Relation of Poor Handgrip Strength or Slow Walking Pace to Risk of Myocardial Infarction and Fatality

We aimed to investigate a causal effect of functional sarcopenia status, including poor handgrip strength and slow walking pace, on cardiovascular diseases. This study was an observational cohort study including observational analysis and Mendelian randomization. We studied the UK Biobank prospective cohort (n = 324,486) for observational analysis with poor handgrip strength or self-reported slow walking pace as the exposures, investigating risk of myocardial infarction or mortality. Genetic instruments for the exposures were developed in 337,138 individuals of white British ancestries, and coronary artery disease outcome (60,801 cases/123,504 controls) from the independent CARDIoGRAMplustC4D cohort was studied by two-sample Mendelian randomization. The findings were replicated by one-sample analysis by polygenic risk score analysis within the UK Biobank. Both slow walking pace and poor handgrip strength were significantly associated with higher risks of incident myocardial infarction and mortality, particularly from cardiovascular deaths, in the observational investigation. Genetically predicted poor handgrip strength (odds ratio: 1.128 [1.041 to 1.222]) and slow walking pace (odds ratio: 1.171 [1.022 to 1.342]) showed causal effects on the coronary artery disease risks in the independent cohort. The results were again identified by the one-sample Mendelian randomization, as the higher polygenic risk score for poor handgrip strength and slow walking pace was associated with a higher risk of mortality. In conclusion, this study supports the causal effects of slow walking pace and poor handgrip strength on the risks of cardiovascular disease and mortality. The functional sarcopenia status are targetable causative factors for interventions aiming to reduce risks of cardiovascular disease or mortality.

Short-term Exposure to Air Pollution and Attributable Risk of Kidney Diseases: A Nationwide Time-series Study

BACKGROUND

Several studies have shown that long-term exposure to air pollution is associated with reduced kidney function. However, less is known about effects of short-term exposure to air pollution on kidney disease aggravation and resultant emergency room (ER) burden. This study aimed to estimate excess ER visits attributable to short-term air pollution and to provide evidence relevant to air pollution standards to protect kidney patients.

METHODS

We conducted time-series analysis using National Health Insurance data covering all persons in South Korea (2003-2013). We collected daily data for air pollutants (particulate matter ≤10 µm [PM10], ozone [O3], carbon monoxide [CO], and sulfur dioxide [SO2]) and ER visits for total kidney and urinary system disease, acute kidney injury (AKI), and chronic kidney disease (CKD). We performed a two-stage time-series analysis to estimate excess ER visits attributable to air pollution by first calculating estimates for each of 16 regions, and then generating an overall estimate.

RESULTS

For all kidney and urinary disease (902,043 cases), excess ER visits attributable to air pollution existed for all pollutants studied. For AKI (76,330 cases), we estimated the highest impact on excess ER visits from O3, while for CKD (210,929 cases), the impacts of CO and SO2 were the highest. The associations between air pollution and kidney ER visits existed for days with air pollution concentrations below current World Health Organization guidelines.

CONCLUSION

This study provides quantitative estimates of ER burdens attributable to air pollution. Results are consistent with the hypothesis that stricter air quality standards benefit kidney patients.

Impact of DBP on all-cause and cardiovascular mortality: results from the National Health and Nutrition Examination survey, 1999-2014

INTRODUCTION

Hypertension is common and has a significant effect on cardiovascular morbidity and death. However, despite the development of several guidelines to manage SBP, there is little research or guidance on the evaluation and management of DBP or isolated diastolic hypertension (IDH).

METHOD

To determine the association of DBP with all-cause and cardiovascular mortality, we used NHANES data from 1999 to 2014 and included adults aged at least 18 years. The relationship between DBP, IDH and all-cause, cardiovascular mortality was evaluated.

RESULTS

Of the 35 109 participants, all-cause death occurred in 10.6%, and cardiovascular death occurred in 2.1% over a median follow-up of 7.2 years. Multivariate Cox regression analysis revealed that the risk of all-cause mortality was significantly higher in the lowest (≤56.9 mmHg) DBP groups than in the reference group (DBP 74-76.9 mmHg). However, the risk of cardiovascular mortality was significantly higher in the lowest and highest (≥83 mmHg) DBP group than in the reference group. The risk of all-cause mortality was higher for most groups with SBP at least 140 mmHg than for the reference group with DBP 74-76.9 mmHg and SBP 100-139.9 mmHg. Both the 2018 ESC/NICE and the 2017 AHA/ACC-defined IDH was not significantly associated with all-cause mortality.

CONCLUSION

DBP and all-cause mortality had an inverse relationship, whereas DBP and cardiovascular mortality had a U-shaped relationship, with the DBP reference group having the lowest risk for all-cause and cardiovascular mortality. There was no significant relationship between IDH and death.

