Alkaline Phosphatase and Parathyroid Hormone Levels: International Variation and Associations With Clinical Outcomes in the DOPPS.

Introduction: Secondary hyperparathyroidism (SHPT) increases the risk of fractures and cardiovascular (CV) disease in patients on hemodialysis (HD). The relationship between parathyroid hormone (PTH) and outcomes has been inconsistent, possibly due to variable bone responsiveness to PTH. The KDIGO guideline suggests monitoring total alkaline phosphatase (ALP), but the role of ALP versus PTH in the management of mineral and bone disorder (MBD) is not clear. Methods: The analysis included 28,888 patients on HD in 9 countries in Dialysis Outcomes and Practice Patterns Study (DOPPS) phase 3 to 7 (2005-2021). The primary exposures of interest were normalized ALP and PTH, which are raw values divided by facility upper normal limit, measured at study enrollment. Cox models were used to estimate hazard ratios of all-cause or CV mortality and any or hip fracture adjusted for potential confounders. Linear mixed models, adjusted for potential confounders, were employed to investigate the relationship between normalized ALP levels and patient characteristics. Results: Normalized PTH showed a J-shaped association with all-cause or CV mortality, and a weak linear association with fracture. In contrast, normalized ALP showed a strong association with all outcomes. Factors associated with higher ALP levels after controlling for PTH included Black race, longer dialysis vintage, diabetes mellitus, hypocalcemia, hypophosphatemia, elevated C-reactive protein (CRP), and the use of cinacalcet. Conclusion: Total ALP is a more robust exposure of adverse outcomes than PTH in patients on HD. PTH responsiveness is affected by race, primary renal disease, comorbidities, and mineral metabolism and therapy. Our results indicate that it may be useful to evaluate target organ response, rather than PTH alone when considering the consequences of (SHPT).

Pathways for Diagnosing and Treating CKD-Associated Pruritus: A Narrative Review.

Purpose of Review: Chronic kidney disease (CKD)-associated pruritus is a common, persistent, and distressing itch experienced by patients across the CKD spectrum. Although the disorder is associated with adverse outcomes and poor health-related quality of life, it remains underdiagnosed and undertreated. The purpose of this narrative review is to offer health care providers guidance on how to effectively identify, assess, and treat patients with CKD-associated pruritus, with the goal of reducing symptom burden and improving patient-important outcomes, such as quality of life (QoL). Sources of Information: A panel of nephrologists and researchers from across Canada and the United States was assembled to develop this narrative review based on the best available data, current treatment guidelines, and their clinical experiences. Methods: A panel of nephrologists who actively care for patients with pruritus receiving dialysis from across Canada was assembled. Two researchers from the United States were also included based on their expertise in the diagnosis and management of CKD-associated pruritus. Throughout Spring 2023, the panel met to discuss key topics in the identification, assessment, and management of CKD-associated pruritus. Panel members subsequently developed summaries of the pertinent information based on the best available data, current treatment guidelines, and added information on their own clinical experiences. In all cases, approval of the article was sought and achieved through discussion. Key Findings: This narrative review provides pragmatic guidance addressing: (1) methods for screening CKD-associated pruritus, (2) assessing severity, (3) management of CKD-associated pruritus, and (4) suggested areas for future research. The panel developed a 3-pillar framework for proactive assessment and severity scoring in CKD-aP: systematic screening for CKD-associated pruritus (pillar 1), assessment of pruritus intensity (pillar 2), and understanding the impact of CKD-associated pruritus on the patient's QoL (pillar 3). Management of CKD-associated pruritus can include ensuring optimization of dialysis adequacy, achieving mineral metabolism targets (ie, calcium, phosphate, and parathyroid hormone). However, treatment of CKD-associated pruritus usually requires additional interventions. Patients, regardless of CKD-associated pruritus severity, should be counseled on adequate skin hydration and other non-pharmacological strategies to reduce pruritus. Antihistamines should be avoided in favor of evidence-based treatments, such as difelikefalin and gabapentin. Limitations: A formal systematic review (SR) of the literature was not undertaken, although published SRs were reviewed. The possibility for bias based on the experts' own clinical experiences may have occurred. Key takeaways are based on the current available evidence, of which head-to-head clinical trials are lacking. Funding: This work was funded by an arm's length grant from Otsuka Canada Pharmaceutical Inc. (the importer and distributer of difelikefalin in Canada). LiV Medical Education Agency Inc. provided logistical and editorial support.

