Approximately 750 million people worldwide suffer from chronic kidney diseases (CKD)-a leading cause of cardiovascular morbidity and premature mortality-but early identification of progressive kidney function decline in patients at risk is still a challenge. CKD diagnosis relies on estimated glomerular filtration rate (eGFR) and albuminuria screening, primarily reflecting glomerular injury. Nevertheless, in a substantial proportion of affected subjects progressive CKD initially remains undetected, since kidney function deteriorates through ongoing tubulointerstitial injury without significant albuminuria, a condition known as 'non-albuminuric' CKD. Urinary Dickkopf-3 (uDKK3) has emerged as an innovative biomarker of progressive CKD, which is expressed by proximal tubular epithelial cells as a response to continuing injury. It is secreted into the urine, where it signals ongoing fibrogenic activity within the kidney. Clinical studies across a broad range of CKD etiologies-in adults and children alike-have shown that elevated uDKK3 significantly improved detection and prediction of progressive CKD after adjustment for established CKD risk markers including albuminuria. Moreover, in primarily non-albuminuric populations, e.g. those with type 2 diabetes and patients with heart or lung diseases, uDKK3 identifies high-risk individuals for future decline of kidney function. These findings support the hypothesis that CKD progression follows different pathways of mainly glomerular or tubulointerstitial injury. It is therefore plausible to use complementary biomarkers for CKD screening-albuminuria and uDKK3-each reflecting a distinct biological dimension of kidney injury. We discuss the limitations of albuminuria screening and propose a framework for integrating tubular markers like uDKK3 into future CKD screening strategies.

Accurate prediction of diabetic kidney disease progression is challenging, but mandatory. Urinary Dickkopf-3 (uDKK3), a tubular epithelia-derived glycoprotein and marker of tubular injury, is a promising biomarker for kidney function decline. We explored the clinical utility of uDKK3 to predict kidney function decline and adverse cardiovascular events in patients with T2DM in a primary healthcare setting. In this cohort study, 3232 patients with T2DM were analyzed. The primary endpoint was a composite of a sustained eGFR decline ≥40%, a sustained increase in albuminuria of at least 30% including a transition in albuminuria class, progression to ESKD, and death from kidney failure. After adjustment for confounding variables, uDKK3 values >200 pg/g creatinine were associated with a higher risk of the composite kidney endpoint during a median follow-up of 4.26 years. Furthermore, uDKK3 improved the prediction of the 1-year eGFR decline on top of albuminuria. Individuals with high uDKK3 levels also had an increased risk for adverse cardiovascular events and all-cause mortality. uDKK3 identifies patients with T2DM at high risk for kidney function decline on top of established biomarkers (albuminuria and eGFR). In primary care, uDKK3 may help to identify high-risk patients who might benefit from intensified treatment and/or referrals to specialists.

BK polyomavirus (BKPyV) reactivation can lead to allograft failure in kidney transplant recipients, yet no approved antivirals exist. Although archetype (ww-) strains predominate in patients, drug screening predominantly utilizes laboratory-adapted rearranged (rr-) strains, potentially limiting therapeutic translation. In this study, we employed a new replication assay to evaluate antiviral activity of retinoids and CDK inhibitors against patient-derived ww- and rr-BKPyV isolates. A viral dynamics model was used to estimate the net antiviral benefit (NAB) of compounds to identify antiviral effects independent of cell growth inhibition. As a result, bexarotene and fenretinide were effective against various patient-derived ww- and rr-BKPyV isolates. They had a stronger antiviral activity than acitretin, which was more strain-specific and tazarotenic acid showing only modest effects. In the model integrating all experimental datasets, bexarotene had a positive NAB in a broad concentration range with an EC50 comparable to peak plasma levels observed in clinical trials. However, fenretinide displayed a positive NAB within a narrower concentration range. The CDK inhibitors Ro-3306 and roscovitine exhibited limited or no positive NAB, respectively. Notably, although the mTOR inhibitor sirolimus appeared to have additive antiviral effects when applied together with bexarotene, it displayed a negative NAB, rather attributing its activity to changes on cell growth/viability. In summary, bexarotene represents a promising therapeutic repurposing candidate for BKPyV reactivation in transplant patients, suggesting clinically achievable therapeutic efficacy. Clinical validation is warranted to translate these findings into therapeutic solutions for transplant recipients.

