Kidney Function Decline and Serious Adverse Drug Reactions in Patients With CKD

RATIONALE & OBJECTIVE

Adverse drug reactions (ADRs) are common in patients with chronic kidney disease (CKD). The impact of kidney function decline on serious ADR risk has been poorly investigated. We comprehensively describe ADRs and assess the relationship between estimated glomerular filtration rate (eGFR) and serious ADR risk.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

3,033 participants in French Chronic Kidney Disease-Renal Epidemiology and Information Network (CKD-REIN) cohort study, a nationwide sample of nephrology outpatients with moderate to advanced CKD.

PREDICTORS

Demographic and biological data (including eGFR), medication prescriptions.

OUTCOME

ADRs (preventable or not) were prospectively identified from hospital discharge reports, medical records, and patient interviews. Expert pharmacologists used validated tools to adjudicate ADRs.

ANALYTICAL APPROACH

Restricted cubic splines in fully adjusted cause-specific Cox proportional hazard models were used to evaluate the relationship between eGFR and the risk of serious ADRs (overall and by subtype).

RESULTS

During a median follow-up period of 4.7 years, 360 patients experienced 488 serious ADRs. Kidney and urinary disorders (n=170) and hemorrhage (n=170) accounted for 70% of serious ADRs. The most common medications classes were antithrombotics and renin-angiotensin system inhibitors. The majority of those serious ADRs were associated with hospitalization (n=467), with 32 directly or indirectly associated with death and 22 associated with a life-threatening event. More than 27% of the 488 serious ADRs were preventable or potentially preventable. The eGFR is a major risk factor for serious ADRs. The risk of acute kidney injury was 2.2% higher and risk of bleeding ADRs was 8% higher for each 1mL/min/1.73m2 lower baseline eGFR.

LIMITATIONS

The results cannot be extrapolated to patients who are not being treated by a nephrologist.

CONCLUSIONS

ADRs constitute a major cause of hospitalization in CKD patients for whom lower eGFR level is a major risk factor.

PLAIN-LANGUAGE SUMMARY

Patients with chronic kidney disease (CKD) have complex clinical presentations, take multiple medications, and often receive inappropriate prescriptions. Using data from a large, prospective CKD cohort, we found a high incidence of serious adverse drug reactions (ADRs). The 2 most common serious ADRs were drug-induced acute kidney injury and bleeding. A large proportion of serious ADRs required hospital admission, and 11% led to death or were life threatening. Lower kidney function was a major risk factor for serious ADRs. Many of these serious ADRs were determined to be partly preventable through greater adherence to prescription guidelines. This report enhances our understanding of the potential toxicity of drugs taken by patients with moderate to advanced CKD. It emphasizes the importance of monitoring kidney function when prescribing drugs, particularly for high-risk medications such as antithrombotic agents.

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.

Association of COVID-19 Versus COVID-19 Vaccination With Kidney Function and Disease Activity in Primary Glomerular Disease: A Report of the Cure Glomerulonephropathy Study

RATIONALE & OBJECTIVE

Patients with glomerular disease (GN) may be at increased risk of severe COVID-19, yet concerns over vaccines causing disease relapse may lead to vaccine hesitancy. We examined the associations of COVID-19 with longitudinal kidney function and proteinuria and compared these with similar associations with COVID-19 vaccination.

STUDY DESIGN

Observational cohort study from July 1, 2021, to January 1, 2023.

SETTING & PARTICIPANTS

A prospective observational study network of 71 centers from North America and Europe (CureGN) with children and adults with primary minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, or IgA nephropathy.

EXPOSURE

COVID-19 and COVID-19 vaccination.

OUTCOME

Repeated measure of estimated glomerular filtration rate (eGFR); recurrent time-to-event outcome of GN disease worsening as defined by doubling of the urinary protein-creatinine ratio (UPCR) to at least 1.5g/g or increase in dipstick urine protein by 2 ordinal levels to 3+(300mg/dL) or above.

ANALYTICAL APPROACH

Interrupted time series analysis for eGFR. Prognostic matched sequential stratification recurrent event analysis for GN disease worsening.

RESULTS

Among 2,055 participants, 722 (35%) reported COVID-19 infection; of these, 92 (13%) were hospitalized, and 3 died (<1%). The eGFR slope before COVID-19 infection was-1.40mL/min/1.73m2 (± 0.29 SD); within 6 months after COVID-19 infection, the eGFR slope was-4.26mL/min/1.73m2 (± 3.02 SD), which was not significantly different (P=0.34). COVID-19 was associated with increased risk of worsening GN disease activity (HR, 1.35 [95% CI, 1.01-1.80]). Vaccination was not associated with a change in eGFR (-1.34mL/min/1.73m2±0.15 SD vs-2.16mL/min/1.73m2±1.74 SD; P=0.6) or subsequent GN disease worsening (HR 1.02 [95% CI, 0.79-1.33]) in this cohort.

LIMITATIONS

Infrequent or short follow-up.

CONCLUSIONS

Among patients with primary GN, COVID-19 infection was severe for 1 in 8 cases and was associated with subsequent worsening of GN disease activity, as defined by proteinuria. By contrast, vaccination against COVID-19 was not associated with change in disease activity or kidney function decline. These results support COVID-19 vaccination for patients with GN.

PLAIN-LANGUAGE SUMMARY

In this cohort study of 2,055 patients with minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, or IgA nephropathy, COVID-19 resulted in hospitalization or death for 1 in 8 cases and was associated with a 35% increase in risk for worsening proteinuria. By contrast, vaccination did not appear to adversely affect kidney function or proteinuria. Our data support vaccination for COVID-19 in patients with glomerular disease.

