Chronic Renal Insufficiency Cohort Study Research Articles

Population-Based Limits of Urine Creatinine Excretion

The validity of a timed urine collection is typically judged by measurement of urine creatinine excretion, but prevailing limits may be unreliable. We sought to empirically derive population-based limits of excretion for evaluating the validity of a timed urine collection. Covariate and 24-hour urine data were obtained from 3582 participants in the Chronic Renal Insufficiency Cohort (CRIC) study, 814 participants in the Modification of Diet in Renal Disease (MDRD) study, 1010 participants in the Jackson Heart Study (JHS), and 8536 participants in the Prevention of Renal Vascular End Stage Disease (PREVEND) study. Weight, height, age, sex, and serum creatinine concentrations were evaluated as potential predictors of urine creatinine excretion using Akaike Information Criteria, R-squared values, and deviance. Bias and precision of the fitted models were assessed by analyses of residuals. Agreement between 24-hour creatinine clearance and 125I-iothalamate clearance was assessed before and after exclusion of potentially invalid urine samples. A best-fitting model to predict 24-hour urine creatinine excretion among the 9199 discovery cohort members included sex-specific terms for weight, height, and age (R-squared= 0.328). This model had a median bias of+4.3 mg creatinine/day (95% confidence interval-5.6,+13.3 mg/day) in 4599 validation cohort members, and 82% of observed values were within 30% of predicted model. Serum creatinine concentrations only marginally improved model precision but reduced bias in persons with advanced chronic kidney disease (CKD). The limits of urine creatinine excretion derived here represent the most valid and representative data for appraising the adequacy of a timed urine collection.

Associations of Anxiety during the COVID-19 Pandemic with Patient Characteristics and Behaviors in CKD Patients: Findings from the Chronic Renal Insufficiency Cohort (CRIC) Study.

Chronic kidney disease (CKD) is associated with anxiety and depression. Although the coronavirus disease 2019 (COVID-19) pandemic has increased stressors on patients with CKD, assessments of anxiety and its predictors and consequences on behaviors, specifically virus mitigation behaviors, are lacking. From June to October 2020, we administered a survey to 1873 patients in the Chronic Renal Insufficiency Cohort (CRIC) Study, asking participants about anxiety related to the COVID-19 pandemic. We examined associations between anxiety and participant demographics, clinical indexes, and health literacy and whether anxiety was associated with health-related behaviors and COVID-19 mitigation behaviors. The mean age of the study population was 70 years (SD=9.6 years), 47% were women, 39% were Black non-Hispanic, 14% were Hispanic, and 38% had a history of cardiovascular disease. In adjusted analyses, younger age, being a woman, Hispanic ethnicity, cardiovascular disease, household income <$20,000, and marginal or inadequate health literacy predicted higher anxiety. Higher global COVID-19-related anxiety scores were associated with higher odds of reporting always wearing a mask in public (OR=1.3 [95% CI, 1.14 to 1.48], P<0.001) and of eating less healthy foods (OR=1.29 [95% CI, 1.13 to 1.46], P<0.001), reduced physical activity (OR=1.32 [95% CI, 1.2 to 1.45], P<0.001), and weight gain (OR=1.23 [95% CI, 1.11 to 1.38], P=0.001). Higher anxiety levels related to the COVID-19 pandemic were associated not only with higher self-reported adherence to mask wearing but also with higher weight gain and less adherence to healthy lifestyle behaviors. Interventions are needed to support continuation of healthy lifestyle behaviors in patients with CKD experiencing increased anxiety related to the pandemic.

Predicting incident heart failure among patients with type 2 diabetes mellitus: The DM-CURE risk score.

Early identification and prediction of incident heart failure (HF) is important because of severe morbidity and mortality. This study aimed to predict onset of HF among patients with diabetes. A time-varying Cox model was derived from ACCORD clinical trial to predict the risk of incident HF, defined by hospitalization for HF (HHF). External validation was performed on patient-level data from the Harmony Outcome trial and Chronic Renal Insufficiency Cohort (CRIC) study. The model was transformed into an integer-based scoring algorithm for 10-year risk evaluation. A stepwise algorithm identified and selected predictors from demographic characteristics, physical examination, laboratory results, medical history, medication and health care utilization, to develop a risk prediction model. The main outcome was incident HF, defined by HHF. The C statistic and Brier score were used to assess model performance. In total, 9649 patients with diabetes free of HF were used, with median follow-up of 4 years and 299 incident hospitalization of HF events. The model identified several predictors for the 10-year HF incidence risk score 'DM-CURE': socio-Demographic [education, age at type 2 diabetes (T2DM) diagnosis], Metabolic (glycated haemoglobin, systolic blood pressure, body mass index, high-density lipoproteins), diabetes-related Complications (myocardial infarction, revascularization, cardiovascular medications, neuropathy, hypertension duration, albuminuria, urine albumin-to-creatinine ratio, End Stage Kidney Disease), and health care Utilization (all-cause hospitalization, emergency room visits) for Risk Evaluation. Among them, the strongest impact factors for future HF were age at T2DM diagnosis, health care utilization and cardiovascular disease-related variables. The model showed good discrimination (C statistic: 0.838, 95% CI: 0.821-0.855) and calibration (Brier score: 0.006, 95% CI: 0.006-0.007) in the ACCORD data and good performance in the validation data (Harmony: C statistic: 0.881, 95% CI: 0.863-0.899; CRIC: C statistic: 0.813, 95% CI: 0.794-0.833). The 10-year risk of incident HF increased in a graded fashion, from ≤1% in quintile 1 (score ≤14), 1%-5% in quintile 2 (score 15-23), 5%-10% in quintile 3 (score 24-27), 10%-20% in quintile 4 (score 28-33) and ≥20% in quintile 5 (score >33). The DM-CURE model and score were useful for population risk stratification of incident HHF among patients with T2DM and can be easily applied in clinical practice.