Motif de la revue: Le prurit associé à l'insuffisance rénale chronique (IRC) est une démangeaison cutanée fréquente, persistante et invalidante que les patients de tout le specter de l'IRC peuvent ressentir. Bien que le prurit soit associé à des effets indésirables et à une mauvaise qualité de vie liée à la santé, il demeure sous-diagnostiqué et sous-traité. L'objectif de cette revue narrative est d'offrir des conseils aux professionnels de la santé sur la façon d'identifier, d'évaluer et de traiter efficacement les patients atteints de prurit associé à l'IRC; ceci dans le but de réduire la charge des symptômes et d'améliorer les résultats importants pour les patients, notamment leur qualité de vie (QdV). Sources de l'information: Un comité de néphrologues et de chercheurs de partout au Canada et des États-Unis a été constitué pour élaborer la présente revue narrative à partir des meilleures données disponibles, des lignes directrices actuelles pour le traitement et de leurs expériences cliniques. Méthodologie: Un groupe de néphrologues canadiens qui s'occupent activement de patients dialysés souffrant de prurit a été constitué. Deux chercheurs des États-Unis ont été inclus au groupe en raison de leur expertise dans le diagnostic et la prise en charge du prurit associé à l'IRC. Le comité s'est réuni tout au long du printemps 2023 pour discuter de sujets clés en lien avec l'identification, l'évaluation et la prise en charge du prurit associé à l'IRC. Les membres du comité ont par la suite rédigé des résumés des informations pertinentes en se basant sur les meilleures données disponibles et les lignes directrices actuelles pour le traitement, auxquels ils ont ajouté des informations issues de leurs propres expériences cliniques. Dans tous les cas, l'approbation du manuscrit a été sollicitée et obtenue par discussion. Principaux résultats: Cette revue narrative offre des conseils pragmatiques sur les points suivants: (1) les méthodes de dépistage du prurit associé à l'IRC; (2) l'évaluation de sa gravité; (3) sa prise en charge; et (4) les domaines suggérés pour de futures recherches. Le comité a développé un cadre à trois piliers pour l'évaluation proactive du prurit associé à l'IRC et l'établissement d'un score de gravité: le dépistage systématique du prurit associé à l'IRC (pilier 1), l'évaluation de son intensité (pilier 2) et la compréhension de son impact sur la QdV du patient (pilier 3). La prise en charge du prurit associé à l'IRC peut inclure l'optimisation de l'adéquation de la dialyse et l'atteinte des cibles du métabolisme minéral (c.-à-d. calcium, phosphate et hormone parathyroïdienne). Cependant, son traitement nécessite habituellement des interventions supplémentaires. Les patients, quelle que soit la gravité du prurit associé à l'IRC, devraient être avisés d'hydrater adéquatement leur peau et informés des autres stratégies non pharmacologiques afin de réduire le prurit. On devrait éviter les antihistaminiques et les remplacer par des traitements fondés sur des données probantes comme la difélikéfaline et la gabapentine. Limites: Aucune revue systématique de la littérature n'a été formellement entreprise, bien que les revues systématiques publiées aient été examinées. La possibilité d'un biais fondé sur les expériences cliniques des experts est envisageable. Les principales conclusions de cette étude sont fondées sur les données probantes actuellement disponibles, pour lesquelles il n'existe pas d'essais cliniques comparatifs. Financement: Ces travaux ont été financés par une subvention indépendante d'Otsuka Canada Pharmaceutical Inc. (l'importateur et distributeur de la difélikéfaline au Canada). Un soutien logistique et éditorial a été fourni par liV Medical Education Agency Inc.

International variations in serum PTH and calcium levels and their mortality associations in peritoneal dialysis patients: Results from PDOPPS.

BACKGROUND: Mineral bone disorder (MBD) in chronic kidney disease (CKD) is associated with high symptom burden, fractures, vascular calcification, cardiovascular disease and increased morbidity and mortality. CKD-MBD studies have been limited in peritoneal dialysis (PD) patients. Here, we describe calcium and parathyroid hormone (PTH) control, related treatments and mortality associations in PD patients. METHODS: We used data from eight countries (Australia and New Zealand (A/NZ), Canada, Japan, Thailand, South Korea, United Kingdom, United States (US)) participating in the prospective cohort Peritoneal Dialysis Outcomes and Practice Patterns Study (2014-2022) among patients receiving PD for >3 months. We analysed the association of baseline PTH and albumin-adjusted calcium (calciumAlb) with all-cause mortality using Cox regression, adjusted for potential confounders, including serum phosphorus and alkaline phosphatase. RESULTS: Mean age ranged from 54.6 years in South Korea to 63.5 years in Japan. PTH and serum calciumAlb were measured at baseline in 12,642 and 14,244 patients, respectively. Median PTH ranged from 161 (Japan) to 363 pg/mL (US); mean calciumAlb ranged from 9.1 (South Korea, US) to 9.8 mg/dL (A/NZ). The PTH/mortality relationship was U-shaped, with the lowest risk at PTH 300-599 pg/mL. Mortality was nearly 20% higher at serum calciumAlb 9.6+ mg/dL versus 8.4-<9.6 mg/dL. MBD therapy prescriptions varied substantially across countries. CONCLUSIONS: A large proportion of PD patients in this multi-national study have calcium and/or PTH levels in ranges associated with substantially higher mortality. These observations point to the need to substantially improve MBD management in PD to optimise patient outcomes. LAY SUMMARY: Chronic kidney disease-mineral bone disorder (MBD) is a systemic condition, common in dialysis patients, that results in abnormalities in parathyroid hormone (PTH), calcium, phosphorus and vitamin D metabolism. A large proportion of peritoneal dialysis (PD) patients in this current multi-national study had calcium and/or PTH levels in ranges associated with substantially higher risks of death. Our observational study design limits our ability to determine whether these abnormal calcium and PTH levels cause more death due to possible confounding that was not accounted for in our analysis. However, our findings, along with other recent work showing 48-75% higher risk of death for the one-third of PD patients having high phosphorus levels (>5.5 mg/dL), should raise strong concerns for a greater focus on improving MBD management in PD patients.

CKD-Associated Pruritus and Clinical Outcomes in Nondialysis CKD.

