New Creatinine- and Cystatin C-Based Equations to Estimate GFR without Race

BACKGROUND

Current equations for estimated glomerular filtration rate (eGFR) that use serum creatinine or cystatin C incorporate age, sex, and race to estimate measured GFR. However, race in eGFR equations is a social and not a biologic construct.

METHODS

We developed new eGFR equations without race using data from two development data sets: 10 studies (8254 participants, 31.5% Black) for serum creatinine and 13 studies (5352 participants, 39.7% Black) for both serum creatinine and cystatin C. In a validation data set of 12 studies (4050 participants, 14.3% Black), we compared the accuracy of new eGFR equations to measured GFR. We projected the prevalence of chronic kidney disease (CKD) and GFR stages in a sample of U.S. adults, using current and new equations.

RESULTS

In the validation data set, the current creatinine equation that uses age, sex, and race overestimated measured GFR in Blacks (median, 3.7 ml per minute per 1.73 m² of body-surface area; 95% confidence interval [CI], 1.8 to 5.4) and to a lesser degree in non-Blacks (median, 0.5 ml per minute per 1.73 m²; 95% CI, 0.0 to 0.9). When the adjustment for Black race was omitted from the current eGFR equation, measured GFR in Blacks was underestimated (median, 7.1 ml per minute per 1.73 m²; 95% CI, 5.9 to 8.8). A new equation using age and sex and omitting race underestimated measured GFR in Blacks (median, 3.6 ml per minute per 1.73 m²; 95% CI, 1.8 to 5.5) and overestimated measured GFR in non-Blacks (median, 3.9 ml per minute per 1.73 m²; 95% CI, 3.4 to 4.4). For all equations, 85% or more of the eGFRs for Blacks and non-Blacks were within 30% of measured GFR. New creatinine-cystatin C equations without race were more accurate than new creatinine equations, with smaller differences between race groups. As compared with the current creatinine equation, the new creatinine equations, but not the new creatinine-cystatin C equations, increased population estimates of CKD prevalence among Blacks and yielded similar or lower prevalence among non-Blacks.

CONCLUSIONS

New eGFR equations that incorporate creatinine and cystatin C but omit race are more accurate and led to smaller differences between Black participants and non-Black participants than new equations without race with either creatinine or cystatin C alone. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases.).

Metabolites Associated with Coffee Consumption and Incident Chronic Kidney Disease

BACKGROUND AND OBJECTIVES

Moderate coffee consumption has been associated with lower risk of CKD; however, the exact biologic mechanisms underlying this association are unknown. Metabolomic profiling may identify metabolic pathways that explain the association between coffee and CKD. The goal of this study was to identify serum metabolites associated with coffee consumption and examine the association between these coffee-associated metabolites and incident CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using multivariable linear regression, we identified coffee-associated metabolites among 372 serum metabolites available in two subsamples of the Atherosclerosis Risk in Communities study (ARIC; n=3811). Fixed effects meta-analysis was used to pool the results from the two ARIC study subsamples. Associations between coffee and metabolites were replicated in the Bogalusa Heart Study (n=1043). Metabolites with significant associations with coffee in both cohorts were then evaluated for their prospective associations with incident CKD in the ARIC study using Cox proportional hazards regression.

RESULTS

In the ARIC study, mean (SD) age was 54 (6) years, 56% were daily coffee drinkers, and 32% drank >2 cups per day. In the Bogalusa Heart Study, mean (SD) age was 48 (5) years, 57% were daily coffee drinkers, and 38% drank >2 cups per day. In a meta-analysis of two subsamples of the ARIC study, 41 metabolites were associated with coffee consumption, of which 20 metabolites replicated in the Bogalusa Heart Study. Three of these 20 coffee-associated metabolites were associated with incident CKD in the ARIC study.

CONCLUSIONS

We detected 20 unique serum metabolites associated with coffee consumption in both the ARIC study and the Bogalusa Heart Study, and three of these 20 candidate biomarkers of coffee consumption were associated with incident CKD. One metabolite (glycochenodeoxycholate), a lipid involved in primary bile acid metabolism, may contribute to the favorable kidney health outcomes associated with coffee consumption. Two metabolites (O-methylcatechol sulfate and 3-methyl catechol sulfate), both of which are xenobiotics involved in benzoate metabolism, may represent potential harmful aspects of coffee on kidney health.

Use of nephrotoxic medications in adults with chronic kidney disease in Swedish and US routine care

Background

To characterize the use of nephrotoxic medications in patients with chronic kidney disease (CKD) Stages G3–5 in routine care.

Methods

We studied cohorts of adults with confirmed CKD G3–5 undergoing routine care from 1 January 2016 through 31 December 2018 in two health systems [Stockholm CREAtinine Measurements (SCREAM), Stockholm, Sweden (N = 57 880) and Geisinger, PA, USA (N = 16 255)]. We evaluated the proportion of patients receiving nephrotoxic medications within 1 year overall and by baseline kidney function, ranked main contributors and examined the association between receipt of nephrotoxic medication and age, sex, CKD G-stages comorbidities and provider awareness of the patient's CKD using multivariable logistic regression.