Association of Intra-individual Differences in Estimated GFR by Creatinine Versus Cystatin C With Incident Heart Failure

Lower estimated glomerular filtration rate (eGFR) is associated with heart failure (HF) risk. However, eGFR based on cystatin C (eGFRcys) and creatinine (eGFRcr) may differ substantially within an individual. The clinical implications of these differences for risk of HF among persons with chronic kidney disease (CKD) are unknown. Prospective cohort study. 4,512 adults with CKD and without prevalent HF who enrolled in the Chronic Renal Insufficiency Cohort (CRIC) Study. Difference in GFR estimates (eGFRdiff; ie, eGFRcys minus eGFRcr). Incident HF hospitalization. Fine-Gray proportional subhazards regression was used to investigate the associations of baseline, time-updated, and slope of eGFRdiff with incident HF. Of 4,512 participants, one-third had eGFRcys and eGFRcr values that differed by over 15 mL/min/1.73 m2. In multivariable-adjusted models, each 15 mL/min/1.73 m2 lower baseline eGFRdiff was associated with higher risk of incident HF hospitalization (hazard ratio [HR], 1.20 [95% CI, 1.07-1.34]). In time-updated analyses, those with eGFRdiff less than-15 mL/min/1.73 m2 had higher risk of incident HF hospitalization (HR, 1.99 [95% CI, 1.39-2.86]), and those with eGFRdiff≥15 mL/min/1.73 m2 had lower risk of incident HF hospitalization (HR, 0.67 [95% CI, 0.49-0.91]) compared with participants with similar eGFRcys and eGFRcr. Participants with faster declines in eGFRcys relative to eGFRcr had higher risk of incident HF (HR, 1.49 [95% CI, 1.19-1.85]) compared with those in whom eGFRcys and eGFRcr declined in parallel. Entry into the CRIC Study was determined by eGFRcr, which constrained the range of baseline eGFRcr-but not eGFRcys-values. Among persons with CKD who have large differences between eGFRcys and eGFRcr, risk for incident HF is more strongly associated with eGFRcys. Diverging slopes between eGFRcys and eGFRcr over time are also independently associated with risk of incident HF.

Self-reported Physical Activity and Cardiovascular Events in Adults With CKD: Findings From the CRIC (Chronic Renal Insufficiency Cohort) Study

In the general population, there is an association between higher levels of physical activity and lower risk for cardiovascular events and mortality, but this relationship has not been well evaluated in chronic kidney disease (CKD). We investigated the association between self-reported physical activity and outcomes in a CKD cohort. Prospective cohort study. 3,926 participants in the Chronic Renal Insufficiency Cohort (CRIC) Study. Time-updated self-reported physical activity assessed by (1) quartile of moderate-to-vigorous physical activity (MVPA) and (2) meeting guideline-recommended level of physical activity (categorized as active, meeting guidelines; active, not meeting guidelines; or inactive). Atherosclerotic events (myocardial infarction, stroke, or peripheral artery disease), incident heart failure, and all-cause and cardiovascular death. Cox proportional hazards regression. At baseline, compared with the lowest MVPA quartile, those in the highest quartile were more likely to be younger, male, not have prevalent cardiovascular disease, and have higher estimated glomerular filtration rate. Overall, 51% met the physical activity guidelines; of those who did not, 30% were inactive. During the median follow-up period of 13.4 years, there were 772 atherosclerotic events, 848 heart failure events, and 1,553 deaths, and 420 cardiovascular deaths. Compared with the participants in the lowest MVPA quartile, the highest quartile had a lower risk of atherosclerotic events (HR, 0.64 [95% CI, 0.51-0.79]), incident heart failure (HR, 0.71 [95% CI, 0.58-0.87]), and all-cause and cardiovascular death (HRs of 0.54 [95% CI, 0.46-0.63] and 0.47 [95% CI, 0.35-0.64], respectively). The findings were similar for analyses evaluating recommended level of physical activity. Self-reported physical activity may result in some degree of misclassification. Higher self-reported physical activity was associated with lower risk of cardiovascular events and mortality in CKD patients, which may have important implications for clinical practice and the design of interventional studies. In this long-term study of 3,926 adults with chronic kidney disease, we found that individuals with higher levels of physical activity were less likely to experience an atherosclerotic event (for example, a heart attack, stroke, or peripheral arterial disease), new-onset heart failure, and death as compared with those with lower levels of physical activity. The findings were similar for the analyses evaluating adherence to guideline-recommended level of physical activity (that is, for more than 150 minutes per week), and they strengthen the evidence supporting the current guideline recommendations.

