Associations between abrupt transition, dialysis-requiring AKI, and early mortality in ESKD among U.S. veterans.

BACKGROUND: Mortality is high within the first few months of starting chronic dialysis. Pre-ESKD trajectory of kidney function has been shown to be predictive of early death after dialysis initiation. We aim to better understand how two key aspects of pre-dialysis kidney function-an abrupt transition pattern and an episode of dialysis-requiring AKI (AKI-D) leading directly to ESKD-are associated with early mortality after dialysis initiation. METHODS: We extracted national data from U.S. Veterans Health Administration cross-linked with the United States Renal Data System (USRDS) to identify patients who initiated hemodialysis during 2009-2013. We defined abrupt transition as having a mean outpatient eGFR ≥ 30 ml/min/1.73m2 within 1 year prior to ESKD. AKI-D was identified using inpatient serum creatinine measurements (serum Cr increase by at least 50% from baseline) along with billing codes for inpatient receipt of dialysis for AKI within 30 days prior to the ESKD start date. We used multivariable proportional hazards models to examine the association between patterns of kidney function prior to ESKD and all-cause mortality within 90 days after ESKD. RESULTS: Twenty-two thousand eight hundred fifteen patients were identified in the final analytic cohort of Veterans who initiated hemodialysis and entered the USRDS. We defined five patterns of kidney function decline. Most (68%) patients (N = 15,484) did not have abrupt transition and did not suffer an episode of AKI-D prior to ESKD (reference group). The remaining groups had abrupt transition, AKI-D, or both. Patients who had an abrupt transition with (N = 503) or without (N = 3611) AKI-D had the highest risk of early mortality after ESKD onset after adjustment for demographics and comorbidities (adjusted HR 2.10, 95% CI 1.66-2.65 for abrupt transition with AKI-D; adjusted HR 2.10, 95% CI 1.90-2.33 for abrupt transition without AKI-D). In contrast, patients who experienced AKI-D without an abrupt transition pattern (N = 2141 had only a modestly higher risk of early death (adjusted HR 1.19, 95% CI 1.01-1.40). CONCLUSIONS: An abrupt decline in kidney function within 1 year prior to ESKD occurred in nearly 1 in 5 incident hemodialysis patients (18%) in this national cohort of Veterans and was strongly associated with higher early mortality after ESKD onset.

Improving chronic kidney disease detection and treatment in the United States: the chronic kidney disease cascade of care (C3) study protocol.

BACKGROUND: There are major gaps in the implementation of guideline-concordant care for persons with chronic kidney disease (CKD). The CKD Cascade of Care (C3) initiative seeks to improve CKD care by improving detection and treatment of CKD in primary care. METHODS: C3 is a multi-modal initiative deployed in three major academic medical centers within the Department of Veterans Affairs (VA) Health Care System: San Francisco VA, San Diego VA, and Houston VA. The main objective of the first phase of C3 described in this protocol is to establish the infrastructure for universal CKD detection among primary care patients at high-risk for CKD with a triple-marker screen comprising cystatin C, creatinine, and albuminuria. Across the three sites, a comprehensive educational intervention and the integration of primary care-based clinical champions will be employed with the goal of improving CKD detection and treatment. The San Francisco VA will also implement a practice-facilitation intervention leveraging telehealth and health informatics tools and capabilities for enhanced CKD detection. Parallel formative evaluation across the three sites will assess the feasibility and acceptability of integrating cystatin C as part of routine CKD detection in primary care practice. The effectiveness of the interventions will be assessed using a pre-post observational design for change in the proportion of patients tested annually for CKD. Secondary outcomes will assess change in the initiation of cardio-kidney protective therapies and in nephrology referrals of high-risk patients. DISCUSSION: The first phase of C3 is a multi-facility multi-modal initiative that aims to improve CKD care by implementing a triple-marker screen for enhanced CKD detection in primary care.

Heterogeneous Exposure Associations in Observational Cohort Studies: The Example of Blood Pressure in Older Adults.

Heterogeneous exposure associations (HEAs) can be defined as differences in the association of an exposure with an outcome among subgroups that differ by a set of characteristics. In this article, we intend to foster discussion of HEAs in the epidemiologic literature and present a variant of the random forest algorithm that can be used to identify HEAs. We demonstrate the use of this algorithm in the setting of the association between systolic blood pressure and death in older adults. The training set included pooled data from the baseline examination of the Cardiovascular Health Study (1989-1993), the Health, Aging, and Body Composition Study (1997-1998), and the Sacramento Area Latino Study on Aging (1998-1999). The test set included data from the National Health and Nutrition Examination Survey (1999-2002). The hazard ratios ranged from 1.25 (95% confidence interval: 1.13, 1.37) per 10-mm Hg increase in systolic blood pressure among men aged ≤67 years with diastolic blood pressure greater than 80 mm Hg to 1.00 (95% confidence interval: 0.96, 1.03) among women with creatinine concentration ≤0.7 mg/dL and a history of hypertension. HEAs have the potential to improve our understanding of disease mechanisms in diverse populations and guide the design of randomized controlled trials to control exposures in heterogeneous populations.

