Faculty Bibliography

BACKGROUND:Metabolites represent a read-out of cellular processes underlying states of health and disease. METHODS:We evaluated cross-sectional and longitudinal associations between 1255 serum and 1398 urine known and unknown (denoted with "X" in name) metabolites (Metabolon HD4, 721 detected in both biofluids) and kidney function in 1612 participants of the Atherosclerosis Risk in Communities (ARIC) Study. All analyses were adjusted for clinical and demographic covariates, including for baseline eGFR and UACR in longitudinal analyses. RESULTS:At visit 5 of the ARIC study, the mean age of participants was 76 years (SD 6), 56% were women, mean eGFR was 62 ml/min/1.73m2 (SD 20), and median urine albumin-to-creatinine level (UACR) was 13 mg/g (IQR 25). In cross-sectional analysis, 675 serum and 542 urine metabolites were associated with eGFR (Bonferroni-corrected p < 4.0E-5 for serum analyses and p < 3.6E-5 for urine analyses), including 248 metabolites shared across biofluids. Fewer metabolites (75 serum and 91 urine metabolites, including 7 shared across biofluids) were cross-sectionally associated with albuminuria. Guanidinosuccinate, N2,N2-dimethylguanosine, hydroxy-N6,N6,N6-trimethyllysine, X-13844, and X-25422 were significantly associated with both eGFR and albuminuria. Over a mean follow-up of 6.6 years, serum mannose (HR 2.3 [1.6,3.2], p = 2.7E-5) and urine X-12117 (HR 1.7 [1.3,2.2], p = 1.9E-5) were risk factors for UACR doubling, whereas urine sebacate (HR 0.86 [0.80,0.92], p = 1.9E-5) was inversely associated. Compared to clinical characteristics alone, including the top 5 endogenous metabolites in serum and urine associated with longitudinal outcomes improved the outcome prediction (AUCs for eGFR decline: clinical model = 0.79, clinical + metabolites model = 0.87, p = 8.1E-6; for UACR doubling: clinical model = 0.66, clinical + metabolites model = 0.73, p = 2.9E-5). CONCLUSIONS:Metabolomic profiling in different biofluids provided distinct and potentially complementary insights into the biology and prognosis of kidney diseases.

BACKGROUND/UNASSIGNED:There is interest in identifying novel filtration markers that lead to more accurate GFR estimates than current markers (creatinine and cystatin C) and are more consistent across demographic groups. We hypothesize that large-scale metabolomics can identify serum metabolites that are strongly influenced by glomerular filtration rate (GFR) and are more consistent across demographic variables than creatinine, which would be promising filtration markers for future investigation. METHODS/UNASSIGNED:< -0.5), we assessed additional variation by age (height in children), sex, race and body mass index (BMI). RESULTS/UNASSIGNED:< -0.5), 27 were consistently not associated with age (height in children), sex or race. CONCLUSIONS/UNASSIGNED:The majority of metabolite-mGFR correlations were negative and consistent across sex, race, BMI and study. Metabolites with consistent strong negative correlations with mGFR and non-association with demographic variables may represent candidate markers to improve estimation of GFR.

RATIONALE & OBJECTIVE/OBJECTIVE:Smoking is a modifiable risk factor for various adverse events. However, little is known about the association of smoking with the incidence of acute kidney injury (AKI) in the general population. The objective of this study is to investigate the association of cigarette smoking with the risk of AKI. STUDY DESIGN/METHODS:Prospective observational study. SETTING & PARTICIPANTS/METHODS:14,571 participants (mean age 55 [6] years, 55% women and 25% Black participants) from the ARIC study visit 1 (1987-1989) were followed through December 31, 2019. EXPOSURES/METHODS:Smoking parameters (status, duration, pack-years, intensity, and years since cessation). OUTCOMES/RESULTS:Incident hospitalization with AKI, defined by a hospital discharge with a diagnostic code relevant to AKI. ANALYTICAL APPROACH/METHODS:Multivariable Cox regression models. RESULTS:Over a median follow-up of 26.3 years, 2,984 participants had an incident hospitalization with AKI. Current and former smokers had a significantly higher risk of AKI compared to never smokers after adjusting for potential confounders (Hazard ratio [HR], 2.22 [95% CI: 2.02-2.45] and 1.12 [1.02-1.23], respectively). A dose-response association was consistently seen for each of smoking duration, pack-years, and intensity with AKI (e.g., 1.19 [1.16-1.22] per 10 years of smoking). When years since cessation were considered as a time-varying exposure, the risk of AKI associated with smoking, compared to current smokers, began to decrease after 10 years, and became similar to never smokers at 30 years (HR for ≥30 years, 1.07 [0.97-1.20] vs. never smokers). LIMITATIONS/CONCLUSIONS:Self-reported smoking measurements and missing outpatient AKI cases. CONCLUSIONS:In a community-based cohort, all smoking parameters were robustly associated with the risk of AKI. Smoking cessation was associated with decreased risk of AKI, although the excess risk lasted up to 30 years. Our study supports the importance of preventing smoking initiation and promoting smoking cessation for the risk of AKI.