Association of Mitochondrial DNA Copy Number with Risk of Progression of Kidney Disease.

Mitochondrial DNA copy number is a biomarker of mitochondrial function, which has been hypothesized to contribute to pathogenesis of CKD through podocyte injury, tubular epithelial cell damage, and endothelial dysfunction. The prospective association of mitochondrial DNA copy number with CKD progression has not been previously evaluated. Chronic Renal Insufficiency Cohort study participants had serum levels of mitochondrial DNA copy number calculated from probe intensities of mitochondrial single nucleotide polymorphisms genotyped on the Illumina HumanOmni 1-Quad Array. CKD progression was defined as kidney failure or halving of eGFR from baseline. Cox proportional hazards models were used to calculate hazard ratios for mitochondrial DNA copy number and risk of CKD progression. Among 2943 participants, mean age was 58 years, 45% were women, and 48% self-identified as Black. There were 1077 patients who experienced CKD progression over a median follow-up of 6.5 years. The incidence rate of CKD progression was highest for those in the lowest tertile of mitochondrial DNA copy number (tertile 1, 58.1; tertile 2, 50.8; tertile 3, 46.3 per 1000 person-years). Risk for CKD progression was higher for participants with lower levels of mitochondrial DNA copy number after adjustment for established risk factors (for tertile 1 versus 3, hazard ratio, 1.28 [95% confidence interval, 1.10 to 1.50]; for tertile 2 versus 3, hazard ratio, 0.99 [95% confidence interval, 0.85 to 1.16]; trend P=0.002). Similar results were seen among those with albuminuria (for tertile 1 versus 3, hazard ratio, 1.24; 95% confidence interval, 1.05 to 1.47), but there were no statistically significant associations among individuals without albuminuria (for tertile 1 versus 3, hazard ratio, 1.04; 95% confidence interval, 0.70 to 1.53; interaction P<0.001). These findings suggest lower mitochondrial DNA copy number is associated with higher risk of CKD progression, independent of established risk factors among patients with CKD.

Association of Proximal Tubular Secretory Clearance with Long-Term Decline in Cognitive Function.

People with chronic kidney disease (CKD) are at high risk for cognitive impairment and progressive cognitive decline. Retention of protein-bound organic solutes that are normally removed by tubular secretion is hypothesized to contribute to cognitive impairment in CKD. We followed 2362 participants who were initially free of cognitive impairment and stroke in the prospective Chronic Renal Insufficiency Cohort (CRIC) Study. We estimated tubular secretory clearance by the 24-hour kidney clearances of eight endogenous solutes that are primarily eliminated by tubular secretion. CRIC study investigators assessed participants' cognitive function annually using the Modified Mini-Mental State (3MS) Examination. Cognitive decline was defined as a sustained decrease of more than five points in the 3MS score from baseline. Using Cox regression models adjusted for potential confounders, we analyzed associations between secretory solute clearances, serum solute concentrations, and cognitive decline. The median number of follow-up 3MS examinations was six per participant. There were 247 incident cognitive decline events over a median of 9.1 years of follow-up. Lower kidney clearances of five of the eight secretory solutes (cinnamoylglycine, isovalerylglycine, kynurenic acid, pyridoxic acid, and tiglylglycine) were associated with cognitive decline after adjustment for baseline eGFR, proteinuria, and other confounding variables. Effect sizes ranged from a 17% to a 34% higher risk of cognitive decline per 50% lower clearance. In contrast, serum concentrations of the solutes were not associated with cognitive decline. Lower kidney clearances of secreted solutes are associated with incident global cognitive decline in a prospective study of CKD, independent of eGFR. Further work is needed to determine the domains of cognition most affected by decreased secretory clearance and the mechanisms of these associations.

Prospective associations of health literacy with clinical outcomes in adults with CKD: findings from the CRIC study.

