Diversity of plant DNA in stool is linked to dietary quality, age, and household income.

Eating a varied diet is a central tenet of good nutrition. Here, we develop a molecular tool to quantify human dietary plant diversity by applying DNA metabarcoding with the chloroplast trnL-P6 marker to 1,029 fecal samples from 324 participants across two interventional feeding studies and three observational cohorts. The number of plant taxa per sample (plant metabarcoding richness or pMR) correlated with recorded intakes in interventional diets and with indices calculated from a food frequency questionnaire in typical diets (ρ = 0.40 to 0.63). In adolescents unable to collect validated dietary survey data, trnL metabarcoding detected 111 plant taxa, with 86 consumed by more than one individual and four (wheat, chocolate, corn, and potato family) consumed by >70% of individuals. Adolescent pMR was associated with age and household income, replicating prior epidemiologic findings. Overall, trnL metabarcoding promises an objective and accurate measure of the number and types of plants consumed that is applicable to diverse human populations.

Role of Age and Competing Risk of Death in the Racial Disparity of Kidney Failure Incidence after Onset of CKD.

SIGNIFICANCE STATEMENT: Black adults in the United States have 2-4 times higher incidence of kidney failure than White adults. Yet, the reasons underlying this disparity remain poorly understood. Among 547,188 US veterans with new-onset CKD, according to a new race-free GFR equation, Black veterans had a 2.5-fold higher cumulative incidence of kidney failure, compared with White veterans, in any follow-up period from CKD onset. This disparity resulted from a combination of higher hazards of progression to kidney failure and lower hazards of competing-risk death in Black veterans. Both, in turn, were largely explained by the younger age at CKD onset in Black veterans, underscoring an urgent need to prevent early onset and slow progression of CKD in younger Black adults. BACKGROUND: The Black adult population is well known to have higher incidence of kidney failure than their White counterpart in the United States, but the reasons underlying this disparity are unclear. We assessed the racial differences in kidney failure and death from onset of CKD on the basis of the race-free 2021 CKD Epidemiology Collaboration equation and examined the extent to which these differences could be explained by factors at the time of CKD onset. METHODS: We analyzed a national cohort consisting of 547,188 US veterans (103,821 non-Hispanic Black and 443,367 non-Hispanic White), aged 18-85 years, with new-onset CKD between 2005 and 2016 who were followed through 10 years or May 2018 for incident kidney failure with replacement therapy (KFRT) and pre-KFRT death. RESULTS: At CKD onset, Black veterans were, on average, 7.8 years younger than White veterans. In any time period from CKD onset, the cumulative incidence of KFRT was 2.5-fold higher for Black versus White veterans. Meanwhile, Black veterans had persistently >2-fold higher hazards of KFRT throughout follow-up (overall hazard ratio [95% confidence interval], 2.38 [2.31 to 2.45]) and conversely had 17%-48% decreased hazards of pre-KFRT death. These differences were reduced after accounting for the racial difference in age at CKD onset. CONCLUSIONS: The 2.5-fold higher cumulative incidence of kidney failure in Black adults resulted from a combination of higher hazards of progression to kidney failure and lower hazards of the competing risk of death, both of which can be largely explained by the younger age at CKD onset in Black compared with White adults.

Generalized Propensity Score Methods to Assess CKD-Associated Physiologic Factors and Risk of Kidney Failure in the Chronic Renal Insufficiency Cohort (CRIC) Study.

Epidemiologic studies have identified many biochemical risk factors for chronic kidney disease (CKD) progression that are correlates of kidney function, termed here 'CKD-associated physiologic factors'. Uncertainty remains if these factors are risk factors or risk markers accounting for aspects of kidney function not otherwise captured. We aimed to use flexible machine learning, a dynamic covariate history including kidney function informative markers, and generalized propensity score (GPS) weighting, to better control confounding for such exposures. We studied 3,052 adults with CKD in the Chronic Renal Insufficiency Cohort Study. We established a 2-year run-in period and assembled 90 variables that characterize variability and trends of selected CKD-associated physiologic factors and confounders. Using SuperLearner, we created a GPS for each CKD-associated physiologic factor and performed GPS-weighted Cox regressions. For context, we also evaluated results from traditional multivariable Cox proportional hazards models as in prior studies. Similar to traditional approaches, bicarbonate, calcium, potassium, hemoglobin, and PTH were each associated with risk of kidney failure using GPS weighting. The GPS approach detected non-linear associations in many factors, some of which were not detected with traditional models. We conclude that many associations between CKD-associated physiologic factors and kidney outcomes remain strong after GPS weighting.