Results of the CARDIA study suggest that higher dietary potassium may be kidney protective.

The association between dietary sodium and potassium intake with the development of kidney disease remains unclear, particularly among younger individuals. Here, we determined whether dietary sodium and potassium intake are associated with incident chronic kidney disease (CKD) using data from 1,030 adults (age 23-35 in 1990-1991) from the Coronary Artery Risk Development In Young Adults study, based on repeated measurements of estimated glomerular filtration rate (eGFR) and urinary albumin to creatinine ratio (ACR) from 1995 through 2015. Urinary sodium and potassium excretion (mg/day), calculated from three 24-hour urine collections in 1990-1991, were averaged to measure sodium and potassium intake. Serum creatinine was used to calculate eGFR using the CKD EPI equation; spot urine albumin and creatinine were used to calculate ACR, each at five visits from 1995-1996 through 2015-2016. CKD was defined as decreased eGFR (under 60 ml/min/1.73m2) or the development of albuminuria (ACR over 30 mg/g). We used log binomial regression models adjusted for socio-demographic, behavioral, and clinical factors to determine whether sodium and potassium intake were associated with incident CKD (decreased eGFR or developed albuminuria) among those free of CKD in 1995. Dietary sodium intake was not significantly associated with incident CKD. However, every 1,000 mg/day increment of potassium intake in 1990 was significantly associated with a 29% lower risk of incident albuminuria (relative risk 0.71, 95% confidence interval 0.53, 0.95), but not eGFR. Thus, higher dietary potassium intake may protect against the development of kidney damage, particularly albuminuria.

Electronic Decision Support for Management of CKD in Primary Care: A Pragmatic Randomized Trial.

RATIONALE & OBJECTIVE: Most adults with chronic kidney disease (CKD) in the United States are cared for by primary care providers (PCPs). We evaluated the feasibility and preliminary effectiveness of an electronic clinical decision support system (eCDSS) within the electronic health record with or without pharmacist follow-up to improve the management of CKD in primary care. STUDY DESIGN: Pragmatic cluster-randomized trial. SETTING & PARTICIPANTS: 524 adults with confirmed creatinine-based estimated glomerular filtration rates of 30 to 59mL/min/1.73m2 cared for by 80 PCPs at the University of California San Francisco. Electronic health record data were used for patient identification, intervention deployment, and outcomes ascertainment. INTERVENTIONS: Each PCP's eligible patients were randomly assigned as a group into 1 of 3 treatment arms: (1) usual care; (2) eCDSS: testing of creatinine, cystatin C, and urinary albumin-creatinine ratio with individually tailored guidance for PCPs on blood pressure, potassium, and proteinuria management, cardiovascular risk reduction, and patient education; or (3) eCDSS plus pharmacist counseling (eCDSS-PLUS). OUTCOMES: The primary clinical outcome was change in blood pressure over 12 months. Secondary outcomes were PCP awareness of CKD and use of angiotensin-converting enzyme inhibitor/angiotensin receptor blocker and statin therapy. RESULTS: All 80 eligible PCPs participated. Mean patient age was 70 years, 47% were nonwhite, and mean estimated glomerular filtration rate was 56±0.6mL/min/1.73m2. Among patients receiving eCDSS with or without pharmacist counseling (n=336), 178 (53%) completed laboratory measurements and 138 (41%) had laboratory measurements followed by a PCP visit with eCDSS deployment. eCDSS was opened by the PCP for 102 (74%) patients, with at least 1 suggested order signed for 83 of these 102 (81%). Changes in systolic blood pressure were-2.1±1.5mm Hg with usual care, -2.8±1.8mm Hg with eCDSS, and -1.1±1.1 with eCDSS-PLUS (P=0.7). PCP awareness of CKD was 16% with usual care, 26% with eCDSS, and 32% for eCDSS-PLUS (P=0.09). In as-treated analyses, PCP awareness of CKD was significantly greater with eCDSS and eCDSS-PLUS (73% and 69%) versus usual care (47%; P=0.002). LIMITATIONS: Recruitment of smaller than intended sample size and limited uptake of the testing component of the intervention. CONCLUSIONS: Although we were unable to demonstrate the effectiveness of eCDSS to lower blood pressure and uptake of the eCDSS was limited by low testing rates, eCDSS use was high when laboratory measurements were available and was associated with higher PCP awareness of CKD. FUNDING: Grants from government (National Institutes of Health) and not-for-profit (American Heart Association) entities. TRIAL REGISTRATION: Registered at ClinicalTrials.gov with study number NCT02925962.

