Blood Pressure, Incident Cognitive Impairment, and Severity of CKD: Findings From the Chronic Renal Insufficiency Cohort (CRIC) Study.

RATIONALE & OBJECTIVE: Hypertension is a known risk factor for dementia and cognitive impairment. There are limited data on the relation of systolic blood pressure (SBP) and diastolic blood pressure (DBP) with incident cognitive impairment in adults with chronic kidney disease. We sought to identify and characterize the relationship among blood pressure, cognitive impairment, and severity of decreased kidney function in adults with chronic kidney disease. STUDY DESIGN: Longitudinal cohort study. SETTING & PARTICIPANTS: 3,768 participants in the Chronic Renal Insufficiency Cohort (CRIC) Study. EXPOSURE: Baseline SBP and DBP were examined as exposure variables, using continuous (linear, per 10-mm Hg higher), categorical (SBP<120 [reference], 120 to 140,>140mm Hg; DBP<70 (reference), 70 to 80, > 80mm Hg) and nonlinear terms (splines). OUTCOME: Incident cognitive impairment defined as a decline in Modified Mini-Mental State Examination (3MS) score to greater than 1 standard deviation below the cohort mean. ANALYTICAL APPROACH: Cox proportional hazard models adjusted for demographics as well as kidney disease and cardiovascular disease risk factors. RESULTS: The mean age of participants was 58±11 (SD) years, estimated glomerular filtration rate (eGFR) was 44mL/min/1.73m2 ± 15 (SD), and the median follow-up time was 11 (IQR, 7-13) years. In 3,048 participants without cognitive impairment at baseline and with at least 1 follow-up 3MS test, a higher baseline SBP was significantly associated with incident cognitive impairment only in the eGFR>45mL/min/1.73m2 subgroup (adjusted hazard ratio [AHR], 1.13 [95% CI, 1.05-1.22] per 10mm Hg higher SBP]. Spline analyses, aimed at exploring nonlinearity, showed that the relationship between baseline SBP and incident cognitive impairment was J-shaped and significant only in the eGFR>45mL/min/1.73m2 subgroup (P=0.02). Baseline DBP was not associated with incident cognitive impairment in any analyses. LIMITATIONS: 3MS test as the primary measure of cognitive function. CONCLUSIONS: Among patients with chronic kidney disease, higher baseline SBP was associated with higher risk of incident cognitive impairment specifically in those individuals with eGFR>45mL/min/1.73m2. PLAIN-LANGUAGE SUMMARY: High blood pressure is a strong risk factor for dementia and cognitive impairment in studies of adults without kidney disease. High blood pressure and cognitive impairment are common in adults with chronic kidney disease (CKD). The impact of blood pressure on the development of future cognitive impairment in patients with CKD remains unclear. We identified the relationship between blood pressure and cognitive impairment in 3,076 adults with CKD. Baseline blood pressure was measured, after which serial cognitive testing was performed over 11 years. Fourteen percent of participants developed cognitive impairment. We found that a higher baseline systolic blood pressure was associated with an increased risk of cognitive impairment. We found that this association was stronger in adults with mild-to-moderate CKD compared with those with advanced CKD.

Association of urine and plasma ADMA with atherosclerotic risk in DKD cardiovascular disease risk in diabetic kidney disease: findings from the Chronic Renal Insufficiency Cohort (CRIC) study.

BACKGROUND: Chronic kidney disease (CKD) is associated with atherosclerotic cardiovascular disease (ASCVD) risk, especially among those with diabetes. Altered metabolism of solutes that accumulate in CKD [asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA) and trimethylamine N-oxide (TMAO)] may reflect pathways linking CKD with ASCVD. METHODS: This case-cohort study included Chronic Renal Insufficiency Cohort participants with baseline diabetes, estimated glomerular filtration rate <60 mL/min/1.73 m2, and without prior history for each outcome. The primary outcome was incident ASCVD (time to first myocardial infarction, stroke or peripheral artery disease event) and secondary outcome was incident heart failure. The subcohort comprised randomly selected participants meeting entry criteria. Plasma and urine ADMA, SDMA and TMAO concentrations were determined by liquid chromatography-tandem mass spectrometry. Associations of uremic solute plasma concentrations and urinary fractional excretions with outcomes were evaluated by weighted multivariable Cox regression models, adjusted for confounding covariables. RESULTS: Higher plasma ADMA concentrations (per standard deviation) were associated with ASCVD risk [hazard ratio (HR) 1.30, 95% confidence interval (CI) 1.01-1.68]. Lower fractional excretion of ADMA (per standard deviation) was associated with ASCVD risk (HR 1.42, 95% CI 1.07-1.89). The lowest quartile of ADMA fractional excretion was associated with greater ASCVD risk (HR 2.25, 95% CI 1.08-4.69) compared with the highest quartile. Plasma SDMA and TMAO concentration and fractional excretion were not associated with ASCVD. Neither plasma nor fractional excretion of ADMA, SDMA and TMAO were associated with incident heart failure. CONCLUSION: These data suggest that decreased kidney excretion of ADMA leads to increased plasma concentrations and ASCVD risk.

