Major cardiovascular events and subsequent risk of kidney failure with replacement therapy: a CKD Prognosis Consortium study.

AIMS: Chronic kidney disease (CKD) increases risk of cardiovascular disease (CVD). Less is known about how CVD associates with future risk of kidney failure with replacement therapy (KFRT). METHODS AND RESULTS: The study included 25 903 761 individuals from the CKD Prognosis Consortium with known baseline estimated glomerular filtration rate (eGFR) and evaluated the impact of prevalent and incident coronary heart disease (CHD), stroke, heart failure (HF), and atrial fibrillation (AF) events as time-varying exposures on KFRT outcomes. Mean age was 53 (standard deviation 17) years and mean eGFR was 89 mL/min/1.73 m2, 15% had diabetes and 8.4% had urinary albumin-to-creatinine ratio (ACR) available (median 13 mg/g); 9.5% had prevalent CHD, 3.2% prior stroke, 3.3% HF, and 4.4% prior AF. During follow-up, there were 269 142 CHD, 311 021 stroke, 712 556 HF, and 605 596 AF incident events and 101 044 (0.4%) patients experienced KFRT. Both prevalent and incident CVD were associated with subsequent KFRT with adjusted hazard ratios (HRs) of 3.1 [95% confidence interval (CI): 2.9-3.3], 2.0 (1.9-2.1), 4.5 (4.2-4.9), 2.8 (2.7-3.1) after incident CHD, stroke, HF and AF, respectively. HRs were highest in first 3 months post-CVD incidence declining to baseline after 3 years. Incident HF hospitalizations showed the strongest association with KFRT [HR 46 (95% CI: 43-50) within 3 months] after adjustment for other CVD subtype incidence. CONCLUSION: Incident CVD events strongly and independently associate with future KFRT risk, most notably after HF, then CHD, stroke, and AF. Optimal strategies for addressing the dramatic risk of KFRT following CVD events are needed.

Glucose-Lowering Agents and the Risk of Hypoglycemia: a Real-world Study.

BACKGROUND: Sodium-glucose cotransporter-2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP1RA) are increasingly recommended in type 2 diabetes. Hypoglycemia is a serious adverse effect of glucose-lowering agents. Real-world comparison of hypoglycemic risks among SGLT2i, GLP1RA, dipeptidyl peptidase-4 inhibitor (DPP4i), and sulfonylureas is limited. OBJECTIVE: Quantify the risk of hypoglycemia associated with SGLT2i, GLP1RA, DPP4i, and sulfonylureas (the primary reference group). DESIGN: Retrospective cohort study conducted using electronic health records from Geisinger Health, Pennsylvania (2015-2019). PARTICIPANTS: A total of 10,713 patients with type 2 diabetes who newly received SGLT2i (n=1487), GLP1RA (n=1241), DPP4i (n=2938), or sulfonylureas (n=5047). Propensity score-based inverse probability of treatment weighting was used to balance patient characteristics across four treatment groups simultaneously. MAIN MEASURES: Hypoglycemia was defined as capillary blood glucose <70 mg/dL; severe hypoglycemia was defined as capillary blood glucose <54 mg/dL. A weighted Cox proportional hazards regression model was used to estimate the risk of outcomes for pairwise comparisons of SGTL2i, GLP1RA, DPP4i, and sulfonylureas. KEY RESULTS: Median follow-up was 21.3 months. Compared with sulfonylureas, the risk of hypoglycemia was lower with SGLT2i (hazard ratio 0.60 [95% confidence interval 0.48-0.75]), GLP1RA (0.49 [0.34-0.69]), and DPP4i (0.60 [0.48-0.78]). The risk of severe hypoglycemia was also lower with SGLT2i (0.43 [0.35-0.74]), GLP1RA (0.50 [0.28-0.87]), and DPP4i (0.64 [0.46-0.90]) compared to sulfonylureas. The risks of hypoglycemia and severe hypoglycemia were similar across the SGLT2i, GLP1RA, and DPP4i groups (SGLT2i vs. DPP4i: 0.95 [0.67-1.34]; GLP1RA vs. DPP4i: 0.81 [0.55-1.19]; SGLT2i vs. GLP1RA: 1.17 [0.76-1.82] for hypoglycemia). CONCLUSION: SGLT2i and GLP1RA confer a lower risk of hypoglycemia compared with sulfonylureas and similar risk compared with DPP4i. Given the known cardiovascular benefits associated with SGLT2i and GL1PRA, our results suggesting the safety of SGLT2i and GL1PRA further support their use.

