Effect of Neighborhood Food Environment and Socioeconomic Status on Serum Phosphorus Level for Patients on Chronic Dialysis.

BACKGROUND: Elevated blood phosphorus levels are common and associated with a greater risk of death for patients receiving chronic dialysis. Phosphorus-rich foods are prevalent in the American diet, and low-phosphorus foods, including fruits and vegetables, are often less available in areas with more poverty. The relative contributions of neighborhood food availability and socioeconomic status to phosphorus control in patients receiving dialysis are unknown. METHODS: Using longitudinal data from a national dialysis provider, we constructed hierarchical, linear mixed-effects models to evaluate the relationships between neighborhood food environment or socioeconomic status and serum phosphorus level among patients receiving incident dialysis. RESULTS: Our cohort included 258,510 patients receiving chronic hemodialysis in 2005-2013. Median age at dialysis initiation was 64 years, 45% were female, 32% were Black, and 15% were Hispanic. Within their residential zip code, patients had a median of 25 "less-healthy" food outlets (interquartile range, 11-40) available to them compared with a median of four "healthy" food outlets (interquartile range, 2-6). Living in a neighborhood with better availability of healthy food was not associated with a lower phosphorus level. Neighborhood income also was not associated with differences in phosphorus. Patient age, race, cause of ESKD, and mean monthly dialysis duration were most closely associated with phosphorus level. CONCLUSIONS: Neither neighborhood availability of healthy food options nor neighborhood income was associated with phosphorus levels in patients receiving chronic dialysis. Modifying factors, such as nutrition literacy, individual-level financial resources, and adherence to diet restrictions and medications, may be more powerful contributors than food environment to elevated phosphorus.

Use of Dietary Supplements in Living Kidney Donors: A Critical Review.

Dietary supplement use is high among US adults, with the intention by users to promote overall health and wellness. Kidney donors, who are selected based on their overall good health and wellness, can have high utilization rates of dietary supplements. We provide a framework for the evaluation of living kidney donors and use of dietary supplements. In this review, dietary supplements will include any orally administered dietary or complementary nutritional products, but excluding micronutrients (vitamins and minerals), food, and cannabis. Use of dietary supplements can influence metabolic parameters that mask future risk for chronic illness such as diabetes and hypertension. Dietary supplements can also alter bleeding risk, anesthesia and analgesic efficacy, and safety in a perioperative period. Finally, postdonation monitoring of kidney function and risk for supplement-related nephrotoxicity should be part of a kidney donor educational process. For practitioners evaluating a potential kidney donor, we provide a list of the most commonly used herbal supplements and the effects on evaluation in a predonation, perioperative donation, and postoperative donation phase. Finally, we provide recommendations for best practices for integration into a comprehensive care plan for kidney donors during all stages of evaluation. We recommend avoidance of dietary supplements in a kidney donor population, although there is a paucity of data that identifies true harm. Rather, associations, known mechanisms of action, and common sense suggest that we avoid use in this population.

A Pilot Randomized Trial of Financial Incentives or Coaching to Lower Serum Phosphorus in Dialysis Patients.

OBJECTIVE: Among chronic hemodialysis patients, hyperphosphatemia is common and associated with mortality. Behavioral economics and complementary behavior-change theories may offer valuable approaches to achieving phosphorus (PO4) control. The aim was to determine feasibility of implementing financial incentives and structured coaching to improve PO4 in the hemodialysis setting. DESIGN AND METHODS: This pilot randomized controlled trial was conducted in 3 urban dialysis units for 10 weeks among 36 adults with elevated serum PO4 (median >5.5 mg/dL over 3 months). INTERVENTIONS: Twelve participants each were randomized to: (1) financial incentives for lowering PO4, (2) coaching about dietary and medication adherence, or (3) usual care. PO4 was measured during routine clinic operations. Each incentives arm participant received the equivalent of $1.50/day if the PO4 was ≤5.5 mg/dL or >5.5 mg/dL but decreased ≥0.5 mg/dL since the prior measurement. The coach was instructed to contact coaching arm participants at least 3 times per week. MAIN OUTCOME MEASURES: The outcome measures included: (1) enrollment rate, (2) dropout rate, and (3) change in PO4 from beginning to end of 10-week intervention period. RESULTS: Of 66 eligible patients, 36 (55%) enrolled. Median age was 53 years, 83% were black race, and 78% were male. Median baseline PO4 was 6.0 (interquartile range 5.6, 7.5). Using stratified generalized estimation equation analyses, the monthly decline in PO4 was -0.32 mg/dL (95% CI -0.60, -0.04) in the incentives arm, -0.40 mg/dL (-0.60, -0.20) in the coaching arm, and -0.24 mg/dL (-0.60, 0.08) in the usual care arm. No patients dropped out. All intervention arm participants expressed interest in receiving similar support in the future. CONCLUSIONS: This pilot trial demonstrated good feasibility in enrollment and implementation of novel behavioral health strategies to reduce PO4 in dialysis patients.

Increasing use of vitamin D supplementation in the chronic renal insufficiency cohort study.

OBJECTIVE: This study examined rates and determinants of vitamin D supplementation among Chronic Renal Insufficiency Cohort (CRIC) participants and determined the association between dose and 25-hydroxyvitamin D (25(OH)D) level. The 2010 Institute of Medicine Report noted a significant increase in vitamin D supplementation in the general population, but use in chronic kidney disease (CKD) is unknown. METHODS: CRIC is a multicenter prospective observational cohort study of 3,939 participants with a median baseline age of 60 and an estimated glomerular filtration rate (eGFR) of 42.1 mL/minute per 1.73 m2. Of the cohort, 54.9% was male, 42.1% were Black, and 48.4% were diabetic. Multivariable logistic generalized estimating equations were used to examine determinants of supplementation use assessed annually between 2003 and 2011. Cross-sectional linear regression models, based on a subset of 1,155 participants, assessed associations between supplement dose and 25(OH)D level, measured by high-performance liquid chromatography coupled with tandem mass spectrometry. RESULTS: The proportion of participants reporting supplement use increased (P < .0001), from 10% at baseline to 44% at 7-year follow-up visits. This was largely due to initiation of products containing only ergocalciferol or cholecalciferol. The odds of supplementation were greater in older, female, non-Black, married participants with greater education and lower body mass index. Among participants taking supplementation, dose was positively associated with 25(OH)D level, adjusted for race, season, diabetes, dietary intake, eGFR, and proteinuria. Only 3.8% of non-Black and 16.5% of Black participants taking a supplement were deficient (<20 ng/mL), whereas 22.7% of non-Black and 62.4% of black participants not reporting supplement use were deficient. CONCLUSIONS: Vitamin D supplementation rates rose significantly among CRIC participants over 7 years of follow-up and were associated with greater serum 25(OH)D levels. Studies of vitamin D levels on clinical outcomes in CKD and future vitamin D interventional studies should consider these changes in supplementation practices.