Association of Uremic Solutes With Cardiovascular Death in Diabetic Kidney Disease.

RATIONALE & OBJECTIVE: Cardiovascular disease (CVD) is a major cause of mortality among people with diabetic kidney disease (DKD). The pathophysiology is inadequately explained by traditional CVD risk factors. The uremic solutes trimethylamine-N-oxide (TMAO) and asymmetric and symmetric dimethylarginine (ADMA, SDMA) have been linked to CVD in kidney failure with replacement therapy (KFRT), but data are limited in populations with diabetes and less severe kidney disease. STUDY DESIGN: Observational cohort. SETTINGS & PARTICIPANTS: Random subcohort of 555 REGARDS (Reasons for Geographic and Racial Differences in Stroke) study participants with diabetes and estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 at study entry. EXPOSURE: ADMA, SDMA, and TMAO assayed by liquid chromatography-mass spectrometry in plasma and urine. OUTCOME: Cardiovascular mortality (primary outcome); all-cause mortality and incident KFRT (secondary outcomes). ANALYTICAL APPROACH: Plasma concentrations and ratios of urine to plasma concentrations of ADMA, SDMA, and TMAO were tested for association with outcomes. Adjusted Cox regression models were fitted and hazard ratios of outcomes calculated per standard deviation and per doubling, and as interquartile comparisons. RESULTS: The mean baseline eGFR was 44 mL/min/1.73 m2. Cardiovascular death, overall mortality, and KFRT occurred in 120, 285, and 89 participants, respectively, during a mean 6.2 years of follow-up. Higher plasma ADMA and SDMA (HRs of 1.20 and 1.28 per 1-SD greater concentration), and lower ratios of urine to plasma concentrations of ADMA, SDMA, and TMAO (HRs per halving of 1.53, 1.69, and 1.38) were associated with cardiovascular mortality. Higher plasma concentrations of ADMA, SDMA, and TMAO (HRs of 1.31, 1.42, and 1.13 per 1-SD greater concentration) and lower urine to plasma ratios of ADMA, SDMA, and TMAO (HRs per halving of 1.34, 1.37, and 1.26) were associated with all-cause mortality. Higher plasma ADMA and SDMA were associated with incident KFRT by categorical comparisons (HRs of 2.75 and 2.96, comparing quartile 4 to quartile 1), but not in continuous analyses. LIMITATIONS: Single cohort, restricted to patients with diabetes and eGFR < 60 mL/min/1.73 m2, potential residual confounding by GFR, no dietary information. CONCLUSIONS: Higher plasma concentrations and lower ratios of urine to plasma concentrations of uremic solutes were independently associated with cardiovascular and all-cause mortality in DKD. Associations of ratios of urine to plasma concentrations with mortality suggest a connection between renal uremic solute clearance and CVD pathogenesis.

Associations of Plasma Biomarkers of Inflammation, Fibrosis, and Kidney Tubular Injury With Progression of Diabetic Kidney Disease: A Cohort Study.

RATIONALE & OBJECTIVE: Most circulating biomarkers of chronic kidney disease (CKD) progression focus on factors reflecting glomerular filtration. Few biomarkers capture nonglomerular pathways of kidney injury or damage, which may be particularly informative in populations at high risk for CKD progression such as individuals with diabetes. STUDY DESIGN: Cohort study. SETTING & PARTICIPANTS: 594 participants (mean age, 70 years; 53% women) of the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study who had diabetes and an estimated glomerular filtration rate (eGFR)<60mL/min/1.73m2 at baseline. EXPOSURES: Plasma biomarkers of inflammation/fibrosis (TNFR1 and TNFR2, suPAR, MCP-1, YKL-40) and tubular injury (KIM-1) measured at the baseline visit. OUTCOMES: Incident kidney failure with replacement therapy (KFRT). ANALYTICAL APPROACH: Cox proportional hazards regression and least absolute shrinkage and selection operator regression adjusted for established risk factors for kidney function decline, baseline eGFR, and urinary albumin-creatinine ratio (UACR). RESULTS: A total of 98 KFRT events were observed over a mean of 6.2±3.5 (standard deviation) years of follow-up. Plasma biomarkers were modestly associated with baseline eGFR (correlation coefficients ranging from-0.08 to-0.65) and UACR (0.14 to 0.56). In individual biomarker models adjusted for eGFR, UACR, and established risk factors, hazard ratios for incident KFRT per 2-fold higher biomarker concentrations were 1.52 (95% CI, 1.25-1.84) for plasma KIM-1, 1.54 (95% CI, 1.08-2.21) for TNFR1, 1.91 (95% CI, 1.16-3.14) for TNFR2, and 1.39 (95% CI, 1.05-1.84) for YKL-40. In least absolute shrinkage and selection operator regression models accounting for biomarkers in parallel, plasma KIM-1 and TNFR1 remained associated with incident KFRT. LIMITATIONS: Single biomarker measurement, lack of follow-up eGFR assessments. CONCLUSIONS: Individual plasma markers of inflammation/fibrosis (TNFR1, TNFR2, YKL-40) and tubular injury (KIM-1) were associated with risk of incident KFRT in adults with diabetes and an eGFR<60mL/min/1.73m2 after adjustment for established risk factors.