Comparative Effectiveness of Alternative Treatment Approaches to Secondary Hyperparathyroidism in Patients Receiving Maintenance Hemodialysis: An Observational Trial Emulation.

RATIONALE & OBJECTIVE: Optimal approaches to treat secondary hyperparathyroidism (SHPT) in patients on maintenance hemodialysis (HD) have yet to be established in randomized controlled trials (RCTs). STUDY DESIGN: Two observational clinical trial emulations. SETTING & PARTICIPANTS: Both emulations included adults receiving in-center HD from a national dialysis organization. The patients who had SHPT in the period between 2009 and 2014, were insured for≥180 days by Medicare as primary payer, and did not have contraindications or poor health status limiting theoretical trial participation. EXPOSURE: The parathyroid hormone (PTH) Target Trial emulation included patients with new-onset SHPT (first PTH 300-600pg/mL), with 2 arms defined as up-titration of either vitamin D sterols or cinacalcet within 30 days (lower target) or no up-titration (higher target). The Agent Trial emulation included patients with a PTH≥300 pg/mL while on≥6µg weekly of vitamin D sterol (paricalcitol equivalent dose) and no prior history of cinacalcet. The 2 arms were defined by the first dose or agent change within 30 days (vitamin D-favoring [vitamin-D was up-titrated] vs cinacalcet-favoring [cinacalcet was added] vs nondefined [neither applies]). Multiple trials per patient were allowed in trial 2. OUTCOME: The primary outcome was all-cause death over 24 months; secondary outcomes included cardiovascular (CV) hospitalization or the composite of CV hospitalization or death. ANALYTICAL APPROACH: Pooled logistic regression. RESULTS: There were 1,152 patients in the PTH Target Trial (635 lower target and 517 higher target). There were 2,726 unique patients with 6,727 patient trials in the Agent Trial (6,268 vitamin D-favoring trials and 459 cinacalcet-favoring trials). The lower PTH target approach was associated with reduced adjusted hazard of death (HR, 0.71 [95% CI, 0.52-0.93]), CV hospitalization (HR, 0.78 [95% CI, 0.63-0.98]), and their composite (HR, 0.74 [95% CI, 0.61-0.89]). The cinacalcet-favoring approach demonstrated lower adjusted hazard of death compared to the vitamin D-favoring approach (HR, 0.79 [95% CI, 0.62-0.99]), but not of CV hospitalization or the composite outcome. LIMITATIONS: Potential for residual confounding; low use of cinacalcet with low power. CONCLUSIONS: SHPT management that is focused on lower PTH targets may lower mortality and CV disease in patients receiving HD. These findings should be confirmed in a pragmatic randomized trial. PLAIN-LANGUAGE SUMMARY: Optimal approaches to treat secondary hyperparathyroidism (SHPT) have not been established in randomized controlled trials. Data from a national dialysis organization was used to identify patients with SHPT in whom escalated treatment may be indicated. The approach to treatment was defined based on observed upward titration of SHPT-controlling medications: earlier titration (lower target) versus delayed titration (higher target); and the choice of medication (cinacalcet vs vitamin D sterols). In the first trial emulation, we estimated a 29% lower rate of death and 26% lower rate of cardiovascular disease or death for patients managed with a lower versus higher target approach. Cinacalcet versus vitamin D-favoring approaches were not consistently associated with outcomes in the second trial emulation. This observational study suggests the need for additional clinical trials of SHPT treatment intensity.

Designing an Implementable Clinical Prediction Model for Near-Term Mortality and Long-Term Survival in Patients on Maintenance Hemodialysis.