BACKGROUND/UNASSIGNED: METHODS/UNASSIGNED:case definition. VE was calculated as (1 - OR) × 100%. RESULTS/UNASSIGNED:). The adjusted population PCV13 VE was 39% (95% CI 13%-58%), and combination PCV13 and PPSV23 was 39% (95% CI 12%-58%). PPSV23 VE was -3.7% (95% CI -57% to 32%). Stratified by eGFR, adjusted PCV13 VE was consistent in eGFR ≥60 [VE 38% (95% CI 2.9%-61%)] and 30-59 [VE 61% (95% CI 24%-80%)] without significant interaction. VE was not calculable for eGFR <30 due to small sample size. CONCLUSION/UNASSIGNED:).

BACKGROUND:Protein carbamylation, a post-translational protein modification primarily driven by urea, independently associates with adverse clinical outcomes in patients with CKD. Biomarkers used to quantify carbamylation burden have mainly included carbamylated albumin (C-Alb) and homocitrulline (HCit, carbamylated lysine). In this study, we aimed to compare the prognostic utility of these two markers in order to facilitate comparisons of existing studies employing either marker alone, and to inform future carbamylation studies. METHODS:Both serum C-Alb and free HCit levels were assayed from the same timepoint in 1632 individuals with CKD stages 2-4 enrolled in the prospective Chronic Renal Insufficiency Cohort (CRIC) study. Adjusted Cox proportional hazard models were used to assess risks for the outcomes of death (primary) and end stage kidney disease (ESKD) using each marker. C-statistics, net reclassification improvement, and integrated discrimination improvement were used to compare the prognostic value of each marker. RESULTS:Participant demographics included mean (SD) age 59 (11) years; 702 (43%) females; 700 (43%) white. C-Alb and HCit levels were positively correlated with one another (Pearson correlation coefficient 0.64). Higher C-Alb and HCit levels showed similar increased risk of death (e.g., the adjusted hazard ratio [HR] for death in the 4th carbamylation quartile compared to the 1st was 1.90 (95% confidence interval [CI] 1.35-2.66) for C-Alb, and 1.89 [1.27-2.81] for HCit; and on a continuous scale, the adjusted HR for death using C-Alb was 1.24 [1.11 to 1.39] per standard deviation increase, and 1.27 [1.10-1.46] using HCit). Both biomarkers also had similar HRs for ESKD. The C-statistics were similar when adding each carbamylation biomarker to base models (e.g., for mortality models, the C-statistic was 0.725 [0.707-0.743] with C-Alb and 0.725 [0.707-0.743] with HCit, both compared to a base model 0.723). Similarities were also observed for the net reclassification improvement and integrated discrimination improvement metrics. CONCLUSIONS:C-Alb and HCit had similar performance across multiple prognostic assessments. The markers appear readily comparable in CKD epidemiological studies.