Effects of Dietary App-Supported Tele-Counseling on Sodium Intake, Diet Quality, and Blood Pressure in Patients With Diabetes and Kidney Disease.

OBJECTIVES: The aim of this study is to examine the effect of a telehealth intervention that used a dietary app, educational website, and weekly dietitian tele-counseling on sodium intake, diet quality, blood pressure, and albuminuria among individuals with diabetes and early-stage chronic kidney disease. DESIGN AND METHODS: We examined the effects of a dietary app-supported tele-counseling intervention in a single center, single arm study of 44 participants with type 2 diabetes and stage 1-3a chronic kidney disease. Participants recorded and shared dietary data via MyFitnessPal with registered dietitians, who used motivational interviewing to provide telephone counseling weekly for 8 weeks. After the 8-week intensive intervention, participants were followed at 6 and 12 months. Outcomes included 24-hour urine sodium (2 collections per timepoint), Healthy Eating Index 2015 score (three 24-hour dietary recalls per timepoint), 24-hour systolic blood pressure (SBP) and diastolic blood pressure (DBP), and 24-hour urine albumin excretion. RESULTS: Out of 44 consented participants (mean age 60.3 ± 11.9 years, 43% female, 89% white, median estimated glomerular filtration rate was 78.5 mL/min/1.73 m2, median urine albumin excretion 52.9 mg/day, 84% hypertension), 32 (73%) completed 8-week follow-up, 27 (61%) completed 6-month follow-up, and 25 (57%) completed 12-month follow-up. Among participants who completed 12-month follow-up, reported sodium intake decreased by 638 mg/day from baseline of 2,919 mg/day (P < .001). The 24-hour mean urine sodium and albumin excretion did not decline over the study period. Healthy Eating Index 2015 score improved by 7.76 points at 12 months from a mean baseline of 54.6 (P < .001). Both 24-hour SBP and DBP declined at 12 months from baseline (SBP -5.7 mm Hg, 95% confidence interval -10.5 to -1.0, P = .02; DBP -4.1 mm Hg, 95% confidence interval -7.2 to -1.1, P = .01). CONCLUSIONS: Overall, this study demonstrates that a short, intensive, remotely delivered dietary intervention for adults with type 2 diabetes and early chronic kidney disease at high risk for disease progression and cardiovascular complications led to improvement in blood pressure and self-reported sodium intake and diet quality, but no improvement in albuminuria. Future research studies are needed to examine whether remotely delivered dietary interventions can ultimately improve kidney health over time.

Effect of Kidney Function on Relationships between Lifestyle Behaviors and Mortality or Cardiovascular Outcomes: A Pooled Cohort Analysis.

BACKGROUND: Adherence to healthy behaviors reduces risks of cardiovascular disease and death in the general population. However, among people with kidney disease, a group at higher risk for cardiovascular disease, such benefits have not been established. METHODS: We pooled data from three cohort studies with a total of 27,271 participants. Kidney function was categorized on the basis of eGFR (≥60, 45 to <60, and <45 ml/min per 1.73 m2). We used proportional hazard frailty models to estimate associations between healthy behaviors (not smoking, at recommended body mass index [BMI], physical activity, healthy diet, and moderate to no alcohol intake) and outcomes (all-cause death, major coronary events, ischemic stroke, and heart failure events). RESULTS: All recommended lifestyle behaviors were significantly associated with lower risks of death, regardless of eGFR. Not smoking (versus current) and any moderate to vigorous physical activity (versus none) was significantly associated with reduced risks of major coronary and heart failure events, regardless of eGFR. Any (versus no) moderate or vigorous physical activity significantly associated with decreased risk of ischemic stroke events only among those with eGFR ≥60. Moderate to no daily alcohol intake (versus excessive) was significantly associated with an increased risk of major coronary events, regardless of eGFR. For heart failure events, a BMI of 18.5 to 30 associated with decreased risk, regardless of eGFR. Across all eGFR categories, the magnitude of risk reduction for death and all cardiovascular outcomes increased with greater numbers of recommended lifestyle behaviors. CONCLUSIONS: Recommended lifestyle behaviors are associated with lower risk of death and cardiovascular disease events among individuals with or without reduced kidney function, supporting lifestyle behaviors as potentially modifiable risk factors for people with kidney disease.

Association of Multiple Plasma Biomarker Concentrations with Progression of Prevalent Diabetic Kidney Disease: Findings from the Chronic Renal Insufficiency Cohort (CRIC) Study.