Rationale & Objective: Itching is a frequent symptom experienced by people with chronic kidney disease (CKD). We investigated the associations of CKD-associated pruritus (CKD-aP) with clinical outcomes. Study Design: This was a longitudinal cohort study. Setting & Participants: Patients from Brazil, France, and the United States enrolled in the Chronic Kidney Disease Outcomes and Practice Patterns Study (CKDopps) from 2013 to 2021, an international prospective cohort study of adults with nondialysis dependent CKD, and an estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73 m2 were included. Exposure: CKD-aP was self-reported by response to the question: "During the past 4 weeks, to what extent were you bothered by itchy skin?" Outcomes: The outcomes were as follows: CKD progression, kidney replacement therapy (KRT) initiation, mortality, hospitalization, cardiovascular events, infection events. Analytical Approach: Associations with time-to-event outcomes were investigated using Cox proportional hazards models adjusted for potential confounders. Results: There were 4,410 patients from 91 clinics with a median age of 69 years and a median eGFR at patient questionnaire completion of 29 (21-38) mL/min/1.73 m2. The proportion of patients not at all, somewhat, moderately, very much, and extremely bothered by itchy skin was 49%, 27%, 13%, 7%, and 3%, respectively. Patients with more advanced stages of CKD, older age, and greater comorbidities reported to be more likely bothered by itchy skin. Among patients at least moderately bothered, 23% were prescribed at least 1 pharmacotherapy (35% in the United States, 19% in France, 4% in Brazil), including antihistamine (10%), gabapentin (6%), topical corticosteroids (4%), pregabalin (3%), or sedating antihistamine (3%). The HR (95% CI) for patients extremely (vs not at all) bothered was 1.74 (1.11-2.73) for all-cause mortality, 1.56 (1.11-2.18) for all-cause hospitalization, and 1.84 (1.22-2.75) for cardiovascular events. As CKD-aP severity increased, patients also had higher rates of infection events (P = 0.04); CKD-aP severity was not associated with KRT initiation (P = 0.20) or CKD progression (P = 0.87). Limitations: The limitations were 25% nonresponse rate, recall bias, and residual confounding factors. Conclusions: These results demonstrate a strong association between severe itch and clinical outcomes, providing the nephrology community new insights into the possible adverse consequences of CKD-aP in individuals with nondialysis CKD, and warrant further exploration. Plain-Language Summary: Chronic kidney disease-associated pruritus (CKD-aP) is a common disturbing symptom of chronic kidney disease (CKD). This article analyzes longitudinal data from the Chronic Kidney Disease Outcomes and Practice Patterns Study (CKDopps) to describe prevalence of CKD-aP in 4,410 individuals with nondialysis CKD, and its association with clinical outcomes. We found that 51% of the surveyed population were bothered by pruritus. CKD-aP was more prevalent in those with more advanced stages of CKD, older age, and with more comorbid conditions. Compared to those not at all bothered by pruritus, those who were extremely bothered had a higher risk of all-cause mortality, hospitalizations, and cardiovascular events. Severity of CKD-aP was not associated with CKD progression or initiation of kidney replacement therapy.

Pruritus in Hemodialysis Patients: Longitudinal Associations With Clinical and Patient-Reported Outcomes.

RATIONALE & OBJECTIVE: Cross-sectional studies have reported an association of chronic kidney disease-associated pruritus (CKD-aP) with adverse clinical events and patient-reported outcomes (PROs). We studied the longitudinal associations between changes in CKD-aP and clinical outcomes among patients receiving maintenance hemodialysis. STUDY DESIGN: Prospective cohort study. SETTING & PARTICIPANTS: 7,976 hemodialysis recipients across 21 countries in phases 4-6 (2009-2018) of the Dialysis Outcomes and Practice Patterns Study (DOPPS) who had 2 CKD-aP assessments approximately 12 months apart. EXPOSURES: Exposure status was based on the assessment of pruritis initially and again approximately 1 year later. Four groups were identified, including those with moderate or more severe pruritis only at the initial assessment (resolved), only at the second assessment (incident), at neither assessment (absent), or at both assessments (persistent). OUTCOMES: Laboratory values and PROs ascertained at the initial assessment of pruritis and 1 year later. ANALYTICAL APPROACH: Linear mixed model to investigate changes in laboratory values and PROs over the 1-year study period across the 4 exposure groups. RESULTS: 51% of patients had moderate to severe CKD-aP symptoms at either assessment (22% at both). The prevalences of depression, restless sleep, and feeling drained increased over the study period (+13%,+10%, and+14%, respectively) among patients with incident pruritus and decreased (-5%, -8%, and -12%, respectively) among patients with resolved pruritus. Minimal changes in PROs over time were observed for the absent and persistent groups. Changes over time in laboratory values (phosphorus, Kt/V) were not detected for either of these groups. Compared with patients with absent CKD-aP, the adjusted HRs for patients with persistent CKD-aP were 1.29 (95% CI, 1.09-1.53) for all-cause mortality, 1.17 (1.07-1.28) for all-cause hospitalization, and 1.48 (1.26-1.74) for cardiovascular events. LIMITATIONS: No interim evaluation of CKD-aP symptoms between the 2 assessments; potential selection bias from patients who died or were otherwise lost to follow-up before the second assessment. CONCLUSIONS: CKD-aP symptoms are chronic, and these findings highlight the potential value of repeated assessment of this symptom using standardized approaches. Future research should systematically investigate potential causes of CKD-aP and options for its effective treatment. PLAIN-LANGUAGE SUMMARY: Previous research has studied itching and its consequences in hemodialysis recipients only at a single time point. We surveyed 7,976 patients receiving maintenance hemodialysis to assess itching over a period of 1 year. We found that, among those experiencing itching at the initial assessment, more than half had persistent symptoms 1 year later. Those in whom itching developed during follow-up were more likely to experience depression, poor sleep, long recovery times after dialysis, and feeling faint or drained. These patients also rated their quality of life as poorer than those who did not experience itching. These findings emphasize the potential value of clinical detection of itching and the pursuit of effective treatments for patients receiving dialysis experiencing these symptoms.

Active Vitamin D Use and Fractures in Hemodialysis Patients: Results from the International DOPPS.

Active vitamin D is commonly used to control secondary hyperparathyroidism in dialysis patients, but it is unknown whether active vitamin D directly improves bone strength, independently of its ability to suppress parathyroid hormone (PTH). We analyzed the association between the prescription of active vitamin D and incidence of any fracture and hip fracture in 41,677 in-center hemodialysis patients from 21 countries in phases 3 to 6 (2005 to 2018) of the Dialysis Outcomes and Practice Patterns Study (DOPPS). We used Cox regression, adjusted for PTH and other potential confounders, and used a per-protocol approach to censor patients at treatment switch during follow-up. We also used a facility preference approach to minimize confounding by indication. Overall, 55% of patients were prescribed active vitamin D at study enrollment. Event rates (per patient-year) were 0.024 for any fracture and 0.010 for hip fracture. The adjusted hazard ratio (95% confidence interval) comparing patients prescribed versus not prescribed active vitamin D was 1.02 (0.90 to 1.17) for any fracture and 1.00 (0.81 to 1.23) for hip fracture. In the facility preference approach, there was no difference in fracture rate between facilities with higher versus lower active vitamin D prescriptions. Thus, our results do not suggest a PTH-independent benefit of active vitamin D in fracture prevention and support the current KDIGO guideline suggesting the use of active vitamin D only in subjects with elevated or rising PTH. Further research is needed to determine the role of active vitamin D beyond PTH control. © 2023 American Society for Bone and Mineral Research (ASBMR).