Results

During a 1-year period, 20% (SCREAM) and 17% (Geisinger) of patients with CKD received at least one nephrotoxic medication. Among the top nephrotoxic medications identified in both cohorts were non-steroidal anti-inflammatory drugs (given to 11% and 9% of patients in SCREAM and Geisinger, respectively), antivirals (2.5% and 2.0%) and immunosuppressants (2.7% and 1.5%). Bisphosphonate use was common in SCREAM (3.3%) and fenofibrates in Geisinger (3.6%). Patients <65 years of age, women and those with CKD G3 were at higher risk of receiving nephrotoxic medications in both cohorts. Notably, provider awareness of a patient's CKD was associated with lower odds of nephrotoxic medication use {odds ratios [OR] 0.85[95% confidence interval (CI) 0.80–0.90] in SCREAM and OR 0.80 [95% CI 0.72–0.89] in Geisinger}.

Conclusions

One in five patients with CKD received nephrotoxic medications in two distinct health systems. Strategies to increase physician's awareness of patients’ CKD and knowledge of drug nephrotoxicity may reduce prescribing nephrotoxic medications and prevent iatrogenic kidney injury.

Retinopathy and Risk of Kidney Disease in Persons With Diabetes

Rationale & Objective

Retinopathy and chronic kidney disease (CKD) are typically considered microvascular complications of diabetes, and cardiovascular and cerebrovascular diseases are considered macrovascular complications; however, all may share common pathological mechanisms. This study quantified the association of retinopathy with risk of kidney disease and compared with the association with cardiovascular disease in persons with diabetes.

Study Design

Retrospective cohort study.

Setting & Participants

1,759 participants in the ARIC study who had diabetes at visit 4 and underwent retinal examination at visit 3.

Exposure

Retinopathy.

Outcome

Prevalent CKD (estimated glomerular filtration rate [eGFR] < 60 mL/min/1.73 m²), prevalent albuminuria (urinary albumin-creatinine ratio [UACR] > 30 mg/g), incident CKD, incident end-stage kidney disease (ESKD), incident coronary heart disease (CHD), and incident stroke.

Analytical Approach

The cross-sectional association of retinopathy with prevalent CKD and albuminuria was assessed by logistic regression. The associations between retinopathy, incident CKD, incident ESKD, incident CHD, and incident stroke were examined using Cox proportional hazards models. Seemingly unrelated regression was used to compare the strength of association between retinopathy and outcomes.

Results

During the median follow-up period of 14.2 years, 723 participants developed CKD, and there were 109 ESKD events, 399 CHD events, and 196 stroke events. Compared with the participants without retinopathy, participants with retinopathy were more likely to have reduced eGFR (OR, 1.56 [95% CI, 1.09-2.23]) and UACR > 30 mg/g (OR, 1.61 [95% CI, 1.24-2.10]). Retinopathy was associated with risk of incident CKD (HR, 1.22 [95% CI, 1.02-1.46]), ESKD (HR, 1.69 [95% CI, 1.11-2.58]), CHD (HR, 1.46 [95% CI, 1.15-1.84]), and stroke (HR, 1.43 [95% CI, 1.03-1.97]). A stronger relationship was found between retinopathy and CHD when compared with retinopathy and CKD (P = 0.03); all other associations were similar.

Limitations

Retinal examination and kidney measurements were taken at different visits.

Conclusions

The presence of retinopathy was associated with higher prevalence of kidney disease and higher risk of incident CKD, ESKD, and CHD. These results may suggest that a similar mechanism underlies the development of retinopathy and other adverse outcomes in diabetes.

Serum albumin and risks of hospitalization and death: Findings from the Atherosclerosis Risk in Communities study

OBJECTIVES

To determine whether lower serum albumin in community-dwelling, older adults is associated with increased risk of hospitalization and death independent of pre-existing disease.

DESIGN

Prospective cohort study of participants in the fifth visit of the Atherosclerosis Risk in Communities (ARIC) study. Baseline data were collected from 2011 to 2013. Follow-up was available to December 31, 2017. Replication was performed in Geisinger, a health system in rural Pennsylvania.

SETTING

For ARIC, four US communities: Washington County, Maryland; Forsyth County, North Carolina; Jackson, Mississippi; and suburbs of Minneapolis, Minnesota.

PARTICIPANTS

A total of 4947 community-dwelling men and women aged 66 to 90 years.

EXPOSURE

Serum albumin.

MAIN OUTCOMES

Incident all-cause hospitalization and death.

RESULTS

Among the 4947 participants, mean age was 75.5 years (SD: 5.12) and mean baseline serum albumin concentration was 4.05 g/dL (SD: 0.30). Over a median follow-up period of 4.42 years (interquartile interval: 4.16-5.05), 553 participants (11.2%) died and 2457 participants (49.7%) were hospitalized at least once. The total number of hospitalizations was 5725. In analyses adjusted for demographics and numerous clinical characteristics, including tobacco use, obesity, frailty, cardiovascular disease, kidney disease, diabetes C-reactive protein (CRP), cognitive status, alcohol use, medication use, respiratory disease, and systolic blood pressure, 1 g/dL lower baseline serum albumin concentration was associated with higher risk of both hospitalization (incidence rate ratio [IRR]: 1.58; 95% confidence interval [CI]: 1.36-1.82; p < 0.001) and death (hazard ratio [HR]: 1.67; 95% CI: 1.24-2.24; p < 0.001). Associations were weaker with older age but not different by frailty status or level of high-sensitivity CRP. Associations between serum albumin, hospitalizations, and death were also similar in a real-world cohort of primary care patients.