BACKGROUND: Although diabetic kidney disease is the leading cause of ESKD in the United States, identifying those patients who progress to ESKD is difficult. Efforts are under way to determine if plasma biomarkers can help identify these high-risk individuals. METHODS: In our case-cohort study of 894 Chronic Renal Insufficiency Cohort Study participants with diabetes and an eGFR of <60 ml/min per 1.73 m2 at baseline, participants were randomly selected for the subcohort; cases were those patients who developed progressive diabetic kidney disease (ESKD or 40% eGFR decline). Using a multiplex system, we assayed plasma biomarkers related to tubular injury, inflammation, and fibrosis (KIM-1, TNFR-1, TNFR-2, MCP-1, suPAR, and YKL-40). Weighted Cox regression models related biomarkers to progression of diabetic kidney disease, and mixed-effects models estimated biomarker relationships with rate of eGFR change. RESULTS: Median follow-up was 8.7 years. Higher concentrations of KIM-1, TNFR-1, TNFR-2, MCP-1, suPAR, and YKL-40 were each associated with a greater risk of progression of diabetic kidney disease, even after adjustment for established clinical risk factors. After accounting for competing biomarkers, KIM-1, TNFR-2, and YKL-40 remained associated with progression of diabetic kidney disease; TNFR-2 had the highest risk (adjusted hazard ratio, 1.61; 95% CI, 1.15 to 2.26). KIM-1, TNFR-1, TNFR-2, and YKL-40 were associated with rate of eGFR decline. CONCLUSIONS: Higher plasma levels of KIM-1, TNFR-1, TNFR-2, MCP-1, suPAR, and YKL-40 were associated with increased risk of progression of diabetic kidney disease; TNFR-2 had the highest risk after accounting for the other biomarkers. These findings validate previous literature on TNFR-1, TNFR-2, and KIM-1 in patients with prevalent CKD and provide new insights into the influence of suPAR and YKL-40 as plasma biomarkers that require validation.

Mobile Health (mHealth) Technology: Assessment of Availability, Acceptability, and Use in CKD.

RATIONALE & OBJECTIVE: Digital and mobile health (mHealth) technologies improve patient-provider communication and increase information accessibility. We assessed the use of technology, attitudes toward using mHealth technologies, and proficiency in using mHealth technologies among individuals with chronic kidney disease (CKD). STUDY DESIGN: Cross-sectional survey with open text responses. SETTING & PARTICIPANTS: Chronic Renal Insufficiency Cohort (CRIC) Study participants who completed current use and interest in using mHealth technologies questionnaires and the eHealth literacy Survey (eHEALS). EXPOSURE: Participant characteristics. OUTCOMES: Use of technology (ie, internet, email, smartphone, and mHealth applications [apps]), interest in future mHealth use, and proficiency in using digital and mHealth technologies, or eHealth literacy, determined by eHEALS score. ANALYTICAL APPROACH: Poisson regression and a qualitative content analysis of open-ended responses. RESULTS: Study participants (n = 932) had a mean age of 68 years old and an estimated glomerular filtration rate (eGFR) of 54 mL/min/1.73 m2, and 59% were male. Approximately 70% reported current use of internet, email, and smartphones, and 35% used mHealth apps; only 27% had adequate eHealth literacy (eHEALS score ≥ 32). Participants <65 years of age (vs. ≥65), with more education, higher income, better cognition, and adequate health literacy reported more use of technology, and greater interest in using technologies. Participants of White (vs. non-White) race reported more use of internet and email but less interest in future use of mHealth. Younger age, higher annual income, and greater disease self-efficacy were associated with adequate eHealth literacy. Three themes regarding interest in using digital and mHealth technologies emerged: willingness, concerns, and barriers. LIMITATIONS: Residual confounding, ascertainment bias. CONCLUSIONS: Many individuals with CKD currently use the internet and smartphones and are interested in using mHealth in the future, but few use mHealth apps or have adequate eHealth literacy. mHealth technologies present an opportunity to engage individuals with CKD, especially members of racial or ethnic minority groups because those groups reported greater interest in using mHealth technology than the nonminority population. Further research is needed to identify strategies to overcome inadequate eHealth literacy.

Plasma Biomarkers of Tubular Injury and Inflammation Are Associated with CKD Progression in Children.