Limited health literacy is associated with significant morbidity and mortality in the general population but the relation of health literacy with long-term clinical outcomes among adults with chronic kidney disease (CKD) is less clear. Prospective data from the Chronic Renal Insufficiency Cohort (CRIC) Study (n=3715) were used. Health literacy was assessed with the Short Test of Functional Health Literacy in Adults (dichotomized as limited/adequate). Cox proportional hazards models were used to separately examine the relations of health literacy with CKD progression, cardiovascular event (any of the following: myocardial infarction, congestive heart failure, stroke or peripheral artery disease), and all-cause, cardiovascular and non-cardiovascular mortality. Poisson regression was used to assess the health literacy-hospitalization association. Models were sequentially adjusted: Model 1 adjusted for potential confounders (sociodemographic factors), while Model 2 additionally adjusted for potential mediators (clinical and lifestyle factors) of the associations of interest. In confounder-adjusted models, participants with limited (vs adequate) health literacy [555 (15%)] had an increased risk of CKD progression [hazard ratio (HR) 1.34; 95% confidence interval (CI) 1.06-1.71], cardiovascular event (HR 1.67; 95% CI 1.39-2.00), hospitalization (rate ratio 1.33; 95% CI 1.26-1.40), and all-cause (HR 1.54; 95% CI 1.27-1.86), cardiovascular (HR 2.39; 95% CI 1.69-3.38) and non-cardiovascular (HR 1.27; 95% CI 1.01-1.60) mortality. Additional adjustments for potential mediators (Model 2) showed similar results except that the relations of health literacy with CKD progression and non-cardiovascular mortality were no longer statistically significant. In the CRIC Study, adults with limited (vs adequate) health literacy had a higher risk for CKD progression, cardiovascular event, hospitalization and mortality-regardless of adjustment for potential confounders.

Acute Kidney Injury Associates with Long-Term Increases in Plasma TNFR1, TNFR2, and KIM-1: Findings from the CRIC Study.

Some markers of inflammation-TNF receptors 1 and 2 (TNFR1 and TNFR2)-are independently associated with progressive CKD, as is a marker of proximal tubule injury, kidney injury molecule 1 (KIM-1). However, whether an episode of hospitalized AKI may cause long-term changes in these biomarkers is unknown. Among adult participants in the Chronic Renal Insufficiency Cohort (CRIC) study, we identified 198 episodes of hospitalized AKI (defined as peak/nadir inpatient serum creatinine values ≥1.5). For each AKI hospitalization, we found the best matched non-AKI hospitalization (unique patients), using prehospitalization characteristics, including eGFR and urine protein/creatinine ratio. We measured TNFR1, TNFR2, and KIM-1 in banked plasma samples collected at annual CRIC study visits before and after the hospitalization (a median of 7 months before and 5 months after hospitalization). In the AKI and non-AKI groups, we found similar prehospitalization median levels of TNFR1 (1373 pg/ml versus 1371 pg/ml, for AKI and non-AKI, respectively), TNFR2 (47,141 pg/ml versus 46,135 pg/ml, respectively), and KIM-1 (857 pg/ml versus 719 pg/ml, respectively). Compared with matched study participants who did not experience AKI, study participants who did experience AKI had greater increases in TNFR1 (23% versus 10%, P<0.01), TNFR2 (10% versus 3%, P<0.01), and KIM-1 (13% versus -2%, P<0.01). Among patients with CKD, AKI during hospitalization was associated with increases in plasma TNFR1, TNFR2, and KIM-1 several months after their hospitalization. These results highlight a potential mechanism by which AKI may contribute to more rapid loss of kidney function months to years after the acute insult.

Multi-variable biomarker approach in identifying incident heart failure in chronic kidney disease: results from the Chronic Renal Insufficiency Cohort study.

Heart failure (HF) is one of the leading causes of cardiovascular morbidity and mortality in the ever-growing population of patients with chronic kidney disease (CKD). There is a need to enhance early prediction to initiate treatment in CKD. We sought to study the feasibility of a multi-variable biomarker approach to predict incident HF risk in CKD. We examined 3182 adults enrolled in the Chronic Renal Insufficiency Cohort (CRIC) without prevalent HF who underwent serum/plasma assays for 11 blood biomarkers at baseline visit (B-type natriuretic peptide [BNP], CXC motif chemokine ligand 12, fibrinogen, fractalkine, high-sensitivity C-reactive protein, myeloperoxidase, high-sensitivity troponin T (hsTnT), fibroblast growth factor 23 [FGF23], neutrophil gelatinase-associated lipocalin, fetuin A, aldosterone). The population was randomly divided into derivation (n=1629) and validation (n=1553) cohorts. Biomarkers that were associated with HF after adjustment for established HF risk factors were combined into an overall biomarker score (number of biomarkers above the Youden's index cut-off value). Cox regression was used to explore the predictive role of a biomarker panel to predict incident HF. A total of 411 patients developed incident HF at a median follow-up of 7 years. In the derivation cohort, four biomarkers were associated with HF (BNP, FGF23, fibrinogen, hsTnT). In a model combining all four biomarkers, BNP (hazard ratio [HR] 2.96 [95% confidence interval 2.14-4.09]), FGF23 (HR 1.74 [1.30-2.32]), fibrinogen (HR 2.40 [1.74-3.30]), and hsTnT (HR 2.89 [2.06-4.04]) were associated with incident HF. The incidence of HF increased with the biomarker score, to a similar degree in both derivation and validation cohorts: from 2.0% in score of 0% to 46.6% in score of 4 in the derivation cohort to 2.4% in score of 0% to 43.5% in score of 4 in the validation cohort. A model incorporating biomarkers in addition to clinical factors reclassified risk in 601 (19%) participants (352 [11%] participants to higher risk and 249 [8%] to lower risk) compared with clinical risk model alone (net reclassification improvement of 0.16). A basic panel of four blood biomarkers (BNP, FGF23, fibrinogen, and hsTnT) can be used as a standalone score to predict incident HF in patients with CKD allowing early identification of patients at high-risk for HF. Addition of biomarker score to clinical risk model modestly reclassifies HF risk and slightly improves discrimination.