CONCLUSIONS

Lower baseline serum albumin was significantly associated with increased risk of both all-cause hospitalization and death, independent of pre-existing disease. Older adults with low serum albumin should be considered a high-risk population and targeted for interventions to reduce the risk of adverse outcomes.

Proteins Associated with Risk of Kidney Function Decline in the General Population

BACKGROUND

Proteomic profiling may allow identification of plasma proteins that associate with subsequent changesin kidney function, elucidating biologic processes underlying the development and progression of CKD.

METHODS

We quantified the association between 4877 plasma proteins and a composite outcome of ESKD or decline in eGFR by ≥50% among 9406 participants in the Atherosclerosis Risk in Communities (ARIC) Study (visit 3; mean age, 60 years) who were followed for a median of 14.4 years. We performed separate analyses for these proteins in a subset of 4378 participants (visit 5), who were followed at a later time point, for a median of 4.4 years. For validation, we evaluated proteins with significant associations (false discovery rate <5%) in both time periods in 3249 participants in the Chronic Renal Insufficiency Cohort (CRIC) and 703 participants in the African American Study of Kidney Disease and Hypertension (AASK). We also compared the genetic determinants of protein levels with those from a meta-analysis genome-wide association study of eGFR.

RESULTS

In models adjusted for multiple covariates, including baseline eGFR and albuminuria, we identified 13 distinct proteins that were significantly associated with the composite end point in both time periods, including TNF receptor superfamily members 1A and 1B, trefoil factor 3, and β-trace protein. Of these proteins, 12 were also significantly associated in CRIC, and nine were significantly associated in AASK. Higher levels of each protein associated with higher risk of 50% eGFR decline or ESKD. We found genetic evidence for a causal role for one protein, lectin mannose-binding 2 protein (LMAN2).

CONCLUSIONS

Large-scale proteomic analysis identified both known and novel proteomic risk factors for eGFR decline.

Clinical events and patient-reported outcome measures during CKD progression: findings from the Chronic Renal Insufficiency Cohort Study

BACKGROUND

Patients with chronic kidney disease (CKD) face risks of not only end-stage kidney disease (ESKD), cardiovascular disease (CVD) and death, but also decline in kidney function, quality of life (QOL) and mental and physical well-being. This study describes the multidimensional trajectories of CKD using clinical events, kidney function and patient-reported outcome measures (PROMs). We hypothesized that more advanced CKD stages would associate with more rapid decline in each outcome.

METHODS

Among 3939 participants enrolled in the Chronic Renal Insufficiency Cohort (CRIC) Study, we evaluated multidimensional disease trajectories by G- and A-stages of enrollment estimated glomerular filtration rate (eGFR) and albuminuria, respectively. These trajectories included clinical events (ESKD, CVD, heart failure and death), eGFR decline and PROMs [kidney disease QOL (KDQOL) burden, effects and symptoms questionnaires, as well as the 12-item short form mental and physical component summaries]. We also evaluated a group-based multitrajectory model to group participants on the basis of longitudinal PROMs and compared group assignments by enrollment G- and A-stage.

RESULTS

The mean participant age was 58 years, 45% were women, mean baseline eGFR was 44 mL/min/1.73 m2 and median urine albumin:creatinine ratio was 52 mg/g. The incidence of all clinical events was greater and eGFR decline was faster with more advanced G- and A-stages. While baseline KDQOL and physical component measures were lower with more advanced G- and A-stage of CKD, changes in PROMs were inconsistently related to the baseline CKD stage. Groups formed on PROM trajectories were fairly distinct from existing CKD staging (observed agreement 60.6%) and were associated with the risk of ESKD, CVD, heart failure and death.

CONCLUSIONS

More advanced baseline CKD stage was associated with a higher risk of clinical events and faster eGFR decline, and was only weakly related to changes in patient-reported metrics over time.

Albuminuria Testing in Hypertension and Diabetes: An Individual-Participant Data Meta-Analysis in a Global Consortium

Albuminuria is an under-recognized component of chronic kidney disease definition, staging, and prognosis. Guidelines, particularly for hypertension, conflict on recommendations for urine albumin-to-creatinine ratio (ACR) measurement. Separately among 1 344 594 adults with diabetes and 2 334 461 nondiabetic adults with hypertension from the chronic kidney disease Prognosis Consortium, we assessed ACR testing, estimated the prevalence and incidence of ACR ≥30 mg/g and developed risk models for ACR ≥30 mg/g. The ACR screening rate (cohort range) was 35.1% (12.3%-74.5%) in diabetes and 4.1% (1.3%-20.7%) in hypertension. Screening was largely unrelated to the predicted risk of prevalent albuminuria. The median prevalence of ACR ≥30 mg/g across cohorts was 32.1% in diabetes and 21.8% in hypertension. Higher systolic blood pressure was associated with a higher prevalence of albuminuria (odds ratio [95% CI] per 20 mm Hg in diabetes, 1.50 [1.42-1.60]; in hypertension, 1.36 [1.28-1.45]). The ratio of undetected (due to lack of screening) to detected ACR ≥30 mg/g was estimated at 1.8 in diabetes and 19.5 in hypertension. Among those with ACR <30 mg/g, the median 5-year incidence of ACR ≥30 mg/g across cohorts was 23.9% in diabetes and 21.7% in hypertension. Incident albuminuria was associated with initiation of renin-angiotensin-aldosterone system inhibitors (incidence-rate ratio [95% CI], diabetes 3.09 [2.71-3.53]; hypertension 2.87 [2.29-3.59]). In conclusion, despite similar risk of albuminuria to those with diabetes, ACR screening in patients with hypertension was low. Our findings suggest that regular albuminuria screening should be emphasized to enable early detection of chronic kidney disease and initiation of treatment with cardiovascular and renal benefits.

