Supplementary Material for: Association of U.S. Dialysis Facility Neighborhood Characteristics with Facility-Level Kidney Transplantation

<b><i>Background:</i></b> Improving access to optimal healthcare may depend on the attributes of neighborhoods where patients receive healthcare services. We investigated whether the characteristics of dialysis facility neighborhoods - where most patients with end-stage renal disease are treated - were associated with facility-level kidney transplantation.<b><i> Methods:</i></b> We examined the association between census tract (neighborhood)-level sociodemographic factors and facility-level kidney transplantation rate in 3,983 U.S. dialysis facilities where kidney transplantation rates were high. Number of kidney transplants and total person-years contributed at the facility level in 2007-2010 were obtained from the Dialysis Facility Report and linked to the census tract data on sociodemographic characteristics from the American Community Survey 2006-2010 by dialysis facility location.<b> </b>We used multivariable Poisson models with generalized estimating equations to estimate the link between the neighborhood characteristics and transplant incidence. <b><i>Results:</i></b> Dialysis facilities in the United States were located in neighborhoods with substantially greater proportions of black and poor residents, relative to the national average. Most facility neighborhood characteristics were associated with transplant, with incidence rate ratios (95% CI) for standardized increments (in percentage) of neighborhood exposures of: living in poverty, 0.88 (0.84-0.92), black race, 0.83 (0.78-0.89); high school graduates, 1.22 (1.17-1.26); and unemployed, 0.90 (0.85-0.95). <b><i>Conclusion:</i></b> Dialysis facility neighborhood characteristics may be modestly associated with facility rates of kidney transplantation. The success of dialysis facility interventions to improve access to kidney transplantation may partially depend on reducing neighborhood-level barriers

Supplementary Material for: Oxidative Balance Score and the Risk of End-Stage Renal Disease and Cardiovascular Disease

<p><b><i>Background:</i></b> Oxidative balance score (OBS) is a composite measure of oxidative stress-related exposures. The aim of this study was to investigate the association between OBS, end-stage renal disease (ESRD), and cardiovascular disease (CVD). <b><i>Methods:</i></b> Using data from the Chronic Renal Insufficiency Cohort, we calculated the main exposure OBS by summing up 12 apriori-defined pro- and antioxidant factors obtained from the diet history questionnaire and lifestyle assessment. We divided OBS into quartiles (Q1-Q4), with Q1 (predominance of pro-oxidants) as the reference. We analyzed OBS quartiles as an ordinal variable. Crude and adjusted hazards ratios (HRs) and 95% CIs were estimated using Cox proportional hazards models for time to ESRD and CVD. <b><i>Results:</i></b> Compared to Q1, Q4 (high antioxidant) was associated with ESRD in the crude model (HR 1.35, 95% CI 1.08-1.69) and adjusting for age, sex, and race (HR 1.36, 95% CI 1.09-1.71) but not in the fully adjusted model (HR 1.12, 95% CI 0.84-1.51). HR of ESRD increased as the OBS quartiles increased in the crude model (<i>p</i>_trend < 0.05) but not in the fully adjusted model (<i>p</i>_trend = 0.30). Compared to Q1, Q4 was associated with CVD in the crude (HR 1.33, 95% CI 1.06-1.68) but not adjusted models. The HR of CVD increased with an increase in OBS quartiles in the crude model (<i>p</i>_trend < 0.05). <b><i>Conclusion:</i></b> The reverse association between OBS and progression to ESRD suggests that perhaps the effect of oxidative balance-related exposure is different in the setting of established chronic kidney disease.</p

PowerPoint Slides for: Oxidative Balance Score and the Risk of End-Stage Renal Disease and Cardiovascular Disease

<p><b><i>Background:</i></b> Oxidative balance score (OBS) is a composite measure of oxidative stress-related exposures. The aim of this study was to investigate the association between OBS, end-stage renal disease (ESRD), and cardiovascular disease (CVD). <b><i>Methods:</i></b> Using data from the Chronic Renal Insufficiency Cohort, we calculated the main exposure OBS by summing up 12 apriori-defined pro- and antioxidant factors obtained from the diet history questionnaire and lifestyle assessment. We divided OBS into quartiles (Q1-Q4), with Q1 (predominance of pro-oxidants) as the reference. We analyzed OBS quartiles as an ordinal variable. Crude and adjusted hazards ratios (HRs) and 95% CIs were estimated using Cox proportional hazards models for time to ESRD and CVD. <b><i>Results:</i></b> Compared to Q1, Q4 (high antioxidant) was associated with ESRD in the crude model (HR 1.35, 95% CI 1.08-1.69) and adjusting for age, sex, and race (HR 1.36, 95% CI 1.09-1.71) but not in the fully adjusted model (HR 1.12, 95% CI 0.84-1.51). HR of ESRD increased as the OBS quartiles increased in the crude model (<i>p</i>_trend < 0.05) but not in the fully adjusted model (<i>p</i>_trend = 0.30). Compared to Q1, Q4 was associated with CVD in the crude (HR 1.33, 95% CI 1.06-1.68) but not adjusted models. The HR of CVD increased with an increase in OBS quartiles in the crude model (<i>p</i>_trend < 0.05). <b><i>Conclusion:</i></b> The reverse association between OBS and progression to ESRD suggests that perhaps the effect of oxidative balance-related exposure is different in the setting of established chronic kidney disease.</p