Background:Chronic kidney disease (CKD) contributes to global mortality and morbidity, also due to infectious complications resulting from immune system dysregulation. Recently, respiratory syncytial virus (RSV) vaccines based on the prefusion F (preF) glycoprotein have been licensed for prevention of severe disease in elderly and in patients with comorbidities, but data on immunogenicity in patients with CKD are scarce. Methods:We characterized humoral and cellular immunogenicity of 75 patients with CKD stages G3a to G5d both before and 14 days (IQR 2) after vaccination with an adjuvanted protein-based RSVpreF3-vaccine using ELISA and flow cytometry. Data on adverse events were collected through a self-reported questionnaire. Results:Vaccination led to a significant induction of RSV-specific CD4 T cells (P < .0001) and the increase did not differ between the CKD stages. CD8 T cells were not specifically induced. Despite high seroprevalence prior to vaccination, quantitative levels of RSV-specific immunoglobulins IgG and F protein-specific IgG were significantly induced on vaccination (both P < .0001), with a less pronounced increase in patients with advanced CKD. Urinary albumin-creatinine-ratio (UACR) was shown to be predictive of vaccine response in a multivariate regression model using age, serum creatinine and urea as covariates (P = .035). The vaccine was well tolerated with mostly transient adverse events at the injection site. Conclusions:RSV-vaccination led to a robust CD4 T-cell and humoral response in patients with CKD with less pronounced effects in those with high-grade proteinuria. Long-term data on immunogenicity and correlation with clinical outcomes are warranted to define optimal vaccination strategies.

AIMS:Patients with chronic kidney disease (CKD) display a reduced survival following myocardial infarction (MI). As the underlying mechanisms remain unclear, we examined the impact of CKD on cardiac remodeling and function post-MI using a mouse model of adenine-induced CKD. METHODS AND RESULTS:After MI, CKD mice showed a stronger cardiac dysfunction compared to non-CKD controls. While immunohistochemical and immunofluorescence analyses did not reveal changes in cardiomyocyte apoptosis, infarction size, or myofibroblast content, CKD mice exhibited an increased number of circulating myeloid cells post-infarction and more neutrophil infiltration in the heart. Combining RNAseq, untargeted kinome profiling, western blotting, and mass spectrometry revealed that post-MI, CKD enhanced cardiac oxidative stress and the acute stress complex S100A8/A9 in circulation and the heart, and enforced cardiac MAP-kinase p38 activation and NR4A1 phosphorylation as pathways underlying cardiomyocyte dysfunction. S100A8/A9 also exerted an acute detrimental impact on calcium flux and sarcomere shortening in cardiomyocytes ex vivo. Increased myeloid cell-derived S100A8/A9 expression was confirmed in the infarcted human heart by single-nucleus RNAseq, and CKD patients had higher post-infarction S100A8/A9 levels compared to patients without kidney dysfunction. Furthermore, integrating metabolomics, RNAseq, and mitochondrial analysis uncovered a disturbed cardiac metabolism with impaired glycolysis, a reduced glycerol-3-phosphate-shuttle, and a reduced Coenzyme A-bioavailability in CKD vs. non-CKD mice post-MI. These alterations were associated with poorer cardiac performance post-MI, without intrinsic defects in mitochondrial function observed. CONCLUSION:Our study reveals innate immune activation, inflammation, oxidative stress, and metabolic alterations indicative of reduced glycolytic entry and CoA bioavailability along with aggravated cardiac dysfunction post-MI in CKD compared to non-CKD conditions, independent of infarct size, and with poorer cardiac performance in CKD associated with the cardiac metabolic alterations. Combined, this could contribute to the worsened outcome of CKD patients post-MI and reveals cardiac metabolism in CKD as an interesting translational research target.