Are Digital Health Technologies and Models of Nutrition Care the Future of Chronic Kidney Disease Management?

People living with chronic kidney disease (CKD) require long-term support at varying levels of individualization, intensity, and frequency. Mobile and digital models of nutrition care can facilitate long-term behavior change, address nutrition issues proactively, reduce travel burden, and reach people without access to health care more easily. However, while traditional health delivery continues to be digitally disrupted, there are many barriers to address before mobile and digitally supported models of nutrition care can become business as usual in nephrology and nutrition care practice. This paper overviews the current evidence base concerning the past and present mobile and digital health programs to improve nutrition in CKD and highlights the novel future trends in this field. The way nutrition and dietetic care can be feasible, safe, and potentially effective when delivered using various digital and virtual technologies, including consultations, assessments, establishment of diagnoses, formulation of plans, and monitoring/reviewing clinical progress is discussed. Of the available evidence to date, these modalities appear to improve dietary sodium intake and diet quality, self-efficacy, interdialytic weight gain, and body weight. Many barriers exist to sustaining the continued and widespread adoption of digital and mobile health-supported nutrition care in CKD. These include patient-, clinician-, and health system-specific and are discussed in detail. Mobile and digital-supported models of nutrition care present an exciting opportunity to assist kidney dietitians deliver patient-centred nutrition care in CKD.

Association of Rosuvastatin Use with Risk of Hematuria and Proteinuria.

BACKGROUND: Despite reports of hematuria and proteinuria with rosuvastatin use at the time of its approval by the US Food and Drug Association (FDA), little postmarketing surveillance exists to assess real-world risk. Current labeling suggests dose reduction (maximum daily dose of 10 mg) for patients with severe CKD. METHODS: Using deidentified electronic health record data, we analyzed 152,101 and 795,799 new users of rosuvastatin and atorvastatin, respectively, from 2011 to 2019. We estimated inverse probability of treatment-weighted hazard ratios (HRs) of hematuria, proteinuria, and kidney failure with replacement therapy (KFRT) associated with rosuvastatin. We reported the initial rosuvastatin dose across eGFR categories and evaluated for a dose effect on hematuria and proteinuria. RESULTS: Overall, we identified 2.9% of patients with hematuria and 1.0% with proteinuria during a median follow-up of 3.1 years. Compared with atorvastatin, rosuvastatin was associated with increased risk of hematuria (HR, 1.08; 95% confidence interval [95% CI], 1.04 to 1.11), proteinuria (HR, 1.17; 95% CI, 1.10 to 1.25), and KFRT (HR, 1.15; 95% CI, 1.02 to 1.30). A substantial share (44%) of patients with eGFR <30 ml/min per 1.73 m2 was prescribed high-dose rosuvastatin (20 or 40 mg daily). Risk was higher with higher rosuvastatin dose. CONCLUSIONS: Compared with atorvastatin, rosuvastatin was associated with increased risk of hematuria, proteinuria, and KFRT. Among patients with eGFR <30 ml/min per 1.73 m2, 44% were prescribed a rosuvastatin daily dose exceeding the FDA's recommended 10 mg daily dose. Our findings suggest the need for greater care in prescribing and monitoring rosuvastatin, particularly in patients who receive high doses or who have severe CKD.

Effect of age and rural residency on perceptions about SARS-CoV-2 pandemic and vaccination in kidney transplant recipients.