BACKGROUND: After accounting for known risk factors for CKD progression in children, clinical outcomes among children with CKD still vary substantially. Biomarkers of tubular injury (such as KIM-1), repair (such as YKL-40), or inflammation (such as MCP-1, suPAR, TNF receptor-1 [TNFR-1], and TNFR-2) may identify children with CKD at risk for GFR decline. METHODS: We investigated whether plasma KIM-1, YKL-40, MCP-1, suPAR, TNFR-1, and TNFR-2 are associated with GFR decline in children with CKD and in subgroups defined by glomerular versus nonglomerular cause of CKD. We studied participants of the prospective CKiD Cohort Study which enrolled children with an eGFR of 30-90 ml/min per 1.73 m2 and then assessed eGFR annually. Biomarkers were measured in plasma collected 5 months after study enrollment. The primary endpoint was CKD progression, defined as a composite of a 50% decline in eGFR or incident ESKD. RESULTS: Of the 651 children evaluated (median age 11 years; median baseline eGFR of 53 ml/min per 1.73 m2), 195 (30%) had a glomerular cause of CKD. Over a median follow-up of 5.7 years, 223 children (34%) experienced CKD progression to the composite endpoint. After multivariable adjustment, children with a plasma KIM-1, TNFR-1, or TNFR-2 concentration in the highest quartile were at significantly higher risk of CKD progression compared with children with a concentration for the respective biomarker in the lowest quartile (a 4-fold higher risk for KIM-1 and TNFR-1 and a 2-fold higher risk for TNFR-2). Plasma MCP-1, suPAR, and YKL-40 were not independently associated with progression. When stratified by glomerular versus nonglomerular etiology of CKD, effect estimates did not differ significantly. CONCLUSIONS: Higher plasma KIM-1, TNFR-1, and TNFR-2 are independently associated with CKD progression in children.

Hospitalizations among adults with chronic kidney disease in the United States: A cohort study.

BACKGROUND: Adults with chronic kidney disease (CKD) are hospitalized more frequently than those without CKD, but the magnitude of this excess morbidity and the factors associated with hospitalizations are not well known. METHODS AND FINDINGS: Data from 3,939 participants enrolled in the Chronic Renal Insufficiency Cohort (CRIC) Study between 2003 and 2008 at 7 clinical centers in the United States were used to estimate primary causes of hospitalizations, hospitalization rates, and baseline participant factors associated with all-cause, cardiovascular, and non-cardiovascular hospitalizations during a median follow up of 9.6 years. Multivariable-adjusted Poisson regression was used to identify factors associated with hospitalization rates, including demographics, blood pressure, estimated glomerular filtration rate (eGFR), and proteinuria. Hospitalization rates in CRIC were compared with rates in the Nationwide Inpatient Sample (NIS) from 2012. Of the 3,939 CRIC participants, 45.1% were female, and 41.9% identified as non-Hispanic black, with a mean age of 57.7 years, and the mean eGFR is 44.9 ml/min/1.73m2. CRIC participants had an unadjusted overall hospitalization rate of 35.0 per 100 person-years (PY) [95% CI: 34.3 to 35.6] and 11.1 per 100 PY [95% CI: 10.8 to 11.5] for cardiovascular-related causes. All-cause, non-cardiovascular, and cardiovascular hospitalizations were associated with older age (≥65 versus 45 to 64 years), more proteinuria (≥150 to <500 versus <150 mg/g), higher systolic blood pressure (≥140 versus 120 to <130 mmHg), diabetes (versus no diabetes), and lower eGFR (<60 versus ≥60 ml/min/1.73m2). Non-Hispanic black (versus non-Hispanic white) race/ethnicity was associated with higher risk for cardiovascular hospitalization [rate ratio (RR) 1.25, 95% CI: 1.16 to 1.35, p-value < 0.001], while risk among females was lower [RR 0.89, 95% CI: 0.83 to 0.96, p-value = 0.002]. Rates of cardiovascular hospitalizations were higher among those with ≥500 mg/g of proteinuria irrespective of eGFR. The most common causes of hospitalization were related to cardiovascular (31.8%), genitourinary (8.7%), digestive (8.3%), endocrine, nutritional or metabolic (8.3%), and respiratory (6.7%) causes. Hospitalization rates were higher in CRIC than the NIS, except for non-cardiovascular hospitalizations among individuals aged >65 years. Limitations of the study include possible misclassification by diagnostic codes, residual confounding, and potential bias from healthy volunteer effect due to its observational nature. CONCLUSIONS: In this study, we observed that adults with CKD had a higher hospitalization rate than the general population that is hospitalized, and even moderate reductions in kidney function were associated with elevated rates of hospitalization. Causes of hospitalization were predominantly related to cardiovascular disease, but other causes contributed, particularly, genitourinary, digestive, and endocrine, nutritional, and metabolic illnesses. High levels of proteinuria were observed to have the largest association with hospitalizations across a wide range of kidney function levels.

Constructing a measure of health literacy in Sub-Saharan African countries.

We sought to develop and evaluate a health literacy measure in a multi-national study and to examine demographic characteristics associated with health literacy. Data were obtained from Demographic Health Surveys conducted between 2006-15 in 14 countries in Sub-Saharan Africa. Surveys were the same in all countries but translated to local languages as appropriate. We identified eight questions that corresponded to the National Academy of Medicine (NAM) definition of health literacy. Factor analysis was used to extract one measure of health literacy. Logistic regression was employed to examine the relationship between demographic characteristics and health literacy. A total of 224 751 individuals between the ages of 15 and 49 years were included. The derived health literacy measure demonstrated good internal consistency (Cronbach's α = 0.72) and good content validity. The prevalence of high health literacy overall was 35.77%; females 34.08% and males 39.17%; less than or equal to primary education 8.93%, some secondary education 69.40% and ≥complete secondary 84.35%. High health literacy varied across nations, from 8.51% in Niger to 63.89% in Namibia. This is the first known study to evaluate a measure of health literacy relying on the NAM definition utilizing a large sample from 14 countries in Sub-Saharan Africa. Our study derived a robust indicator of NAM-defined health literacy. This indicator could be used to examine determinants and outcomes of health literacy in additional countries.