Chronic kidney disease (CKD) substantially heightens the likelihood of cardiovascular events, in part due to the impaired functionality of high-density lipoprotein (HDL) and its connection with atherosclerosis. Here, 82 patients with CKD stages 2-5 had their plasma isolated and analyzed using mass spectrometry to detect post-translational modifications of apolipoprotein A-I (apoA-I), the main protein component of HDL. Guanidinylation, a non-enzymatic post-translational modification, led to increased levels of apoA-I with CKD progression. The increase in guanidinylated apoA-I became significant from CKD stage 3 onwards. The modification patterns of apoA-I in patients with CKD were mimicked in vitro by exposure to O-methylisourea bisulfate. The thus modified apoA-I was used for functional assays which revealed that guanidinylation compromised the anti-inflammatory and anti-oxidative properties of apoA-I, of potential relevance for clinical findings. Specifically, guanidinylated apoA-I activated inflammatory kinases in macrophages, suggesting a mechanistic link between apoA-I modifications and inflammatory responses. These findings are in favor of alterations in the functional properties of apoA-I in patients with CKD due to guanidinylation. The identification of high guanidinylated apoA-I peptide levels in plasma highlights a novel aspect of protein modification in CKD pathophysiology. The results of our study may provide a better understanding of the molecular mechanisms underlying CKD-related cardiovascular complications and highlight the importance and the need to minimize post-translational modifications in patients with CKD.

Die chronische Nierenkrankheit (CKD) ist einer der wichtigsten Risikofaktoren für Herz-Kreislauf-Erkrankungen (CVD; manifestiert durch koronare Herzkrankheit, Herzinsuffizienz, Arrhythmien und plötzlichen Herztod), und das gleichzeitige Vorliegen sowohl von CVD und CKD hat einen erheblichen Einfluss auf die Prognose der Patienten. Die diagnostischen und therapeutischen Möglichkeiten kardiovaskulärer Erkrankungen sind bei fortgeschrittener CKD häufig eingeschränkt, und für viele interventionelle und medikamentöse Therapien besteht wenig oder keine Evidenz aus großen klinischen Studien. Das vorliegende Konsensuspapier gibt einen Überblick über die Besonderheiten kardiovaskulärer Erkrankungen bei CKD und fasst die aktuelle Evidenz und Empfehlungen zur Therapie von Patienten mit CVD und CKD zusammen.

Introduction: Chronic kidney disease (CKD) affects > 800 million people globally, with prevalence expected to increase, emphasizing the need for effective early detection and management strategies. Urinary Dickkopf-3 (uDKK3), a profibrotic glycoprotein from renal tubular cells, has been linked to acute kidney injury (AKI) and CKD progression. This study assesses uDKK3 as a biomarker for predicting glomerular filtration rate (GFR) decline in the general population. Methods: We conducted a prospective cohort study with 1316 participants aged 55 to 69 years from the Renal Iohexol Clearance Survey (RENIS) (2014–2015), undergoing 1 to 3 GFR measurements using iohexol clearance over 5.3 years. uDKK3 levels were normalized to creatinine (Cr), categorizing participants by uDKK3/Cr levels: undetectable, low (detectable < 400 pg/mg), and high (≥ 400 pg/mg). Linear mixed models were used to evaluate the relationship between uDKK3/Cr levels and GFR decline rate. Logistic regression was used to examine the association between uDKK3/Cr groups and accelerated GFR decline, defined as the top 10% steepest declines. Results: The mean annual GFR decline rate was −1.33 ml/min per 1.73 m2. A total of 1112 individuals had undetectable uDKK3/Cr levels, 167 had low levels, and 37 had high levels. The high uDKK3/Cr level group comprised 63% men and had higher systolic and diastolic blood pressure (BP) levels, despite comparable use of antihypertensive medications. Higher baseline uDKK3/Cr levels significantly correlated with faster GFR decline, independent of traditional CKD risk factors. Participants with high uDKK3/Cr levels had an annual GFR reduction 0.63 ml/min per 1.73 m2 faster than those with undetectable levels (P = 0.049). High uDKK3/Cr levels had an odds ratio of 2.68 for accelerated GFR decline, compared with those with undetectable levels (P = 0.03). Conclusion: Elevated uDKK3 levels were linked to steeper GFR decline, independent of conventional CKD risk factors, confirming uDKK3 as a promising biomarker for early identification of individuals at risk for rapid GFR loss.