Receiving hemodialysis in Hispanic ethnic dense communities is associated with better adherence and outcomes among young patients: a retrospective analysis of the Dialysis Outcomes and Practice Patterns Study.

BACKGROUND: Hispanic ethnic density (HED) is a marker of better health outcomes among Hispanic patients with chronic disease. It is unclear whether community HED is associated with mortality risk among ethnically diverse patients receiving maintenance hemodialysis. METHODS: A retrospective analysis of patients in the United States cohort of the Dialysis Outcomes and Practice Patterns Study (DOPPS) database (2011-2015) was conducted (n = 4226). DOPPS data was linked to the American Community Survey database by dialysis facility zip code to obtain % Hispanic residents (HED). One way ANOVA and Kruskal Wallis tests were used to estimate the association between tertiles of HED with individual demographic, clinical and adherence characteristics, and facility and community attributes. Multivariable Cox proportional hazards models were used to estimate the mortality hazard ratio (HR) and 95% CIs by tertile of HED, stratified by age; a sandwich estimator was used to account for facility clustering. RESULTS: Patients dialyzing in facilities located in the highest HED tertile communities were younger (61.4 vs. 64.4 years), more commonly non-White (62.4% vs. 22.1%), had fewer comorbidities, longer dialysis vintage, and were more adherent to dialysis treatment, but had fewer minutes of dialysis prescribed than those in the lowest tertile. Dialyzing in the highest HED tertile was associated with lower hazard of mortality (HR, 0.86; 95% CI, 0.72-1.00), but this association attenuated with the addition of individual race/ethnicity (HR, 0.92; 95% CI, 0.78-1.09). In multivariable age-stratified analyses, those younger than 64 showed a lower hazard for mortality in the highest (vs. lowest) HED tertile (HR, 0.66; 95% CI, 0.49-0.90). Null associations were observed among patients ≥ 64 years. CONCLUSIONS: Treating in communities with greater HED and racial/ethnic integration was associated with lower mortality among younger patients which points to neighborhood context and social cohesion as potential drivers of improved survival outcomes for patients receiving hemodialysis.

Development and Validation of a Predictive Risk Algorithm for Bleeding in Individuals on Long-term Hemodialysis: An International Prospective Cohort Study (BLEED-HD).

Background: Individuals with kidney disease are at a high risk of bleeding and as such tools that identify those at highest risk may aid mitigation strategies. Objective: We set out to develop and validate a prediction equation (BLEED-HD) to identify patients on maintenance hemodialysis at high risk of bleeding. Design: International prospective cohort study (development); retrospective cohort study (validation). Settings: Development: 15 countries (Dialysis Outcomes and Practice Patterns Study [DOPPS] phase 2-6 from 2002 to 2018); Validation: Ontario, Canada. Patients: Development: 53 147 patients; Validation: 19 318 patients. Measurements: Hospitalization for a bleeding event. Methods: Cox proportional hazards models. Results: Among the DOPPS cohort (mean age, 63.7 years; female, 39.7%), a bleeding event occurred in 2773 patients (5.2%, event rate 32 per 1000 person-years), with a median follow-up of 1.6 (interquartile range [IQR], 0.9-2.1) years. BLEED-HD included 6 variables: age, sex, country, previous gastrointestinal bleeding, prosthetic heart valve, and vitamin K antagonist use. The observed 3-year probability of bleeding by deciles of risk ranged from 2.2% to 10.8%. Model discrimination was low to moderate (c-statistic = 0.65) with excellent calibration (Brier score range = 0.036-0.095). Discrimination and calibration of BLEED-HD were similar in an external validation of 19 318 patients from Ontario, Canada. Compared to existing bleeding scores, BLEED-HD demonstrated better discrimination and calibration (c-statistic: HEMORRHAGE = 0.59, HAS-BLED = 0.59, and ATRIA = 0.57, c-stat difference, net reclassification index [NRI], and integrated discrimination index [IDI] all P value <.0001). Limitations: Dialysis procedure anticoagulation was not available; validation cohort was considerably older than the development cohort. Conclusion: In patients on maintenance hemodialysis, BLEED-HD is a simple risk equation that may be more applicable than existing risk tools in predicting the risk of bleeding in this high-risk population.

Contexte: Les personnes atteintes d'insuffisance rénale présentent un risque élevé d'hémorragie. Des outils permettant de déceler les personnes les plus exposées au risque pourrait aider à mettre en œuvre des stratégies d'atténuation. Objectifs: Nous avons mis au point et validé une équation prédictive (BLEED-HD) afin d'identifier les patients sous hémodialyse d'entretien qui présentent un risque élevé d'hémorragie. Type d'étude: Étude de cohorte prospective internationale (développement); étude de cohorte rétrospective (validation). Cadre: Développement: dans 15 pays (étude DOPPS phases 2 à 6 entre 2002 et 2018); validation: en Ontario (Canada). Sujets: Développement: 53 147 patients; validation: 19 318 patients. Mesures: Hospitalisation pour un événement hémorragique. Méthodologie: Modèles à risques proportionnels de Cox. Résultats: Dans la cohorte DOPPS (âge moyen: 63,7 ans; 39,7 % de femmes), 2 773 patients avaient subi un événement hémorragique (5,2 %; taux d'événements: 32 pour 1 000 années-personnes) avec un suivi médian de 1,6 an (ÉIQ: 0,9 à 2,1). BLEED-HD prend six variables en compte: âge, sexe, pays d'origine, saignement gastro-intestinal antérieur, présence d'une valve cardiaque prothétique et utilisation d'un antagoniste de la vitamine K. La probabilité observée de saignements dans les 3 ans par déciles de risque allait de 2,2 à 10,8 %. La discrimination du modèle variait de faible à modérée (statistique c: 0,65) avec un excellent étalonnage (plage de score de Brier: 0,036-0,095). La discrimination et l'étalonnage de se sont avérés semblables lors de la validation externe auprès de 19 318 patients de l'Ontario (Canada). Par rapport aux scores d'hémorragie existants, l'équation BLEED-HD a démontré une meilleure discrimination et un meilleur étalonnage (statistique c: HEMORRHAGE 0,59; HAS-BLED 0,59 et ATRIA 0,57; différence dans les c-stat, indices NRI et IDI toutes valeurs de p < 0,0001). Limites: L'information sur l'anticoagulant utilisé dans la procédure de dialyse n'était pas disponible; la cohorte de validation était beaucoup plus âgée que la cohorte de développement. Conclusion: Pour les patients sous hémodialyse d'entretien, BLEED-HD est une équation simple de calcul du risque qui peut être plus facilement applicable que les outils existants pour prédire le risque d'hémorragie dans cette population à haut risque.