Genome-wide association study of serum metabolites in the African American Study of Kidney Disease and Hypertension

The genome-wide association study (GWAS) is a powerful means to study genetic determinants of disease traits and generate insights into disease pathophysiology. To date, few GWAS of circulating metabolite levels have been performed in African Americans with chronic kidney disease. Hypothesizing that novel genetic-metabolite associations may be identified in a unique population of African Americans with a lower glomerular filtration rate (GFR), we conducted a GWAS of 652 serum metabolites in 619 participants (mean measured glomerular filtration rate 45 mL/min/1.73m2) in the African American Study of Kidney Disease and Hypertension, a clinical trial of blood pressure lowering and antihypertensive medication in African Americans with chronic kidney disease. We identified 42 significant variant metabolite associations. Twenty associations had been previously identified in published GWAS, and eleven novel associations were replicated in a separate cohort of 818 African Americans with genetic and metabolomic data from the Atherosclerosis Risk in Communities Study. The replicated novel variant-metabolite associations comprised eight metabolites and eleven distinct genomic loci. Nine of the replicated associations represented clear enzyme-metabolite interactions, with high expression in the kidneys as well as the liver. Three loci (ACY1, ACY3, and NAT8) were associated with a common pool of metabolites, acetylated amino acids, but with different individual affinities. Thus, extensive metabolite profiling in an African American population with chronic kidney disease aided identification of novel genome-wide metabolite associations, providing clues about substrate specificity and the key roles of enzymes in modulating systemic levels of metabolites.

Metabolite Biomarkers of CKD Progression in Children

BACKGROUND AND OBJECTIVES

Metabolomics facilitates the discovery of biomarkers and potential therapeutic targets for CKD progression.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We evaluated an untargeted metabolomics quantification of stored plasma samples from 645 Chronic Kidney Disease in Children (CKiD) participants. Metabolites were standardized and logarithmically transformed. Cox proportional hazards regression examined the association between 825 nondrug metabolites and progression to the composite outcome of KRT or 50% reduction of eGFR, adjusting for age, sex, race, body mass index, hypertension, glomerular versus nonglomerular diagnosis, proteinuria, and baseline eGFR. Stratified analyses were performed within subgroups of glomerular/nonglomerular diagnosis and baseline eGFR.

RESULTS

Baseline characteristics were 391 (61%) male; median age 12 years; median eGFR 54 ml/min per 1.73 m²; 448 (69%) nonglomerular diagnosis. Over a median follow-up of 4.8 years, 209 (32%) participants developed the composite outcome. Unique association signals were identified in subgroups of baseline eGFR. Among participants with baseline eGFR ≥60 ml/min per 1.73 m², two-fold higher levels of seven metabolites were significantly associated with higher hazards of KRT/halving of eGFR events: three involved in purine and pyrimidine metabolism (N6-carbamoylthreonyladenosine, hazard ratio, 16; 95% confidence interval, 4 to 60; 5,6-dihydrouridine, hazard ratio, 17; 95% confidence interval, 5 to 55; pseudouridine, hazard ratio, 39; 95% confidence interval, 8 to 200); two amino acids, C-glycosyltryptophan, hazard ratio, 24; 95% confidence interval 6 to 95 and lanthionine, hazard ratio, 3; 95% confidence interval, 2 to 5; the tricarboxylic acid cycle intermediate 2-methylcitrate/homocitrate, hazard ratio, 4; 95% confidence interval, 2 to 7; and gulonate, hazard ratio, 10; 95% confidence interval, 3 to 29. Among those with baseline eGFR <60 ml/min per 1.73 m², a higher level of tetrahydrocortisol sulfate was associated with lower risk of progression (hazard ratio, 0.8; 95% confidence interval, 0.7 to 0.9).

CONCLUSIONS

Untargeted plasma metabolomic profiling facilitated discovery of novel metabolite associations with CKD progression in children that were independent of established clinical predictors and highlight the role of select biologic pathways.

American Diabetes Association Framework for Glycemic Control in Older Adults: Implications for Risk of Hospitalization and Mortality

OBJECTIVE

The 2021 American Diabetes Association (ADA) guidelines recommend different A1C targets in older adults that are based on comorbid health status. We assessed risk of mortality and hospitalizations in older adults with diabetes across glycemic control (A1C <7%, 7 to <8%, ≥8%) and ADA-defined health status (healthy, complex/intermediate, very complex/poor) categories.

RESEARCH DESIGN AND METHODS

Prospective cohort analysis of older adults aged 66-90 years with diagnosed diabetes in the Atherosclerosis Risk in Communities (ARIC) study.