Chronic kidney disease (CKD) is the fastest growing cause of death, expected to become the fifth global cause of death and the third in some countries with long life expectancy, such as Japan and Spain, by 2050. This reflects societal aging, as advancing kidney age is the main risk factor for CKD. The forecasted 140% increase in the death rate from CKD by 2050 is reduced to 33% when adjusted for age. The increasing mortality burden is paralleled by higher personal, healthcare, socio-economic and environmental burdens and the need for kidney replacement therapy to treat kidney failure. To some extent, the higher CKD burden represents the price of success in prolonging longevity by decreasing other causes of death. Now is the time to act to minimize the negative impact of CKD on aging societies through primary prevention and early diagnosis and treatment of CKD. Action aimed at maintaining kidney health and delaying biological kidney aging will contribute to healthy aging, as the kidneys have gerosuppressor functions and CKD has the highest negative impact on body aging among chronic non-communicable diseases. This action should be part of a move towards novel holistic approaches to healthy longevity represented by concepts such as cardiovascular-kidney-metabolic health, geromedicine, gerosuppressors and organ rejuvenation. We discuss a conceptual framework for the present and future of kidney aging and kidney health in the elderly, emphasizing opportunities for intervention that underlie the Japanese Society of Nephrology and European Renal Association call to action on Achieving Kidney Health in Aging/Aged Societies.

Patients with chronic kidney disease (CKD) are at increased risk of thrombotic and hemorrhagic complications. Findings on platelet defects in CKD are conflicting. Therefore, we examined platelet function in CKD stage 3 to 5 dialysis patients without antithrombotic therapy, in CKD5D/hemodialysis patients on acetylsalicylic acid (ASA) as well as in a CKD mouse model. Patients with advanced CKD without antithrombotic therapy show platelet preactivation with a partial secondary platelet dysfunction mainly upon collagen/GPVI stimulation. Platelets from hemodialysis patients on ASA showed a less severe CKD-associated secondary platelet dysfunction compared with those not taking ASA, with comparable observations in CKD mice on ASA vs vehicle.

Background: Patients suffering from chronic kidney disease (CKD) have a high risk of premature cardiovascular morbidity and mortality. It has been suggested that elevated homocysteine (Hcy) or disturbances in the transmethylation pathway may contribute to this high cardiovascular risk burden due to epigenetic mechanisms. The objective of this study was to explore the prognostic value of Hcy, S-adenosylhomocysteine (SAH) and S-adenosylmethionine (SAM) (one-carbon (C1)-metabolites) among patients with CKD. Methods: Plasma concentrations of Hcy, SAM and SAH were measured among 297 participants with CKD (KDIGO GFR category G2-G5). The predefined endpoint was the occurrence of major cardiovascular events (MACE), defined as carotid, coronary and peripheral arterial revascularization, stroke, acute myocardial infarction, major amputation, cardiovascular death and all-cause mortality during a median (IQR) follow-up period of 4.0 [3.2; 4.3] years. Results: Among all participants, the median (IQR) of plasma Hcy, SAH, and SAM levels were 16.6 [13.5; 21.2] µmol/L, 41.5 [26.6; 63.9] nmol/L, 183.4 [151.1; 223.5] nmol/L, respectively. Estimated glomerular filtration rate (eGFR) correlated more strongly with plasma SAH (r = -0.588) than with SAM (r = -0.497) and Hcy (r = -0.424). During the follow-up period, 55 participants experienced MACE. In a univariate Kaplan Meier analysis, all three C1-metabolites were significantly associated with the occurrence of the primary outcome. In a Cox-regression analysis, the association between Hcy and MACE was not significant after adjustment for age and sex (hazard ratio (HR) and 95% confidence intervals (95% CI) for the 3rd vs. 1st tertile = 1.804 (0.868-3.974)). Both SAH and SAM were not associated with MACE after adjustment for age, sex and additionally for renal function markers (SAH: HR 3rd vs. 1st tertile 1.645 95% (0.654-4.411); SAM: HR 3rd vs. 1st tertile 1.920 95% CI (0.764-5.138)). Conclusions: In people with CKD, plasma Hcy, SAH and SAM were not independent predictors of MACE after adjustment for age, sex and renal function. Disturbed renal function may explain elevated C1-metabolites and disturbed transmethylation, while this pathway is not likely to be an appropriate access point to modify the risk of cardiovascular events in CKD patients.