Adverse Gastrointestinal Events With Sodium Polystyrene Sulfonate Use in Patients on Maintenance Hemodialysis: An International Cohort Study.

Background: There are concerns regarding the gastrointestinal (GI) safety of sodium polystyrene sulfonate (SPS), a medication commonly used in the management of hyperkalemia. Objective: To compare the risk of GI adverse events among users versus non-users of SPS in patients on maintenance hemodialysis. Design: International prospective cohort study. Setting: Seventeen countries (Dialysis Outcomes and Practice Patterns Study [DOPPS] phase 2-6 from 2002 to 2018). Patients: 50 147 adults on maintenance hemodialysis. Measurements: An adverse GI event defined by a GI hospitalization or GI fatality with SPS prescription compared with no SPS prescription. Methods: Overlap propensity score-weighted Cox models. Results: Sodium polystyrene sulfonate prescription was present in 13.4% of patients and ranged from 0.42% (Turkey) to 20.6% (Sweden) with 12.5% use in Canada. A total of 935 (1.9%) adverse GI events (140 [2.1%] with SPS, 795 [1.9%] with no SPS; absolute risk difference 0.2%) occurred. The weighted hazard ratio (HR) of a GI event was not elevated with SPS use compared with non-use (HR = 0.93, 95% confidence interval = 0.83-1.6). The results were consistent when examining fatal GI events and/or GI hospitalization separately. Limitations: Sodium polystyrene sulfonate dose and duration were unknown. Conclusions: Sodium polystyrene sulfonate use in patients on hemodialysis was not associated with a higher risk of an adverse GI event. Our findings suggest that SPS use is safe in an international cohort of maintenance hemodialysis patients.

Contexte: Des préoccupations sont soulevées quant à l'innocuité gastro-intestinale (GI) du sulfonate de polystyrène sodique (SPS), un médicament couramment utilisé dans la gestion de l'hyperkaliémie. Objectif: Comparer dans une population de patients sous hémodialyse d'entretien le risque d'effets indésirables gastro-intestinaux chez les utilisateurs du SPS par rapport aux patients non-utilisateurs. Conception: Étude de cohorte prospective internationale. Cadre: 17 pays (phases 2 à 6 de l'essai DOPPS [de 2002 à 2018]). Sujets: 50 147 adultes sous hémodialyse d'entretien. Mesures: La comparaison entre les événements gastro-intestinaux indésirables, définis par une hospitalisation ou un décès en lien avec un problème gastro-intestinal, selon que les patients avaient ou non une prescription de SPS. Méthodologie: Modèles de Cox pondérés par le score de propension au chevauchement. Résultats: Dans l'ensemble de la cohorte, 13,4 % des patients avaient une prescription de SPS; l'usage de SPS variait selon les pays entre 0,42 % (Turquie) et 20,6 % (Suède) avec 12,5 % au Canada. En tout, 935 (1,9 %) événements GI indésirables sont survenus dans l'ensemble de la cohorte, soit 140 (2,1 %) chez les patients avec prescription de SPS et 795 (1,9 %) chez les patients sans prescription de SPS (différence de risque absolue: 0,2 %). Le rapport de risque (RR) pondéré d'un événement GI n'était pas plus élevé avec l'utilisation de SPS (RR = 0,93; IC 95 %: 0,83-1,6). Les résultats étaient cohérents lorsque l'on a examiné séparément les événements gastro-intestinaux (hospitalisation et/ou décès). Limites: La dose et la durée du traitement par SPS étaient inconnues. Conclusion: L'utilisation de SPS chez les patients sous hémodialyse n'a pas été associée à un risque plus élevé d'événements indésirables d'origine gastro-intestinale. Nos résultats suggèrent que l'utilisation du SPS est sans danger dans la cohorte internationale de patients sous hémodialyse d'entretien étudiée.

Gout Prevalence, Practice Patterns, and Associations with Outcomes in North American Dialysis Patients.

INTRODUCTION: Gout occurs frequently in patients with kidney disease and can lead to a significant burden on quality of life. Gout prevalence, and its association with outcomes in hemodialysis (HD) and peritoneal dialysis (PD) populations located in North America, is unknown. METHODS: We used data from North America cohorts of 70,297 HD patients (DOPPS, 2012-2020) and 5117 PD patients (PDOPPS, 2014-2020). We used three definitions of gout for this analysis: (1) having an active prescription for colchicine or febuxostat; (2) having an active prescription for colchicine, febuxostat, or allopurinol; or (3) having an active prescription for colchicine, febuxostat, or allopurinol, or prior diagnosis of gout. Propensity score matching was used to compare outcomes among patients with versus without gout. Outcomes included erythropoietin resistance index (ERI=erythropoiesis stimulating agent dose per week/(hemoglobin×weight)), all-cause mortality, hospitalization, and patient-reported outcomes (PROs). RESULTS: The gout prevalence was 13% in HD and 21% in PD; it was highest among incident dialysis patients. Description of previous history of gout was rare, and identification of gout defined by colchicine (2%-3%) or febuxostat (1%) prescription was less frequent than by allopurinol (9%-12%). Both HD and PD patients with gout (versus no gout) were older, were more likely male, had higher body mass index, and had higher prevalence of cardiovascular comorbidities. About half of patients with a gout history were prescribed urate-lowering therapy. After propensity score matching, mean ERI was 3%-6% higher for gout versus non-gout patients while there was minimal evidence of association with clinical outcomes or PROs. CONCLUSION: In a large cohort of PD and HD patients in North America, we found that gout occurs frequently and is likely under-reported. Gout was not associated with adverse clinical or PROs.