Chronic Kidney Disease Awareness and Longitudinal Health Outcomes: Results from the REasons for Geographic And Racial Differences in Stroke Study.

BACKGROUND: The majority of people with chronic kidney disease (CKD) are unaware of their kidney disease. Assessing the clinical significance of increasing CKD awareness has critical public health and healthcare delivery implications. Whether CKD awareness among persons with CKD is associated with longitudinal health behaviors, disease management, and health outcomes is unknown. METHODS: We analyzed data from participants with CKD in the REasons for Geographic And Racial Differences in Stroke study, a national, longitudinal, population-based cohort. Our predictor was participant CKD awareness. Outcomes were (1) health behaviors (smoking avoidance, exercise, and nonsteroidal anti-inflammatory drug use); (2) CKD management indicators (angiotensin-converting enzyme inhibitor or angiotensin receptor blocker use, statin use, systolic blood pressure, fasting blood glucose, and body mass index); (3) change in estimated glomerular filtration rate (eGFR) and urine albumin-to-creatinine ratio (UACR); and (4) health outcomes (incident end-stage kidney disease [ESKD], coronary heart disease [CHD], stroke, and death). Logistic and linear regressions were used to examine the association of baseline CKD awareness with outcomes of interest, adjusted for CKD stage and participant demographic and clinical factors. RESULTS: Of 6,529 participants with baseline CKD, 285 (4.4%) were aware of their CKD. Among the 3,586 participants who survived until follow-up (median 9.5 years), baseline awareness was not associated with subsequent odds of health behaviors, CKD management indicators, or changes in eGFR and UACR in adjusted analyses. Baseline CKD awareness was associated with increased risk of ESKD (adjusted hazard ratio [aHR] 1.44; 95% CI 1.08-1.92) and death (aHR 1.18; 95% CI 1.00-1.39), but not with subsequent CHD or stroke, in adjusted models. CONCLUSIONS: Individuals aware of their CKD were more likely to experience ESKD and death, suggesting that CKD awareness reflects disease severity. Most persons with CKD, including those that are high-risk, remain unaware of their CKD. There was no evidence of associations between baseline CKD awareness and longitudinal health behaviors, CKD management indicators, or eGFR decline and albuminuria.

A Virtual Multidisciplinary Care Program for Management of Advanced Chronic Kidney Disease: Matched Cohort Study.

BACKGROUND: It is not well established whether a virtual multidisciplinary care program for persons with advanced chronic kidney disease (CKD) can improve their knowledge about their disease, increase their interest in home dialysis therapies, and result in more planned outpatient (versus inpatient) dialysis starts. OBJECTIVE: We aimed to evaluate the feasibility and preliminary associations of program participation with disease knowledge, home dialysis modality preference, and outpatient dialysis initiation among persons with advanced CKD in a community-based nephrology practice. METHODS: In a matched prospective cohort, we enrolled adults aged 18 to 85 years with at least two estimated glomerular filtration rates (eGFRs) of less than 30 mL/min/1.73 m2 into the Cricket Health program and compared them with controls receiving care at the same clinic, matched on age, gender, eGFR, and presence of heart failure and diabetes. The intervention included online education materials, a virtual multidisciplinary team (nurse, pharmacist, social worker, dietician), and patient mentors. Prespecified follow-up time was nine months with extended follow-up to allow adequate time to determine the dialysis start setting. CKD knowledge and dialysis modality choice were evaluated in a pre-post survey among intervention participants. RESULTS: Thirty-seven participants were matched to 61 controls by age (mean 67.2, SD 10.4 versus mean 68.8, SD 9.5), prevalence of diabetes (54%, 20/37 versus 57%, 35/61), congestive heart failure (22%, 8/37 versus 25%, 15/61), and baseline eGFR (mean 19, SD 6 versus mean 21, SD 5 mL/min/1.73 m2), respectively. At nine-month follow-up, five patients in each group started dialysis (P=.62). Among program participants, 80% (4/5) started dialysis as an outpatient compared with 20% (1/5) of controls (OR 6.28, 95% CI 0.69-57.22). In extended follow-up (median 15.7, range 11.7 to 18.1 months), 19 of 98 patients started dialysis; 80% (8/10) of the intervention group patients started dialysis in the outpatient setting versus 22% (2/9) of control patients (hazard ratio 6.89, 95% CI 1.46-32.66). Compared to before participation, patients who completed the program had higher disease knowledge levels (mean 52%, SD 29% versus mean 94%, SD 14% of questions correct on knowledge-based survey, P<.001) and were more likely to choose a home modality as their first dialysis choice (36%, 7/22 versus 68%, 15/22, P=.047) after program completion. CONCLUSIONS: The Cricket Health program can improve patient knowledge about CKD and increase interest in home dialysis modalities, and may increase the proportion of dialysis starts in the outpatient setting.