RESULTS

Of the 1,841 participants (56% women, 29% Black), 32% were classified as healthy, 42% as complex/intermediate, and 27% as very complex/poor health. Over a median 6-year follow-up, there were 409 (22%) deaths and 4,130 hospitalizations (median [25th-75th percentile] 1 per person [0-3]). In the very complex/poor category, individuals with A1C ≥8% (vs. <7%) had higher mortality risk (hazard ratio 1.76 [95% CI 1.15-2.71]), even after adjustment for glucose-lowering medication use. Within the very complex/poor health category, individuals with A1C ≥8% (vs. <7%) had more hospitalizations (incidence rate ratio [IRR] 1.41 [95% CI 1.03-1.94]). In the complex/intermediate group, individuals with A1C ≥8% (vs. <7%) had more hospitalizations, even with adjustment for glucose-lowering medication use (IRR 1.64 [1.21-2.24]). Results were similar, but imprecise, when the analysis was restricted to insulin or sulfonylurea users (n = 663).

CONCLUSIONS

There were substantial differences in mortality and hospitalizations across ADA health status categories, but older adults with A1C <7% were not at elevated risk, regardless of health status. Our results support the 2021 ADA guidelines and indicate that <7% is a reasonable treatment goal in some older adults with diabetes.

Plasma Metabolomic Signatures of Healthy Dietary Patterns in the Chronic Renal Insufficiency Cohort (CRIC) Study

BACKGROUND

In individuals with chronic kidney disease (CKD), healthy dietary patterns are inversely associated with CKD progression. Metabolomics, an approach that measures many small molecules in biofluids, can identify biomarkers of healthy dietary patterns.

OBJECTIVES

We aimed to identify known metabolites associated with greater adherence to 4 healthy dietary patterns in CKD patients.

METHODS

We examined associations between 486 known plasma metabolites and Healthy Eating Index (HEI)-2015, Alternative Healthy Eating Index (AHEI)-2010, the Dietary Approaches to Stop Hypertension (DASH) diet, and alternate Mediterranean diet (aMED) in 1056 participants (aged 21-74 y at baseline) in the Chronic Renal Insufficiency Cohort (CRIC) Study. Usual dietary intake was assessed using a semiquantitative FFQ. We conducted multivariable linear regression models to study associations between healthy dietary patterns and individual plasma metabolites, adjusting for sociodemographic characteristics, health behaviors, and clinical factors. We used principal component analysis to identify groups of metabolites associated with individual food components within healthy dietary patterns.

RESULTS

After Bonferroni correction, we identified 266 statistically significant diet-metabolite associations (HEI: n = 60; AHEI: n = 78; DASH: n = 77; aMED: n = 51); 78 metabolites were associated with >1 dietary pattern. Lipids with a longer acyl chain length and double bonds (unsaturated) were positively associated with all 4 dietary patterns. A metabolite pattern low in saturated diacylglycerols and triacylglycerols, and a pattern high in unsaturated triacylglycerols was positively associated with intake of healthy food components. Plasmalogens were negatively associated with the consumption of nuts and legumes and healthy fat, and positively associated with the intake of red and processed meat.

CONCLUSIONS

We identified many metabolites associated with healthy dietary patterns, indicative of food consumption. If replicated, these metabolites may be considered biomarkers of healthy dietary patterns in patients with CKD.

Trends in Receipt of American Diabetes Association Guideline-Recommended Care Among U.S. Adults With Diabetes: NHANES 2005-2018

OBJECTIVE

To characterize national trends and characteristics of adults with diabetes receiving American Diabetes Association (ADA) guideline-recommended care.

RESEARCH DESIGN AND METHODS

We performed serial cross-sectional analyses of 4,069 adults aged ≥20 years with diabetes who participated in the 2005-2018 National Health and Nutrition Examination Survey (NHANES).

RESULTS

Overall, the proportion of U.S. adults with diabetes receiving ADA guideline-recommended care meeting all five criteria by self-report in the past year (having a primary doctor for diabetes and one or more visits for this doctor, HbA_1c testing, an eye examination, a foot examination, and cholesterol testing) increased from 25.0% in 2005-2006 to 34.1% in 2017-2018 (P-trend = 0.004). For participants with age ≥65 years, it increased from 29.3% in 2005-2006 to 44.2% in 2017-2018 (P-trend = 0.001), whereas for participants with age 40-64 and 20-39 years, it did not change significantly during the same time period: 25.2% to 25.8% (P-trend = 0.457) and 9.9% to 26.0% (P-trend = 0.401), respectively. Those who were not receiving ADA guideline-recommended care were more likely to be younger, of lower socioeconomic status, uninsured, newly diagnosed with diabetes, not on diabetes medication, and free of hypercholesterolemia.

CONCLUSIONS

Receipt of ADA guideline-recommended care increased only among adults with diabetes aged ≥65 years in the past decade. In 2017-2018, only one of three U.S. adults with diabetes reported receiving ADA guideline-recommended care, with even a lower receipt of care among those <65 years of age. Efforts are needed to improve health care delivery and equity in diabetes care. Insurance status is an important modifiable determinant of receiving ADA guideline-recommended care.

25-hydroxyvitamin D, Fibroblast Growth Factor 23, and Risk of Acute Kidney Injury Over 20 Years of Follow-Up

INTRODUCTION

Low serum 25-hydroxyvitamin D levels have been identified as a risk factor for acute kidney injury (AKI) among critically ill patients. Whether low 25-hydroxyvitamin D levels are associated with long-term incidence of hospitalization with AKI in the general population is unknown.