Associations between long term air pollution exposure and first hospital admission for kidney and total urinary system diseases in the US Medicare population: nationwide longitudinal cohort study

Objective

To estimate the associations between long term exposure to air pollution and the first hospital admission related to kidney and total urinary system diseases.

Design

Nationwide longitudinal cohort study.

Setting

Data were collected from the Medicare fee-for-service for beneficiaries living in 34 849 zip codes across the continental United States from 2000 to 2016. Exposure variables were annual averages of traffic related pollutants (fine particles (PM_2.5) and nitrogen dioxide (NO₂)) that were assigned according to the zip code of residence of each beneficiary with the use of validated and published hybrid ensemble prediction models.

Participants

All beneficiaries aged 65 years or older who were enrolled in Medicare part A fee-for-service (n=61 097 767).

Primary and secondary outcome measures

First hospital admission with diagnosis codes for total kidney and urinary system disease or chronic kidney disease (CKD), analyzed separately.

Results

The average annual concentrations of air pollution were 9.8 µg/m³ for PM_2.5 and 18.9 ppb for NO₂. The total number of first admissions related to total kidney and urinary system disease and CKD were around 19.0 million and 5.9 million, respectively (2000-16). For total kidney and urinary system disease, hazard ratios were 1.076 (95% confidence interval 1.071 to 1.081) for a 5 µg/m³ increase in PM_2.5 and 1.040 (1.036 to 1.043) for a 10 ppb increase in NO₂. For CKD, hazard ratios were 1.106 (1.097 to 1.115) for a 5 µg/m³ increase in PM_2.5 and 1.013 (1.008 to 1.019) for a 10 ppb increase in NO₂. These positive associations between PM_2.5 and kidney outcomes persisted at concentrations below national health based air quality standards.

Conclusions

The findings suggest that higher annual air pollution levels were associated with increased risk of first hospital admission related to diseases of the kidney and urinary system or CKD in the Medicare population.

Evaluating a shared decision-making intervention regarding dialysis modality: development and validation of self-assessment items for patients with chronic kidney disease

Background

Shared decision-making is a two-way symmetrical communication process in which clinicians and patients work together to achieve the best outcome. This study aimed to develop self-assessment items as a decision aid for choosing a dialysis modality in patients with chronic kidney disease (CKD) and to assess the construct validity of the newly developed items.

Methods

Five focus group interviews were performed to extract specific self-assessment items regarding patient values in choosing a dialysis modality. After survey items were refined, a survey of 330 patients, consisting of 152 hemodialysis (HD) and 178 peritoneal dialysis (PD) patients, was performed to validate the self-assessment items.

Results

The self-assessment for the decision aid was refined to 35 items. The structure of the final items appeared to have three dimensions of factors; health, lifestyle, and dialysis environment. The health factor consisted of 12 subscales (α = 0.724), the lifestyle factor contained 11 subscales (α = 0.624), and the dialysis environment factor was represented by 12 subscales (α = 0.694). A structural equation model analysis showed that the relationship between the decision aid factors (health, lifestyle, and dialysis environment), patients’ CKD perception, and cognition of shared decision-making differed between HD patients and PD patients.

Conclusion

We developed and validated self-assessment items as part of a decision aid to help patients with CKD. This attempt may assist CKD patients in making informed and shared decisions closely aligned with their values when considering dialysis modality.

Red blood cell distribution width as a predictor of mortality among patients regularly visiting the nephrology outpatient clinic

The association between increased red blood cell distribution width (RDW) and mortality among patients treated on an outpatient basis in the nephrology outpatient clinic is unclear. Therefore, our study aimed to investigate the association between baseline and time-averaged RDW and mortality risk in patients treated in our nephrology outpatient clinic. Our multi-center retrospective analysis was based on data of 16,417 outpatient nephrology patients with available baseline renal function and RWD values. The median baseline RDW was 13.0% (range, 10.0–32.1%). The high-RDW group was defined as the top quartile (≥ 13.8%, n = 4302). The crude mortality rate was 15.0% (n = 1806) at a median follow-up of 127.5 months. From the results of the multivariate Cox proportional hazards regression model adjusted for covariates, including eGFR, hemoglobin, and factors of anemia treatment, patients with a high time-averaged RDW had increased mortality risk (adjusted hazard ratio, 1.505; 95% confidence interval, 1.326–1.708; P < 0.001), irrespective of sex, presence of anemia, and chronic kidney disease, except in individuals aged < 45 years. Thus, increased baseline and time-averaged RDW were significantly associated with increased mortality in patients aged > 45 years treated on an outpatient basis in the nephrology clinic.