APOL1 Kidney Risk Variants and Cardiovascular Disease: An Individual Participant Data Meta-Analysis.

BACKGROUND: Two coding variants in the apo L1 gene (APOL1) are strongly associated with kidney disease in blacks. Kidney disease itself increases the risk of cardiovascular disease, but whether these variants have an independent direct effect on the risk of cardiovascular disease is unclear. Previous studies have had inconsistent results. METHODS: We conducted a two-stage individual participant data meta-analysis to assess the association of APOL1 kidney-risk variants with adjudicated cardiovascular disease events and death, independent of kidney measures. The analysis included 21,305 blacks from eight large cohorts. RESULTS: Over 8.9±5.0 years of follow-up, 2076 incident cardiovascular disease events occurred in the 16,216 participants who did not have cardiovascular disease at study enrollment. In fully-adjusted analyses, individuals possessing two APOL1 kidney-risk variants had similar risk of incident cardiovascular disease (coronary heart disease, myocardial infarction, stroke and heart failure; hazard ratio 1.11, 95% confidence interval, 0.96 to 1.28) compared to individuals with zero or one kidney-risk variant. The risk of coronary heart disease, myocardial infarction, stroke and heart failure considered individually was also comparable by APOL1 genotype. APOL1 genotype was also not associated with death. There was no difference in adjusted associations by level of kidney function, age, diabetes status, or body-mass index. CONCLUSIONS: In this large, two-stage individual participant data meta-analysis, APOL1 kidney-risk variants were not associated with incident cardiovascular disease or death independent of kidney measures.

Neighborhood Social Context and Kidney Function Over Time: The Multi-Ethnic Study of Atherosclerosis.

RATIONALE & OBJECTIVE: Although socioeconomic status has been associated with chronic kidney disease (CKD), little is known about its relationship to residential neighborhood context. STUDY DESIGN: Secondary analysis of the Multi-Ethnic Study of Atherosclerosis (MESA), a prospective cohort study designed to investigate the development and progression of subclinical cardiovascular disease. SETTING & PARTICIPANTS: 6,814 men and women who were between 45 and 84 years of age and free of cardiovascular disease were recruited between 2000 and 2002 from Baltimore, MD; Chicago, IL; Forsyth County, NC; Los Angeles, CA; New York, NY; and St. Paul, MN. EXPOSURES: A composite neighborhood problem score (calculated based on 7 participant-reported domains at study entry: adequacy of food sources, availability of parks/playground, noise, sidewalks, traffic, trash and litter, and violence) and a social cohesion score (calculated based on 5 participant-reported attributes of people in their neighborhood: close knit; get along; willing to help neighbors; trustworthy; and share values). OUTCOMES: Estimated glomerular filtration rate (eGFR; calculated using the CKD-EPI [CKD Epidemiology Collaboration] creatinine-cystatin C equation) and an indicator of eGFR decline > 30% since study entry using follow-up eGFR quantified at 4 examinations: 2000 to 2002, 2004 to 2005, 2005 to 2007, and 2010 to 2011. ANALYTICAL APPROACH: Associations between each neighborhood measure (in separate models) and eGFR decline > 30% from baseline and annualized eGFR change were estimated using Cox proportional hazards and linear mixed regression models, respectively, adjusting for potential confounders. RESULTS: While neighborhood social context differs by race/ethnicity, neither neighborhood problems nor social cohesion was independently associated with eGFR decline after adjustment for confounders. LIMITATIONS: Incomplete capture of the early stages of eGFR decline, reliance on observational data, limited variation in neighborhood measures, and the potential for residual confounding. CONCLUSIONS: Although we showed no independent association between neighborhood context and eGFR decline, it is associated with many CKD risk factors and further work is needed to clarify whether it has an independent role in CKD.

Relationship of Estimated GFR and Albuminuria to Concurrent Laboratory Abnormalities: An Individual Participant Data Meta-analysis in a Global Consortium.