BACKGROUND: Transplant patients have poor outcomes in coronavirus-disease 2019 (COVID-19). The pandemic's effects on rural patients' overall care experience, attitudes to telemedicine, and vaccination are poorly understood. METHODS: We administered a cross-sectional survey to adult kidney transplant recipients in central Pennsylvania across four clinical sites between March 29, 2021 and June 2, 2021. We assessed the pandemic's impact on care access, telemedicine experience, attitudes toward preventive measures, vaccination, and variation by sociodemographic variables. RESULTS: Survey completion rate was 51% (303/594). Of these, 52.8% were rural residents. The most common impact was use of telemedicine (79.2%). Predominant barriers to telemedicine were lack of video devices (10.9%), perceived complexity (5.6%), and technical issues (5.3%). On a 0-10 Likert scale, the mean positive impression for telemedicine was 7.7; lower for patients with telephone-only versus video visits (7.0 vs. 8.2; p < .001), and age ≥60 years (7.4 vs. 8.1; p = .01) on univariate analyses. Time/travel savings were commonly identified (115/241, 47.7%) best parts of telemedicine and lack of personal connection (70/166, 42.2%) the worst. Only 68.9% had received any dose of COVID vaccination. The vaccinated group members were older (58.4 vs. 53.5 years; p = .007), and less likely rural (47.8% vs. 65.2%; p = .005). Common themes associated with vaccine hesitancy included concerns about safety (27/59, 46%), perceived lack of data (19/59, 32%), and distrust (17/59, 29%). At least one misconception about the vaccines or COVID-19 was quoted by 29% of vaccine-hesitant patients. CONCLUSIONS: Among respondents, the pandemic significantly impacted healthcare experience, especially in older patients in underserved communities. COVID-19 vaccination rate was relatively low, driven by misconceptions and lack of trust.

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.

Strategies to Treat Obesity in Patients With CKD.

Obesity prevalence continues to increase worldwide, accompanied by a rising tide of hypertension, diabetes, and chronic kidney disease (CKD). Although body mass index is typically used to assess obesity in clinical practice, altered body composition (eg, reduced muscle mass and increased visceral adiposity) are common among patients with CKD. Weight loss achieved through behavioral modification or medications reduces albuminuria and in some cases slows the decline in estimated glomerular filtration rate. Use of medications that promote weight loss with favorable cardiovascular risk profiles should be promoted, particularly in patients with type 2 diabetes, obesity, and CKD. For those who fail to achieve weight loss through lifestyle modification, bariatric surgery should be considered because observational studies have shown reductions in risk for estimated glomerular filtration rate decline and kidney failure. Uncertainty persists on the risk to benefit ratio of intentional weight loss in patients with kidney failure due to the lack of prospective trials and limitations of observational data. Regardless, sleeve gastrectomy is increasingly being used for patients with kidney failure and severe obesity, with success in achieving sustained weight loss, improved access to kidney transplantation, and favorable posttransplantation outcomes. More research is needed assessing long-term cardiovascular and kidney outcomes of most weight loss medications.

Conversion of Urine Protein-Creatinine Ratio or Urine Dipstick Protein to Urine Albumin-Creatinine Ratio for Use in Chronic Kidney Disease Screening and Prognosis : An Individual Participant-Based Meta-analysis.

BACKGROUND: Although measuring albuminuria is the preferred method for defining and staging chronic kidney disease (CKD), total urine protein or dipstick protein is often measured instead. OBJECTIVE: To develop equations for converting urine protein-creatinine ratio (PCR) and dipstick protein to urine albumin-creatinine ratio (ACR) and to test their diagnostic accuracy in CKD screening and staging. DESIGN: Individual participant-based meta-analysis. SETTING: 12 research and 21 clinical cohorts. PARTICIPANTS: 919 383 adults with same-day measures of ACR and PCR or dipstick protein. MEASUREMENTS: Equations to convert urine PCR and dipstick protein to ACR were developed and tested for purposes of CKD screening (ACR ≥30 mg/g) and staging (stage A2: ACR of 30 to 299 mg/g; stage A3: ACR ≥300 mg/g). RESULTS: Median ACR was 14 mg/g (25th to 75th percentile of cohorts, 5 to 25 mg/g). The association between PCR and ACR was inconsistent for PCR values less than 50 mg/g. For higher PCR values, the PCR conversion equations demonstrated moderate sensitivity (91%, 75%, and 87%) and specificity (87%, 89%, and 98%) for screening (ACR >30 mg/g) and classification into stages A2 and A3, respectively. Urine dipstick categories of trace or greater, trace to +, and ++ for screening for ACR values greater than 30 mg/g and classification into stages A2 and A3, respectively, had moderate sensitivity (62%, 36%, and 78%) and high specificity (88%, 88%, and 98%). For individual risk prediction, the estimated 2-year 4-variable kidney failure risk equation using predicted ACR from PCR had discrimination similar to that of using observed ACR. LIMITATION: Diverse methods of ACR and PCR quantification were used; measurements were not always performed in the same urine sample. CONCLUSION: Urine ACR is the preferred measure of albuminuria; however, if ACR is not available, predicted ACR from PCR or urine dipstick protein may help in CKD screening, staging, and prognosis. PRIMARY FUNDING SOURCE: National Institute of Diabetes and Digestive and Kidney Diseases and National Kidney Foundation.