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).

Utility of the Kidney Failure Risk Equation and Estimated GFR for Estimating Time to Kidney Failure in Advanced CKD

RATIONALE & OBJECTIVE

The Kidney Failure Risk Equation (KFRE) predicts the 2-year risk of kidney failure for patients with chronic kidney disease (CKD). Translating KFRE-predicted risk or estimated glomerular filtration rate (eGFR) into time to kidney failure could inform decision making for patients approaching kidney failure.

STUDY DESIGN

Retrospective cohort.

SETTING & PARTICIPANTS

CKD Outcomes and Practice Patterns Study (CKDOPPS) cohort of patients with an eGFR<60mL/min/1.73m2 from 34 US nephrology practices (2013-2021).

EXPOSURE

2-year KFRE risk or eGFR.

OUTCOME

Kidney failure defined as initiation of dialysis or kidney transplantation.

ANALYTICAL APPROACH

Accelerated failure time (Weibull) models used to estimate the median, 25th, and 75th percentile times to kidney failure starting from KFRE values of 20%, 40%, and 50%, and from eGFR values of 20, 15, and 10mL/min/1.73m2. We examined variability in time to kidney failure by age, sex, race, diabetes status, albuminuria, and blood pressure.

RESULTS

Overall, 1,641 participants were included (mean age 69±13 years; median eGFR of 28mL/min/1.73m2 [IQR 20-37mL/min/1.73 m2]). Over a median follow-up period of 19 months (IQR, 12-30 months), 268 participants developed kidney failure, and 180 died before reaching kidney failure. The median estimated time to kidney failure was widely variable across patient characteristics from an eGFR of 20mL/min/1.73m2 and was shorter for younger age, male sex, Black (versus non-Black), diabetes (vs no diabetes), higher albuminuria, and higher blood pressure. Estimated times to kidney failure were comparably less variable across these characteristics for KFRE thresholds and eGFR of 15 or 10mL/min/1.73m2.

LIMITATIONS

Inability to account for competing risks when estimating time to kidney failure.

CONCLUSIONS

Among those with eGFR<15mL/min/1.73m2 or KFRE risk>40%), both KFRE risk and eGFR showed similar relationships with time to kidney failure. Our results demonstrate that estimating time to kidney failure in advanced CKD can inform clinical decisions and patient counseling on prognosis, regardless of whether estimates are based on eGFR or the KFRE.

PLAIN-LANGUAGE SUMMARY

Clinicians often talk to patients with advanced chronic kidney disease about the level of kidney function expressed as the estimated glomerular filtration rate (eGFR) and about the risk of developing kidney failure, which can be estimated using the Kidney Failure Risk Equation (KFRE). In a cohort of patients with advanced chronic kidney disease, we examined how eGFR and KFRE risk predictions corresponded to the time patients had until reaching kidney failure. Among those with eGFR<15mL/min/1.73m2 or KFRE risk > 40%), both KFRE risk and eGFR showed similar relationships with time to kidney failure. Estimating time to kidney failure in advanced CKD using either eGFR or KFRE can inform clinical decisions and patient counseling on prognosis.

Availability and prioritisation of COVID-19 vaccines among patients with advanced chronic kidney disease and kidney failure during the height of the pandemic: a global survey by the International Society of Nephrology

OBJECTIVE

Patients with advanced chronic kidney disease (CKD) or kidney failure receiving replacement therapy (KFRT) are highly vulnerable to COVID-19 infection, morbidity and mortality. Vaccination is effective, but access differs around the world. We aimed to ascertain the availability, readiness and prioritisation of COVID-19 vaccines for this group of patients globally.

SETTING AND PARTICIPANTS

Collaborators from the International Society of Nephrology (ISN), Dialysis Outcomes and Practice Patterns Study and ISN-Global Kidney Health Atlas developed an online survey that was administered electronically to key nephrology leaders in 174 countries between 2 July and 4 August 2021.

RESULTS

Survey responses were received from 99 of 174 countries from all 10 ISN regions, among which 88/174 (50%) were complete. At least one vaccine was available in 96/99 (97%) countries. In 71% of the countries surveyed, patients on dialysis were prioritised for vaccination, followed by patients living with a kidney transplant (KT) (62%) and stage 4/5 CKD (51%). Healthcare workers were the most common high priority group for vaccination. At least 50% of patients receiving in-centre haemodialysis, peritoneal dialysis or KT were estimated to have completed vaccination at the time of the survey in 55%, 64% and 51% of countries, respectively. At least 50% of patients in all three patient groups had been vaccinated in >70% of high-income countries and in 100% of respondent countries in Western Europe.The most common barriers to vaccination of patients were vaccine hesitancy (74%), vaccine shortages (61%) and mass vaccine distribution challenges (48%). These were reported more in low-income and lower middle-income countries compared with high-income countries.

CONCLUSION

Patients with advanced CKD or KFRT were prioritised in COVID-19 vaccination in most countries. Multiple barriers led to substantial variability in the successful achievement of COVID-19 vaccination across the world, with high-income countries achieving the most access and success.

Regional differences in the reduction in cerebral FDG uptake induced by the ketogenic diet

BACKGROUND

The postulated benefits of the ketogenic diet in the management of multiple medical conditions have seen more patients who are in therapeutic ketosis attending 18F-FDG PET scans. This study aimed to investigate the effect of ketosis on cerebral glucose metabolism in a clinical PET scanning environment using 18F-FDG uptake as a surrogate marker.