BACKGROUND:Glucagon-like peptide-1 receptor agonists (GLP-1RA) have cardiovascular benefits in type 2 diabetes, but none of the cardiovascular trials studied atrial fibrillation/atrial flutter (AF) as a primary endpoint. Data from post-marketing surveillance studies remains sparse. OBJECTIVE:To examine the real-world risk of AF comparing GLP-1RA with other non-insulin glucose-lowering agents. DESIGN/METHODS:Cohort study using de-identified electronic health record data from the Optum Labs Data Warehouse. PARTICIPANTS/METHODS:Adult patients with diabetes who were newly prescribed add-on non-insulin glucose-lowering agents and were on metformin between 2005-2020. EXPOSURES/METHODS:New users of GLP-1RA were separately compared with new users of dipeptidyl peptidase-4 inhibitors (DPP4i) and sodium-glucose cotransporter 2 inhibitors (SGLT2i), using 1:1 propensity score matching to adjust for differences in patient characteristics. MAIN MEASURES/METHODS:The primary outcome was incident AF, defined and captured by diagnosis code for AF. Incidence rate difference (IRD) and hazard ratio (HR) were estimated in the matched cohorts. KEY RESULTS/RESULTS:In the matched cohort of 14,566 pairs of GLP-1RA and DPP4i followed for a median of 3.8 years, GLP-1RA use was associated with a lower risk of AF (IRD, -1.0; 95% CI, -1.8 to -0.2 per 1000 person-years; HR, 0.82; 95% CI, 0.70 to 0.96). In the matched cohort of 9,424 pairs of patients on GLP-1RA and SGLT2i with a median follow-up of 2.9 years, there was no difference in the risk for AF (IRD, 0.4; 95% CI -0.7 to 1.5 per 1000 person-years; HR, 1.12; 95% CI, 0.89 to 1.42). CONCLUSIONS:In this real-word study, GLP-1RA was associated with a lower risk of AF compared with DPP4i, but no difference compared with SGLT2i, suggesting that cardiovascular benefits of GLP-1RA use may extend to prevention for AF in patients with diabetes. Our findings call for future randomized controlled trials to focus on the effects of GLP-1RA on AF prevention.

RATIONALE & OBJECTIVE/UNASSIGNED:While urine excretion of nitrogen estimates the total protein intake, biomarkers of specific dietary protein sources have been sparsely studied. Using untargeted metabolomics, this study aimed to identify serum metabolomic markers of 6 protein-rich foods and to examine whether dietary protein-related metabolites are associated with incident chronic kidney disease (CKD). STUDY DESIGN/UNASSIGNED:Prospective cohort study. SETTING & PARTICIPANTS/UNASSIGNED:A total of 3,726 participants from the Atherosclerosis Risk in Communities study without CKD at baseline. EXPOSURES/UNASSIGNED:Dietary intake of 6 protein-rich foods (fish, nuts, legumes, red and processed meat, eggs, and poultry), serum metabolites. OUTCOMES/UNASSIGNED:with ≥25% estimated glomerular filtration rate decline relative to visit 1, hospitalization or death related to CKD, or end-stage kidney disease). ANALYTICAL APPROACH/UNASSIGNED:Multivariable linear regression models estimated cross-sectional associations between protein-rich foods and serum metabolites. C statistics assessed the ability of the metabolites to improve the discrimination of highest versus lower 3 quartiles of intake of protein-rich foods beyond covariates (demographics, clinical factors, health behaviors, and the intake of nonprotein food groups). Cox regression models identified prospective associations between protein-related metabolites and incident CKD. RESULTS/UNASSIGNED:). LIMITATIONS/UNASSIGNED:Residual confounding and sample-storage duration. CONCLUSIONS/UNASSIGNED:We identified candidate biomarkers of fish, nuts, red and processed meat, eggs, and poultry. A fish-related metabolite, 1-docosahexaenoylglycerophosphocholine (22:6n3), was associated with a lower risk of CKD.