Insulin resistance and chronic kidney disease progression, cardiovascular events, and death: findings from the chronic renal insufficiency cohort study.

BACKGROUND: Insulin resistance contributes to the metabolic syndrome, which is associated with the development of kidney disease. However, it is unclear if insulin resistance independently contributes to an increased risk of chronic kidney disease (CKD) progression or CKD complications. Additionally, predisposing factors responsible for insulin resistance in the absence of diabetes in CKD are not well described. This study aimed to describe factors associated with insulin resistance and characterize the relationship of insulin resistance to CKD progression, cardiovascular events and death among a cohort of non-diabetics with CKD. METHODS: Data was utilized from Chronic Renal Insufficiency Cohort Study participants without diabetes (N = 1883). Linear regression was used to assess associations with insulin resistance, defined using the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR). The relationship of HOMA-IR, fasting glucose, hemoglobin A1c (HbA1c), and C-peptide with CKD progression, cardiovascular events, and all-cause mortality was examined with Cox proportional hazards models. RESULTS: Novel positive associations with HOMA-IR included serum albumin, uric acid, and hemoglobin A1c. After adjustment, HOMA-IR was not associated with CKD progression, cardiovascular events, or all-cause mortality. There was a notable positive association of one standard deviation increase in HbA1c with the cardiovascular endpoint (HR 1.16, 95% CI: 1.00-1.34). CONCLUSION: We describe potential determinants of HOMA-IR among a cohort of non-diabetics with mild-moderate CKD. HOMA-IR was not associated with renal or cardiovascular events, or all-cause mortality, which adds to the growing literature describing an inconsistent relationship of insulin resistance with CKD-related outcomes.

CKD Self-management: Phenotypes and Associations With Clinical Outcomes.

BACKGROUND: To slow chronic kidney disease (CKD) progression and its complications, patients need to engage in self-management behaviors. The objective of this study was to classify CKD self-management behaviors into phenotypes and assess the association of these phenotypes with clinical outcomes. STUDY DESIGN: Prospective cohort study. SETTING & PARTICIPANTS: Adults with mild to moderate CKD enrolled in the Chronic Renal Insufficiency Cohort (CRIC) Study. 3,939 participants in the CRIC Study recruited between 2003 and 2008 served as the derivation cohort and 1,560 participants recruited between 2013 and 2015 served as the validation cohort. PREDICTORS: CKD self-management behavior phenotypes. OUTCOMES: CKD progression, atherosclerotic events, heart failure events, death from any cause. MEASUREMENTS: Latent class analysis stratified by diabetes was used to identify CKD self-management phenotypes based on measures of body mass index, diet, physical activity, blood pressure, smoking status, and hemoglobin A1c concentration (if diabetic); Cox proportional hazards models. RESULTS: 3 identified phenotypes varied according to the extent of implementation of recommended CKD self-management behaviors: phenotype I characterized study participants with the most recommended behaviors; phenotype II, participants with a mixture of recommended and not recommended behaviors; and phenotype III, participants with minimal recommended behaviors. In multivariable-adjusted models for those with and without diabetes, phenotype III was strongly associated with CKD progression (HRs of 1.82 and 1.49), death (HRs of 1.95 and 4.14), and atherosclerotic events (HRs of 2.54 and 1.90; each P < 0.05). Phenotype II was associated with atherosclerotic events and death among those with and without diabetes. LIMITATIONS: No consensus definition of CKD self-management; limited to baseline behavior data. CONCLUSIONS: There are potentially 3 CKD self-management behavior phenotypes that distinguish risk for clinical outcomes. These phenotypes may inform the development of studies and guidelines regarding optimal self-management.

Health literacy assessment in developing countries: a case study in Zambia.

Education and literacy are key determinants of health but do not necessarily ensure health literacy (HL). The Institute of Medicine's (IOM) definition of HL is widely accepted, but there is no consensus over its constituent parts. Developing a practical measure of HL is a priority, but challenging. We aimed to derive a measure of HL in data from the Demographic and Health Surveys (DHS) Program administered by the United States Agency for International Development (USAID), which includes items representing domains of HL as defined by the IOM. We accessed data from the DHS conducted in Zambia in 2007. We applied factor analysis methods to eight survey questions that corresponded to elements of the IOM definition. We derived a single indicator and evaluated for reliability and validity. The derived dichotomous measure of HL demonstrated reliability (Cronbach's α = 0.68), good content validity, and importantly was composed of the elements described by the IOM including capacity to obtain, interpret and understand health information, and make appropriate health decisions. Only 46.5% of males and 24.5% of females had high literacy. HL varied considerably across other subgroups. This is the first study to derive a robust indicator of HL following the IOM definition in a large national sample. By applying and evaluating this method in future studies, researchers can use this approach in other DHS datasets to measure HL in additional countries, and ultimately test how HL relates to health outcomes.