Cardiac Biomarkers and Risk of Atherosclerotic Cardiovascular Disease in Patients with CKD.

Several cardiac biomarkers of cardiac stress, inflammation, and fibrosis (N-terminal pro brain-type natriuretic peptide [NT-proBNP], high-sensitivity troponin T [hsTnT], growth differentiation factor 15 [GDF-15], and soluble ST2 [sST2]) have been associated with atherosclerotic disease in the general population. We hypothesized that these cardiac biomarkers may also be associated with the atherosclerotic cardiovascular disease in patients with CKD. We analyzed levels of NT-proBNP, hsTnT, GDF-15, and sST2 in a cohort of 2732 participants with mild to moderate CKD from the Chronic Renal Insufficiency Cohort (CRIC) study. Outcomes included incident atherosclerotic disease, defined as the first instance of myocardial infarction, stroke, or peripheral vascular disease. We used Cox proportional hazard models to the test the association of each cardiac biomarker with risk of incident atherosclerotic disease, adjusting for multiple possible confounders. When modeled continuously (per SD increase in the log-transformed biomarker), NT-proBNP, hsTnT, GDF-15, and sST2 were significantly associated with incident atherosclerotic disease after adjustment for multiple potential confounders: (NT-proBNP HR, 1.51; 95% CI, 1.27 to 1.81; hsTnT HR, 1.61; 95% CI, 1.38 to 1.89; GDF-15 HR, 1.44; 95% CI, 1.19 to 1.73; and sST2 HR, 1.19; 95% CI, 1.04 to 1.36). NT-proBNP, hsTnT, GDF-15, and sST2 were significantly associated with incident atherosclerotic cardiovascular disease in patients with CKD. These associations may highlight important mechanisms for the development of atherosclerotic disease in CKD.

Rates of Cardiovascular Disease and CKD Progression in Young Adults with CKD across Racial and Ethnic Groups.

Significant racial and ethnic disparities in cardiovascular (CV) and kidney function outcomes in older adults with chronic kidney disease (CKD) have been reported. However, little is known about the extent to which these disparities exist in patients with CKD during the foundational period of young adulthood. The objective of this study was to determine risk factors and rates of CV disease and CKD progression in young adults with CKD across racial and ethnic groups. We studied all participants aged 21-40 years of age enrolled in the Chronic Renal Insufficiency Cohort (CRIC) Study (n=317). Baseline CV risk factors were described across racial and ethnic groups. Outcomes included CV events or death (first incidence of heart failure, myocardial infarction, and stroke or death) and CKD progression (>50% decline in eGFR from baseline or end stage kidney disease [ESKD]). Incidence rate ratios (IRRs) were compared as a secondary analysis for participants identifying as Black or Hispanic with those identifying as White or another race and ethnicity. Adjusted models included age, sex, and per APOL1 high-risk allele. CV risk factors were higher in Black and Hispanic participants, including mean SBP, BMI, median UACr, and LDL. Black and Hispanic participants had higher incidence rates of HF (17.5 versus 5.1/1000 person-years), all-cause mortality (15.2 versus 7.1/1000 person-years), and CKD progression (125 versus 59/1000 person-years). In conclusion, we found a higher prevalence of CV risk factors, some modifiable, in young adults with CKD who identify as Black or Hispanic. Future strategies to ameliorate the racial and ethnic inequality in health outcomes earlier in life for patients with CKD should be prioritized.

Association of rheumatoid arthritis with mortality in chronic kidney disease: a cohort study.