METHODS

A retrospective audit was conducted of the brain 18F-FDG uptake in 52 patients who underwent PET scans for possible cardiac sarcoidosis or suspected intracardiac infection, following a ketogenic diet and prolonged fasting. SUVbw for whole brain and separate brain regions was compared with serum glucose and serum ketone body (beta-hydroxybutyrate) levels.

RESULTS

The expected negative association between serum glucose levels and whole brain 18F-FDG uptake was confirmed. A reduction in SUVbw due to increasing serum ketones levels was also observed that was independent of and in addition to the effects of glucose. The magnitude of the reduction in SUVbw related to serum glucose level and serum ketone level was found to be greater in the precuneus than in the cerebellum or whole brain.

CONCLUSION

In a real-world clinical PET setting, cerebral 18F-FDG uptake appears to be affected by glycaemia and ketonaemia. This means when assessing the brain, both serum glucose and ketone levels need to be considered when SUVs are used to distinguish between pathologic and physiologic states. The magnitude of this effect appears to vary between different brain regions. This regional difference should be taken into consideration when selecting the appropriate brain region for SUV normalisation, particularly when undertaking database comparison in the assessment of dementia.

Serum Phosphorus Level Rises in US Hemodialysis Patients Over the Past Decade: A DOPPS Special Report

Mineral bone disorder (MBD) is a frequent consequence of chronic kidney disease, more so in patients with kidney failure treated by kidney replacement therapy. Despite the wide availability of interventions to control serum phosphate and parathyroid hormone levels, unmet gaps remain on optimal targets and best practices, leading to international practice pattern variations over time. In this Special Report, we describe international trends from the Dialysis Outcomes and Practice Patterns Study (DOPPS) for MBD biomarkers and treatments from 2002-2021, including data from a group of 7 European countries (Belgium, France, Germany, Italy, Spain, Sweden, United Kingdom), Japan, and the United States. From 2002-2012, mean phosphate levels declined in Japan (5.6 to 5.2 mg/dL), Europe (5.5 to 4.9 mg/dL), and the United States (5.7 to 5.0 mg/dL). Since then, levels rose in the United States (to mean 5.6 mg/dL, 2021), were stable in Japan (5.3 mg/dL), and declined in Europe (4.8 mg/dL). In 2021, 52% (United States), 27% (Europe), and 39% (Japan) had phosphate >5.5 mg/dL. In the United States, overall phosphate binder use was stable (80%-84% over 2015-2021), and parathyroid hormone levels rose only modestly. Although these results potentially stem from pervasive knowledge gaps in clinical practice, the noteworthy steady increase in serum phosphate in the United States over the past decades may be consequential to patient outcomes, an uncertainty that hopefully will soon be addressed by ongoing clinical trials. The DOPPS will continue to monitor international trends as new interventions and strategies ensue for MBD management in chronic kidney disease.

Hemoglobin and Clinical Outcomes in Hemodialysis: An Analysis of US Medicare Data From 2018 to 2020

Rationale & Objective

Anemia management in patients treated with maintenance dialysis remains a challenge. We sought to update information in this area by evaluating the association between hemoglobin and various outcome and utilization measures using data-rich Medicare sources.

Study Design

Observational cohort study using data from the Consolidated Renal Operations in a Web-enabled Network and Medicare claims.

Setting & Participants

We studied 371,250 prevalent patients treated with hemodialysis, covering 3,326,072 patient-months in 2019.

Exposure

Monthly patient hemoglobin concentrations.

Outcomes

We examined several outcomes, including mortality, all-cause hospitalization, cause-specific hospitalization, and emergency department utilization in the month following the exposure measurement.

Analytical Approach

For each monthly observation period, we calculated unadjusted and adjusted (for demographics and comorbid condition) hazard ratios using Cox regression.

Results

The hemoglobin concentration was <10.5 g/dL for 40% of observations. We found an inverse association between mortality and hemoglobin measured over a range from <9 g/dL (HR, 2.53; 95% CI, 2.45-2.61; P < 0.0001, reference = 10.5-11 g/dL) to 11-11.5 g/dL (HR, 0.92; 95% CI, 0.89-0.96; P < 0.0001). Mortality risk started to increase at hemoglobin levels >11.5 g/dL. All-cause hospitalization, cause-specific hospitalization (including cardiovascular, infection, and several subcategories including coronavirus disease 2019 hospitalization), and emergency department utilization were inversely associated with hemoglobin concentration, with risk reduction stabilizing at hemoglobin levels of approximately 11.5-12 g/dL and higher.

Limitations

As with prior observational studies, the observed associations are not necessarily causal.

Conclusions

In a large US hemodialysis population, there were better clinical outcomes at higher hemoglobin concentrations over short exposure and follow-up periods, consistent with other observational studies that generally used longer exposure and follow-up times. Mortality risk increased at hemoglobin concentrations >11.5 g/dL, consistent with findings from erythropoiesis-stimulating agent clinical trials. The apparently beneficial short-term effects associated with higher hemoglobin concentrations suggest that hemoglobin measurements capture unmeasured elements of patient risk.

Barriers to conservative care from patients' and nephrologists' perspectives: the CKD-REIN study

BACKGROUND

Conservative care is increasingly considered an alternative to kidney replacement therapy for kidney failure management, mostly among the elderly. We investigated its status and the barriers to its implementation from patients' and providers' perspectives.