Association of single and serial measures of serum phosphorus with adverse outcomes in patients on peritoneal dialysis: results from the international PDOPPS.

BACKGROUND: While high serum phosphorus levels have been related to adverse outcomes in hemodialysis patients, further investigation is warranted in persons receiving peritoneal dialysis (PD). METHODS: Longitudinal data (2014-17) from the Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS), a prospective cohort study, were used to examine associations of serum phosphorus with all-cause mortality and major adverse cardiovascular events via Cox regression adjusted for confounders. Serum phosphorus levels were parameterized by four methods: (i) baseline serum phosphorus; (ii) mean 6-month serum phosphorus; (iii) number of months with serum phosphorus >4.5 mg/dL; and (iv) mean area-under-the-curve of 6-month serum phosphorus control. RESULTS: The study included 5847 PD patients from seven countries; 9% of patients had baseline serum phosphorus <3.5 mg/dL, 24% had serum phosphorus ≥3.5 to ≤4.5 mg/dL, 30% had serum phosphorus >4.5 to <5.5 mg/dL, 20% had serum phosphorus ≥5.5 to <6.5 mg/dL, and 17% had serum phosphorus ≥6.5 mg/dL. Compared with patients with baseline serum phosphorus ≥3.5 to ≤4.5 mg/dL, the adjusted all-cause mortality hazard ratio (HR) was 1.19 (0.92,1.53) for patients with baseline serum phosphorus ≥5.5 to <6.5 mg/dL and HR was 1.53 (1.14,2.05) for serum phosphorus ≥6.5 mg/dL. Associations between serum phosphorus measurements over 6 months and clinical outcomes were even stronger than for a single measurement. CONCLUSIONS: Serum phosphorus >5.5 mg/dL was highly prevalent (37%) in PD patients, and higher serum phosphorus levels were a strong predictor of morbidity and death, particularly when considering serial phosphorus measurements. This highlights the need for improved treatment strategies in this population. Serial serum phosphorus measurements should be considered when assessing patients' risks of adverse outcomes.

Utility of a Single Itch-Related Question and the Skindex-10 Questionnaire for Assessing Pruritus and Predicting Health-Related Quality of Life in Patients Receiving Hemodialysis.

Rationale & Objective: Chronic kidney disease-associated pruritus has been linked with poorer mental and physical health-related quality of life (HR-QOL) in patients receiving hemodialysis. We used the Skindex-10 questionnaire and a single itch-related question to evaluate their prediction of HR-QOL. Study Design: Prospective, international cohort. Setting & Participants: We analyzed data from 4,940 patients receiving hemodialysis from 17 countries enrolled in phase 5 (2013) of the Dialysis Outcomes and Practice Patterns Study. Predictors: The responses to the 10 questions of Skindex-10 (0-6 scale) pertaining to itchiness in the past week were summed to create a summary score (range, 0-60). Concurrently, a single question from the Kidney Disease Quality of Life 36-item survey asked "during the past 4 weeks, to what extent were you bothered by itchy skin?" with 5 responses, ranging from "not at all" to "extremely" bothered. Outcomes: Physical component summary (PCS) and mental component summary (MCS) scores of HR-QOL. Analytical Approach: We used separate linear regression models to evaluate the predictive power, based on R2 values, for 3 models: 1 for each predictor and 1 with both predictors. Results: The correlation between the single itch-related question and the Skindex-10 score was 0.72. A 10-point higher Skindex-10 score was associated with a 1.2-point lower PCS score (95% CI, -1.4 to -0.9) and a 1.5-point lower MCS score (95% CI, -1.7 to -1.3) . The R2 value for PCS was 0.065 when the single question was used and only 0.033 when Skindex-10 was used as the predictor; the R2 value for MCS was 0.056 for the single question versus 0.052 for Skindex-10. Limitations: Measurement bias and translation issues in the questionnaires. Conclusions: The single question about the extent to which the patients were bothered by itchy skin was highly correlated with the Skindex-10 score and at least as predictive of key HR-QOL measures. In daily clinical practice, using 1 simple question about the extent to which patients are bothered by itchy skin can be a feasible and efficient method for the routine assessment of pruritus.

Etelcalcetide Versus Cinacalcet in Hemodialysis Patients in the United States: A Facility Calcimimetic Approach to Assess Real-World Effectiveness.