Causal effects of atrial fibrillation on brain white and gray matter volume: a Mendelian randomization study

BACKGROUND

Atrial fibrillation (AF) and brain volume loss are prevalent in older individuals. We aimed to assess the causal effect of atrial fibrillation on brain volume phenotypes by Mendelian randomization (MR) analysis.

METHODS

The genetic instrument for AF was constructed from a previous genome-wide association study (GWAS) meta-analysis (15,993 AF patients and 113,719 controls of European ancestry). The outcome summary statistics for head-size-normalized white or gray matter volume measured by magnetic resonance imaging were provided by a previous GWAS of 33,224 white British participants in the UK Biobank. Two-sample MR by the inverse variance-weighted method was performed, supported by pleiotropy-robust MR sensitivity analysis. The causal estimates for the effect of AF on ischemic stroke were also investigated in a dataset that included the findings from the MEGASTROKE study (34,217 stroke patients and 406,111 controls of European ancestry). The direct effects of AF on brain volume phenotypes adjusted for the mediating effect of ischemic stroke were studied by multivariable MR.

RESULTS

A higher genetic predisposition for AF was significantly associated with lower grey matter volume [beta -0.040, standard error (SE) 0.017, P=0.017], supported by pleiotropy-robust MR sensitivity analysis. Significant causal estimates were identified for the effect of AF on ischemic stroke (beta 0.188, SE 0.026, P=1.03E-12). The total effect of AF on lower brain grey matter volume was attenuated by adjusting for the effect of ischemic stroke (direct effects, beta -0.022, SE 0.033, P=0.528), suggesting that ischemic stroke is a mediator of the identified causal pathway. The causal estimates were nonsignificant for effects on brain white matter volume as an outcome.

CONCLUSIONS

This study identified that genetic predisposition for AF is significantly associated with lower gray matter volume but not white matter volume. The results indicated that the identified total effect of AF on gray matter volume may be mediated by ischemic stroke.

First snapshot on behavioral characteristics and related factors of patients with chronic kidney disease in South Korea during the COVID-19 pandemic (June to October 2020)

Background

The recent novel coronavirus disease 2019 (COVID-19) pandemic has led to unprecedented changes in behavior. We evaluated the current status of precautionary behavior and physical activity in chronic kidney disease (CKD) patients during the COVID-19 pandemic.

Methods

A population of CKD patients (n = 306) registered in the Study on Kidney Disease and Environmental Chemicals (SKETCH, Clinical Trial No. NCT04679168) cohort recruited from June 2020 to October 2020 was included in the study. We conducted a questionnaire survey related to risk perception of COVID-19, precautionary behavior, and physical activity.

Results

There were 187 patients (61.1%) with estimated glomerular filtration rate of <45 mL/min/1.73 m². This population showed a higher degree of risk perception for COVID-19 than the general population. Age was the most significant determinant of risk perception among CKD patients. During the pandemic, social distancing and hygiene-related behavior were significantly increased (p < 0.001). The frequency of exercise was decreased only in those who took regular exercise, without diabetes, or with a lower Charlson comorbidity index (CCI) (p < 0.001), with no change among the other groups. Socioeconomic status and comorbidities significantly affected behavioral characteristics regardless of the category. Education and income were significantly associated with precautionary behaviors such as staying at home and hand sanitizer use. Patients with higher CCI status significantly increased frequency of exercise (adjusted odds ratio, 2.10; 95% confidence interval, 1.01–4.38).

Conclusion

CKD patients showed higher risk perception with active precautionary behavioral changes than the general population. Healthcare providers should be aware of the characteristics to comprise precautionary behavior without reducing physical activity.

Long-term risk of all-cause mortality in live kidney donors: a matched cohort study

Background

Long-term outcomes of live kidney donors remain controversial, although this information is crucial for selecting potential donors. Thus, this study compared the long-term risk of all-cause mortality between live kidney donors and healthy control.

Methods

We performed a retrospective cohort study including donors from seven tertiary hospitals in South Korea. Persons who underwent voluntary health screening were included as controls. We created a matched control group considering age, sex, era, body mass index, baseline hypertension, diabetes, estimated glomerular filtration rate, and dipstick albuminuria. The study outcome was progression to end-stage kidney disease (ESKD), and all-cause mortality as identified in the linked claims database.