RATIONALE & OBJECTIVE: Chronic kidney disease (CKD) is complicated by abnormalities that reflect disruption in filtration, tubular, and endocrine functions of the kidney. Our aim was to explore the relationship of specific laboratory result abnormalities and hypertension with the estimated glomerular filtration rate (eGFR) and albuminuria CKD staging framework. STUDY DESIGN: Cross-sectional individual participant-level analyses in a global consortium. SETTING & STUDY POPULATIONS: 17 CKD and 38 general population and high-risk cohorts. SELECTION CRITERIA FOR STUDIES: Cohorts in the CKD Prognosis Consortium with data for eGFR and albuminuria, as well as a measurement of hemoglobin, bicarbonate, phosphorus, parathyroid hormone, potassium, or calcium, or hypertension. DATA EXTRACTION: Data were obtained and analyzed between July 2015 and January 2018. ANALYTICAL APPROACH: We modeled the association of eGFR and albuminuria with hemoglobin, bicarbonate, phosphorus, parathyroid hormone, potassium, and calcium values using linear regression and with hypertension and categorical definitions of each abnormality using logistic regression. Results were pooled using random-effects meta-analyses. RESULTS: The CKD cohorts (n=254,666 participants) were 27% women and 10% black, with a mean age of 69 (SD, 12) years. The general population/high-risk cohorts (n=1,758,334) were 50% women and 2% black, with a mean age of 50 (16) years. There was a strong graded association between lower eGFR and all laboratory result abnormalities (ORs ranging from 3.27 [95% CI, 2.68-3.97] to 8.91 [95% CI, 7.22-10.99] comparing eGFRs of 15 to 29 with eGFRs of 45 to 59mL/min/1.73m2), whereas albuminuria had equivocal or weak associations with abnormalities (ORs ranging from 0.77 [95% CI, 0.60-0.99] to 1.92 [95% CI, 1.65-2.24] comparing urinary albumin-creatinine ratio > 300 vs < 30mg/g). LIMITATIONS: Variations in study era, health care delivery system, typical diet, and laboratory assays. CONCLUSIONS: Lower eGFR was strongly associated with higher odds of multiple laboratory result abnormalities. Knowledge of risk associations might help guide management in the heterogeneous group of patients with CKD.

Association of C2, a derivative of the radial artery pressure waveform, with new onset of type 2 diabetes mellitus: the MESA study.

BACKGROUND: Although microvascular dysfunction is known to result from diabetes, it might also lead to diabetes. Lower values of C2, a derivative of the radial artery pressure waveform, indicate microvascular dysfunction and predict hypertension and cardiovascular disease (CVD). We studied the association of C2 with incident diabetes in subjects free of overt CVD. METHODS: Among multi-ethnic participants (n = 5214), aged 45-84 years with no diabetes, C2 was derived from the radial artery pressure waveform. Incident diabetes (N = 651) was diagnosed as new fasting glucose ≥ 126 mg/dL or antidiabetic medicine over ~ 10 years. The relative incidence density (RID) for incident diabetes per standard deviation (SD) of C2 was studied during ~ 10 years follow-up using four levels of adjustment. RESULTS: Mean C2 at baseline was 4.58 ± 2.85 mL/mmHg × 100. The RID for incident diabetes per SD of C2 was 0.90 (95% CI 0.82-0.99, P = 0.03). After adjustment for demographics plus body size, the corresponding RID was 0.81 (95% CI 0.73-0.89, P < 0.0001); body mass index (BMI) was the dominant covariate here. After adjustment for demographics plus cardiovascular risk factors, the RID was 0.98 (95% CI 0.89, 1.07, P = 0.63). After adjustment for all the parameters in the previous models, the RID was 0.87 (95% CI 0.78, 0.96, P = 0.006). CONCLUSIONS: In a multi-ethnic sample free of overt CVD and diabetes at baseline, C2 predicted incident diabetes after adjustment for demographics, BMI and CVD risk factors. Differences in arterial blood pressure wave morphology may indicate a long-term risk trajectory for diabetes, independently of body size and the classical risk factors.

Novel "Predictor Patch" Method for Adding Predictors Using Estimates From Outside Datasets　- A Proof-of-Concept Study Adding Kidney Measures to Cardiovascular Mortality Prediction.

BACKGROUND: Cardiovascular guidelines include risk prediction models for decision making that lack the capacity to include novel predictors.Methods and Results:We explored a new "predictor patch" approach to calibrating the predicted risk from a base model according to 2 components from outside datasets: (1) the difference in observed vs. expected values of novel predictors and (2) the hazard ratios (HRs) for novel predictors, in a scenario of adding kidney measures for cardiovascular mortality. Using 4 US cohorts (n=54,425) we alternately chose 1 as the base dataset and constructed a base prediction model with traditional predictors for cross-validation. In the 3 other "outside" datasets, we developed a linear regression model with traditional predictors for estimating expected values of glomerular filtration rate and albuminuria and obtained their adjusted HRs of cardiovascular mortality, together constituting a "patch" for adding kidney measures to the base model. The base model predicted cardiovascular mortality well in each cohort (c-statistic 0.78-0.91). The addition of kidney measures using a patch significantly improved discrimination (cross-validated ∆c-statistic 0.006 [0.004-0.008]) to a similar degree as refitting these kidney measures in each base dataset. CONCLUSIONS: The addition of kidney measures using our new "predictor patch" approach based on estimates from outside datasets improved cardiovascular mortality prediction based on traditional predictors, providing an option to incorporate novel predictors to an existing prediction model.

Validating laboratory defined chronic kidney disease in the electronic health record for patients in primary care.