METHODS

Among 12,380 participants (mean age, 57 years; 24% black) in the Atherosclerosis Risk in Communities (ARIC) Study who attended visit 2 (1990-1992), we explored the association of serum 25-hydroxyvitamin D with incident hospitalization with AKI. Multivariable Cox models were used to estimate hazard ratios (HRs). We also examined the association of serum fibroblast growth factor 23 (FGF23) with AKI.

RESULTS

During a median follow-up of 24.3 years, 2145 participants had incident hospitalization with AKI (crude incidence rate: 8.3; 95% confidence interval [CI]: 8.0-8.7, per 1,000 person-years). In multivariable Cox models (including adjustment for kidney function), lower 25-hydroxyvitamin D and higher FGF23 levels were each significantly associated with an increased risk of AKI (HR: 1.35; 95% CI: 1.17-1.54, for lowest vs. highest quartile for 25-hydroxyvitamin D, and HR: 1.19; 95% CI: 1.05-1.36, for highest vs. lowest quartile for FGF23). The association was consistent across demographic and clinical subgroups, regardless of whether AKI was the primary diagnosis for hospitalization, and when adjusting for incident chronic kidney disease (CKD) or cardiovascular disease (CVD) as a time-varying covariate.

CONCLUSION

Among middle- to older-age adults in the community, low 25-hydroxyvitamin D and high FGF23 levels were independently associated with an increased risk of AKI. Future studies should explore underlying mechanisms linking these bone mineral metabolism markers with kidney injury.

Large-scale plasma proteomic analysis identifies proteins and pathways associated with dementia risk

The plasma proteomic changes that precede the onset of dementia could yield insights into disease biology and highlight new biomarkers and avenues for intervention. We quantified 4,877 plasma proteins in nondemented older adults in the Atherosclerosis Risk in Communities cohort and performed a proteome-wide association study of dementia risk over five years (n = 4,110; 428 incident cases). Thirty-eight proteins were associated with incident dementia after Bonferroni correction. Of these, 16 were also associated with late-life dementia risk when measured in plasma collected nearly 20 years earlier, during mid-life. Two-sample Mendelian randomization causally implicated two dementia-associated proteins (SVEP1 and angiostatin) in Alzheimer's disease. SVEP1, an immunologically relevant cellular adhesion protein, was found to be part of larger dementia-associated protein networks, and circulating levels were associated with atrophy in brain regions vulnerable to Alzheimer's pathology. Pathway analyses for the broader set of dementia-associated proteins implicated immune, lipid, metabolic signaling and hemostasis pathways in dementia pathogenesis.

Reducing Kidney Function Decline in Patients With CKD: Core Curriculum 2021

An estimated 8% to 16% of the world's population has chronic kidney disease, defined by low glomerular filtration rate or albuminuria. Progression of chronic kidney disease is associated with adverse outcomes, including incident kidney failure with replacement therapy, accelerated cardiovascular disease, disability, and mortality. Therefore, slowing kidney function decline is paramount in the management of a patient with chronic kidney disease. Ascertaining the cause of kidney disease is an important first step and may compel specific therapies. Effective approaches that apply to the vast majority of patients with chronic kidney disease include the optimization of blood pressure and blockade of the renin-angiotensin-aldosterone system, particularly if albuminuria is present. Recent studies suggest that sodium/glucose cotransporter 2 inhibitors are highly effective treatments in patients with diabetes and/or albuminuria. For patients with type 2 diabetes, glycemic control is important in preventing the development of microvascular complications, and glucagon-like peptide 1 receptor agonists may help reduce albuminuria levels. Other strategies include correcting metabolic acidosis, maintaining ideal body weight, following diets that are low in sodium and animal protein, and avoiding potential nephrotoxins such as nonsteroidal anti-inflammatories, proton-pump inhibitors, and iodinated contrast.

Mortality and Access to Kidney Transplantation in Patients with Sickle Cell Disease-Associated Kidney Failure

BACKGROUND AND OBJECTIVES

Patients with sickle cell disease-associated kidney failure have high mortality, which might be lowered by kidney transplantation. However, because they show higher post-transplant mortality compared with patients with other kidney failure etiologies, kidney transplantation remains controversial in this population, potentially limiting their chance of receiving transplantation. We aimed to quantify the decrease in mortality associated with transplantation in this population and determine the chance of receiving transplantation with sickle cell disease as the cause of kidney failure as compared with other etiologies of kidney failure.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using a national registry, we studied all adults with kidney failure who began maintenance dialysis or were added to the kidney transplant waiting list in 1998-2017. To quantify the decrease in mortality associated with transplantation, we measured the absolute risk difference and hazard ratio for mortality in matched pairs of transplant recipients versus waitlisted candidates in the sickle cell and control groups. To compare the chance of receiving transplantation, we estimated hazard ratios for receiving transplantation in the sickle cell and control groups, treating death as a competing risk.