METHODS

We analysed data from 1204 patients with advanced chronic kidney disease (CKD) [estimated glomerular filtration rate (eGFR) <30 mL/min/1.73 m2] enrolled at 40 nationally representative nephrology clinics (2013-16) who completed a self-administered questionnaire about the information they received and their preferred treatment option, including conservative care, if their kidneys failed. Nephrologists (n = 137) also reported data about their clinics' resources and practices regarding conservative care.

RESULTS

All participating facilities reported they were routinely able to offer conservative care, but only 37% had written protocols and only 5% had a person or team primarily responsible for it. Overall, 6% of patients were estimated to use conservative care. Among nephrologists, 82% reported they were fairly or extremely comfortable discussing conservative care, but only 28% usually or always offered this option for older (>75 years) patients approaching kidney failure. They used various terminology for this care, with conservative management and non-dialysis care mentioned most often. Among patients, 5% of those >75 years reported receiving information about this option and 2% preferring it.

CONCLUSIONS

Although reported by nephrologists to be widely available and easily discussed, conservative care is only occasionally offered to older patients, most of whom report they were not informed of this option. The lack of a person or team responsible for conservative care and unclear information appear to be key barriers to its implementation.

Patiromer utilization in patients with advanced chronic kidney disease under nephrology care in Germany

Background

Hyperkalemia (HK) is a frequent condition in patients with chronic kidney disease (CKD) that is associated with high morbidity and mortality. Patiromer has recently been introduced as a potassium binder. Data on patiromer use in patients with CKD in the real-world setting in Europe are lacking. We describe time to discontinuation and changes in serum potassium levels among German CKD stage 3-5 patients starting patiromer.

Methods

Duration of patiromer use was estimated by Kaplan-Meier curve, starting at patiromer initiation and censoring for death, dialysis, transplant or loss to follow-up. Serum potassium levels and renin-angiotensin-aldosterone system inhibitor (RAASi) use are described at baseline and during follow-up, restricted to patients remaining on patiromer.

Results

We identified 140 patiromer users within our analysis sample [81% CKD stage 4/5, 83% receiving RAASi, and median K+ 5.7 (5.4, 6.3) mmol/L]. Thirty percent of patiromer users had prior history of polystyrene sulfonate use. Overall, 95% of patiromer users stayed on treatment past 1 month, with 53% continuing for over a year. Mean serum potassium levels decreased after patiromer initiation and remained stable under treatment during follow-up (up to 180 days). Among these patients, 73%-82% used RAASis during the time periods before and after patiromer initiation, with no obvious trend indicating discontinuation.

Conclusion

Real-world evidence of patiromer use in Germany shows that, in line with what has been observed in clinical trials, patients on patiromer have a reduction in serum potassium when used long-term. Moreover, most patients on patiromer do not discontinue treatment prior to 1 year after initiation.

Variation in Peritoneal Dialysis Time on Therapy by Country: Results from the Peritoneal Dialysis Outcomes and Practice Patterns Study

BACKGROUND AND OBJECTIVES

Quantifying contemporary peritoneal dialysis time on therapy is important for patients and providers. We describe time on peritoneal dialysis in the context of outcomes of hemodialysis transfer, death, and kidney transplantation on the basis of the multinational, observational Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS) from 2014 to 2017.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Among 218 randomly selected peritoneal dialysis facilities (7121 patients) in the PDOPPS from Australia/New Zealand, Canada, Japan, Thailand, the United Kingdom, and the United States, we calculated the cumulative incidence from peritoneal dialysis start to hemodialysis transfer, death, or kidney transplantation over 5 years and adjusted hazard ratios for patient and facility factors associated with death and hemodialysis transfer.

RESULTS

Median time on peritoneal dialysis ranged from 1.7 (interquartile range, 0.8-2.9; the United Kingdom) to 3.2 (interquartile range, 1.5-6.0; Japan) years and was longer with lower kidney transplantation rates (range: 32% [the United Kingdom] to 2% [Japan and Thailand] over 3 years). Adjusted hemodialysis transfer risk was lowest in Thailand, but death risk was higher in Thailand and the United States compared with most countries. Infection was the leading cause of hemodialysis transfer, with higher hemodialysis transfer risks seen in patients having psychiatric disorder history or elevated body mass index. The proportion of patients with total weekly Kt/V ≥1.7 at a facility was not associated with death or hemodialysis transfer.

CONCLUSIONS

Countries in the PDOPPS with higher rates of kidney transplantation tended to have shorter median times on peritoneal dialysis. Identification of infection as a leading cause of hemodialysis transfer and patient and facility factors associated with the risk of hemodialysis transfer can facilitate interventions to reduce these events.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2022_05_31_CJN16341221.mp3.

Diabetes Prevalence, Treatment, Control, and Outcomes Among Hemodialysis Patients in the Gulf Cooperation Council Countries

INTRODUCTION

Diabetes mellitus (DM) is a leading cause of end-stage kidney disease (ESKD). We provide the first description of DM prevalence, related outcomes, and the hemoglobin A1c (HbA1c)/mortality relationship in national hemodialysis (HD) patient samples across the Gulf Cooperation Council (GCC) countries.

METHODS

We analyzed data from the prospective Dialysis Outcomes and Practice Patterns Study (DOPPS) in the GCC (2012-2018, N = 2274 HD patients ≥18 years old). Descriptive statistics were calculated, and all-cause mortality was analyzed for patients with DM versus without DM and by HbA1c levels in patients with DM by Cox regression with progressive confounder adjustments.