RATIONALE & OBJECTIVE: The life expectancy of patients treated with maintenance hemodialysis (MHD) is heterogeneous. Knowledge of life-expectancy may focus care decisions on near-term versus long-term goals. The current tools are limited and focus on near-term mortality. Here, we develop and assess potential utility for predicting near-term mortality and long-term survival on MHD. STUDY DESIGN: Predictive modeling study. SETTING & PARTICIPANTS: 42,351 patients contributing 997,381 patient months over 11 years, abstracted from the electronic health record (EHR) system of midsize, nonprofit dialysis providers. NEW PREDICTORS & ESTABLISHED PREDICTORS: Demographics, laboratory results, vital signs, and service utilization data available within dialysis EHR. OUTCOME: For each patient month, we ascertained death within the next 6 months (ie, near-term mortality) and survival over more than 5 years during receipt of MHD or after kidney transplantation (ie, long-term survival). ANALYTICAL APPROACH: We used least absolute shrinkage and selection operator logistic regression and gradient-boosting machines to predict each outcome. We compared these to time-to-event models spanning both time horizons. We explored the performance of decision rules at different cut points. RESULTS: All models achieved an area under the receiver operator characteristic curve of≥0.80 and optimal calibration metrics in the test set. The long-term survival models had significantly better performance than the near-term mortality models. The time-to-event models performed similarly to binary models. Applying different cut points spanning from the 1st to 90th percentile of the predictions, a positive predictive value (PPV) of 54% could be achieved for near-term mortality, but with poor sensitivity of 6%. A PPV of 71% could be achieved for long-term survival with a sensitivity of 67%. LIMITATIONS: The retrospective models would need to be prospectively validated before they could be appropriately used as clinical decision aids. CONCLUSIONS: A model built with readily available clinical variables to support easy implementation can predict clinically important life expectancy thresholds and shows promise as a clinical decision support tool for patients on MHD. Predicting long-term survival has better decision rule performance than predicting near-term mortality. PLAIN-LANGUAGE SUMMARY: Clinical prediction models (CPMs) are not widely used for patients undergoing maintenance hemodialysis (MHD). Although a variety of CPMs have been reported in the literature, many of these were not well-designed to be easily implementable. We consider the performance of an implementable CPM for both near-term mortality and long-term survival for patients undergoing MHD. Both near-term and long-term models have similar predictive performance, but the long-term models have greater clinical utility. We further consider how the differential performance of predicting over different time horizons may be used to impact clinical decision making. Although predictive modeling is not regularly used for MHD patients, such tools may help promote individualized care planning and foster shared decision making.

Progression of Coronary Artery Calcification and Risk of Clinical Events in CKD: The Chronic Renal Insufficiency Cohort Study.

RATIONALE & OBJECTIVE: Coronary artery calcification (CAC) progresses rapidly in people with chronic kidney disease (CKD) compared with the general population. We studied the association between CAC progression and higher risks of atherosclerotic cardiovascular disease (CVD), congestive heart failure, and all-cause mortality among adults with CKD. STUDY DESIGN: Prospective cohort study. SETTING: & Participants: 1,310 participants in the Chronic Renal Insufficiency Cohort (CRIC) Study who had at least one CAC scan with no prior history of CVD and with observed or imputed data on changes in CAC over time. EXPOSURE: Observed or imputed CAC progression, categorized as incident CAC among participants with zero CAC on the baseline scan, or progressive CAC when the baseline scan demonstrated CAC and there was an increase in CAC ≥50 Agatston units per year. OUTCOMES: Atherosclerotic CVD (myocardial infarction or stroke), congestive heart failure, and all-cause mortality. ANALYTICAL APPROACH: Cause-specific Cox proportional hazards regression, stratified by presence of CAC at baseline. RESULTS: A total of 545 participants without and 765 with prevalent CAC at baseline were included. During a mean 3.3 years between CAC assessments, 177 (32.5%) participants without baseline CAC developed incident CAC while 270 participants (35.3%) with baseline CAC developed a ≥50 Agatston units per year increase in CAC. After multivariable adjustment, incident CAC was associated with 2.42-fold higher rate of atherosclerotic CVD (95% confidence interval [CI]: 1.23-4.79) and 1.82-fold higher rate of all-cause mortality (95% CI: 1.03-3.22). Progressive CAC (≥50 units per year) was not associated with atherosclerotic CVD (hazard ratio [HR]: 1.42; 95% CI: 0.85-2.35) but was associated with a 1.73-fold higher rate of all-cause mortality (95% CI: 1.31-2.28). Progressive CAC was not associated with incident heart failure. LIMITATIONS: Residual confounding and limited statistical power for some outcomes. CONCLUSIONS: Among adults with CKD stages 2-4, CAC progression over a mean 3.3 years was associated with higher risk of atherosclerotic CVD and all-cause mortality. The associations were strongest among participants without CAC at baseline.