RESULTS

Compared with their matched waitlisted candidates, 189 transplant recipients with sickle cell disease and 220,251 control recipients showed significantly lower mortality. The absolute risk difference at 10 years post-transplant was 20.3 (98.75% confidence interval, 0.9 to 39.8) and 19.8 (98.75% confidence interval, 19.2 to 20.4) percentage points in the sickle cell and control groups, respectively. The hazard ratio was also similar in the sickle cell (0.57; 95% confidence interval, 0.36 to 0.91) and control (0.54; 95% confidence interval, 0.53 to 0.55) groups (interaction P=0.8). Nonetheless, the sickle cell group was less likely to receive transplantation than the controls (subdistribution hazard ratio, 0.73; 95% confidence interval, 0.61 to 0.87). Similar disparities were found among waitlisted candidates (subdistribution hazard ratio, 0.62; 95% confidence interval, 0.53 to 0.72).

CONCLUSIONS

Patients with sickle cell disease-associated kidney failure exhibited similar decreases in mortality associated with kidney transplantation as compared with those with other kidney failure etiologies. Nonetheless, the sickle cell population was less likely to receive transplantation, even after waitlist registration.

Association Between Midlife Obesity and Kidney Function Trajectories: The Atherosclerosis Risk in Communities (ARIC) Study

RATIONALE & OBJECTIVE

Obesity has been related to risk for chronic kidney disease. However, the associations of different measures of midlife obesity with long-term kidney function trajectories and whether they differ by sex and race are unknown.

STUDY DESIGN

Observational study.

SETTING & PARTICIPANTS

13,496 participants from the Atherosclerosis Risk in Communities (ARIC) Study.

PREDICTORS

Midlife obesity status as measured by body mass index (BMI), waist-to-hip ratio, and predicted percent fat at baseline.

OUTCOMES

Estimated glomerular filtration rate (eGFR) calculated using serum creatinine level measured at 5 study visits, and incident kidney failure with replacement therapy (KFRT).

ANALYTICAL APPROACH

Mixed models with random intercepts and random slopes for eGFR. Cox proportional hazards models for KFRT.

RESULTS

Baseline mean age was 54 years, median eGFR was 103mL/min/1.73m2, and median BMI was 27kg/m2. Over 30 years of follow-up, midlife obesity measures were associated with eGFR decline in White and Black women but not consistently in men. Adjusted for age, center, smoking, and coronary heart disease, the differences in eGFR slope per 1-SD higher BMI, waist-to-hip ratio, and predicted percent fat were 0.09 (95% CI, -0.18 to 0.36), -0.25 (95% CI, -0.50 to 0.01), and-0.14 (95% CI, -0.41 to 0.13) mL/min/1.73m2 per decade for White men; -0.91 (95% CI, -1.15 to-0.67), -0.82 (95% CI, -1.06 to-0.58), and-1.02 (95% CI, -1.26 to-0.78) mL/min/1.73m2 per decade for White women; -0.70 (95% CI, -1.54 to 0.14), -1.60 (95% CI, -2.42 to-0.78), and-1.24 (95% CI, -2.08 to-0.40) mL/min/1.73m2 per decade for Black men; and-1.24 (95% CI, -2.08 to-0.40), -1.50 (95% CI, -2.05 to-0.95), and-1.43 (95% CI, -2.00 to-0.86) mL/min/1.73m2 per decade for Black women. Obesity indicators were independently associated with risk for KFRT for all sex-race groups except White men.

LIMITATIONS

Loss to follow-up during 3 decades of follow-up with 5 eGFR assessments.

CONCLUSIONS

Obesity status is a risk factor for future decline in kidney function and development of KFRT in Black and White women, with less consistent associations among men.

Adherence to Healthy Dietary Patterns and Risk of CKD Progression and All-Cause Mortality: Findings From the CRIC (Chronic Renal Insufficiency Cohort) Study

RATIONALE & OBJECTIVE

Current dietary guidelines recommend that patients with chronic kidney disease (CKD) restrict individual nutrients, such as sodium, potassium, phosphorus, and protein. This approach can be difficult for patients to implement and ignores important nutrient interactions. Dietary patterns are an alternative method to intervene on diet. Our objective was to define the associations of 4 healthy dietary patterns with risk for CKD progression and all-cause mortality among people with CKD.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

2,403 participants aged 21 to 74 years with estimated glomerular filtration rates of 20 to 70mL/min/1.73m2 and dietary data in the Chronic Renal Insufficiency Cohort (CRIC) Study.

EXPOSURES

Healthy Eating Index-2015, Alternative Healthy Eating Index-2010, alternate Mediterranean diet (aMed), and Dietary Approaches to Stop Hypertension (DASH) diet scores were calculated from food frequency questionnaires.

OUTCOMES

(1) CKD progression defined as≥50% estimated glomerular filtration rate decline, kidney transplantation, or dialysis and (2) all-cause mortality.

ANALYTICAL APPROACH

Cox proportional hazards regression models adjusted for demographic, lifestyle, and clinical covariates to estimate hazard ratios (HRs) and 95% CIs.

RESULTS

There were 855 cases of CKD progression and 773 deaths during a maximum of 14 years. Compared with participants with the lowest adherence, the most highly adherent tertile of Alternative Healthy Eating Index-2010, aMed, and DASH had lower adjusted risk for CKD progression, with the strongest results for aMed (HR, 0.75; 95% CI, 0.62-0.90). Compared with participants with the lowest adherence, the highest adherence tertiles for all scores had lower adjusted risk for all-cause mortality for each index (24%-31% lower risk).