BACKGROUND: Electronic health record (EHR) data is increasingly used to identify patients with chronic kidney disease (CKD). EHR queries used to capture CKD status, identify comorbid conditions, measure awareness by providers, and track adherence to guideline-concordant processes of care have not been validated. METHODS: We extracted EHR data for primary-care patients with two eGFRcreat 15-59 mL/min/1.73 m^2 at least 90 days apart. Two nephrologists manually reviewed a random sample of 50 charts to determine CKD status, associated comorbidities, and physician awareness of CKD. We also assessed the documentation of a CKD diagnosis with guideline-driven care. RESULTS: Complete data were available on 1767 patients with query-defined CKD of whom 822 (47%) had a CKD diagnosis in their chart. Manual chart review confirmed the CKD diagnosis in 34 or 50 (68%) patients. Agreement between the reviewers and the EHR diagnoses on the presence of comorbidities was good (κ > 0.70, p < 0.05), except for congestive heart failure, (κ = 0.45, p < 0.05). Reviewers felt the providers were aware of CKD in 23 of 34 (68%) of the confirmed CKD cases. A CKD diagnosis was associated with higher odds of guideline-driven care including CKD-specific laboratory tests and prescriptions for statins. After adjustment, CKD diagnosis documentation was not significantly associated with ACE/ARB prescription. CONCLUSIONS: Identifying CKD status by historical eGFRs overestimates disease prevalence. A CKD diagnosis in the patient chart was a reasonable surrogate for provider awareness of disease status, but CKD awareness remains relatively low. CKD in the patient chart was associated with higher rates of albuminuria testing and use of statins, but not use of ACE/ARB.

APOL1 nephropathy risk variants do not associate with subclinical atherosclerosis or left ventricular mass in middle-aged black adults.

Prior studies reported associations of APOL1 nephropathy risk variants with subclinical atherosclerosis. However, these findings were limited to older individuals with high comorbidities. To evaluate this in younger individuals, we calculated associations of APOL1 risk variants (high risk [2 risk variants] vs. low risk [0-1 risk variant]) with prevalent, incident, or progressive coronary artery calcification, a carotid intima media thickness over the 90th percentile, and left ventricular hypertrophy in 1315 black participants of the Coronary Artery Risk Development in Young Adults (CARDIA) study. The mean age of this cohort was 44.6 years and their mean estimated glomerular filtration rate was 102.5 ml/min/1.73m2. High-risk participants were found to be younger and have a higher prevalence of albuminuria than low-risk participants. In Poisson regression models adjusted for comorbidities and kidney function, the risk of prevalent coronary artery calcification (relative risk [95% confidence interval] 1.12 [0.72,1.71]), the incident coronary artery calcification (1.50 [0.87,2.59]), and the progression of coronary artery calcification (1.40 [0.88,2.23]) did not significantly differ in high vs. low-risk participants. Furthermore, the risk of carotid intima media thickness over the 90th percentile (1.28 [0.78,2.10]) and left ventricular hypertrophy (1.02[0.73,1.43]) did not significantly differ in high vs. low-risk participants in fully-adjusted models. Thus, APOL1 risk variants did not associate with subclinical markers of atherosclerosis or left ventricular hypertrophy in middle-aged black adults with preserved kidney function.

Changes in Blood Pressure During Young Adulthood and Subsequent Kidney Function Decline: Findings From the Coronary Artery Risk Development in Young Adulthood (CARDIA) Study.

BACKGROUND: Many studies have focused on the association between a single blood pressure (BP) measurement and risk for adverse outcomes. However, the association of BP trajectories during young adulthood with subsequent decline in kidney function has not been well defined. STUDY DESIGN: Observational cohort study. SETTING & PARTICIPANTS: 3,429 participants in the Coronary Artery Risk Development in Young Adulthood (CARDIA) Study enrolled between the ages of 18 and 30 years. PREDICTORS: BP slope during the first 10 years of participation in CARDIA, derived from linear mixed models incorporating all repeated BP measures. OUTCOME: Decline in estimated glomerular filtration rate (eGFR) during the interval between years 10 and 20 of CARDIA participation using cystatin C measured at years 10, 15, and 20. RESULTS: Mean age of CARDIA participants at year 0 was 25.1 years, 56% were women, and 53% were white. Every 10-mmHg higher level of systolic (SBP) and diastolic BP (DBP) in year 10 was associated with change in eGFR of -0.09 (95% CI, -0.13 to -0.06) and -0.07 (95% CI, -0.12 to -0.03) mL/min/1.73m2 per year, respectively. Every 10-mmHg increase in SBP slope between years 0 and 10 was associated with a subsequent -0.52 (95% CI, -1.02 to -0.03) mL/min/1.73m2 per year change in kidney function after adjustment for comorbid conditions and SBP at year 10. Similarly, every 10-mmHg increase in DBP slope between years 0 and 10 was associated with a subsequent change in kidney function of -0.65 (95% CI, -1.23 to -0.07) mL/min/1.73m2 per year, after adjustment for comorbid conditions and DBP in year 10. LIMITATIONS: Observational design. CONCLUSIONS: During young adulthood, increasing SBP and DBP are associated with a higher rate of subsequent kidney function decline, independent of BP measured at the beginning of eGFR assessment.