Supporting Self-Management of Healthy Behaviors in Chronic Kidney Disease and Hypertension: The SMART-HABITS Pilot Randomized Trial.

BACKGROUND: Support programs for self-management are under-utilized among people with chronic kidney disease (CKD). We examined the feasibility of a smartphone-based intervention to support physical activity and blood pressure monitoring, Supporting Self-Management of Healthy Behaviors (SMART-HABITS), for individuals with CKD and hypertension. METHODS: SMART-HABITS was piloted in a 12-week randomized cross-over trial among people with CKD and hypertension. Participants were asked to monitor blood pressure ≥3-times/week and step counts ≥5-times/week. Participants were randomized to blood pressure communication approach-self-report through text message for six weeks vs. automatic reporting with a smartphone application (app) paired to a Bluetooth enabled blood pressure machine for the alternate six weeks. The approach to monitoring and reporting steps was the same during both phases. Primary outcomes were adoption (retention and use of SMART-HABITS dashboard), adherence (% of transmitted blood pressure and step counts), and acceptability as assessed with surveys and interviews. Secondary outcomes were reach, maintenance, CKD knowledge, digital health literacy, self-management, self-efficacy, quality of life, step counts and blood pressure values. Interviews were conducted at study end. RESULTS: Of the 47 randomized participants, 44 (94%) completed the Text phase and 43 (92%) completed the App phase. Median age was 63 years, 49% were female, and 45% were Black. Retention was 91%. Blood pressure adherence was 87% in the Text phase and 74% in the App phase, and step count adherence was 97%. Acceptability scores were high and interviews largely conveyed acceptance. CKD knowledge increased but remaining survey scores did not change. Mean step counts increased from the pre-study period similarly in both phases. Blood pressure did not change over time. CONCLUSION: Implementing a smartphone support tool for self-management was feasible among people with CKD and hypertension. The approach can supplement clinic-based care and potentially lead to less cardiovascular disease and CKD progression.

Characterization of CKD illness representation profiles using patient-level factors.

BACKGROUND: Illness perceptions are the unique perspective individuals have on their illness, based on their context and experiences, and are associated with patient outcomes including coping and adherence. The purpose of this study was to explore characteristics that may be driving membership in illness perceptions cluster groups for adults with chronic kidney disease (CKD). METHODS: This study was conducted within the multicenter longitudinal Chronic Renal Insufficiency Cohort (CRIC) Study. Cross-sectional data were collected and combined with CRIC data. Illness perceptions were measured using the Revised Illness Perception Questionnaire. Clustering analysis was conducted in R, and bivariate analysis including linear regression was performed in STATA 16. RESULTS: The sample (n = 197) had a mean age of 68, was 52% women, 53% non-White, and mean estimated glomerular filtration rate (eGFR) 56 ml/min/1.73 m2. Three cluster groups were identified, labeled as "Disengaged" (n = 20), "Well-Resourced" (n = 108), and "Distressed" (n = 69). The "Disengaged" group was characterized by low CKD knowledge, many recent hospitalization days, and the lowest perceived CKD burden. The "Well-Resourced" group was characterized by the highest levels of education, CKD knowledge, optimism, and medication adherence. The "Distressed" group was characterized by the highest levels of depression scores, comorbidity burden, CKD burden, CKD symptoms, and lowest optimism. Group membership significantly predicted the number of hospitalization days in adjusted analyses. CONCLUSIONS: Illness perceptions groups are associated with number of hospitalization days but are independent of many patient characteristics. Illness perceptions data could be used to tailor care for specific patients at risk for poor health outcomes.

Urine Biomarkers of Kidney Tubule Health and Risk of Incident CKD in Persons Without Diabetes: The ARIC, MESA, and REGARDS Studies.

