(1) Background: Current dietary recommendations for dialysis patients suggest that high phosphorus diets may be associated with adverse outcomes such as hyperphosphatemia and death. However, there has been concern that excess dietary phosphorus restriction may occur at the expense of adequate dietary protein intake in this population. We hypothesized that higher dietary phosphorus intake is associated with higher mortality risk among a diverse cohort of hemodialysis patients. (2) Methods: Among 415 patients from the multi-center prospective Malnutrition, Diet, and Racial Disparities in Kidney Disease Study, we examined the associations of absolute dietary phosphorus intake (mg/day), ascertained by food frequency questionnaires, with all-cause mortality using multivariable Cox models. In the secondary analyses, we also examined the relationship between dietary phosphorus scaled to 1000 kcal of energy intake (mg/kcal) and dietary phosphorus-to-protein ratio (mg/g) with survival. (3) Results: In expanded case-mix + laboratory + nutrition adjusted analyses, the lowest tertile of dietary phosphorus intake was associated with higher mortality risk (ref: highest tertile): adjusted HR (aHR) (95% CI) 3.33 (1.75–6.33). In the analyses of dietary phosphorus scaled to 1000 kcal of energy intake, the lowest tertile of intake was associated with higher mortality risk compared to the highest tertile: aHR (95% CI) 1.74 (1.08, 2.80). Similarly, in analyses examining the association between dietary phosphorus-to-protein ratio, the lowest tertile of intake was associated with higher mortality risk compared to the highest tertile: aHR (95% CI) 1.67 (1.02–2.74). (4) Conclusions: A lower intake of dietary phosphorus was associated with higher mortality risk in a prospective hemodialysis cohort. Further studies are needed to clarify the relationship between specific sources of dietary phosphorus intake and mortality in this population.

Introduction: Chronic kidney disease-mineral and bone disorders (CKD-MBD) are prevalent in patients undergoing maintenance dialysis. Yet, there are limited and mixed evidence on the effects of different dialysis modalities involving longer treatment times or higher frequencies on CKD-MBD markers. Methods: This cohort study used data from 132,523 incident dialysis patients treated with any of the following modalities: conventional thrice-weekly in-center hemodialysis, nocturnal in-center hemodialysis (NICHD), home hemodialysis (HHD), or peritoneal dialysis (PD) from 2007 to 2011. We used marginal structural models fitted with inverse probability weights to adjust for fixed and time-varying confounding and informative censoring. We estimated the average effects of treatments with different dialysis modalities on time-varying serum concentrations of CKD-MBD markers: albumin-corrected calcium, phosphate, parathyroid hormone (PTH), and alkaline phosphatase (ALP) using pooled linear regression. Results: Most of the cohort were exclusively treated with conventional in-center hemodialysis, while few were ever treated with NICHD or HHD. At the baseline, PD patients had the lowest mean and median values of PTH, while NICHD patients had the highest median values. During follow-up, compared to hemodialysis patients, patients treated with NICHD had lower mean serum PTH (19.8 pg/mL [95% confidence interval: 2.8, 36.8] lower), whereas PD and HHD patients had higher mean PTH (39.7 pg/mL [31.6, 47.8] and 51.2 pg/mL [33.0, 69.3] higher, respectively). Compared to hemodialysis patients, phosphate levels were lower for patients treated with NICHD (0.44 mg/dL [0.37, 0.52] lower), PD (0.15 mg/dL [0.12, 0.19] lower), or HHD (0.33 mg/dL [0.27, 0.40] lower). There were no clinically meaningful associations between dialysis modalities and concentrations of calcium or ALP. Conclusion: In incident dialysis patients, compared to treatment with conventional in-center hemodialysis, treatments with other dialysis modalities with longer treatment times or higher frequency were associated with different patterns of serum phosphate and PTH. Given the recent growth in the use of dialysis modalities other than hemodialysis, the associations between the treatment and the CKD-MBD markers warrant additional study.

Background: Transitioning to maintenance hemodialysis (HD) is a vulnerable period for persons with end-stage renal disease (ESRD), punctuated by high rates of depression, hospitalizations and death. Screening for depression during this time may help to improve patient outcomes but formal inquiry has yet to be conducted. Among a national Veteran cohort, we examined whether depression screening in the year prior to HD initiation led to improved outcomes in the year thereafter. Methods: Associations between pre-ESRD depression screening and post-ESRD outcomes were examined with Cox proportional hazards models (mortality) and Poisson regression models (hospitalization). Hierarchal adjustment models accounted for sociodemographic, clinical, pre-ESRD care and dialysis characteristics. Results: The final analytic cohort of the study was 30 013 Veterans of whom 64% underwent pre-ESRD depression screening. During the 12 months post-transition, the crude all-cause mortality rate was 0.32 person-year for those screened and 0.35 person-year for those not screened, while the median (interquartile range) hospitalizations were 2 (2, 2) per year for both groups. In fully adjusted models, pre-ESRD depression screening was associated with a lower risk of mortality [hazard ratio (95% confidence interval): 0.94 (0.90–0.99)] and hospitalization [incidence rate ratio (95% confidence interval): 0.97 (0.9–0.99)]. Conclusion: Depression screening among adults prior to maintenance HD transition may be associated with better outcomes during the following year.