The FDA Metformin Label Change and Racial and Sex Disparities in Metformin Prescription among Patients with CKD.

BACKGROUND: In 2016, the Food and Drug Administration (FDA) changed labeling regarding metformin contraindications in patients with diabetes and CKD from using serum creatinine-based thresholds to using eGFR-based thresholds. Because race and sex affect serum creatinine levels independently of GFR, the earlier creatinine-based contraindication may have inadvertently caused racial and sex disparities in metformin prescription among patients with low eGFR. METHODS: In an analysis of 15,946 Black and White primary care patients with diabetes and eGFR≥30 ml/min per 1.73 m2 in a large health system (the primary cohort), we assessed the association of race and sex with metformin prescription across eGFR level before and after the FDA label change. For a replication cohort, we meta-analyzed data from 36 cohorts with 1,051,723 patients from OptumLabs Data Warehouse. RESULTS: In the primary cohort, before the label change, Black patients with eGFR of 30-44 ml/min per 1.73 m2 were prescribed metformin less often than White counterparts (adjusted prevalence ratio [aPR], 0.65; 95% confidence interval [95% CI], 0.52 to 0.82); this disparity was significantly attenuated after the label change (aPR, 0.90; 95% CI, 0.74 to 1.09; P value for interaction by period =0.04). Results were consistent in the replication cohorts. Men with eGFR of 30-44 ml/min per 1.73 m2 received metformin prescriptions less often than women counterparts before the label change; this was nonsignificantly attenuated after the label change, but we found significant attenuation in the replication cohorts (aPRpre-label change, 0.76; 95% CI, 0.73 to 0.79; aPRpost-label change, 0.85; 95% CI, 0.83 to 0.88; P value for interaction by period <0.001). CONCLUSIONS: The metformin label change to an eGFR-based contraindication may have reduced racial and sex disparities in metformin prescription in moderate kidney dysfunction.

Remote Dietary Counseling Using Smartphone Applications in Patients With Stages 1-3a Chronic Kidney Disease: A Mixed Methods Feasibility Study.

OBJECTIVE(S): Although healthy dietary patterns are associated with decreased mortality in patients with chronic kidney disease (CKD), few patients receive dietitian counseling due to concerns such as dietitian availability, travel distance, and cost. Our objective was to determine the feasibility of dietary smartphone application-supported telecounseling to reduce sodium intake and improve dietary quality in patients with early CKD. METHODS: This was a pre-post, mixed methods feasibility study of 16 patients with Stage 1-3a CKD in central/northeast Pennsylvania. Patients recorded and shared dietary data via smartphone applications with registered dietitians, who used motivational interviewing to provide telephone counseling weekly for 8 weeks. Seven patients were assigned to a customized study-specific application and nine patients to a commercially available, free application (MyFitnessPal). Participant satisfaction was assessed via survey, and participants were invited to complete a semistructured interview. Outcomes assessed included sodium intake, Healthy Eating Index 2015 score, weight, and 24-hour blood pressure (BP). RESULTS: Mean age was 64.7 years, 31% were female, 100% were white, 13% had income <$25,000. Adherence was excellent with 14 (88%) entering dietary data at least 75% of total days. Patients reported high satisfaction with the intervention and dietitian telecounseling. Use of dietary apps was viewed positively for allowing tracking of sodium and energy intake although some participants experienced functionality issues with the customized application that were not generally experienced by those using the commercially available free application. Sodium intake (-604 mg/day, 95% confidence interval [CI]: -1,104 to -104), Healthy Eating Index 2015 score (3.97, 95% CI: 0.03-7.91), weight (-3.4, 95% CI: -6.6 to -0.1), daytime systolic BP (-5.8, 95% CI: -12.1 to 0.6), and daytime diastolic BP (-4.1, 95% CI: -7.9 to -0.2) improved after the intervention. CONCLUSIONS: An application-supported telecounseling program with a registered dietitian appears to be a feasible and well-accepted strategy to improve dietary quality and improve cardiovascular risk factors in patients with early kidney disease.

ALG9 Mutation Carriers Develop Kidney and Liver Cysts.