Respiratory syncytial virus (RSV) prefusion F-based vaccines have recently been approved for immunosuppressed individuals, but data in solid organ transplant (SOT) recipients remain limited. This observational study assessed natural RSV immunity among 52 controls and 197 patients with immunodeficiencies, of which 46 kidney transplant recipients, 30 lung transplant (LuTx) recipients, and 19 patients with chronic kidney disease subsequently received a single dose of a protein-based RSV vaccine to quantify and characterize RSV-specific antibodies and T cells pre- and postvaccination using enzyme-linked immunosorbent assay and flow cytometry. Reactogenicity was self-reported. Over 90% had natural pan-RSV-specific immunoglobulin G, and 30% to 58% had RSV-specific CD4 T cells. Vaccination was well tolerated and led to a significant increase in antibodies and polyfunctional CD4 T cells (P < .0001), with similar T cell levels to both RSV-subtypes A and B. CD4 T cell responses were comparable between kidney transplant and patients with chronic kidney disease, but significantly lower in LuTx recipients (P = .023) and in SOT recipients within the first year posttransplant (P = .005). The vaccine did not induce any CD8 T cells. In conclusion, a single RSV vaccine dose induced strong immunoglobulin G and CD4 T cell responses with RSV-A/B cross-reactivity. However, LuTx and early posttransplant SOT recipients showed reduced T cell responses. Alternative strategies may be required to improve immunogenicity in heavily immunosuppressed SOT recipients.

Previously, urinary Dickkopf-related protein 3 (uDKK3), a stress-induced tubular cell-derived profibrotic glycoprotein, was shown to be associated with tubulointerstitial fibrosis and loss of kidney function in patients with chronic kidney disease. However, its value in kidney transplant recipients (KTR) is debated, potentially because of a disturbing influence of uDKK3 that is also excreted by native kidneys. We aimed to investigate changes of uDKK3 over time and to evaluate its association with changes of kidney function in KTR without urine production prior to transplantation. Data of KTR enrolled in the TransplantLines Biobank and Cohort Study were used. To eliminate the influence of uDKK3 from the recipients’ kidneys, we only selected KTR that underwent dialysis and were anuric prior to transplantation. uDKK3 was measured using a commercially available ELISA kit in the 24-hour urine samples that were taken at 3, 6, 12, and 24 months after transplantation. The estimated glomerular filtration rate (eGFR) was calculated using the 2009 CKD-EPI creatinine-based equation. Changes in uDKK3 over time and its association with eGFR were analyzed using a linear mixed model. The fitted model was checked for homogeneity of variance and normality of residuals to ensure that the model assumption was not violated. uDKK3 were log2-transformed when assessing the changes in uDKK3 over time and scaled when assessing the association with eGFR, as it gives the best model fit based on the Akaike Information Criterion values. Missing observations in covariates were multiply imputed using Multiple Imputation by Chained Equations. We included 78 KTR (67% male, 63% received a kidney from a deceased donor, 29% with delayed graft function) in the analyses. At baseline (3 months after transplantation), mean (SD) age was 56 (15) years, mean (SD) eGFR was 46 (17) ml/min/1.73 m², median [Q1–Q3] 24 h urinary protein excretion was 0.19 [0.12–0.24] g/24 h, and median [Q1–Q3] 24 h uDKK3 excretion was 1827 [485–5496] ng/24 h. The median [Q1–Q3] intra-individual variation of 24 h uDKK3 excretion over the observed period was 6.8 [5.6–12.4] %. The effect of time on 24 h uDKK3 excretion was not significant (P = 0.3), indicating that the level of 24 h uDKK3 excretion did not significantly change over the observation period (Fig. 1). For the association of 24 h uDKK3 excretion and eGFR, our analysis showed that eGFR decreases by approximately 2.05 mL/min/1.73 m2 per 1 SD increase in 24 h uDKK3 excretion (Table 1). There was no interaction between 24 h uDKK3 excretion and time (pinteraction = 0.2), indicating that the association between 24 h uDKK3 excretion and eGFR did not change over time. Furthermore, there was also no interaction between 24 h uDKK3 excretion and 24 h urinary protein excretion (pinteraction = 0.4). Our findings showed that uDKK3 is a stable biomarker. Furthermore, it is independently associated with loss of eGFR, regardless of the time measurement. This showed that uDKK3 is a potential non-invasive biomarker for monitoring the outcome of KTR.

