

Methods

Incident users of allopurinol and febuxostat were identified from two tertiary referral centers. One-to-one propensity score matching between the allopurinol and febuxostat groups was performed. Participants were followed up until the occurrence of clinical outcomes, urate-lowering agent discontinuation, mortality, or the end of the study period, whichever occurred first. The primary outcomes were a 30% decline in estimated glomerular filtration rate (eGFR) and end-stage renal disease. Differential trends of eGFR decline were estimated using a linear mixed-effects model.

Results

Each group included 654 participants. Baseline eGFRs were 40.1 [26.6–57.3] and 39.1 [27.9–58.3] mL/min/1.73 m² in the allopurinol and febuxostat group, respectively. Adjusted least square mean change in serum urate was −1.58 mg/dL [95% confidence interval (CI), −1.78 to −1.38] and -2.69 mg/dL (95% CI, −2.89 to −2.49) in the allopurinol and febuxostat groups, respectively. Despite lower serum urate levels, febuxostat was significantly more associated with a 30% decline in eGFR (hazard ratio 1.26; 95% CI 1.03–1.54) and end-stage renal disease (hazard ratio 1.91, 95% CI 1.42–2.58) than allopurinol. Annual eGFR decline in febuxostat users was estimated to be more rapid than in allopurinol users by 2.14 (standard error 0.71) mL/min/1.73 m² per year.

Conclusions

Allopurinol demonstrated attenuation of chronic kidney disease progression and prevention of hypouricemia, compared to febuxostat. Because the treatment can be renoprotective, further studies on its effects on chronic kidney disease are required.

Association between behavioral patterns and mortality among US adults: National Health and Nutrition Examination Survey, 2007–2014

Few large-scale studies have been conducted to show the joint effects of mortality associated with physical activity and sedentarism. Therefore, we examined the relationship between all-cause mortality and behavioral patterns among adults in the United States. Data of 17,730 non-institutionalized US civilians aged ≥20 years were extracted from the 2007–2014 National Health and Nutrition Examination Survey. We set the criteria for metabolic equivalents as 600 according to the WHO guideline, and sedentary time as 300 min/day according to the median. The Cox proportional hazards model was adjusted for demographic and lifestyle characteristics. During the 58.54±28.18 months follow-up, all-cause mortality rate was 4% and heart-related and cancer mortality rate was 1%. Participants in the high metabolic equivalents and low sedentary time group had a lower risk of all-cause (hazard ratio = 0.41, 95% confidence interval = 0.34–0.50), cardiovascular (hazard ratio = 0.36; 95% confidence interval = 0.23–0.55), and cancer (hazard ratio = 0.55; 95% confidence interval = 0.37–0.83) mortality, compared to those in the low metabolic equivalents and high sedentary time group. Sufficient physical activity and less sedentary behavior reduce all-cause and cause-specific mortality in adults in the United States, especially cardiovascular mortality among the elderly. Additional nationwide policies to improve behavioral patterns among adults need to be implemented in the United States.

Nonlinear causal effects of estimated glomerular filtration rate on myocardial infarction risks: Mendelian randomization study

BACKGROUND

Previous observational studies suggested that a reduction in estimated glomerular filtration rate (eGFR) or a supranormal eGFR value was associated with adverse cardiovascular risks. However, a previous Mendelian randomization (MR) study under the linearity assumption reported null causal effects from eGFR on myocardial infarction (MI) risks. Further investigation of the nonlinear causal effect of kidney function assessed by eGFR on the risk of MI by nonlinear MR analysis is warranted.

METHODS

In this MR study, genetic instruments for log-eGFR based on serum creatinine were developed from European samples included in the CKDGen genome-wide association study (GWAS) meta-analysis (N=567,460). Alternate instruments for log-eGFR based on cystatin C were developed from a GWAS of European individuals that included the CKDGen and UK Biobank data (N=460,826). Nonlinear MR analysis for the risk of MI was performed using the fractional polynomial method and the piecewise linear method on data from individuals of white British ancestry in the UK Biobank (N=321,024, with 12,205 MI cases).

RESULTS

Nonlinear MR analysis demonstrated a U-shaped (quadratic P value < 0.001) association between MI risk and genetically predicted eGFR (creatinine) values, as MI risk increased as eGFR declined in the low eGFR range and the risk increased as eGFR increased in the high eGFR range. The results were similar even after adjustment for clinical covariates, such as blood pressure, diabetes mellitus, dyslipidemia, or urine microalbumin levels, or when genetically predicted eGFR (cystatin C) was included as the exposure.

CONCLUSION

Genetically predicted eGFR is significantly associated with the risk of MI with a parabolic shape, suggesting that kidney function impairment, either by reduced or supranormal eGFR, may be causally linked to a higher MI risk.