Association of serum albumin levels with kidney function decline and incident chronic kidney disease in elders.

Background: Previous studies in HIV-infected individuals have demonstrated serum albumin to be strongly associated with kidney function decline, independent of urine albumin and inflammatory markers. Lower serum albumin concentrations may be an under-appreciated risk factor for kidney function decline in elders. Methods: We performed a cohort analysis in the Health Aging and Body Composition Study, a cohort of well-functioning, bi-racial, community-dwelling elders between the age of 70 and 79 years. We examined the associations of serum albumin concentration with longitudinal kidney function decline by estimated glomerular filtration rate (eGFR). Outcomes included linear eGFR decline, rapid kidney function decline defined as >30% decrease in eGFR, defined as a final eGFR <60 mL/min/1.73 m2 in those with an eGFR >60 mL/min/1.73 m2 at baseline. Cystatin C-based eGFR was calculated at baseline, Year 3 and Year 10. Results: Mean age was 74 years, and mean eGFR was 73 mL/min/1.73 m2 at baseline. The mean rate of eGFR change was 1.81 mL/min/1.73 m2 per year. After multivariate adjustment, lower serum albumin concentrations were strongly and independently associated with kidney function decline (-0.11 mL/min/1.73 m2 per year for each standard deviation decrease serum albumin; -0.01 to - 0.20) with no attenuation after adjustment for urine albumin and inflammatory markers (-0.12, -0.03 to - 0.22). When divided into quartiles, serum albumin levels ≤3.80 g/dL were associated with increased odds of rapid kidney function decline (odds ratio 1.59; 1.12-2.26) and increased risk of incident chronic kidney disease (incident rate ratio 1.29; 1.03-1.62) relative to levels >4.21g/dL. Urine albumin to creatinine ratio (ACR) was also significantly and independently associated with kidney function decline (-0.08 mL/min/1.73 m2 per year for urine ACR >30 mg/g; -0.82 to - 0.13). Conclusions: Lower serum albumin levels are strongly and independently associated with kidney function decline in elders, independent of clinical risk factors, urine albumin and measured inflammatory markers.

Patterns of blood pressure response during intensive BP lowering and clinical events: results from the secondary prevention of small subcortical strokes trial.

PURPOSE: We applied cluster analysis to identify discrete patterns of concomitant responses of systolic (SBP), diastolic (DBP) and pulse pressure (PP) during intensive BP lowering; and to evaluate their clinical relevance and association with risk of mortality, major vascular events (MVEs), and stroke. MATERIAL AND METHODS: We used an unsupervised cluster procedure to identify distinct patterns of BP change during the first 9 months of anti-hypertensive therapy intensification among 1,331 participants in the Secondary Prevention of Small Subcortical Strokes Trial who were previously randomized to lower BP target (SBP < 130 mm Hg) after lacunar stroke. RESULTS: The cluster procedure partitioned participants into three groups in the lower SBP target arm, persons with: 1) mildly elevated baseline SBP and minimal visit-to-visit BP variability (mild reducers); 2) moderately elevated baseline SBP and moderate visit-to-visit BP variability (moderate reducers); and 3) very elevated baseline SBP with very large visit-to-visit BP variability during intensification (large reducers). In the lower SBP target group, moderate reducers had a higher risk of death (adjusted HR 1.6 [95% CI 1.0-2.7]), MVE (adjusted HR 2.1 [95% CI 1.4-3.2]), and stroke (adjusted HR 2.6[95% CI 1.7-4.1]) compared to mild reducers. Large reducers had the highest risk of death (adjusted HR 2.3 [95% CI 1.2-4.4]), but risk of MVE (HR = 1.7 [95%CI 0.9-3.1]) and stroke (HR = 1.6 [95%CI: 0.8-3.5]) were not statistically significantly different compared to mild reducers. CONCLUSIONS: Among persons with prior lacunar stroke, baseline BP levels, and BP variability in the setting of intensive BP lowering can identify discrete groups of persons at higher risk of adverse outcomes.

Effect of Intensive Versus Usual Blood Pressure Control on Kidney Function Among Individuals With Prior Lacunar Stroke: A Post Hoc Analysis of the Secondary Prevention of Small Subcortical Strokes (SPS3) Randomized Trial.