BACKGROUND AND HYPOTHESIS/OBJECTIVE:New equations to estimate GFR based on creatinine (eGFRcr), cystatin C (eGFRcys) or both (eGFRcr-cys) have been developed by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and the European Kidney Function Consortium (EKFC). There is a need to evaluate the performance of these equations in diverse European settings to inform implementation decisions, especially among people with key comorbid conditions. METHODS:We performed a cross-sectional study including 6174 adults referred for single-point plasma clearance of iohexol in Stockholm, Sweden, with 9579 concurrent measurements of creatinine and cystatin C. We assessed the performance of the CKD-EPI 2009/2012/2021, EKFC 2021/2023, revised Lund-Malmö (RLM) 2011 and CAPA 2014 equations against measured GFR (mGFR). RESULTS:Mean age was 56 years, mGFR was 62 mL/min/1.73m2 and 40% were female. Comorbid conditions were common: cardiovascular disease (30%), liver disease (28%), diabetes (26%) and cancer (26%). All eGFRcr-cys equations had small bias and P30 close to 90%, and performed better than eGFRcr or eGFRcys equations. Among eGFRcr equations, CKD-EPI 2009 and CKD-EPI 2021 showed larger bias and lower P30 than EKFC 2021 and RLM. There were no meaningful differences in performance across eGFRcys equations. Findings were consistent across comorbid conditions, and eGFRcr-cys equations showed good performance in patients with liver disease, cancer and heart failure. CONCLUSIONS:In conclusion, eGFRcr-cys equations performed best, with minimal variation among equations in this Swedish cohort. The lower performance of CKD-EPI eGFRcr equations compared with EKFC and Lund-Malmö may reflect differences in population characteristics and mGFR methods. Implementing eGFRcr equations will require a trade-off between accuracy and uniformity across regions.

BACKGROUND:Chronic kidney disease (CKD) has been implicated as a risk factor for venous thromboembolism, but the evidence is limited to relatively healthy populations. The objective of the current study was to discern whether parameters of kidney function and damage are associated with the occurrence of venous thromboembolism after hospitalization. METHODS:We conducted a retrospective study including 23,899 and 11,552 adult individuals hospitalized within Geisinger Health System and NYU Langone Health from 2004 to 2019 and 2012 to 2022, respectively. A Poisson model was used to evaluate adjusted incidence rates of venous thromboembolism according to estimated glomerular filtration rate (eGFR) and albuminuria categories in each cohort. Cox proportional hazards models were used to analyze associations of eGFR and urinary albumin to creatinine ratio (UACR) with venous thromboembolism and hazard ratios were meta-analyzed across cohorts. RESULTS:Both lower eGFR and higher UACR were associated with higher risks of venous thromboembolism. In the Geisinger cohort, the incidence of venous thromboembolism after hospital discharge ranged from 10.7 (95% CI 9.2 - 12.6) events per 1000 person-years in individuals in G1A1 (eGFR >90 mL/min/1.73 m2 and UACR <30 mg/g) to 27.7 (95% CI 20.6 - 37.2) events per 1000 person-years in individuals with G4-5A3 (eGFR <30 mL/min/1.73 m2 and UACR >300 mg/g). A similar pattern was observed in the NYU cohort. Meta-analyses of the two cohorts showed that every 10 mL/min/1.73m2 reduction in eGFR below 60 mL/min/1.73m2 was associated with a 6% higher risk of venous thromboembolism (HR 1.06 [1.02 - 1.11], P = 0.01), and each two-fold higher UACR was associated with a 5% higher risk of venous thromboembolism (HR 1.05 [1.03 - 1.07], P <0.001). CONCLUSIONS:Both eGFR and UACR were independently associated with higher risk of venous thromboembolism after hospitalization. The incidence rate was higher with greater severity of CKD.

BACKGROUND/UNASSIGNED:), which may be less accurate in older adults. OBJECTIVE/UNASSIGNED:) and 8 outcomes. DESIGN/UNASSIGNED:Population-based cohort study. SETTING/UNASSIGNED:Stockholm, Sweden, 2010 to 2019. PARTICIPANTS/UNASSIGNED:82 154 participants aged 65 years or older with outpatient creatinine and cystatin C testing. MEASUREMENTS/UNASSIGNED:Hazard ratios for all-cause mortality, cardiovascular mortality, and kidney failure with replacement therapy (KFRT); incidence rate ratios for recurrent hospitalizations, infection, myocardial infarction or stroke, heart failure, and acute kidney injury. RESULTS/UNASSIGNED:, and for KFRT they were 2.6 (CI, 1.2 to 5.8) and 1.4 (CI, 0.7 to 2.8), respectively. Similar findings were observed in subgroups, including those with a urinary albumin-creatinine ratio below 30 mg/g. LIMITATION/UNASSIGNED:No GFR measurements. CONCLUSION/UNASSIGNED:was more strongly associated with adverse outcomes and the associations were more uniform. PRIMARY FUNDING SOURCE/UNASSIGNED:Swedish Research Council, National Institutes of Health, and Dutch Kidney Foundation.