Fruit and Vegetable Intake Patterns, Kidney Failure, and Mortality in Adults with and without Chronic Kidney Disease in the United States.

BACKGROUND: Fruits and vegetables (F&Vs) are vital components of healthy diets but may be restricted in chronic kidney disease (CKD) to avoid high-potassium intake. We previously generated F&V patterns for patients in the National Health and Nutrition Examination Survey (NHANES) and demonstrated an increased prevalence of the overall low-intake pattern in patients with CKD. OBJECTIVE: To evaluate the association of F&V patterns (overall low intake, high unprocessed, moderate processed, and high ultraprocessed) with the risk of kidney failure and its composite with death. METHODS: Adults in NHANES III with valid dietary data and longitudinal follow-up for kidney failure and death were included. F&V patterns were identified using 24-h dietary recalls and latent class analysis, yielding 4 patterns. Cox models were used to evaluate the prospective association between each pattern and hazard of kidney failure or a composite of kidney failure or death over ≤20 y. Models were adjusted for demographics and select comorbidities and weighted for the complex survey design. Secondary analyses evaluated serum carotenoids as objective biomarkers of F&V intake. RESULTS: Among 16,726 eligible participants in NHANES III, F&V consumption consistent with the high-ultraprocessed pattern associated with the highest risk of kidney failure after demographic and comorbidity adjustment, but attenuated with adjustment for kidney function. The high unprocessed pattern associated with the lowest adjusted risk of death or kidney failure combined [hazard ratio (HR): 0.73; 95% confidence interval (CI): 0.65, 0.81 relative to overall low intake]. Higher-serum carotenoids were associated with a lower adjusted risk of death or kidney failure combined (HR: 0.57; 95% CI: 0.49, 0.65 for quartile 4 compared with quartile 1). Results were similar in patients with CKD at baseline. CONCLUSIONS: Higher intake of unprocessed F&Vs was associated with better outcomes in the general population and patients with CKD. Results emphasize the need to safely improve F&V intake in CKD.

Longitudinal Pilot Evaluation of the Gut Microbiota Comparing Patients With and Without Chronic Kidney Disease.

OBJECTIVE: The gut microbiota contributes to metabolic diseases, such as diabetes and hypertension, but is poorly characterized in chronic kidney disease (CKD). DESIGN AND METHODS: We enrolled 24 adults within household pairs, in which at least one member had self-reported kidney disease, diabetes, or hypertension. CKD was classified based on estimated glomerular filtration rate < 60 mL/min/1.73 m2 or urine-albumin-to-creatinine ratio of ≥ 30 mg/g. Participants collected stool and dietary recalls seasonally over a year. Gut microbiota was characterized using 16s rRNA and metagenomic sequencing. RESULTS: Ten participants had CKD (42%) with a median (interquartile range) estimated glomerular filtration rate of 49 (44, 54) mL/min/1.73 m2. By 16s rRNA sequencing, there was moderate to high intraclass correlation (ICC = 0.63) for seasonal alpha diversity (Shannon index) within individuals and modest differences by season (P < .01). ICC was lower with metagenomics, which has resolution at the species level (ICC = 0.26). There were no differences in alpha or beta diversity by CKD with either method. Among 79 genera, Frisingicoccus, Tuzzerella, Faecalitalea, and Lachnoclostridium had lower abundance in CKD, while Collinsella, Lachnospiraceae_ND3007, Veillonella, and Erysipelotrichaceae_UCG_003 were more abundant in CKD (each nominal P < .05) using 16s rRNA sequencing. Higher Collinsella and Veillonella and lower Lachnoclostridium in CKD were also identified by metagenomics. By metagenomics, Coprococcus catus and Bacteroides stercoris were more and less abundant in CKD, respectively, at false discovery rate corrected P = .02. CONCLUSIONS: We identified candidate taxa in the gut microbiota associated with CKD. High ICC in individuals with modest seasonal impacts implies that follow-up studies may use less frequent sampling.