Rationale & Objective: Some US hemodialysis (HD) facilities switched from oral cinacalcet to intravenous etelcalcetide as the primary calcimimetic therapy to control parathyroid hormone (PTH) levels after the introduction of etelcalcetide in 2017. Although clinical trials have demonstrated the superior efficacy of etelcalcetide versus cinacalcet, evidence comparing real-world effectiveness is lacking. Study Design: Prospective cohort. Setting & Participants: Patients receiving HD enrolled in US Dialysis Outcomes and Practice Patterns Study facilities. Exposure: We classified HD facilities on the basis of whether >75% of calcimimetic users were prescribed etelcalcetide ("etelcalcetide-first") or cinacalcet ("cinacalcet-first") from March-August 2019. Outcomes: PTH, calcium, and phosphorus levels among calcimimetic users, all averaged in the 6 months after the exposure assessment period. Analytical Approach: We used adjusted linear regression to compare outcomes using 2 approaches: (1) cross-sectional comparison of etelcalcetide-first and cinacalcet-first HD facilities; (2) pre-post comparison of HD facilities that switched from cinacalcet-first to etelcalcetide-first using facilities that remained cinacalcet-first as a comparison group. Results: We identified 45 etelcalcetide-first and 67 cinacalcet-first HD facilities; etelcalcetide-first (vs cinacalcet-first) facilities were more likely to be from small or independent dialysis organizations (86% vs 22%) and had higher total calcimimetic use (43% vs 29%) and lower active vitamin D use (66% vs 82%). In the cross-sectional analysis comparing etelcalcetide-first and cinacalcet-first HD facilities, the adjusted mean difference in PTH levels was -115 pg/mL (95% CI, -196 to -34) and the prevalence of a PTH level of >600 pg/mL was lower (prevalence difference, -11.4%; 95% CI, -19.3% to -3.5%). Among facilities that switched to etelcalcetide-first, the mean PTH level decreased from 671 to 484 pg/mL and the prevalence of a PTH level of >600 pg/mL decreased from 39% to 21%. Among facilities that remained cinacalcet-first, the mean PTH level increased from 632 to 698 pg/mL and the prevalence of a PTH level of >600 pg/mL increased from 37% to 43%. The adjusted difference-in-difference between the switch to etelcalcetide-first and the continuation of cinacalcet-first was -169 pg/mL (-249 to -90 pg/mL) for the mean PTH and -14.4% (-22.0% to -6.8%) for a PTH level of >600 pg/mL. We also observed slightly lower serum calcium levels and minimal differences in serum phosphorus levels between the etelcalcetide-first and the cinacalcet-first facilities. Limitations: Residual confounding. Conclusions: We observed better PTH control in HD facilities that switched from using cinacalcet to etelcalcetide as the primary calcimimetic therapy. Further research is needed to investigate how the greater real-world effectiveness of intravenous etelcalcetide (vs oral cinacalcet) may affect clinical outcomes.

Resistance to Erythropoiesis-Stimulating Agents among Patients on Hemodialysis Is Typically Transient.

INTRODUCTION: This study examines factors associated with erythropoiesis-stimulating agent (ESA) hyporesponsiveness, the duration of ESA hyporesponsiveness, the frequency of new episodes, and variation across countries. METHODS: We used international Dialysis Outcomes and Practice Patterns Study data from 2015 to 2018 (N = 26,656) to investigate changes in ESA Resistance Index (ERI), calculated as epoetin dose divided by [hemoglobin × body weight] in patients on hemodialysis. We illustrated the proportion of patients who moved to other ERI quintiles over 12 months, and we studied the incidence and duration of ESA resistance. We examined case-mix factors associated with quintiles of ERI. RESULTS: Most patients migrated out of their original ERI quintile within 4 months. Only 22% of patients in the top quintile of ERI at baseline (4.4% of all patients) remained in the top quintile during all 12 months of follow-up. A total of 42% of patients manifested an upper-quintile ERI during at least 1 month. Median duration of a new episode of ESA resistance was 2 months. Catheter hemoaccess, elevated C-reactive protein, lower transferrin saturation, lower serum albumin concentration, and recent hospitalization occurred more frequently among patients in the highest ERI quintile at baseline. ERI values were highest in the USA, Italy, and Mideastern nations and lowest in Russia and Japan. DISCUSSION/CONCLUSION: It is a misconception to envision a sizable, fixed segment of the population with permanent resistance to ESA - resistance fluctuates frequently. The implications of these findings for prescription of ESAs and of hypoxia-inducible factor-prolyl hydroxylase inhibitors are discussed.

Etelcalcetide Utilization, Dosing Titration, and Chronic Kidney Disease-Mineral and Bone Disease (CKD-MBD) Marker Responses in US Hemodialysis Patients.

RATIONALE & OBJECTIVE: Clinical trial data have demonstrated the efficacy of etelcalcetide for reducing parathyroid hormone (PTH) levels in hemodialysis (HD) patients. We provide a real-world summary of etelcalcetide utilization, dosing, effectiveness, and discontinuation since its US introduction in April 2017. STUDY DESIGN: New-user design within prospective cohort. SETTING & PARTICIPANTS: 2,596 new users of etelcalcetide from April 2017 through August 2019 in a national sample of adult maintenance HD patients in the US Dialysis Outcomes and Practice Patterns Study (DOPPS). PREDICTORS: Baseline PTH, prior cinacalcet use, initial etelcalcetide dose. OUTCOME: Trajectories of etelcalcetide dose, chronic kidney disease-mineral and bone disease (CKD-MBD) medications, and levels of PTH, serum calcium, and phosphorus in the 12 months after etelcalcetide initiation. ANALYTICAL APPROACH: Cumulative incidence methods for etelcalcetide discontinuation and linear generalized estimating equations for trajectory analyses. RESULTS: By August 2019, etelcalcetide prescriptions increased to 6% of HD patients from their first use in April 2017. Starting etelcalcetide dose was 15 mg/wk in 70% of patients and 7.5 mg/wk in 27% of patients; 49% of new users were prescribed cinacalcet in the prior 3 months. Etelcalcetide discontinuation was 9%, 17%, and 27% by 3, 6, and 12 months after initiation. One year after etelcalcetide initiation, mean PTH levels declined by 40%, from 948 to 566 pg/mL, and the proportion of patients with PTH within target (150-599 pg/mL) increased from 33% to 64% overall, from 0 to 60% among patients with baseline PTH ≥ 600 pg/mL, and from 30% to 63% among patients with prior cinacalcet use. The proportion of patients with serum phosphorus > 5.5 mg/dL decreased from 55% to 45%, while the prevalence of albumin-corrected serum calcium < 7.5 mg/dL remained at 1%-2%. There were increases in use of active vitamin D (from 77% to 87%) and calcium-based phosphate binders (from 41% to 50%) in the 12 months after etelcalcetide initiation. LIMITATIONS: Data are unavailable for provider dosing protocols, dose holds, or reasons for discontinuation. CONCLUSIONS: In the 12 months after etelcalcetide initiation, patients had large and sustained reductions in PTH levels. These results support the utility of etelcalcetide as an effective therapy to achieve the KDIGO-recommended guidelines for CKD-MBD markers in HD patients.