Supplementary Material for: Awareness of the New Kidney Allocation System among United States Dialysis Providers with Low Waitlisting

It is unknown whether dialysis facility staff are aware of the new kidney allocation system implemented in December 2014, which changed how deceased donor kidneys are allocated and waiting time is calculated. U.S. dialysis facilities with low annual waitlisting (<15.2%) were surveyed as part of a large randomized study. Among 653 facilities, 57.9% of staff were aware of the policy change, with medical directors (84.4%) being more aware than social workers (73.3%), facility administrators (53.1%), nurse managers (46.4%), and other staff (43.8%). Targeted education among dialysis facilities with low waitlisting may help extend the reach of the new policy

Supplementary Material for: Race, Mineral Homeostasis and Mortality in Patients with End-Stage Renal Disease on Dialysis

<b><i>Background:</i></b> Abnormalities in mineral homeostasis are ubiquitous in patients on dialysis, and influenced by race. In this study, we determine the race-specific relationship between mineral parameters and mortality in patients initiating hemodialysis. <b><i>Methods:</i></b> We measured the levels of fibroblast growth factor 23 (FGF23) and 25-hydroxyvitamin D (25 D) in 184 African American and 327 non-African American hemodialysis patients who enrolled between 1995 and 1998 in the Choices for Healthy Outcomes in Caring for ESRD Study. Serum calcium, phosphorus, parathyroid hormone (PTH) and total alkaline phosphatase levels were averaged from clinical measurements during the first 4.5 months of dialysis. We evaluated the associated prospective risk of mortality using multivariable Cox proportional hazards models stratified by race. <b><i>Results:</i></b> PTH and total alkaline phosphatase levels were higher, whereas calcium, phosphorus, FGF23 and 25 D levels were lower in African Americans compared to those of non-African Americans. Higher serum phosphorus and FGF23 levels were associated with greater mortality risk overall; however, phosphorus was only associated with risk among African Americans (HR 5.38, 95% CI 2.14-13.55 for quartile 4 vs. 1), but not among non-African Americans (p-interaction = 0.04). FGF23 was associated with mortality in both groups, but more strongly in African Americans (HR 3.91, 95% CI 1.74-8.82 for quartiles 4 vs. 1; p-interaction = 0.09). Serum calcium, PTH, and 25 D levels were not consistently associated with mortality. The lowest and highest quartiles of total alkaline phosphatase were associated with higher mortality risk, but this did not differ by race (p-interaction = 0.97). <b><i>Conclusions:</i></b> Aberrant phosphorus homeostasis, reflected by higher phosphorus and FGF23, may be a risk factor for mortality in patients initiating hemodialysis, particularly among African Americans

Supplementary Material for: Oxidative Balance Score and Chronic Kidney Disease

<br><strong><em>Background:</em></strong> The oxidative balance score (OBS) is a composite estimate of the overall pro- and antioxidant exposure status in an individual. The aim of this study was to determine the association between OBS and renal disease. <b><i>Methods:</i></b> Using the Reasons for Geographic and Racial Differences in Stroke cohort study, OBS was calculated by combining 13 a priori-defined pro- and antioxidant factors by using baseline dietary and lifestyle assessment. OBS was divided into quartiles (Q1-Q4) with the lowest quartile, Q1 (predominance of pro-oxidants), as the reference. Multivariable logistic regression and Cox proportional hazards models were used to estimate adjusted ORs for albuminuria defined as urine albumin/creatinine ratio (ACR) >30 mg/g, macroalbuminuria defined as ACR >300 mg/g and chronic kidney disease (CKD) defined as estimated glomerular filtration rate <60 ml/min/1.73 m² according to the Chronic Kidney Disease Epidemiology Collaboration and hazards ratios for end-stage renal disease (ESRD), respectively. <b><i>Results:</i></b> Of the 19,461 participants analyzed, 12.9% had albuminuria and 10.1% had CKD at baseline; over a median follow-up of 3.5 years (range 2.14-4.32 years), 0.46% developed ESRD. Higher OBS quartiles were associated with lower prevalence of CKD (OR vs. Q1: Q2 = 0.93 [95% CI 0.80-1.08]; Q3 = 0.90 [95% CI 0.77-1.04] and Q4 = 0.79 [95% CI 0.67-0.92], p for trend <0.01). The associations between OBS and albuminuria (p for trend 0.31) and incident ESRD (p for trend 0.56) were not significant in the fully adjusted models. <b><i>Conclusions:</i></b> These findings suggest that higher OBS is associated with lower prevalence of CKD. Lack of association with ESRD incidence in the multivariable analyses indicates that temporal relation between OBS and renal damage remains unclear