Results

We screened 1,878 kidney donors and 78,115 health screening examinees from 2003 to 2016. After matching, 1,701 persons remained in each group. The median age of the matched study subjects was 44 years, and 46.6% were male. Among the study subjects, 2.7% and 16.6% had underlying diabetes and hypertension, respectively. There were no ESKD events in the matched donor and control groups. There were 24 (1.4%) and 12 mortality cases (0.7%) in the matched donor and control groups, respectively. In the age-sex adjusted model, the risk for all-cause mortality was significantly higher in the donor group than in the control group. However, the significance was not retained after socioeconomic status was included as a covariate (adjusted hazard ratio, 1.82; 95% confidence interval, 0.87-3.80).

Conclusion

All-cause mortality was similar in live kidney donors and matched non-donor healthy controls with similar health status and socioeconomic status in the Korean population.

Nicotine exacerbates tacrolimus-induced renal injury by programmed cell death

BACKGROUND/AIMS

Cigarette smoking is an important modifiable risk factor in kidney disease progression. However, the underlying mechanisms for this are lacking. This study aimed to assess whether nicotine (NIC), a major toxic component of cigarette smoking, would exacerbates tacrolimus (TAC)-induced renal injury.

METHODS

Sprague-Dawley rats were treated daily with NIC, TAC, or both drugs for 4 weeks. The influence of NIC on TAC-caused renal injury was examined via renal function, histopathology, oxidative stress, mitochondria, endoplasmic reticulum (ER) stress, and programmed cell death (apoptosis and autophagy).

RESULTS

Both NIC and TAC significantly impaired renal function and histopathology, while combined NIC and TAC treatment aggravated these parameters beyond the effects of either alone. Increased oxidative stress, ER stress, mitochondrial dysfunction, proinf lammatory and profibrotic cytokine expressions, and programmed cell death from either NIC or TAC were also aggravated by the two combined.

CONCLUSION

Our observations suggest that NIC exacerbates chronic TAC nephrotoxicity, implying that smoking cessation may be beneficial for transplant smokers taking TAC.

Exposure to phthalates and environmental phenols in association with chronic kidney disease (CKD) among the general US population participating in multi-cycle NHANES (2005-2016)

Exposure to consumer chemicals has been associated with chronic kidney disease (CKD) among humans, but their associations with estimated glomerular filtration rate (eGFR) are inconsistent. Such observations may be due to potential bias caused by the method of urine dilution adjustment and lack of consideration for multiple chemical exposure in the association models. This study aimed to identify major urinary chemicals associated with CKD by applying an alternative adjustment method of urine dilution ('novel' covariate-adjusted creatinine adjustment vs 'traditional' creatinine adjustment) and with a mixture exposure concept in the association model. For this purpose, the adult participants of US National Health and Nutrition Examination Survey (NHANES) 2005-2016 (n = 9008) were used, and the associations of urinary exposure biomarkers of major consumer chemicals, e.g., phthalates, bisphenol A, benzophenone-3, and parabens, with CKD related parameters of eGFR and albumin-to-creatinine ratio (ACR), were assessed. The use of the novel covariate-adjusted creatinine standardization resulted in significant inverse associations with eGFR for most measured chemicals, unlike the results with the use of the conventional creatinine adjustment. Phthalate metabolites, such as monobutyl phthalate (MBP) and mono-benzyl phthalate (MBzP), were positively associated with ACR. Even in mixture exposure models using weighted quantile sum (WQS) regression, MBzP, metabolites of di-(2-ethylhexyl) phthalate (DEHP), and bisphenol A (BPA) were revealed as major drivers of the association with eGFR or ACR. Results of sensitivity analyses with the subpopulation with normal eGFR range (n = 7041) were generally similar. Our observation suggests that exposure to benzyl butyl phthalate (BBP), DEHP, and BPA may be responsible for declined eGFR and increased ACR even at the exposure levels occurring among general adults.

Metabolic risks in living kidney donors in South Korea

Background

Considering the growing prevalence of Western lifestyles and related chronic diseases occurring in South Korea, this study aimed to explore the progression of metabolic risk factors in living kidney donors.

Methods

This study enrolled living kidney donors from seven hospitals from 1982 to 2016. The controls were individuals that voluntarily received health check-ups from 1995 to 2016 that were matched with donors according to age, sex, diabetes status, baseline estimated glomerular filtration rate, and date of the medical record. Data on hyperuricemia, hypertension, hypercholesterolemia, and overweight/obesity were collected to determine metabolic risks. Logistic regressions with interaction terms between the medical record date and donor status were used to compare the trends in metabolic risks over time in the two groups.

Results

A total of 2,018 living kidney donors and matched non-donors were included. The median age was 44.0 years and 54.0% were women. The living kidney donors showed a lower absolute prevalence for all metabolic risk factors, except for those that were overweight/obese, than the non-donors. The proportion of subjects that were overweight/obese was consistently higher over time in the donor group. The changes over time in the prevalence of each metabolic risk were not significantly different between groups, except for a lower prevalence of metabolic risk factors ≥ 3 in donors.