BACKGROUND: Mutations in PKD1 or PKD2 cause typical autosomal dominant polycystic kidney disease (ADPKD), the most common monogenic kidney disease. Dominantly inherited polycystic kidney and liver diseases on the ADPKD spectrum are also caused by mutations in at least six other genes required for protein biogenesis in the endoplasmic reticulum, the loss of which results in defective production of the PKD1 gene product, the membrane protein polycystin-1 (PC1). METHODS: We used whole-exome sequencing in a cohort of 122 patients with genetically unresolved clinical diagnosis of ADPKD or polycystic liver disease to identify a candidate gene, ALG9, and in vitro cell-based assays of PC1 protein maturation to functionally validate it. For further validation, we identified carriers of ALG9 loss-of-function mutations and noncarrier matched controls in a large exome-sequenced population-based cohort and evaluated the occurrence of polycystic phenotypes in both groups. RESULTS: Two patients in the clinically defined cohort had rare loss-of-function variants in ALG9, which encodes a protein required for addition of specific mannose molecules to the assembling N-glycan precursors in the endoplasmic reticulum lumen. In vitro assays showed that inactivation of Alg9 results in impaired maturation and defective glycosylation of PC1. Seven of the eight (88%) cases selected from the population-based cohort based on ALG9 mutation carrier state who had abdominal imaging after age 50; seven (88%) had at least four kidney cysts, compared with none in matched controls without ALG9 mutations. CONCLUSIONS: ALG9 is a novel disease gene in the genetically heterogeneous ADPKD spectrum. This study supports the utility of phenotype characterization in genetically-defined cohorts to validate novel disease genes, and provide much-needed genotype-phenotype correlations.

Evaluating Glomerular Filtration Rate Slope as a Surrogate End Point for ESKD in Clinical Trials: An Individual Participant Meta-Analysis of Observational Data.

BACKGROUND: Decline in eGFR is a biologically plausible surrogate end point for the progression of CKD in clinical trials. However, it must first be tested to ensure strong associations with clinical outcomes in diverse populations, including patients with higher eGFR. METHODS: To investigate the association between 1-, 2-, and 3-year changes in eGFR (slope) with clinical outcomes over the long term, we conducted a random effects meta-analysis of 3,758,551 participants with baseline eGFR≥60 ml/min per 1.73 m2 and 122,664 participants with eGFR<60 ml/min per 1.73 m2 from 14 cohorts followed for an average of 4.2 years. RESULTS: Slower eGFR decline by 0.75 ml/min per 1.73 m2 per year over 2 years was associated with lower risk of ESKD in participants with baseline eGFR≥60 ml/min per 1.73 m2 (adjusted hazard ratio, 0.70; 95% CI, 0.68 to 0.72) and eGFR<60 ml/min per 1.73 m2 (0.71; 95% CI, 0.68 to 0.74). The relationship was stronger with 3-year slope. For a rapidly progressing population with predicted 5-year risk of ESKD of 8.3%, an intervention that reduced eGFR decline by 0.75 ml/min per 1.73 m2 per year over 2 years would reduce the ESKD risk by 1.6%. For a hypothetical low-risk population with a predicted 5-year ESKD risk of 0.58%, the same intervention would reduce the risk by only 0.13%. CONCLUSIONS: Slower decline in eGFR was associated with lower risk of subsequent ESKD, even in participants with eGFR≥60 ml/min per 1.73 m2, but those with the highest risk would be expected to benefit the most.

Kidney-Failure Risk Projection for the Living Kidney-Donor Candidate.

BACKGROUND: Evaluation of candidates to serve as living kidney donors relies on screening for individual risk factors for end-stage renal disease (ESRD). To support an empirical approach to donor selection, we developed a tool that simultaneously incorporates multiple health characteristics to estimate a person's probable long-term risk of ESRD if that person does not donate a kidney. METHODS: We used risk associations from a meta-analysis of seven general population cohorts, calibrated to the population-level incidence of ESRD and mortality in the United States, to project the estimated long-term incidence of ESRD among persons who do not donate a kidney, according to 10 demographic and health characteristics. We then compared 15-year projections with the observed risk among 52,998 living kidney donors in the United States. RESULTS: A total of 4,933,314 participants from seven cohorts were followed for a median of 4 to 16 years. For a 40-year-old person with health characteristics that were similar to those of age-matched kidney donors, the 15-year projections of the risk of ESRD in the absence of donation varied according to race and sex; the risk was 0.24% among black men, 0.15% among black women, 0.06% among white men, and 0.04% among white women. Risk projections were higher in the presence of a lower estimated glomerular filtration rate, higher albuminuria, hypertension, current or former smoking, diabetes, and obesity. In the model-based lifetime projections, the risk of ESRD was highest among persons in the youngest age group, particularly among young blacks. The 15-year observed risks after donation among kidney donors in the United States were 3.5 to 5.3 times as high as the projected risks in the absence of donation. CONCLUSIONS: Multiple demographic and health characteristics may be used together to estimate the projected long-term risk of ESRD among living kidney-donor candidates and to inform acceptance criteria for kidney donors. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and others.).