RESULTS

DM in the GCC ranged from 45% to 74% in patients with HD by country. Patients with DM were 13 years older (59.9 vs. 46.7 years) and had greater body mass index (BMI), shorter median years on dialysis (1.5 vs. 3.0 years), and higher comorbidity burden. In patients with DM, insulin use was 26% to 50% across countries, with variable oral antidiabetic drug use (2%-32%); median HbA1c levels were 6.1% to 7.5% across countries. Patients with DM (vs. without DM) had higher crude death rates (15.6 vs. 6.2 deaths per 100 patient-years, mean follow-up 1.3 years) and adjusted mortality (hazard ratio [HR] = 1.72 [95% CI 1.23-2.39]). In patients with DM, mortality was lowest at HbA1c 6.5% to 7.5%, with mortality particularly elevated at high HbA1c >9% (HR = 2.13 [95% CI 1.10-4.10]).

CONCLUSION

Patients with DM in the GCC have high comorbidity burden and mortality rates despite a relatively young mean age. In GCC countries, a holistic strategy for improving diabetes care and outcomes for HD patients is needed at the primary, secondary, and tertiary levels.

An Investigation into Possible Sex Differences in Association of Hemoglobin with Survival Among Hemodialysis Patients in the J-DOPPS Cohort

AIMS

Lower hemoglobin levels are common among females without kidney diseases. However, little is known about the sex-specific management of anemia in hemodialysis patients.

METHODS

This prospective cohort study investigated the role of sex differences in the association between categorical baseline or time-varying hemoglobin levels and all-cause mortality via cox regression using data from 6890 patients the Japan Dialysis Outcomes and Practice Patterns Study (J-DOPPS, 2005-2015). Likelihood ratio tests were used to evaluate the effect modification of sex on the relationship between hemoglobin and mortality.

RESULTS

A total of 781 patients died during the median follow-up of 31 months. Mortality risk, adjusted for case mix, varied between five hemoglobin categories, with the highest category (≥12 g/dl) having a hazard ratio of 0.73 (0.41-1.29) for females and 2.02 (1.03-3.95) for males versus 10-10.9 g/dl. Despite this difference, the p-value comparing the overall among males versus females was.35. Similar associations were observed in models stratified by patient age (<75 years), time on dialysis (≤1 year), and models lagging the hemoglobin exposure.

CONCLUSIONS

The results based on this sample of Japanese hemodialysis patients did not support the hypothesis that the association between hemoglobin and survival differed by sex. We also could not conclude that the association was identical, as the parameter estimates are consistent with male patients having a relatively greater mortality risk than female patients at higher hemoglobin levels. More detailed investigations into the effects of higher hemoglobin levels by sex might help better understand strategies for anemia management.

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.

Urea levels and cardiovascular disease in patients with chronic kidney disease

BACKGROUND

Elevated serum urea levels are common in moderate-to-advanced CKD. Several studies have shown that urea is a direct and indirect uremic toxin, especially with regard to cardiovascular disease. We sought to determine whether serum urea levels are associated with adverse cardiovascular events and death before renal replacement therapy (RRT) in patients with CKD.

METHODS

CKD-REIN is a prospective cohort of CKD nephrology outpatients not receiving maintenance dialysis. The 2507 patients included in the analysis were divided into three groups according to the baseline serum urea level (T1 < 10.5, T2:10.5 to 15.1, and T3 ≥ 15.1 mmol/L). Cox proportional hazard models were used to estimate hazard ratios (HRs) for first atheromatous or nonatheromatous cardiovascular (CV) events, and all-cause mortality before RRT. The models were adjusted for baseline comorbidities, laboratory data, and medications.

FINDINGS

Of the 2507 included patients (median [interquartile range (IQR)] age: 69[61-77]; mean (standard deviation) eGFR 33.5(11.6) mL/min/1.73 m²), 54% had a history of cardiovascular disease. After multiple adjustments for cardiovascular risk factors (including eGFR), patients in T3 had a higher risk of atheromatous and nonatheromatous cardiovascular events than patient in T1 (n events = 451, HR[95%CI]: 1.93[1.39-2.69]). The adjusted HRs for death before RRT (n events = 407) were 1.31[0.97; 1.76] and 1.73[1.22; 2.45] for patients T2 and those in T3, respectively.

INTERPRETATION

Our data suggested that urea is a predictor of cardiovascular outcomes beyond CV risk factors including eGFR.

Potential Surrogate Outcomes for Kidney Failure in Advanced CKD: Evaluation of Power and Predictive Ability in CKDopps

Rationale & Objective

Potential surrogate end points for kidney failure have been proposed in chronic kidney disease (CKD); however, they must be evaluated to ensure accurate, powerful, and harmonized research, particularly among patients with advanced CKD. The aim of the current study was to investigate the power and predictive ability of surrogate kidney failure end points in a population with moderate-to-advanced CKD.

Study Design

Analysis of longitudinal data of a large multinational CKD observational study (Chronic Kidney Disease Outcomes and Practice Patterns Study).

Setting & Participants

CKD stage 3-5 patients from Brazil, France, Germany, and the United States.

Outcomes

Reaching an estimated glomerular filtration rate (eGFR) < 15 mL/min/1.73 m² or eGFR decline of ≥40%, and composite end points of these individual end points.

Analytical Approach

Each end point was used as a time-varying indicator in the Cox model to predict the time to kidney replacement therapy (KRT; dialysis or transplant) and was compared by the number of events and prediction accuracy.