Association of Acute Kidney Injury and Cardiovascular Disease Following Percutaneous Coronary Intervention: Assessment of Interactions by Race, Diabetes, and Kidney Function.

RATIONALE & OBJECTIVE: Black patients and those with diabetes or reduced kidney function experience a disproportionate burden of acute kidney injury (AKI) and cardiovascular events. However, whether these factors modify the association between AKI and cardiovascular events after percutaneous coronary intervention (PCI) is unknown and was the focus of this study. STUDY DESIGN: Observational cohort. SETTING & PARTICIPANTS: Patients who underwent PCI at Duke between January 1, 2003, and December 31, 2013, with data available in the Duke Databank for Cardiovascular Disease. EXPOSURE: AKI, defined as ≥1.5-fold relative elevation in serum creatinine within 7 days from a reference value ascertained 30 days before PCI, or a 0.3 mg/dL increase from the reference value within 48 hours. OUTCOME: A composite of all-cause death, myocardial infarction, stroke, or revascularization during the first year after PCI. ANALYTICAL APPROACH: Cox regression models adjusted for potential confounders and with interaction terms between AKI and race, diabetes, or baseline estimated glomerular filtration rate (eGFR). RESULTS: Among 9,422 patients, 9% (n = 865) developed AKI, and the primary composite outcome occurred in 21% (n = 2,017). AKI was associated with a nearly 2-fold higher risk of the primary outcome (adjusted HR, 1.94 [95% CI, 1.71-2.20]). The association between AKI and cardiovascular risk did not significantly differ by race (P interaction, 0.4), diabetes, (P interaction, 0.06), or eGFR (P interaction, 0.2). However, Black race and severely reduced eGFR, but not diabetes, each had a cumulative impact with AKI on risk for the primary outcome. Compared with White patients with no AKI as the reference, the risk for the outcome was highest in Black patients with AKI (HR, 2.27 [95% CI, 1.83-2.82]), followed by White patients with AKI (HR, 1.87 [95% CI, 1.58-2.21]), and was least in patients of other races with AKI (HR, 1.48 [95% CI, 0.88-2.48]). LIMITATIONS: Residual confounding, including the impact of clinical care following PCI on cardiovascular outcomes of AKI. CONCLUSIONS: Neither race, diabetes, nor reduced eGFR potentiated the association of AKI with cardiovascular risk, but Black patients with AKI had a qualitatively greater risk than White patients with AKI or patients of other races with AKI. PLAIN-LANGUAGE SUMMARY: This study examined differences by race, diabetes, or kidney function in the well-known association of AKI with increased risk for cardiovascular outcomes among patients undergoing percutaneous coronary intervention. The authors found that AKI was associated with a greater risk for cardiovascular outcomes, but this risk did not differ by patients' race, diabetes status, or level of kidney function before the procedure. That said, the risk for cardiovascular outcomes was numerically highest among Black patients compared with White patients or those of other races. These study findings suggest that future efforts to prevent AKI among patients undergoing the procedure could reduce racial disparities in risk for unfavorable cardiovascular outcomes afterward.

Patterns of Fruit and Vegetable Intake in Adults With and Without Chronic Kidney Disease in the United States.

OBJECTIVE: To characterize patterns of fruit and vegetable (F&V) intake in US adults with and without chronic kidney disease (CKD). METHODS: We used 24-hour dietary recall data from multiple cycles of the National Health and Nutrition Examination Survey spanning 3 groups from 1988 to 2018 (1988-1994; 2003-2010; 2011-2018). We categorized F&Vs based on food processing and phytochemical content. We assessed patterns of F&Vs using latent class analysis and compared intake patterns across the 3 temporal cohorts and CKD status using weighted multinomial logistic regression. RESULTS: Four similar patterns of F&Vs emerged in each cycle: Overall Low Intake, High Unprocessed, High Ultra-Processed, and Moderate Processed F&Vs. The Overall Low Intake pattern was most prevalent in all cohorts and CKD groups. After adjustment for demographic variables and selected health conditions, participants with compared to without CKD were more likely to be classified as Overall Low Intake in each cohort, although this was not significant in the National Health and Nutrition Examination Survey 2011-2018. CONCLUSIONS: Low consumption of F&Vs was more common in patients with CKD. Longitudinal studies are needed to determine if low intake is a risk factor for, or response to, CKD.