Improving proteinuria screening with mailed smartphone urinalysis testing in previously unscreened patients with hypertension: a randomized controlled trial.

BACKGROUND: Proteinuria screening is recommended for patients with hypertension to screen for kidney disease and identify those at elevated risk for cardiovascular disease. However, screening rates among hypertensive patients are low. Home testing strategies may be useful in improving proteinuria screening adherence. METHODS: We conducted an individual-level, randomized trial at 55 primary care clinic sites in the Geisinger Health System to evaluate the effectiveness of a strategy using home smartphone urinalysis test (Dip.io) to complete proteinuria screening in previously unscreened non-diabetic patient portal users with hypertension. All patients received an educational letter and a standing urinalysis lab order, and then were randomized to control (usual care) or intervention. Intervention arm participants were invited to complete proteinuria screening with a mailed home smartphone urinalysis test. Co-primary outcomes were completion of proteinuria screening and number of albuminuria cases (albumin/creatinine ratio [ACR] ≥ 30 mg/g or protein/creatinine ratio ≥ 150 mg/g) at the end of 3 months. We also evaluated patient satisfaction with the home test, and compliance with recommendations for patients with newly detected albuminuria. RESULTS: A total of 999 patients were randomized to intervention or control. Out of 499 patients assigned to the intervention arm, 253 were reached by phone, and 69/97 (71.1%) consented patients completed the home test. Overall, the intervention increased proteinuria screening completion (28.9% vs. 18.0%; p < 0.001) with no effect on the number of albuminuria cases (4 vs. 4) although only 6/57 (10.5%) patients with trace or 1+ urine dipstick protein had a follow-up quantitative test. Among the 55 patients who completed a survey after the home test, 89% preferred testing at home rather than the physician's office. CONCLUSIONS: A strategy using a home urinalysis smartphone test increased proteinuria screening rates in previously unscreened patients with hypertension and may be useful in increasing rates of proteinuria screening compliance. Future studies should evaluate use of home testing kits to screen for and confirm albuminuria, and determine whether improving early detection of kidney disease can improve future kidney health. TRIAL REGISTRATION: Clinical Trial Registry: NCT03470701 (First posted 3/20/2018) https://clinicaltrials.gov/ct2/show/NCT03470701 . This study was retrospectively registered.

Dietary Phosphorus Intake and the Kidney.

Although phosphorus is an essential nutrient required for multiple physiological functions, recent research raises concerns that high phosphorus intake could have detrimental effects on health. Phosphorus is abundant in the food supply of developed countries, occurring naturally in protein-rich foods and as an additive in processed foods. High phosphorus intake can cause vascular and renal calcification, renal tubular injury, and premature death in multiple animal models. Small studies in human suggest that high phosphorus intake may result in positive phosphorus balance and correlate with renal calcification and albuminuria. Although serum phosphorus is strongly associated with cardiovascular disease, progression of kidney disease, and death, limited data exist linking high phosphorus intake directly to adverse clinical outcomes. Further prospective studies are needed to determine whether phosphorus intake is a modifiable risk factor for kidney disease.

Higher net acid excretion is associated with a lower risk of kidney disease progression in patients with diabetes.