Rationale & Objective: Tubulointerstitial damage is a feature of early chronic kidney disease (CKD), but current clinical tests capture it poorly. Urine biomarkers of tubulointerstitial health may identify risk of CKD. Study Design: Prospective cohort (Atherosclerosis Risk in Communities [ARIC]) and case-cohort (Multi-Ethnic Study of Atherosclerosis [MESA] and Reasons for Geographic and Racial Differences in Stroke [REGARDS]). Setting & Participants: Adults with estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m2 and without diabetes in the ARIC, REGARDS, and MESA studies. Exposures: Baseline urine monocyte chemoattractant protein-1 (MCP-1), alpha-1-microglobulin (α1m), kidney injury molecule-1, epidermal growth factor, and chitinase-3-like protein 1. Outcome: Incident CKD or end-stage kidney disease. Analytical Approach: Multivariable Cox proportional hazards regression for each cohort; meta-analysis of results from all 3 cohorts. Results: 872 ARIC participants (444 cases of incident CKD), 636 MESA participants (158 cases), and 924 REGARDS participants (488 cases) were sampled. Across cohorts, mean age ranged from 60 ± 10 to 63 ± 8 years, and baseline eGFR ranged from 88 ± 13 to 91 ± 14 mL/min/1.73 m2. In ARIC, higher concentrations of urine MCP-1, α1m, and kidney injury molecule-1 were associated with incident CKD. In MESA, higher concentration of urine MCP-1 and lower concentration of epidermal growth factor were each associated with incident CKD. In REGARDS, none of the biomarkers were associated with incident CKD. In meta-analysis of all 3 cohorts, each 2-fold increase α1m concentration was associated with incident CKD (HR, 1.19; 95% CI, 1.08-1.31). Limitations: Observational design susceptible to confounding; competing risks during long follow-up period; meta-analysis limited to 3 cohorts. Conclusions: In 3 combined cohorts of adults without prevalent CKD or diabetes, higher urine α1m concentration was independently associated with incident CKD. 4 biomarkers were associated with incident CKD in at least 1 of the cohorts when analyzed individually. Kidney tubule health markers might inform CKD risk independent of eGFR and albuminuria.

This study analyzed 3 cohorts (ARIC, MESA, and REGARDS) of adults without diabetes or prevalent chronic kidney disease (CKD) to determine the associations of 5 urinary biomarkers of kidney tubulointerstitial health with incident CKD, independent of traditional measures of kidney health. Meta-analysis of results from all 3 cohorts suggested that higher baseline levels of urine alpha-1-microglobulin were associated with incident CKD at follow-up. Results from individual cohorts suggested that in addition to alpha-1-microglobulin, monocyte chemoattractant protein-1, kidney injury molecule-1, and epidermal growth factor may also be associated with the development of CKD. These findings underscore the importance of kidney tubule interstitial health in defining risk of CKD independent of creatinine and urine albumin.

Plasma Biomarkers and Incident CKD Among Individuals Without Diabetes.

Rationale & Objective: Biomarkers of kidney disease progression have been identified in individuals with diabetes and underlying chronic kidney disease (CKD). Whether or not these markers are associated with the development of CKD in a general population without diabetes or CKD is not well established. Study Design: Prospective observational cohort. Setting & Participants: In the Atherosclerosis Risk in Communities) study, 948 participants were studied. Exposures: The baseline plasma biomarkers of kidney injury molecule-1 (KIM-1), monocyte chemoattractant protein-1 (MCP-1), soluble urokinase plasminogen activator receptor (suPAR), tumor necrosis factor receptor 1 (TNFR-1), tumor necrosis factor receptor 2 (TNFR-2), and human cartilage glycoprotein-39 (YKL-40) measured in 1996-1998. Outcome: Incident CKD after 15 years of follow-up defined as ≥40% estimated glomerular filtration rate decline to <60 mL/min/1.73 m2 or dialysis dependence through United States Renal Data System linkage. Analytical Approach: Logistic regression and C statistics. Results: There were 523 cases of incident CKD. Compared with a random sample of 425 controls, there were greater odds of incident CKD per 2-fold higher concentration of KIM-1 (OR, 1.49; 95% CI, 1.25-1.78), suPAR (OR, 2.57; 95% CI, 1.74-3.84), TNFR-1 (OR, 2.20; 95% CI, 1.58-3.09), TNFR-2 (OR, 2.03; 95% CI, 1.37-3.04). After adjustment for all biomarkers, KIM-1 (OR, 1.42; 95% CI, 1.19-1.71), and suPAR (OR, 1.86; 95% CI, 1.18-2.92) remained associated with incident CKD. Compared with traditional risk factors, the addition of all 6 biomarkers improved the C statistic from 0.695-0.731 (P < 0.01) and using the observed risk of 12% for incident CKD, the predicted risk gradient changed from 5%-40% (for the 1st-5th quintile) to 4%-44%. Limitations: Biomarkers and creatinine were measured at one time point. Conclusions: Higher levels of KIM-1, suPAR, TNFR-1, and TNFR-2 were associated with higher odds of incident CKD among individuals without diabetes. Plain-Language Summary: For people with diabetes or kidney disease, several biomarkers have been shown to be associated with worsening kidney disease. Whether these biomarkers have prognostic significance in people without diabetes or kidney disease is less studied. Using the Atherosclerosis Risk in Communities study, we followed individuals without diabetes or kidney disease for an average of 15 years after biomarker measurement to see if these biomarkers were associated with the development of kidney disease. We found that elevated levels of KIM-1, suPAR, TNFR-1, and TNFR-2 were associated with the development of kidney disease. These biomarkers may help identify individuals who would benefit from interventions to prevent the development of kidney disease.