Rheumatoid arthritis (RA) is associated with an increased risk of cardiovascular disease (CVD) as well as with an increased risk of chronic kidney disease (CKD), also a known cardiovascular risk factor. However, it is not known if RA is a predictor of adverse outcomes in patients with CKD. We hypothesized that among a cohort of patients with CKD, RA would be associated with an increased risk of mortality. We conducted a retrospective study of 3939 participants with CKD from the prospective Chronic Renal Insufficiency Cohort (CRIC) study. The primary outcome of interest was all-cause mortality. Secondary outcomes included CKD progression (defined as end-stage kidney disease or 50% decline in estimated glomerular filtration rate), cardiovascular endpoints, and composite of myocardial infarction, cerebrovascular accident, heart failure, or death. Multivariable Cox proportional hazards regression was utilized, adjusting for potential confounders including age, sex, race/ethnicity, body mass index, current smoker, and education. The study cohort included 83 participants with RA on a disease modifying anti-rheumatic drug (DMARD). In the adjusted analysis, CKD-RA status was significantly associated with an increased risk of death (adjusted HR, aHR, 1.73 (1.27, 2.35)) and composite outcome (aHR 1.65 (1.27-2.15)) even after adjusting for traditional risk factors. Similar statistically significant associations were observed between CKD-RA and other secondary outcomes except for CKD progression. RA was associated with higher mortality among individuals with CKD but not progressive renal decline. Further studies evaluating the mechanisms behind this association are needed. Key Points • Rheumatoid arthritis (RA) is associated with an increased risk of cardiovascular disease (CVD) as well as with an increased risk of chronic kidney disease (CKD), also a known cardiovascular risk factor. However, it is not known if RA is an independent predictor of adverse outcomes in patients with CKD • In this study, we observed that CKD patients with RA experience higher mortality as well as an increased risk of CVD compared to patients with CKD without comorbid RA • These data provide rationale for more aggressive monitoring for CVD in patients with CKD and RA. They also underscore the need for determining which interventions can help decrease the burden of mortality in these patients.

Black and White Adults With CKD Hospitalized With Acute Kidney Injury: Findings From the Chronic Renal Insufficiency Cohort (CRIC) Study

Few studies have investigated racial disparities in acute kidney injury (AKI), in contrast to the extensive literature on racial differences in the risk of kidney failure. We sought to study potential differences in risk in the setting of chronic kidney disease (CKD). Prospective cohort study. We studied 2,720 self-identified Black or White participants with CKD enrolled in the Chronic Renal Insufficiency Cohort (CRIC) Study from July 1, 2013, to December 31,2017. Self-reported race (Black vs White). Hospitalized AKI (≥50% increase from nadir to peak serum creatinine). Cox regression models adjusting for demographics (age and sex), prehospitalization clinical risk factors (diabetes, blood pressure, cardiovascular disease, estimated glomerular filtration rate, proteinuria, receipt of angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers), and socioeconomic status (insurance status and education level). In a subset of participants with genotype data, we adjusted for apolipoprotein L1 gene (APOL1) high-risk status and sickle cell trait. Black participants (n= 1,266) were younger but had a higher burden of prehospitalization clinical risk factors. The incidence rate of first AKI hospitalization among Black participants was 6.3 (95% CI, 5.5-7.2) per 100 person-years versus 5.3 (95% CI, 4.6-6.1) per 100 person-years among White participants. In an unadjusted Cox regression model, Black participants were at a modestly increased risk of incident AKI (HR, 1.22 [95% CI, 1.01-1.48]) compared with White participants. However, this risk was attenuated and no longer significant after adjusting for prehospitalization clinical risk factors (adjusted HR, 1.02 [95% CI, 0.83-1.25]). There were only 11 AKI hospitalizations among individuals with high-risk APOL1 risk status and 14 AKI hospitalizations among individuals with sickle cell trait. Participants were limited to research volunteers and potentially not fully representative of all CKD patients. In this multicenter prospective cohort of CKD patients, racial disparities in AKI incidence were modest and were explained by differences in prehospitalization clinical risk factors.

Patient-Reported Symptoms and Subsequent Risk of Myocardial Infarction in Chronic Kidney Disease.

Although patient-reported symptoms often precede acute presentations of cardiovascular disease, patients with nondialysis-requiring CKD are less likely to have typical symptoms of atherosclerotic disease when presenting with acute myocardial infarction. However, the associations between typical atherosclerotic symptoms and subsequent risk of myocardial infarction are unknown in ambulatory patients with CKD. To determine whether typical atherosclerotic symptoms are associated with risk for subsequent myocardial infarction in people with CKD, we examined participants from the Chronic Renal Insufficiency Cohort Study. Chest pain, shortness of breath, and inability to climb stairs were evaluated annually using the Kidney Disease Quality of Life Instrument. Associations between categorical time-updated symptoms and physician-adjudicated incident myocardial infarction were assessed using Cox regression models. Among 3910 participants (mean age of 58±11 years; mean eGFR =44±15 ml/min per 1.73 m2), there were 476 incident myocardial infarctions over a median follow-up period of 10.4 years (interquartile range, 5.36-12.6 years). Median time from symptom assessment to incident myocardial infarction was 213 days (interquartile range, 111-333 days). Compared with no symptoms, mild, and moderate or worse, symptoms of chest pain (hazard ratio, 1.30; 95% confidence interval, 1.01 to 1.67; and hazard ratio, 1.70; 95% confidence interval, 1.27 to 2.27, respectively) and shortness of breath (hazard ratio, 1.37; 95% confidence interval, 1.10 to 1.70; and hazard ratio, 1.33; 95% confidence interval, 1.05 to 1.69, respectively) were significantly associated with greater risks for subsequent myocardial infarction. Participants reporting mild and severe limitations in climbing stairs (versus no limitation) had significantly higher adjusted risk of myocardial infarction (hazard ratio, 1.44; 95% confidence interval, 1.10 to 1.89; and hazard ratio, 1.89; 95% confidence interval, 1.44 to 2.49, respectively). In a large ambulatory cohort of adults with CKD, symptoms of atherosclerotic cardiovascular disease were strongly associated with a higher risk for subsequent myocardial infarction. This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2022_03_17_CJN12080921.mp3.