Results

8,211 patients had a median baseline eGFR of 27 mL/min/1.73 m² (interquartile range, 21-36 mL/min/1.73 m²) and 1,448 KRT events over a median follow-up of 2.7 years (interquartile range, 1.2-3.0 years). Among CKD stage 4 patients, the eGFR < 15 mL/min/1.73 m² end point had higher prognostic ability than 40% eGFR decline, but the end points were similar for CKD stage 3 patients. The combination of eGFR < 15 mL/min/1.73 m² and 40% eGFR decline had the highest prognostic ability for predicting KRT, regardless of the CKD stage. Including KRT in the composite can increase the number of events and, therefore, the power.

Limitations

Variable visit frequency resulted in variable eGFR measurement frequency.

Conclusions

The composite end point can be useful for CKD progression studies among patients with advanced CKD. Harmonized use of this approach has the potential to accelerate the translation of new discoveries to clinical practice by identifying risk factors and treatments for kidney failure.

Sex-Specific Differences in Mortality and Incident Dialysis in the Chronic Kidney Disease Outcomes and Practice Patterns Study

Introduction

More men than women start kidney replacement therapy (KRT) although the prevalence of chronic kidney disease (CKD) is higher in women than men. We therefore aimed at analyzing sex-specific differences in clinical outcomes among 8237 individuals with CKD in stages 3 to 5 from Brazil, France, Germany, and the United States participating in the Chronic Kidney Disease Outcomes and Practice Patterns Study (CKDopps).

Methods

Fine and Gray models, evaluating the effect of sex on time to events, were adjusted for age, Black race (model A); plus diabetes, cardiovascular disease, albuminuria (model B); plus estimated glomerular filtration rate (eGFR) slope during the first 12 months after enrollment and first eGFR after enrollment (model C).

Results

There were more men than women at baseline (58% vs. 42%), men were younger than women, and men had higher eGFR (28.9 ± 11.5 vs. 27.0 ± 10.8 ml/min per 1.73 m²). Over a median follow-up of 2.7 and 2.5 years for men and women, respectively, the crude dialysis initiation and pre-emptive transplantation rates were higher in men whereas that of pre-KRT death was more similar. The adjusted subdistribution hazard ratios (SHRs) between men versus women for dialysis were 1.51 (1.27–1.80) (model A), 1.32 (1.10–1.59) (model B), and 1.50 (1.25–1.80) (model C); for pre-KRT death, were 1.25 (1.02–1.54) (model A), 1.14 (0.92–1.40) (model B), and 1.15 (0.93–1.42) (model C); for transplantation, were 1.31 (0.73–2.36) (model A), 1.44 (0.76–2.74) (model B), and 1.53 (0.79–2.94) (model C).

Conclusion

Men had a higher probability of commencing dialysis before death, unexplained by CKD progression alone. Although the causal mechanisms are uncertain, this finding helps interpret the preponderance of men in the dialysis population.

Changes in practice patterns in Japan from before to after JSDT 2013 guidelines on hemodialysis prescriptions: results from the JDOPPS

BACKGROUND

The Japanese Society for Dialysis Therapy (JSDT) published in 2013 inaugural hemodialysis (HD) guidelines. Specific targets include 1.4 for single-pool Kt/V (spKt/V) with a minimum dose of 1.2, minimum dialysis session length of 4 hours, minimum blood flow rate (BFR) of 200 mL/min, fluid removal rate no more than 15 mL/kg/hr, and hemodiafiltration (HDF) therapy for certain identified symptoms. We evaluated the effect of these guidelines on actual practice in the years spanning 2005 - 2018.

METHODS

Analyses were carried out to describe trends in the above HD prescription practices from December 2005 to April 2013 (before guideline publication) to August 2018 based on prevalent patient cross-sections from approximately 60 randomly selected HD facilities participating in the Japan Dialysis Outcomes and Practice Patterns Study.

RESULTS

From April 2006 to August 2017 continual rises occurred in mean spKt/V (from 1.35 to 1.49), and percent of patients having spKt/V>1.2 (71% to 85%). Mean BFR increased with time from 198.3 mL/min (April 2006) to 218.4 mL/min (August 2017) , along with percent of patients with BFR >200 ml/min (65% to 85%). HDF use increased slightly from 6% (April 2006 and August 2009) to 8% by April 2013, but increased greatly thereafter to 23% by August 2017. In contrast, mean HD treatment time showed little change from 2006-2017, whereas mean UFR declined from 11.3 in 2006 to 8.4 mL/Kg/hour in 2017.

CONCLUSIONS

From 2006 - 2018 Japanese HD patients experienced marked improvement in reaching the spKt/V target specified by the 2013 JSDT guidelines. This may have been due to moderate increase in mean BFR even though mean HD session length did not change much. In addition, HDF use increased dramatically in this time period. Other HD delivery changes during this time, such as increased use of super high flux dialyzers, also merit study. While we cannot definitively conclude a causal relationship between the publication of the guidelines and the subsequent practice changes in Japan, those changes moved practice closer to the recommendations of the guidelines.

Secondary hyperparathyroidism, weight loss, and longer term mortality in haemodialysis patients: results from the DOPPS

BACKGROUND

Wasting is a common complication of kidney failure that leads to weight loss and poor outcomes. Recent experimental data identified parathyroid hormone (PTH) as a driver of adipose tissue browning and wasting, but little is known about the relations among secondary hyperparathyroidism, weight loss, and risk of mortality in dialysis patients.

METHODS

We included 42,319 chronic in-centre haemodialysis patients from the Dialysis Outcomes and Practice Patterns Study phases 2-6 (2002-2018). Linear mixed models were used to estimate the association between baseline PTH and percent weight change over 12 months, adjusting for country, demographics, comorbidities, and labs. Accelerated failure time models were used to assess 12 month weight loss as a mediator between baseline high PTH and mortality after 12 months.