LIMITATIONS

Self-reported dietary intake.

CONCLUSIONS

Greater adherence to several healthy dietary patterns is associated with lower risk for CKD progression and all-cause mortality among people with CKD. Guidance to adopt healthy dietary patterns can be considered as a strategy for managing CKD.

High-Sensitivity Cardiac Troponin, Natriuretic Peptide, and Long-Term Risk of Acute Kidney Injury: The Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Cardiac markers such as high-sensitivity cardiac troponin T (hs-cTnT) and N-terminal pro-B natriuretic peptide (NTproBNP) are predictors of developing acute kidney injury (AKI) during hospitalization for surgery or revascularization. However, their associations with the long-term risk of AKI in the general population are uncharacterized.

METHODS

We conducted a prospective cohort study in 10 669 participants of the Atherosclerosis Risk in Communities Study (visit 4, 1996-1998, mean age, 63 years, 56% female, 22% black race) to examine the association of plasma concentrations of hs-cTnT and NTproBNP with the incident hospitalization with AKI. We used multivariable Cox regression analysis to estimate hazard ratios (HRs).

RESULTS

During follow-up, 1907 participants had an incident hospitalization with AKI. Participants with higher concentrations of hs-cTnT had a higher risk of hospitalization with AKI in a graded fashion (adjusted HR, 1.88 [95%CI , 1.59-2.21] for ≥14 ng/L, 1.36 [1.18-1.57] for 9-13 ng/L, and 1.16 [1.03-1.30] for 5-8 ng/L compared to <5 ng/L). The graded association was also observed for NTproBNP (HR, 2.27 [1.93-2.68] for ≥272.7 pg/mL, 1.67 [1.45-1.93] for 142.4-272.6 pg/mL, and 1.31 [1.17-1.47] for 64.0-142.3 pg/mL compared to <64.0 pg/mL). The addition of hs-cTnT and NTproBNP to a model with established predictors significantly improved 10-year risk prediction for hospitalization with AKI (Δc-statistic, 0.015 [95%CI, 0.006-0.024]).

CONCLUSIONS

In middle-aged to older black and white adults in the community, higher concentrations of hs-cTnT and NTproBNP were robustly associated with an increased risk of hospitalization with AKI. These results suggest the usefulness of hs-cTnT and NT-proBNP to identify people at risk of AKI in the general population.

Estimating Kidney Failure Risk Using Electronic Medical Records

Background

The four-variable kidney failure risk equation (KFRE) is a well-validated tool for patients with GFR <60 ml/min per 1.73 m² and incorporates age, sex, GFR, and urine albumin-creatinine ratio (ACR) to forecast individual risk of kidney failure. Implementing the KFRE in electronic medical records is challenging, however, due to low ACR testing in clinical practice. The aim of this study was to determine, when ACR is missing, whether to impute ACR from protein-to-creatinine ratio (PCR) or dipstick protein for use in the four-variable KFRE, or to use the three-variable KFRE, which does not require ACR.

Methods

Using electronic health records from OptumLabs Data Warehouse, patients with eGFR <60 ml/min per 1.73 m² were categorized on the basis of the availability of ACR testing within the previous 3 years. For patients missing ACR, we extracted urine PCR and dipstick protein results, comparing the discrimination of the three-variable KFRE (age, sex, GFR) with the four-variable KFRE estimated using imputed ACR from PCR and dipstick protein levels.

Results

There were 976,299 patients in 39 health care organizations; 59% were women, the mean age was 72 years, and mean eGFR was 47 ml/min per 1.73 m². The proportion with ACR testing was 19% within the previous 3 years. An additional 2% had an available PCR and 36% had a dipstick protein; the remaining 43% had no form of albuminuria testing. The four-variable KFRE had significantly better discrimination than the three-variable KFRE among patients with ACR testing, PCR testing, and urine dipstick protein levels, even with imputed ACR for the latter two groups. Calibration of the four-variable KFRE was acceptable in each group, but the three-variable equation showed systematic bias in the groups that lacked ACR or PCR testing.

Conclusions

Implementation of the KFRE in electronic medical records should incorporate ACR, even if only imputed from PCR or urine dipstick protein levels.

The case for early identification and intervention of chronic kidney disease: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference

Chronic kidney disease (CKD) causes substantial global morbidity and increases cardiovascular and all-cause mortality. Unlike other chronic diseases with established strategies for screening, there has been no consensus on whether health systems and governments should prioritize early identification and intervention for CKD. Guidelines on evaluating and managing early CKD are available but have not been universally adopted in the absence of incentives or quality measures for prioritizing CKD care. The burden of CKD falls disproportionately upon persons with lower socioeconomic status, who have a higher prevalence of CKD, limited access to treatment, and poorer outcomes. Therefore, identifying and treating CKD at the earliest stages is an equity imperative. In 2019, Kidney Disease: Improving Global Outcomes (KDIGO) held a controversies conference entitled "Early Identification and Intervention in CKD." Participants identified strategies for screening, risk stratification, and treatment for early CKD and the key health system and economic factors for implementing these processes. A consensus emerged that CKD screening coupled with risk stratification and treatment should be implemented immediately for high-risk persons and that this should ideally occur in primary or community care settings with tailoring to the local context.