Trajectories of Uremic Symptom Severity and Kidney Function in Patients with Chronic Kidney Disease.

Uremic symptoms, including fatigue, anorexia, pruritus, nausea, paresthesia, and pain, are attributed to the accumulation of organic waste products normally cleared by the kidneys, but whether kidney function is the primary driver of changes in symptom severity over time is not known. The goal of our study was to evaluate the association between eGFR and uremic symptom severity score in patients with CKD. We identified 3685 participants with CKD not on dialysis in the prospective, observational Chronic Renal Insufficiency Cohort (CRIC) Study with baseline assessment of eGFR and uremic symptom severity. Symptoms were assessed by separate questions on the Kidney Disease Quality of Life-36 instrument (zero- to 100-point scale). The longitudinal association between eGFR and uremic symptom severity score was examined with multivariable adjusted linear mixed-effects models with random intercepts and random slopes. The mean±SD eGFR at baseline was 44±15 ml/min per 1.73 m2, and participants had a median of six (interquartile range 3-11) simultaneous assessments of eGFR and uremic symptoms over the duration of follow-up. The most prevalent symptoms at baseline were pain (57%), fatigue (52%), paresthesia (45%), and pruritus (42%). In adjusted models, a decrease in eGFR of 5 ml/min per 1.73 m2 was associated with a worsening of the symptom severity score by two points or less for each uremic symptom (P<0.01; zero- to 100-point scale). The association between eGFR and uremic symptom severity score was nonlinear. When starting from a lower initial eGFR, a 5 ml/min per 1.73 m2 decrease in eGFR was associated with a greater magnitude of uremic symptom worsening. The prevalence of uremic symptoms in CKD is high, with significant variability in patient symptom change over time. Declines in eGFR were associated with worsening of uremic symptom severity, but the magnitude of these changes is small and of uncertain clinical significance.

Socioeconomic characteristics of those with peripheral artery disease in the chronic renal insufficiency cohort.

The association between socioeconomic factors and peripheral arterial disease (PAD) has not been as well characterized as other cardiovascular conditions. We sought to define how annual income and education level are associated with PAD in a well-characterized diverse set of adults with chronic kidney disease (CKD). The Chronic Renal Insufficiency Cohort Study (CRIC) is a multi-center, prospective cohort study designed to examine risk factors for progression of CKD and cardiovascular disease. Demographic, income, and education-level data, as well as clinical data including ankle-brachial index (ABI) were collected at baseline. Annual income was categorized as < $25,000, $25,000-50,000, $50,000-100,000, or above $100,000; educational level was categorized as some high school, high school graduate, some college, or college graduate. Participants with missing income data or incompressible ABI (>1.4) were excluded from initial analysis. Logistic regression was used to estimate the association of income and/or education level with PAD, defined as an enrollment ABI of <0.90, history of PAD, or history of PAD intervention. A total of 4122 were included, mean age of participants was 59.5years, 56% were male, and 44% were Black. There were 763 CRIC participants with PAD at study enrollment (18.5%). In the final multivariable logistic regression model, Black race (OR = 1.3, 95% CI 1.1-1.6, p = 0.004) and level of annual household income remained independently associated with PAD at the time of enrollment (income <$25,000 OR = 1.9, 95% CI 1.3-2.8, p < 0.001; income $25,000-50,000 OR = 1.6, 95% CI 1.1-2.3, p = 0.011; income $50,000-100,000 OR = 1.2, 95% CI 0.9-1.8, p = 0.246), relative to a baseline annual income of >$100,000 (overall p-value <0.001). Decreasing level of educational attainment was not independently associated with increased PAD at enrollment, but lower level of educational attainment was associated with increased PAD when income data was not adjusted for (p = 0.001). Interestingly, Black race (OR = 0.7, 95% CI 0.6-0.8, p < 0.001), female gender (OR = 0.8, 95% CI 0.7-0.9, p = 0.007), and income <$25,000 (OR = 0.7, 95% CI 0.5-0.9, p = 0.008) were significantly associated with decreased statin use even after controlling for cardiovascular conditions. In this prospectively followed CKD cohort, lower annual household income and Black race were significantly associated with increased PAD at study enrollment. In contrast, educational level was not associated with PAD when adjusted for patient income data. Black race, female gender, and low income were independently associated with decreased statin use, populations which could be targets of future public health programs.

Deoxycholic Acid and Coronary Artery Calcification in the Chronic Renal Insufficiency Cohort.