RESULTS

Baseline PTH was inversely associated with 12 month weight change: 12 month weight loss >5% was observed in 21%, 18%, 18%, 17%, 15%, and 14% of patients for PTH ≥600 pg/mL, 450-600, 300-450, 150-300, 50-150, and <50 pg/mL, respectively. In adjusted analyses, 12 month weight change compared with PTH 150-299 pg/mL was -0.60%, -0.12%, -0.10%, +0.15%, and +0.35% for PTH ≥600, 450-600, 300-450, 50-150, and <50 pg/mL, respectively. This relationship was robust regardless of recent hospitalization and was more pronounced in persons with preserved appetite. During follow-up after the 12 month weight measure [median, 1.0 (interquartile range, 0.6-1.7) years; 6125 deaths], patients with baseline PTH ≥600 pg/mL had 11% [95% confidence interval (CI), 9-13%] shorter lifespan, and 18% (95% CI, 14-23%) of this effect was mediated through weight loss ≥2.5%.

CONCLUSIONS

Secondary hyperparathyroidism may be a novel mechanism of wasting, corroborating experimental data, and, among chronic dialysis patients, this pathway may be a mediator between elevated PTH levels and mortality. Future research should determine whether PTH-lowering therapy can limit weight loss and improve longer term dialysis outcomes.

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

RATIONALE AND 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

2596 new users of etelcalcetide from April 2017 through August 2019 in a national sample of adult, chronic HD patients in the US Dialysis Outcomes and Practice Patterns Study (DOPPS).

PREDICTORS

Baseline PTH, prior cinacalcet use, initial etelcalcetide dose.

OUTCOME(S)

Trajectories of etelcalcetide dose, use of mineral bone disorder (MBD) medications, and levels of PTH, serum calcium, and phosphorus in the 12 months following 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/week in 70% of patients and 7.5 mg/week 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 post-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%. Use of active vitamin D (from 77% to 87%) and Ca-based phosphate binders (from 41% to 50%) increased in the 12 months following etelcalcetide initiation.

LIMITATIONS

Data unavailable for provider dosing protocols, dose holds, or reasons for discontinuation.

CONCLUSIONS

In the 12 months following 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.

Serum Biomarkers of Iron Stores Are Associated with Increased Risk of All-Cause Mortality and Cardiovascular Events in Nondialysis CKD Patients, with or without Anemia

BACKGROUND

Approximately 30%-45% of patients with nondialysis CKD have iron deficiency. Iron therapy in CKD has focused primarily on supporting erythropoiesis. In patients with or without anemia, there has not been a comprehensive approach to estimating the association between serum biomarkers of iron stores, and mortality and cardiovascular event risks.

METHODS

The study included 5145 patients from Brazil, France, the United States, and Germany enrolled in the Chronic Kidney Disease Outcomes and Practice Patterns Study, with first available transferrin saturation (TSAT) and ferritin levels as exposure variables. We used Cox models to estimate hazard ratios (HRs) for all-cause mortality and major adverse cardiovascular events (MACE), with progressive adjustment for potentially confounding variables. We also used linear spline models to further evaluate functional forms of the exposure-outcome associations.

RESULTS

Compared with patients with a TSAT of 26%-35%, those with a TSAT ≤15% had the highest adjusted risks for all-cause mortality and MACE. Spline analysis found the lowest risk at TSAT 40% for all-cause mortality and MACE. Risk of all-cause mortality, but not MACE, was also elevated at TSAT ≥46%. Effect estimates were similar after adjustment for hemoglobin. For ferritin, no directional associations were apparent, except for elevated all-cause mortality at ferritin ≥300 ng/ml.

CONCLUSIONS

Iron deficiency, as captured by TSAT, is associated with higher risk of all-cause mortality and MACE in patients with nondialysis CKD, with or without anemia. Interventional studies evaluating the effect on clinical outcomes of iron supplementation and therapies for alternative targets are needed to better inform strategies for administering exogenous iron.

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.

Worldwide Early Impact of COVID-19 on Dialysis Patients and Staff and Lessons Learned: A DOPPS Roundtable Discussion

As the worst global pandemic of the past century, coronavirus disease 2019 (COVID-19) has had a disproportionate effect on maintenance dialysis patients and their health care providers. At a virtual roundtable on June 12, 2020, Dialysis Outcomes and Practice Patterns Study (DOPPS) investigators from 15 countries in Asia, Europe, and the Americas described and compared the effects of COVID-19 on dialysis care, with recent updates added. Most striking is the huge difference in risk to dialysis patients and staff across the world. Per-population cases and deaths among dialysis patients vary more than 100-fold across participating countries, mirroring burden in the general population. International data indicate that the case-fatality ratio remains at 10% to 30% among dialysis patients, confirming the gravity of infection, and that cases are much more common among in-center than home dialysis patients. This latter finding merits urgent study because in-center patients often have greater community exposure, and in-center transmission may be uncommon under optimal protocols. Greater telemedicine use is a welcome change here to stay, and our community needs to improve emergency planning and protect dialysis staff from the next pandemic. Finally, the pandemic's challenges have prompted widespread partnering and innovation in kidney care and research that must be sustained after this global health crisis.

Beta-2 microglobulin and all-cause mortality in the era of high-flux hemodialysis: results from the Dialysis Outcomes and Practice Patterns Study

BACKGROUND

Beta-2 microglobulin (β2M) accumulates in hemodialysis (HD) patients, but its consequences are controversial, particularly in the current era of high-flux dialyzers. High-flux HD treatment improves β2M removal, yet β2M and other middle molecules may still contribute to adverse events. We investigated patient factors associated with serum β2M, evaluated trends in β2M levels and in hospitalizations due to dialysis-related amyloidosis (DRA), and estimated the effect of β2M on mortality.