Higher diet-dependent nonvolatile acid load is associated with faster chronic kidney disease (CKD) progression, but most studies have used estimated acid load or measured only components of the gold standard, net acid excretion (NAE). Here we measured NAE as the sum of urine ammonium and titratable acidity in 24-hour urines from a random subset of 980 participants in the Chronic Renal Insufficiency Cohort (CRIC) Study. In multivariable models accounting for demographics, comorbidity and kidney function, higher NAE was significantly associated with lower serum bicarbonate (0.17 mEq/l lower serum bicarbonate per 10 mEq/day higher NAE), consistent with a larger acid load. Over a median of 6 years of follow-up, higher NAE was independently associated with a significantly lower risk of the composite of end-stage renal disease or halving of estimated glomerular filtration rate among diabetics (hazard ratio 0.88 per 10 mEq/day higher NAE), but not those without diabetes (hazard ratio 1.04 per 10 mEq/day higher NAE). For comparison, we estimated the nonvolatile acid load as net endogenous acid production using self-reported food frequency questionnaires from 2848 patients and dietary urine biomarkers from 3385 patients. Higher net endogenous acid production based on biomarkers (urea nitrogen and potassium) was modestly associated with faster CKD progression consistent with prior reports, but only among those without diabetes. Results from the food frequency questionnaires were not associated with CKD progression in any group. Thus, disparate results obtained from analyses of nonvolatile acid load directly measured as NAE and estimated from diet suggest a novel hypothesis that the risk of CKD progression related to low NAE or acid load may be due to diet-independent changes in acid production in diabetes.

Phosphorus Additives and Albuminuria in Early Stages of CKD: A Randomized Controlled Trial.

BACKGROUND: Little is known about the effects of phosphorus additives on patients with kidney disease. STUDY DESIGN: Randomized, double-blind, crossover trial. SETTING & PARTICIPANTS: 31 adults with early stages of presumed chronic kidney disease (estimated glomerular filtration rate ≥ 45mL/min/1.73m2; urine albumin-creatinine ratio sex-specific cutoff points: men ≥ 17mg/g, women ≥ 25mg/g). INTERVENTION: Higher versus lower phosphorus intake for 3 weeks. Higher phosphorus intake was achieved by the addition of commercially available diet beverages and breakfast bars to diet. OUTCOMES: Change in 24-hour urine albumin excretion and plasma fibroblast growth factor 23 level. MEASUREMENTS: Two 24-hour urine collections and a single fasting blood draw at the end of each period. RESULTS: Mean baseline values for phosphorus intake, 24-hour urine phosphorus excretion, and estimated glomerular filtration rate were 1,113±549 (SD) mg/d, 688±300mg/d, and 74.6±22.0mL/min/1.73m2. Median urine albumin excretion of 82.7 (IQR, 39.6-174.1) mg/d. Although phosphorus intake from study products increased by 993mg/d (P<0.001) during the higher compared to lower phosphorus additive period, background phosphorus intake decreased by 151mg/d (P=0.004). Higher phosphorus additive consumption increased 24-hour urine phosphorus excretion by 505 (95% CI, 381 to 629) mg/d (P<0.001), but did not significantly increase albuminuria (higher vs lower: 14.3%; 95% CI, -2.5% to 34.0%; P=0.1) or fibroblast growth factor 23 level (higher vs lower: 3.4%; 95% CI, -5.9% to 13.6%; P=0.4). LIMITATIONS: Small sample size, short duration of intervention, changes in background diet during the intervention. CONCLUSIONS: A 3-week consumption of higher phosphorus food additives did not significantly increase albuminuria. Further studies are needed to confirm these results.

Race, Serum Potassium, and Associations With ESRD and Mortality.

BACKGROUND: Recent studies suggest that potassium levels may differ by race. The basis for these differences and whether associations between potassium levels and adverse outcomes differ by race are unknown. STUDY DESIGN: Observational study. SETTING & PARTICIPANTS: Associations between race and potassium level and the interaction of race and potassium level with outcomes were investigated in the Racial and Cardiovascular Risk Anomalies in Chronic Kidney Disease (RCAV) Study, a cohort of US veterans (N=2,662,462). Associations between African ancestry and potassium level were investigated in African Americans in the Atherosclerosis Risk in Communities (ARIC) Study (N=3,450). PREDICTORS: Race (African American vs non-African American and percent African ancestry) for cross-sectional analysis; serum potassium level for longitudinal analysis. OUTCOMES: Potassium level for cross-sectional analysis; mortality and end-stage renal disease for longitudinal analysis. RESULTS: The RCAV cohort was 18% African American (N=470,985). Potassium levels on average were 0.162mmol/L lower in African Americans compared with non-African Americans, with differences persisting after adjustment for demographics, comorbid conditions, and potassium-altering medication use. In the ARIC Study, higher African ancestry was related to lower potassium levels (-0.027mmol/L per each 10% African ancestry). In both race groups, higher and lower potassium levels were associated with mortality. Compared to potassium level of 4.2mmol/L, mortality risk associated with lower potassium levels was lower in African Americans versus non-African Americans, whereas mortality risk associated with higher levels was slightly greater. Risk relationships between potassium and end-stage renal disease were weaker, with no difference by race. LIMITATIONS: No data for potassium intake. CONCLUSIONS: African Americans had slightly lower serum potassium levels than non-African Americans. Consistent associations between potassium levels and percent African ancestry may suggest a genetic component to these differences. Higher and lower serum potassium levels were associated with mortality in both racial groups.