BackgroundDeoxycholic acid (DCA) is a secondary bile acid that may promote vascular calcification in experimental settings. Higher DCA levels were associated with prevalent coronary artery calcification (CAC) in a small group of individuals with advanced chronic kidney disease. Whether DCA levels are associated with CAC prevalence, incidence, and progression in a large and diverse population of individuals with chronic kidney disease stages 2 to 4 is unknown.Methods and ResultsIn the CRIC (Chronic Renal Insufficiency Cohort) study, we evaluated cross‐sectional (n=1057) and longitudinal (n=672) associations between fasting serum DCA levels and computed tomographic CAC using multivariable‐adjusted regression models. The mean age was 57±12 years, 47% were women, and 41% were Black. At baseline, 64% had CAC (CAC score >0 Agatston units). In cross‐sectional analyses, models adjusted for demographics and clinical factors showed no association between DCA levels and CAC >0 compared with no CAC (prevalence ratio per 1‐SD higher log DCA, 1.08 [95% CI, 0.91–1.26). DCA was not associated with incident CAC (incidence per 1‐SD greater log DCA, 1.08 [95% CI, 0.85–1.39]) or CAC progression (risk for increase in ≥100 and ≥200 Agatston units per year per 1‐SD greater log DCA, 1.05 [95% CI, 0.84–1.31] and 1.26 [95% CI, 0.77–2.06], respectively).ConclusionsAmong CRIC study participants, DCA was not associated with prevalent, incident, or progression of CAC.

Prognostic value of echocardiography for heart failure and death in adults with chronic kidney disease

BackgroundAdults with chronic kidney disease (CKD) are at increased risk of heart failure (HF) morbidity and mortality. Despite well-characterized abnormalities in cardiac structure in CKD, it remains unclear how to optimally leverage echocardiography to risk stratify CKD patients. MethodsWe evaluated associations between echocardiographic parameters and risk of HF hospitalization and death using Cox proportional hazard models and forward selection with integrated discrimination improvement (IDI). ResultsThe study included 3,505 participants enrolled in the Chronic Renal Insufficiency Cohort (CRIC) study. Mean age was 59 ± 11 years, HF prevalence was 10%, and mean left ventricular (LV) ejection fraction (LVEF) was 54 ± 9%. During median 11 (interquartile range: 8-12) years of follow-up, event rates per 100-person years for HF hospitalizations and death, respectively, were 9.4 (95% Confidence Interval [CI]: 7.9-11.3) and 8.9 (95% CI: 7.6-10.5) for participants with LVEF <40%, 3.5 (95% CI: 3.0-4.2) and 4.6 (95% CI: 4.0-5.2) for patients with LVEF 40% to 49%, and 1.9 (95% CI: 1.7-2.1) and 3.1 (95% CI: 2.9-3.3) for patients with LVEF >50%. The rate of HF hospitalizations and deaths increased with lower eGFR across all LVEF categories. LV mass index, LVEF, and LV geometry had the strongest association with outcomes but provided modest incremental prognostic value to a baseline clinical model (IDI = 0.14 and ΔAUC = 0.017 for HF hospitalization, IDI = 0.12 and ΔAUC = 0.008 for death). ConclusionsBaseline echocardiographic parameters are independently associated with increased risk of subsequent HF morbidity and mortality but provide only marginal incremental prognostic utility beyond clinical characteristics in the setting of CKD.

Risk Prediction Models for Atherosclerotic Cardiovascular Disease in Patients with Chronic Kidney Disease: The CRIC Study.

Individuals with CKD may be at high risk for atherosclerotic cardiovascular disease (ASCVD). However, there are no ASCVD risk prediction models developed in CKD populations to inform clinical care and prevention. We developed and validated 10-year ASCVD risk prediction models in patients with CKD that included participants without self-reported cardiovascular disease from the Chronic Renal Insufficiency Cohort (CRIC) study. ASCVD was defined as the first occurrence of adjudicated fatal and nonfatal stroke or myocardial infarction. Our models used clinically available variables and novel biomarkers. Model performance was evaluated based on discrimination, calibration, and net reclassification improvement. Of 2604 participants (mean age 55.8 years; 52.0% male) included in the analyses, 252 had incident ASCVD within 10 years of baseline. Compared with the American College of Cardiology/American Heart Association pooled cohort equations (area under the receiver operating characteristic curve [AUC]=0.730), a model with coefficients estimated within the CRIC sample had higher discrimination (P=0.03), achieving an AUC of 0.736 (95% confidence interval [CI], 0.649 to 0.826). The CRIC model developed using clinically available variables had an AUC of 0.760 (95% CI, 0.678 to 0.851). The CRIC biomarker-enriched model had an AUC of 0.771 (95% CI, 0.674 to 0.853), which was significantly higher than the clinical model (P=0.001). Both the clinical and biomarker-enriched models were well-calibrated and improved reclassification of nonevents compared with the pooled cohort equations (6.6%; 95% CI, 3.7% to 9.6% and 10.0%; 95% CI, 6.8% to 13.3%, respectively). The 10-year ASCVD risk prediction models developed in patients with CKD, including novel kidney and cardiac biomarkers, performed better than equations developed for the general population using only traditional risk factors.