Conclusion

Over time, metabolic risks in living kidney donors are generally the same as in non-donors, except for a lower prevalence of metabolic risk factors ≥3 in donors.

Declining trend of preemptive kidney transplantation and impact of pretransplant dialysis: a Korean nationwide prospective cohort study

We evaluated the temporal trend of preemptive kidney transplantation (KT) and the effect of pretransplant dialysis duration on post-transplant outcomes. This was a nationwide cohort study of the first-time 3392 living donor KT (LDKT) recipients (2014-2019). The annual changes in proportion of preemptive KT, factors associated with preemptive KT, and post-transplant outcomes were analyzed. Preemptive KT was performed in 816 (24.1%) patients. Annual trend analysis revealed gradual decrease in preemptive KT over time (P = 0.042). Among the underlying causes of preemptive KT, the proportion of diabetes increased and that of glomerulonephritis decreased during the study period. Glomerulonephritis as the primary renal disease was a predictor of preemptive KT. Patients with pretransplant dialysis >6 months showed increased graft failure risk than preemptive KT in the subdistribution of hazard model for competing risk (adjusted hazard ratio [aHR], 2.53; 95% confidence interval [CI], 1.09-5.87; P = 0.031) and in propensity score-matched analysis (aHR, 2.45; 95% CI, 1.02-5.92; P = 0.034); however, pretransplant dialysis ≤6 months showed comparable graft survival with preemptive KT in both analyses. Preemptive KT declined over successive years, associated with an increase in diabetes and a decrease in glomerulonephritis as underlying causes of KT. Short period of dialysis less than 6 months does not affect graft survival compared with preemptive KT; however, longer dialysis decreases graft survival.

Effects of periostin deficiency on kidney aging and lipid metabolism

Periostin plays a crucial role in fibrosis, which is involved in kidney aging. A few studies have shown that lipid metabolism is involved in kidney aging. We investigated the role of periostin in lipid metabolism during kidney aging. Renal function, fibrosis, and inflammatory markers were studied using urine, blood, and tissue samples from wild-type (WT) C57BL/6 mice and Postn-null mice of 2 and 24 months of age. Lipids were quantitatively profiled using liquid chromatography-tandem mass spectrometry in the multiple reaction monitoring mode. Renal function was worse and tubular atrophy/interstitial fibrosis, periostin expression, and inflammatory and fibrotic markers were more severe in aged WT mice than in young WT mice. In aged Postn-null mice, these changes were mitigated. Thirty-five differentially regulated lipids were identified. Phosphatidylcholines, cholesteryl ester, cholesterol, ceramide-1-phosphate, and CCL5 expression were significantly higher in aged WT mice than in aged Postn-null mice. Particularly, linoleic acid, linolenic acid, arachidonic acid, and docosahexaenoic acid differed strongly between the two groups. Lysophosphatidylcholine acyltransferase 2, which converts lysophosphatidylcholine to phosphatidylcholine, was significantly higher in aged WT mice than in aged Postn-null mice. Periostin expression in the kidneys increased with age, and periostin ablation delayed aging. Changes in lipids and their metabolism were found in Postn-null mice. Further research on the precise mechanisms of and relationships between lipid expression and metabolism, kidney aging, and periostin expression is warranted.

The Prognostic Significance of Body Mass Index and Metabolic Parameter Variabilities in Predialysis CKD: A Nationwide Observational Cohort Study

BACKGROUND

The association between variabilities in body mass index (BMI) or metabolic parameters and prognosis of patients with CKD has rarely been studied.

METHODS

In this retrospective observational study on the basis of South Korea's national health screening database, we identified individuals who received ≥3 health screenings, including those with persistent predialysis CKD (eGFR <60 ml/min per 1.73 m² or dipstick albuminuria ≥1). The study exposure was variability in BMI or metabolic parameters until baseline assessment, calculated as the variation independent of the mean and stratified into quartiles (with Q4 the highest quartile and Q1 the lowest). We used Cox regression adjusted for various clinical characteristics to analyze risks of all-cause mortality and incident myocardial infarction, stroke, and KRT.

RESULTS

The study included 84,636 patients with predialysis CKD. Comparing Q4 versus Q1, higher BMI variability was significantly associated with higher risks of all-cause mortality (hazard ratio [HR], 1.66; 95% confidence interval [95% CI], 1.53 to 1.81), P [for trend] <0.001), KRT (HR, 1.20; 95% CI, 1.09 to 1.33; P<0.001), myocardial infarction (HR, 1.19; 95% CI, 1.05 to 1.36, P=0.003), and stroke (HR, 1.19; 95% CI, 1.07 to 1.33, P=0.01). The results were similar in the subgroups divided according to positive or negative trends in BMI during the exposure assessment period. Variabilities in certain metabolic syndrome components (e.g., fasting blood glucose) also were significantly associated with prognosis of patients with predialysis CKD. Those with a higher number of metabolic syndrome components with high variability had a worse prognosis.