BACKGROUND: The effect of intensive blood pressure (BP) lowering on kidney function among individuals with established cerebrovascular disease and preserved estimated glomerular filtration rate (eGFR) is not established. METHODS AND RESULTS: Among 2610 participants randomized to a lower (<130 mm Hg) versus higher (130-149 mm Hg) systolic BP target with repeated measures of serum creatinine, we evaluated differences by study arm in annualized eGFR decline and rapid decline (eGFR decline >30%) using linear mixed models and logistic regression, respectively. We assessed associations of both treatment and kidney function decline with stroke, major vascular events, and the composite of stroke, death, major vascular events, or myocardial infarction using multivariable Cox regression, separately and jointly including a test for interaction. Analyses were conducted by treatment arm. Mean age was 63±11 years; 949 participants (36%) were diabetic; and mean eGFR was 80±19 mL·min(-1)·1.73 m(-2). At 9 months, achieved systolic BP was 137±15 versus 127±14 mm Hg in the higher versus lower BP group, and differences were maintained throughout follow-up (mean, 3.2 years). Compared with the higher target, the lower BP target had a -0.50-mL·min(-1)·1.73 m(-2) per year (95% confidence interval [CI], -0.79 to -0.21) faster eGFR decline. Differences were most pronounced during the first year (-2.1 mL·min(-1)·1.73 m(-2); 95% CI, -0.97 to -3.2), whereas rates of eGFR decline did not differ after year 1 (-0.095; 95% CI, -0.47 to 0.23). A total of 313 patients (24%) in the lower BP group had rapid kidney function decline compared with 247 (19%) in the higher BP group (odds ratio, 1.4; 95% CI, 1.1-1.6). Differences in rapid decline by treatment arm were apparent in the first year (odds ratio, 1.4; 95% CI, 1.1-1.8) but were not significant after year 1 (odds ratio, 1.0; 95% CI, 0.73-1.4). Rapid decline was associated with higher risk for stroke, major vascular events, and composite after full adjustment among individuals randomized to the higher BP target (stroke hazard ratio, 1.93; 95% CI, 1.15-3.21) but not the lower BP arm (stroke hazard ratio, 0.93; 95% CI, 0.50-1.75; all P for interaction <0.06). CONCLUSIONS: In patients with prior lacunar stroke and relatively preserved kidney function, intensive BP lowering was associated with a greater likelihood of rapid kidney function decline. Differences were observed primarily during the first year of antihypertensive treatment. Rapid kidney function decline was not associated with increased risk for clinical events among those undergoing intensive BP lowering. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicalTrials.gov. Unique identifier: NCT00059306.

Preventive nephrology in the era of "I" evidence: should we screen for chronic kidney disease?

In this issue, Ferguson and colleagues demonstrate that chronic kidney disease (CKD) screening in populations burdened with CKD may be cost effective. Whether we should screen for CKD, however, continues to be debated despite the availability of effective clinical strategies that mitigate the risks of CKD progression. This study highlights the need for pragmatic trials to test the effectiveness of early CKD detection combined with optimization of clinical management and calls for innovation to tackle CKD.

APOL1 genetic variants are not associated with longitudinal blood pressure in young black adults.

Whether APOL1 polymorphisms contribute to the excess risk of hypertension among blacks is unknown. To assess this we evaluated whether self-reported race and, in blacks, APOL1 risk variants (high-risk [2 risk alleles] versus low-risk [0-1 risk allele]) were associated with longitudinal blood pressure. Blood pressure trajectories were determined using linear mixed-effects (slope) and latent class models (5 distinct groups) during 25 years of follow-up in the Coronary Artery Risk Development in Young Adults Study. Associations of race and APOL1 genotypes with blood pressure change, separately, using linear mixed-effects and multinomial logistic regression models, adjusting for demographic, socioeconomic, and traditional hypertension risk factors, anti-hypertensive medication use, and kidney function were evaluated. Among 1700 whites and 1330 blacks (13% APOL1 high-risk, mean age 25 years; 46% male) mean mid-, ([systolic + diastolic blood pressure]/2), systolic, and diastolic blood pressures were 89, 110, and 69 mm Hg, respectively. One percent of participants used anti-hypertensive medications at baseline. Compared to whites, blacks, regardless of APOL1 genotype, had significantly greater increases in mid-blood pressure and were more likely to experience significantly increasing mid-blood pressure trajectories with adjusted relative risk ratios of 5.21 and 7.27 for moderate-increasing and elevated-increasing versus low-stable blood pressure, respectively. Among blacks, longitudinal mid-blood pressure changes and mid-blood pressure trajectory classification were similar by APOL1 risk status. Modeling systolic and diastolic blood pressure as outcomes yielded similar findings. From young adulthood to mid-life, blacks have greater blood pressure increases versus whites that are not fully explained by traditional risk factors. Thus APOL1 variants are not associated with longitudinal blood pressure in blacks.