Background: Hyperkalemia is associated with kidney function decline in patients with non-dialysis dependent chronic kidney disease, but this relationship is unclear for residual kidney function (RKF) among hemodialysis (HD) patients. Methods: We conducted a retrospective cohort study of 6655 patients, who started HD January 2007 and December 2011 and who had data on renal urea clearance (KRU). Serum potassium levels were stratified into four groups (i.e. ≤4.0, >4.0 to ≤4.5, >4.5 to ≤5.0 and >5.0 mEq/L) and 1-year KRU slope for each group was estimated by a linear mixed-effects model. Results: Higher serum potassium was associated with a greater decline in KRU, and the greatest decrease in KRU (–0.20, 95% confidence interval –0.50 to –0.06) was observed for baseline potassium >5.0 mEq/L in the fully adjusted model. Mediation analysis showed that KRU slope mediated 1.78% of the association between serum potassium and mortality. Conclusions: Hyperkalemia is associated with a decline in RKF amongst incident HD patients. These findings may have important clinical implications in the management of hyperkalemia in advanced CKD if confirmed in additional clinical trials.

Background: Serum bicarbonate or total carbon dioxide (CO2) concentrations decline as chronic kidney disease (CKD) progresses and rise after dialysis initiation. While metabolic acidosis accelerates the progression of CKD and is associated with higher mortality among patients with end stage renal disease (ESRD), there are scarce data on the association of CO2 concentrations before ESRD transition with post-ESRD mortality. Methods: A historical cohort from the Transition of Care in CKD (TC-CKD) study includes 85,505 veterans who transitioned to ESRD from October 1, 2007, through March 31, 2014. After 1,958 patients without follow-up data, 3 patients with missing date of birth, and 50,889 patients without CO2 6 months prior to ESRD transition were excluded, the study population includes 32,655 patients. Associations between CO2 concentrations averaged over the last 6 months and its rate of decline during the 12 months prior to ESRD transition and post-ESRD all-cause, cardiovascular (CV), and non-CV mortality were examined by using hierarchical adjustment with Cox regression models. Results: The cohort was on average 68 ± 11 years old and included 29% Black veterans. Baseline concentrations of CO2 were 23 ± 4 mEq/L, and median (interquartile range) change in CO2 were −1.8 [−3.4, −0.2] mEq/L/year. High (≥28 mEq/L) and low (<18 mEq/L) CO2 concentrations showed higher adjusted mortality risk while there was no clear trend in the middle range. Consistent associations were observed irrespective of sodium bicarbonate use. There was also a U-shaped association between the change in CO2 and all-cause, CV, and non-CV mortality with the lowest risk approximately at −2.0 and 0.0 mEq/L/year among sodium bicarbonate nonusers and users, respectively, and the highest mortality was among patients with decline in CO2 >4 mEq/L/year. Conclusion: Both high and low pre-ESRD CO2 levels (≥28 and <18 mEq/L) during 6 months prior to dialysis transition and rate of CO2 decline >4 mEq/L/year during 1 year before dialysis initiation were associated with greater post-ESRD all-cause, CV, and non-CV mortality. Further studies are needed to determine the optimal management of CO2 in patients with advanced CKD stages transitioning to ESRD.

Liver disease is often associated with dysfunctional potassium homeostasis but is not a well-established risk factor for hyperkalemia. This retrospective cohort study examined the potential relationship between liver disease and recurrent hyperkalemia. Patients with ≥1 serum potassium measurement between January 2004 and December 2018 who experienced hyperkalemia (serum potassium >5.0 mmol/L) were identified from the United States Veterans Affairs database. A competing risk regression model was used to analyze the relationship between patient characteristics and recurrent hyperkalemia. Of 1,493,539 patients with incident hyperkalemia, 71,790 (4.8%) had liver disease (one inpatient or two outpatient records) within 1 year before the index hyperkalemia event. Recurrent hyperkalemia within 1 year after the index event occurred in 234,807 patients (15.7%) overall, 19,518 (27.2%) with liver disease, and 215,289 (15.1%) without liver disease. The risk of recurrent hyperkalemia was significantly increased in patients with liver disease versus those without (subhazard ratio, 1.34; 95% confidence interval, 1.32–1.37; p < 0.0001). Aside from vasodilator therapy, the risk of recurrent hyperkalemia was not increased with concomitant medication. In this cohort study, liver disease was an independent risk factor strongly associated with recurrent hyperkalemia within 1 year, independent of concomitant renin–angiotensin–aldosterone system inhibitor or potassium-sparing diuretic use.