CONCLUSIONS

Higher variabilities in BMI and certain metabolic syndrome components are significantly associated with a worse prognosis in patients with predialysis CKD.

Outcomes of Remote Patient Monitoring for Automated Peritoneal Dialysis: A Randomized Controlled Trial

INTRODUCTION

We hypothesize that remote patient monitoring (RPM) for automated peritoneal dialysis (APD) and feedback could enhance patient self-management and improve outcomes. The aim of this study was to evaluate the efficacy of RPM-APD compared to traditional APD (T-APD) without RPM.

METHODS

In this multicenter, randomized controlled trial, patients on APD were randomized to T-APD (n = 29) or RPM-APD (n = 28) at 12 weeks and followed until 25 weeks. Health-related quality of life (HRQOL), patient and medical staff satisfaction with RPM-APD, and dialysis-related outcomes were compared between the 2 groups.

RESULTS

We found no significant differences in HRQOL scores at the time of enrollment and randomization between RPM-APD and T-APD. At the end of the study, the RPM-APD group showed better HRQOL for the sleep domain (p = 0.049) than the T-APD group and the T-APD group showed better HRQOL for the sexual function domain (p = 0.030) than the RPM-APD group. However, we found no significant interactions between the time and groups in terms of HRQOL. Different HRQOL domains significantly improved over time in patients undergoing RPM-APD (effects of kidney disease, p = 0.025) and T-APD (burden of kidney disease, p = 0.029; physical component summary, p = 0.048). Though medical staff satisfaction with RPM-APD was neutral, most patients were quite satisfied with RPM-APD (median score 82; possible total score 105 on 21 5-item scales) and the rating scores were maintained during the study period. We found no significant differences in dialysis adherence, accuracy, adequacy, overhydration status, blood pressure, or the number of unplanned visits between the 2 groups.

DISCUSSION/CONCLUSION

Although HRQOL and dialysis-related outcomes were comparable between RPM-APD and T-APD, RPM-APD was positive in terms of patient satisfaction. Further long-term and large-scale studies will be required to determine the efficacy of RPM-APD.

TRIAL REGISTRATION

CRIS identifier: KCT0003390, registered on December 14, 2018 - retrospectively registered, https://cris.nih.go.kr/cris/search/search_result_st01.jsp?seq=12348.

Hepatocyte growth factor and soluble cMet levels in plasma are prognostic biomarkers of mortality in patients with severe acute kidney injury

Background

Hepatocyte growth factor (HGF)/cMet pathway is necessary for repair and regeneration following acute kidney injury (AKI). We evaluated the clinical potential of plasma HGF and soluble cMet as prognostic biomarkers for severe AKI requiring continuous renal replacement therapy (CRRT).

Methods

One hundred thirty-six patients with severe AKI who participated in the VENUS (volume management under body composition monitoring in critically ill patients on CRRT) trial between 2017 and 2019 were enrolled in this study. We investigated associations between plasma HGF and cMet concentrations and all-cause mortality.

Results

Plasma HGF and soluble cMet levels were positively correlated. Patients were divided into three groups based on their HGF and soluble cMet concentrations. The day D 0, D2, and D7 highest concentration HGF groups had significantly higher in-hospital mortality after adjusting for sex, body mass index, Acute Physiology and Chronic Health Evaluation II, and age-adjusted Charlson comorbidity index score, especially on D7 (hazard ratio, 4.26; 95% confidence interval, 1.71–10.62; p = 0.002). D7 soluble cMet level was also associated with mortality. Receiver operating characteristic curve analysis indicated that D7 HGF and soluble cMet levels were best at predicting mortality. Addition of plasma HGF and soluble cMet to conventional prognostic indices significantly improved the predictive value for mortality on D7. However, plasma HGF and soluble cMet were not associated with fluid status.

Conclusion

Plasma HGF and soluble cMet levels were significant predictors of the outcomes of severe AKI patients undergoing CRRT. There was no correlation between plasma HGF and soluble cMet levels and fluid balance.