ABSTRACT To date, no drugs are approved for BK polyomavirus (BKPyV) reactivation, a major cause of nephropathy after kidney transplantation. Recently, tumor necrosis factor‐α (TNF‐α) blockade has been proposed as a promising therapy, however, the effect of TNF‐α on the clinically most common archetype (ww) BKPyV remained unclear. Assays in primary renal proximal tubule epithelial cells (RPTEC) allowed efficient replication only of BKPyV strains with rearranged (rr) non‐coding control regions (NCCR), which may develop at later disease stages, but not of ww‐BKPyV. Here, we optimized culture conditions allowing robust replication of patient‐derived ww‐BKPyV, while efficiently preserving their ww‐NCCR. TNF‐α promoted rr‐BKPyV replication, while the T H 1 cytokine IFN‐γ suppressed it, also in the presence of TNF‐α. Surprisingly, TNF‐α alone was sufficient to suppress all ww‐BKPyV strains tested. Comprehensive analysis using siRNAs, and chimeric or mutated BKPyV‐strains revealed that the response to TNF‐α depends on the NCCR type, and that the NF‐κB p65 pathway but not the conserved NF‐κB binding site is essential for the TNF‐α‐induced enhancement of rr‐BKPyV replication. Our data suggest that in immunosuppressed patients with archetype‐dominated infections, TNF‐α blockade could interfere with natural TNF‐α‐mediated anti‐BKPyviral control, and this could be detrimental when IFN‐γ‐driven T H 1 responses are impaired. Ongoing inflammation, however, could lead to the selection of rearrangements responding to NCCR‐activating pathways downstream of NF‐κB p65 signaling, that may overcome the initial TNF‐α‐mediated suppression. Our findings also highlight the importance of using clinically relevant BKPyV isolates for drug testing and discovery, for which this new assay paves the way.

Early detection is a key strategy to prevent kidney disease, its progression and related complications, but numerous studies show that awareness of kidney disease at the population level is low. Therefore, increasing knowledge and implementing sustainable solutions for early detection of kidney disease are public health priorities. Economic and epidemiological data underscore why kidney disease should be placed on the global public health agenda - kidney disease prevalence is increasing globally and it is now the seventh leading risk factor for mortality worldwide. Moreover, demographic trends, the obesity epidemic and the sequelae of climate change are all likely to increase kidney disease prevalence further, with serious implications for survival, quality of life and health care spending worldwide. Importantly, the burden of kidney disease is highest among historically disadvantaged populations that often have limited access to optimal kidney disease therapies, which greatly contributes to current socioeconomic disparities in health outcomes. This joint statement from the International Society of Nephrology, European Renal Association and American Society of Nephrology, supported by three other regional nephrology societies, advocates for the inclusion of kidney disease in the current WHO statement on major non-communicable disease drivers of premature mortality. Addressing the burden of non-communicable diseases is a global public health priority. In this joint Consensus Statement, the American Society of Nephrology, the European Renal Association and the International Society of Nephrology highlight the need to recognize kidney disease as a key driver of premature mortality, in addition to other non-communicable diseases already prioritized by the World Health Organization.

Objectives: Trimethylamine N-oxide (TMAO) is a gut bacteria-mediated liver metabolite of dietary betaine, choline, and carnitine, which is excreted by glomerular filtration. We studied whether TMAO is excreted by cardiovascular disease (CVD) in patients with chronic kidney disease (CKD). Methods: Among 478 patients with CKD stage G2 (n = 104), G3a (n = 163), G3b (n = 123), and G4 (n = 88), we studied the association between fasting plasma concentrations of TMAO, choline, or betaine at baseline and kidney function, prevalent CVD, and future renal outcomes during a mean follow-up of 5.1 years. Results: Decreased glomerular filtration rate was associated with higher plasma concentrations of TMAO, choline, and betaine. Baseline concentrations of TMAO were higher in participants with preexisting CVD compared to those without CVD (8.4 [10.1] vs. 7.8 [8.0] mmol/L; P = .047), but the difference was not significant after adjusting for confounders. During the follow-up, 147 participants experienced CVD or died, and 144 reached the predefined renal endpoint. In the adjusted regression analyses, TMAO or choline concentrations in the upper three quartiles (vs. the lowest quartile) were not associated with any of the study's clinical endpoints. In contrast, the adjusted hazard ratio of plasma betaine in the highest quartile versus the lowest quartile was 2.14 (1.32, 3.47) for the CVD endpoint and 1.64 (1.00, 2.67) for the renal endpoint. Conclusions: Elevated plasma TMAO concentrations were explained by impaired kidney function. Elevated plasma concentrations of betaine, but not those of TMAO or choline, constituted a risk factor for adverse outcomes. TMAO might not be an appropriate target to reduce CVD or renal outcomes in patients with preexisting CKD.