Causal effects from non-alcoholic fatty liver disease on kidney function: A Mendelian randomization study

BACKGROUND AND AIMS

An observational association between nonalcoholic fatty liver disease (NAFLD) and kidney function impairment has been reported. We aimed to investigate the causal effects from NAFLD on estimated glomerular filtration rate (eGFR) by a Mendelian randomization (MR) study.

METHODS

We first performed single-variant MR with rs738409 as a genetic instrument for NAFLD. Another genetic instrument was developed from a genome-wide association study for biopsy-confirmed NAFLD among individuals of European ancestry (1483 cases and 17 781 controls). The eGFR outcome was assessed in individuals of white British ancestry from the UK Biobank (N = 321 405). The associations were reassessed in the negative control subgroup (body mass index < 30 kg/m² , absence of central obesity, and serum alanine aminotransferase level ≤ 20 IU/mL) with a low probability of developing NAFLD. As a replication analysis, a summary-level MR was performed with the European ancestry CKDGen dataset (N = 567 460).

RESULTS

In the UK Biobank, a genetic predisposition for NAFLD, determined either by the single SNP rs738409 or by the group of variants, was significantly associated with a reduced eGFR even with adjustment for metabolic disorders. Although the associations were not significant in the negative control subgroup with a low probability of developing NAFLD, they were significant in the subgroup with a remaining risk of NAFLD, suggesting the absence of a horizontal pleiotropic pathway. The summary-level MR from the CKDGen dataset supported the causal effects of NAFLD on reduced eGFR.

CONCLUSIONS

This MR analysis supports the causal reduction in kidney function by NAFLD.

Association between visit-to-visit blood pressure variability and risks of dementia in CKD patients: a nationwide observational cohort study

Background

The association between visit-to-visit blood pressure (BP) variability and dementia risk in chronic kidney disease (CKD) patients has rarely been studied.

Methods

In this retrospective observational study, individuals who received three or more general health screenings were identified in the nationwide database of Korea. Those with persistent non-dialysis-dependent CKD [estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m² or dipstick albuminuria ≥1+] were included. The study exposure was systolic or diastolic BP variability, calculated as the variation independent of the mean and categorized into quartiles (Q4: the highest quartile; Q1: the lowest quartile). The risks of all-cause dementia, including Alzheimer's disease and vascular dementia, were analyzed by Cox regression adjusted for various clinical characteristics, including baseline BP and eGFR values.

Results

We included 103 139 CKD patients and identified 7574 (7%) dementia events, including 5911 (6%) Alzheimer's disease cases, 886 (1%) vascular dementia events and 777 (1%) cases categorized as other types of dementia. Higher systolic BP variability was significantly associated with higher risks of all-cause dementia {[Q4 versus Q1], hazard ratio [HR] 1.173 [95% confidence interval (CI) 1.102-1.249], P for trend < .001}. The results were also significant for the risk of Alzheimer's disease [HR 1.162 (95% CI 1.083-1.248), P < .001] and vascular dementia [HR 1.282 (95% CI 1.064-1.545), P = .039]. The results were similar when diastolic BP variability was the exposure, as high diastolic BP variability was significantly associated with higher risks of all-cause dementia [HR 1.191 (95% CI 1.117,1.270), P < .001].

Conclusions

Higher visit-to-visit BP variability is significantly associated with a higher risk of dementia in CKD patients.

Albuminuria within the Normal Range Can Predict All-Cause Mortality and Cardiovascular Mortality

BACKGROUND

Despite interest in low-grade albuminuria and poor clinical outcomes, evidence from a large-scale population is lacking. Therefore, we identified the association of low-grade albuminuria within the normal range with all-cause and cardiovascular (CV) mortality.

METHODS

After excluding individuals with urine albumin-creatinine ratio (ACR) ≥30 mg/g (n=6094), this cohort study analyzed 43,396 adults who participated in the National Health and Nutrition Examination Survey (1999-2016). Participants were divided into four quartiles of ACR. The primary outcome was all-cause mortality, and the secondary outcome was CV mortality. Multivariable Cox proportional hazards models were used.

RESULTS

During a median 7.9 years of follow-up, 3516 (9%) participants died. Compared with the reference group (Q1, ACR <4.171 mg/g), low-grade albuminuria groups were associated with all-cause mortality (Q3, ACR ≥6.211 to <10.010 mg/g, hazard ratio [HR], 1.25 [95% CI, 1.11 to 1.41]; Q4, ACR ≥10.010 mg/g, HR, 1.57 [95% CI, 1.41 to 1.76]) in a multivariable hazards model. A similar pattern was also seen in the association of low-grade albuminuria with CV mortality. Subgroup analyses showed that low-grade albuminuria was also associated with all-cause mortality in the nondiabetic group, nonhypertensive group, and non-CKD group (eGFR ≥60 ml/min per 1.73 m²).

CONCLUSIONS

Our findings suggest that low-grade albuminuria is associated with all-cause and CV mortality. Low-grade albuminuria should be monitored, even for patients with low CV risk.