Effects of air pollution on mortality of patients with chronic kidney disease: A large observational cohort study

Due to industrialization, the burden of diseases associated with air pollution is increasing. Although the risk associated with air pollution in the general population has been actively investigated, few studies have been conducted on the effects of exposure to air pollution in patients with chronic kidney disease (CKD) in East Asia. A total of 29,602 patients with CKD in Seoul participated in a retrospective cohort at three medical centers. We assessed the association of individualized exposure to five types of air pollutants (PM_2.5, PM₁₀, NO₂, SO₂, and CO) using inverse distance weighting (IDW) on mortality in CKD patients in the Cox proportional hazard model that was adjusted for sex, age, eGFR, hemoglobin, hypertension, diabetes, and area-level characteristics. During the 6.14 ± 3.96 years, 3863 deaths (13%) were observed. We confirmed the significant effects of PM_2.5 (hazard ratio [HR] 1.17, 95% confidence interval [CI] 1.07-0.29) and CO (HR 1.17, 95% CI 1.00-1.38) on mortality in CKD patients. Different associations were found when stratified by age, body mass index, smoking, and drinking status. Long-term exposure to air pollutants had negative effects on mortality in patients with CKD. These effects were prominent in patients aged over 65 years, patients with a lean body, and those who did not drink alcohol.

Atrial fibrillation and kidney function: a bidirectional Mendelian randomization study

AIMS

The aim of this study was to investigate the causal effects between atrial fibrillation (AF) and kidney function.

METHODS AND RESULTS

We performed a bidirectional summary-level Mendelian randomization (MR) analysis implementing the results from a large-scale genome-wide association study for estimated glomerular filtration rate (eGFR) by the CKDGen (N = 765 348) and AF (N = 588 190) to identify genetic instruments. The inverse variance weighted method was the main MR method used. For replication, an allele score-based MR was performed by individual-level data within a UK Biobank cohort of white British ancestry individuals (N = 337 138). A genetic predisposition to AF was significantly associated with decreased eGFR [for log-eGFR, beta -0.003 (standard error, 0.0005), P < 0.001] and increased risk of chronic kidney disease [beta 0.059 (0.0126), P < 0.001]. The significance remained in MR sensitivity analyses and the causal estimates were consistent when we limited the analysis to individuals of European ancestry. Genetically predicted eGFR did not show a significant association with the risk of AF [beta -0.366 (0.275), P = 0.183]. The results were similar in allele score-based MR, as allele score for AF was significantly associated with reduced eGFR [for continuous eGFR, beta -0.079 (0.021), P < 0.001], but allele score for eGFR did not show a significant association with risk of AF [beta -0.005 (0.008), P = 0.530].

CONCLUSIONS

Our study supports that AF is a causal risk factor for kidney function impairment. However, an effect of kidney function on AF was not identified in this study.

Economic Impact of Donating a Kidney on Living Donors: A Korean Cohort Study

RATIONALE & OBJECTIVE

Although existing studies have reported adverse health outcomes after kidney donation, its socioeconomic impact on living donors requires further study.

STUDY DESIGN

A retrospective observational cohort study including a matched comparison group.

SETTING & PARTICIPANTS

1,285 living kidney donors from 7 tertiary hospitals between 2003 and 2016, and a matched comparison group consisting of the same number of health screening examinees with similar baseline clinical characteristics and socioeconomic status. All participants were receiving Korean national health insurance.

EXPOSURE

Kidney donation as reflected in the Korean National Health Insurance System (NHIS) database.

OUTCOME

Changes in household economic status estimated by Korean national health insurance fees and changes in employment status reflected in the NHIS database.

ANALYTICAL APPROACH

The outcomes of the donor group and matched control group were compared annually using multivariable logistic regression analyses adjusted for clinical and demographic characteristics.

RESULTS

The median ages of the donors and matched controls were 45 and 46 years, respectively; 44.6% of both groups were male. Compared to the comparison group, living donors were at higher risk of being unemployed or losing employment during the first 2 years after donation (eg, first-year loss of employment: odds ratio (OR), 2.27 [95% CI, 1.55-3.33]); however, this association did not persist. Donors also had a significantly lower odds of improvement in economic status (OR, 0.57 [95% CI, 0.47-0.71]) and a higher odds of deterioration in financial status (OR, 1.54 [95% CI, 1.23-1.93]) in the first year after transplantation and subsequently.

LIMITATIONS

Unmeasured differences between donors and matched controls creating residual selection bias and confounding.

CONCLUSIONS

Living kidney donors may suffer loss of employment and poor economic status after their voluntary donation. The socioeconomic impact on these donors should be considered in conjunction with the potential long-term adverse health outcomes after donation.