Bariatric surgery is associated with improvement in kidney outcomes.

Severe obesity is associated with increased risk of kidney disease. Whether bariatric surgery reduces the risk of adverse kidney outcomes is uncertain. To resolve this we compared the risk of estimated glomerular filtration rate (eGFR) decline of ≥30% and doubling of serum creatinine or end-stage renal disease (ESRD) in 985 patients who underwent bariatric surgery with 985 patients who did not undergo such surgery. Patients were matched on demographics, baseline body mass index, eGFR, comorbidities, and previous nutrition clinic use. Mean age was 45 years, 97% were white, 80% were female, and 33% had baseline eGFR <90 ml/min per 1.73 m(2). Mean 1-year weight loss was 40.4 kg in the surgery group compared with 1.4 kg in the matched cohort. Over a median follow-up of 4.4 years, 85 surgery patients had an eGFR decline of ≥30% (22 had doubling of serum creatinine/ESRD). Over a median follow-up of 3.8 years, 177 patients in the matched cohort had an eGFR decline of ≥30% (50 had doubling of serum creatinine/ESRD). In adjusted analysis, bariatric surgery patients had a significant 58% lower risk for an eGFR decline of ≥30% (hazard ratio 0.42, 95% confidence interval 0.32-0.55) and 57% lower risk of doubling of serum creatinine or ESRD (hazard ratio 0.43, 95% confidence interval: 0.26-0.71) compared with the matched cohort. Results were generally consistent among subgroups of patients with and without eGFR <90 ml/min per 1.73 m(2), hypertension, and diabetes. Thus, bariatric surgery may be an option to prevent kidney function decline in severely obese individuals.

Effect of glycemic index and carbohydrate intake on kidney function in healthy adults.

BACKGROUND: Replacing carbohydrate with protein acutely increases glomerular filtration rate (GFR) but is associated with faster, long-term kidney disease progression. The effects of carbohydrate type (i.e. glycemic index, GI) on kidney function are unknown. METHODS: We conducted an ancillary study of a randomized, crossover feeding trial in overweight/obese adults without diabetes or kidney disease (N = 163). Participants were fed each of four healthy, DASH-like diets for 5 weeks, separated by 2-week washout periods. Weight was kept constant. The four diets were: high GI (GI ≥65) with high %carb (58 % kcal) (reference diet), low GI (≤45) with low %carb (40 % kcal), low GI with high %carb; and high GI with low %carb. Plasma was collected at baseline and after each feeding period. Study outcomes were cystatin C, ß2-microglobulin (ß2M), and estimated GFR based on cystatin C (eGFRcys). RESULTS: Mean (SD) age was 52 (11) years; 52 % were women; 50 % were black. At baseline, mean (SD) cystatin C, ß2M, and eGFRcys were 0.8 (0.1) mg/L, 1.9 (0.4) mg/L, and 104 (16) mL/min/1.73 m(2). Compared to the high GI/high %carb diet, reducing GI, %carb, or both increased eGFRcys by 1.9 mL/min/1.73 m(2) (95 % CI: 1.1, 2.7; P < 0.001), 3.0 mL/min/1.73 m(2) (1.9, 4.0; P < 0.001), and 4.5 mL/min/1.73 m(2) (3.5, 5.4; P < 0.001), respectively. Increases in eGFRcys from reducing GI were significantly associated with increases in eGFRcys from reducing %carb (P < 0.001). Results for cystatin C and ß2M reflected eGFRcys. CONCLUSIONS: Reducing GI increased GFR. Reducing %carb by increasing calories from protein and fat, also increased GFR. Future studies on GI should examine the long-term effects of this increase in GFR on kidney injury markers and clinical outcomes. TRIAL REGISTRATION: Clinical Trials.gov, number: NCT00608049 (first registered January 23, 2008).