Hyperkalemia excursions are associated with an increased risk of mortality and hospitalizations in hemodialysis patients.

BACKGROUND: Hyperkalemia is common among hemodialysis (HD) patients and has been associated with adverse clinical outcomes. Previous studies considered a single serum potassium (K) measurement or time-averaged values, but serum K excursions out of the target range may be more reflective of true hyperkalemia events. We assessed whether hyperkalemia excursions lead to an elevated risk of adverse clinical outcomes. METHODS: Using data from 21 countries in Phases 4-6 (2009-18) of the Dialysis Outcomes and Practice Patterns Study (DOPPS), we investigated the associations between peak serum K level, measured monthly predialysis, over a 4-month period ('peak K') and clinical outcomes over the subsequent 4 months using Cox regression, adjusted for potential confounders. RESULTS: The analysis included 62 070 patients contributing a median of 3 (interquartile range 2-6) 4-month periods. The prevalence of hyperkalemia based on peak K was 58% for >5.0, 30% for >5.5 and 12% for >6.0 mEq/L. The all-cause mortality hazard ratio for peak K (reference ≤5.0 mEq/L) was 1.15 [95% confidence interval (CI) 1.09, 1.21] for 5.1-5.5 mEq/L, 1.19 (1.12, 1.26) for 5.6-6.0 mEq/L and 1.33 (1.23, 1.43) for >6.0 mEq/L. Results were qualitatively consistent when analyzing hospitalizations and a cardiovascular composite outcome. CONCLUSIONS: Among HD patients, we identified a lower K threshold (peak K 5.1-5.5 mEq/L) than previously reported for increased risk of hospitalization and mortality, with the implication that a greater proportion (>50%) of the HD population may be at risk. A reassessment of hyperkalemia severity ranges is needed, as well as an exploration of new strategies for effective management of chronic hyperkalemia.

The Role of Place in Disparities Affecting Black Men Receiving Hemodialysis.

INTRODUCTION: Black men are over-represented in the end stage kidney disease population and are at disproportionate risk of unfavorable outcomes. There is a paucity of investigation to elucidate the mediators of this risk. This study attempts to identify residential community attributes as a possible contributor. METHODS: A post-hoc analysis of prospectively collected data from a cohort of Black men enrolled in the US Dialysis Outcomes and Practice Patterns Study (DOPPS), 2010--2015, linked to the American Community Survey, by dialysis facility zip codes was undertaken. The exposure variable was the dialysis facility community composition as defined by percent Black residents. Negative binomial regression was used to estimate incidence rate ratio (IRR) of hospitalization (first outcome) for Black men in crude and adjusted models. Similarly, Cox proportional hazards modeling was used to estimate mortality (second outcome) for Black men by type of community. RESULTS: A total of 702 Black men receiving chronic hemodialysis were included in the study. Black men receiving hemodialysis in communities with greater proportions of Black residents had lower Charlson scores and fewer comorbidities, but a higher rate of hypertension. They had equivalent adherence to dialysis treatments, but a lower rate of arteriovenous fistula use and fewer dialysis minutes prescribed. Black men receiving dialysis in communities with a greater proportion of Black residents (per 10% increase) had higher adjusted hospitalization rates (IRR 1.09, 95% confidence interval [CI] 1.00-1.19) and mortality (hazard ratio [HR] 1.29, 95% CI 1.05-1.59). CONCLUSIONS: This study supports the unique role of residential community as a risk factor for Black men with end stage kidney disease, showing higher hospitalization and mortality in those treating in Black versus non-Black communities, despite equivalent adherence and fewer comorbidities.

Self-reported Pruritus and Clinical, Dialysis-Related, and Patient-Reported Outcomes in Hemodialysis Patients.

RATIONALE & OBJECTIVE: Chronic kidney disease (CKD)-associated pruritus, generalized itching related to CKD, affects many aspects of hemodialysis patients' lives. However, information regarding the relationship between pruritus and several key outcomes in hemodialysis patients remains limited. STUDY DESIGN: Prospective cohort. SETTING & PARTICIPANTS: 23,264 hemodialysis patients from 21 countries in the Dialysis Outcomes and Practice Patterns Study (DOPPS) phases 4 to 6 (2009-2018). EXPOSURE: Pruritus severity, based on self-reported degree to which patients were bothered by itchy skin (5-category ordinal scale from "not at all" to "extremely"). OUTCOMES: Clinical, dialysis-related, and patient-reported outcomes. ANALYTICAL APPROACH: Cox regression for time-to-event outcomes and modified Poisson regression for binary outcomes, adjusted for potential confounders. RESULTS: The proportion of patients at least moderately bothered by pruritus was 37%, and 7% were extremely bothered. Compared with the reference group ("not at all"), the adjusted mortality HR for patients extremely bothered by pruritus was 1.24 (95% CI, 1.08-1.41). Rates of cardiovascular and infection-related deaths and hospitalizations were also higher for patients extremely versus not at all bothered by pruritus (HR range, 1.17-1.44). Patients extremely bothered by pruritus were also more likely to withdraw from dialysis and miss hemodialysis sessions and were less likely to be employed. Strong monotonic associations were observed between pruritus severity and longer recovery time from a hemodialysis session, lower physical and mental quality of life, increased depressive symptoms, and poorer sleep quality. LIMITATIONS: Residual confounding, recall bias, nonresponse bias. CONCLUSIONS: Our findings demonstrate how diverse and far-reaching poor outcomes are for patients who experience CKD-associated pruritus, specifically those with more severe pruritus. There is need for change in practice patterns internationally to effectively identify and treat patients with pruritus to reduce symptom burden and improve quality of life and possibly even survival.