GDF-15 Predicts In-Hospital Mortality of Critically Ill Patients with Acute Kidney Injury Requiring Continuous Renal Replacement Therapy: A Multicenter Prospective Study

Growth differentiation factor-15 (GDF-15) is a stress-responsive cytokine. This study evaluated the association between GDF-15 and in-hospital mortality among patients with severe acute kidney injury (AKI) requiring continuous renal replacement therapy (CRRT). Among the multicenter prospective CRRT cohort between 2017 and 2019, 66 patients whose blood sample was available were analyzed. Patients were divided into three groups according to the GDF-15 concentrations. The median GDF-15 level was 7865.5 pg/mL (496.9 pg/mL in the healthy control patients). Baseline characteristics were not different among tertile groups except the severity scores and serum lactate level, which were higher in the third tertile. After adjusting for confounding factors, the patients with higher GDF-15 had significantly increased risk of mortality (second tertile: adjusted hazards ratio [aHR], 3.67; 95% confidence interval [CI], 1.05-12.76; p = 0.041; third tertile: aHR, 6.81; 95% CI, 1.98-23.44; p = 0.002). Furthermore, GDF-15 predicted in-hospital mortality (area under the curve, 0.710; 95% CI, 0.585-0.815) better than APACHE II and SOFA scores. Serum GDF-15 concentration was elevated in AKI patients requiring CRRT, higher in more severe patients. GDF-15 is a better independent predictor for in-hospital mortality of critically ill AKI patients than the traditional risk scoring system such as APACHE II and SOFA scores.

A Mendelian randomization study found causal linkage between telomere attrition and chronic kidney disease

Chronic kidney disease (CKD) is highly prevalent in the elderly population. However, it is rarely investigated whether kidney function is causally linked to biological aging itself. In this Mendelian randomization study, genetic instruments for telomere attrition were applied to a CKDGen genome wide association study results for 41,395 cases of CKD among 480,698 individuals as summary-level Mendelian randomization. A replicative analysis was performed by polygenic score analysis using independent United Kingdom Biobank data for 8,118 cases of CKD among 321,024 white individuals of British ancestry. Reverse-direction Mendelian randomization analysis was performed utilizing genetic instruments for log-estimated glomerular filtration rate change with Z-standardized telomere length outcome data for 326,075 participants in the UK Biobank. Genetic predisposition toward telomere attrition (one Z score decrease in length) was found to be a causative factor for a higher CKD risk [Odds Ratio 1.20 (95% confidence interval 1.08‒1.33)], as supported by pleiotropy-robust Mendelian randomization sensitivity analyses implemented using the CKDGen data. Based on United Kingdom Biobank data, the polygenic score for telomere attrition was significantly associated with a higher risk of CKD [1.20 (1.04‒1.39)]. In reverse-direction Mendelian randomization, the genetically predicted kidney function decrease was significantly associated with a higher degree of telomere attrition [beta 0.039 (0.009‒0.069)]. Thus, our study supports the causal linkage between telomere attrition and kidney function impairment.

Causal linkage between adult height and kidney function: An integrated population-scale observational analysis and Mendelian randomization study

As adult height is linked to various health outcomes, further investigation of its causal effects on kidney function later in life is warranted. This study involved a cross-sectional observational analysis and summary-level Mendelian randomization (MR) analysis. First, the observational association between height and estimated GFR determined by creatinine (eGFRcreatinine) or cystatin C (eGFRcystatinC) was investigated in 467,182 individuals aged 40-69 using UK Biobank. Second, the genetic instrument for adult height, as reported by the GIANT consortium, was implemented, and summary-level MR of eGFRcreatinine and CKDcreatinine in a CKDGen genome-wide association study was performed (N = 567,460), with multivariable MR being adjusted for the effects of genetic predisposition on body mass index. To replicate the findings, additional two-sample MR using the summary statistics of eGFRcystatinC and CKDcystatinC in UK Biobank was performed (N = 321,405). In observational analysis, adult height was inversely associated with both eGFRcreatinine (per 1 SD, adjusted beta -1.039, standard error 0.129, P < 0.001) and eGFRcystatinC (adjusted beta -1.769, standard error 0.161, P < 0.001) in a multivariable model adjusted for clinicodemographic, anthropometric, metabolic, and social factors. Moreover, multivariable summary-level MR showed that a taller genetically predicted adult height was causally linked to a lower log-eGFRcreatinine (adjusted beta -0.007, standard error 0.001, P < 0.001) and a higher risk of CKDcreatinine (adjusted beta 0.083, standard error 0.019, P < 0.001). Other pleiotropy-robust sensitivity MR analysis results supported the findings. In addition, similar results were obtained by two-sample MR of eGFRcystatinC (adjusted beta -1.303, standard error 0.140, P < 0.001) and CKDcystatinC (adjusted beta 0.153, standard error 0.025, P < 0.001) in UK Biobank. In conclusion, the results of this study suggest that a taller adult height is causally linked to worse kidney function in middle-aged to elderly individuals, independent of the effect of body mass index.