METHODS

We studied European and Japanese participants in the Dialysis Outcomes and Practice Patterns Study. Analysis of DRA-related hospitalizations spanned 1998-2018 (n = 23 976), and analysis of β2M and mortality in centers routinely measuring β2M spanned 2011-18 (n = 5332). We evaluated time trends with linear and Poisson regression and mortality with Cox regression.

RESULTS

Median β2M changed nonsignificantly from 2.71 to 2.65 mg/dL during 2011-18 (P = 0.87). Highest β2M tertile patients (>2.9 mg/dL) had longer dialysis vintage, higher C-reactive protein and lower urine volume than lowest tertile patients (≤2.3 mg/dL). DRA-related hospitalization rates [95% confidence interval (CI)] decreased from 1998 to 2018 from 3.10 (2.55-3.76) to 0.23 (0.13-0.42) per 100 patient-years. Compared with the lowest β2M tertile, adjusted mortality hazard ratios (95% CI) were 1.16 (0.94-1.43) and 1.38 (1.13-1.69) for the middle and highest tertiles. Mortality risk increased monotonically with β2M modeled continuously, with no indication of a threshold.

CONCLUSIONS

DRA-related hospitalizations decreased over 10-fold from 1998 to 2018. Serum β2M remains positively associated with mortality, even in the current high-flux HD era.

Association between Dipeptidyl Peptidase-4 Inhibitor Prescription and Erythropoiesis-Stimulating Agent Hyporesponsiveness in Hemodialysis Patients with Diabetes Mellitus

INTRODUCTION

Dipeptidyl peptidase-4 (DPP-4) has been hypothesized to improve responsiveness to erythropoiesis-stimulating agent (ESA). We aimed to describe the trend in DPP-4 inhibitor prescription patterns and assess the association between DPP-4 inhibitor prescription and ESA hyporesponsiveness (eHypo) in Japanese hemodialysis (HD) patients with diabetes mellitus (DM).

METHODS

We analyzed data from the Japan Dialysis Outcomes and Practice Patterns Study phase 4-6 (2009-2017) on patients with DM who underwent HD thrice per week for at least 4 months. The primary exposure of interest was having a DPP-4 inhibitor prescription. The primary analysis outcomes were a binary indicator of eHypo (mean hemoglobin <10 and mean ESA dose >6,000 units/week over 4 months) and the natural log-transformed ESA resistance index (ERI). We used conditional logistic regression to compare within-patient changes in eHypo before and after initial DPP-4 inhibitor prescription. We used linear generalized estimating equation models to compare continuous ERI outcomes while accounting for within-patient repeated measurements with an exchangeable correlation structure.

RESULTS

There was a monotonic increase in DPP-4 inhibitor prescription according to study year up to 20% in 2017. Moreover, 12.8% of patients with a DPP-4 inhibitor prescription were ESA hyporesponsive before the initial DPP-4 inhibitor prescription. After DPP-4 inhibitor prescription, the odds of eHypo and mean log-ERI remained unchanged in the whole cohort of our study. The interaction analysis of DPP-4 inhibitor and sideropenia showed that DPP-4 inhibitors attenuated eHypo in the patients without iron deficiency.

CONCLUSION

Our findings indicate a recent increase in DPP-4 inhibitor prescription among Japanese HD patients with DM. DPP-4 inhibitors could improve ERI in patients undergoing HD without iron deficiency.

Medical Director Practice of Advising Increased Dietary Protein Intake in Hemodialysis Patients With Hyperphosphatemia: Associations With Mortality in the Dialysis Outcomes and Practice Patterns Study

OBJECTIVES

Patients undergoing hemodialysis (HD) may have poor nutritional status and hyperphosphatemia. Nephrologists sometimes manage hyperphosphatemia by prescribing phosphate binders and/or recommending restriction of dietary phosphate including protein-rich foods; the later may, however, adversely affect nutritional status.

DESIGN AND METHODS

The analysis includes 8805 HD patients on dialysis ≥ 120 days in 12 countries in Dialysis Outcomes and Practice Patterns Study (DOPPS) phase 4 (2009-2011), from 248 facilities. The primary exposure variable was response to the following question: "For patients with serum albumin 3.0 g/dL and phosphate 6.0 mg/dL, do you recommend to (A) increase or (B) decrease/no change in dietary protein intake (DPI)?". The association between medical director's practice of recommending an increase in DPI and all-cause mortality was analyzed with Cox regression adjusted for potential confounders. Linear and logistic regressions were used to model the cross-sectional associations between DPI advice practice and intermediate markers of patient nutrition.

RESULTS

Median follow-up was 1.6 years. In the case scenario, 91% of medical directors in North America had a practice of recommending DPI increase compared to 58% in Europe (range = 36%-83% across 7 countries) and 56% in Japan. The practice of advising DPI increase was weakly associated with lower mortality [HR (95% CI): 0.88 (0.76-1.02)]. The association tended to be stronger in patients with age 70+ years [HR (95% CI): 0.82 (0.69-0.97), P = .12 for interaction]. The practice of advising DPI increase was associated with 0.276 mg/dL higher serum creatinine levels (95% CI: 0.033-0.520) after adjustment for case mix.

CONCLUSIONS

Medical director's practice of recommending an increase in DPI for HD patients with low albumin and high phosphate levels was associated with higher serum creatinine levels and potentially lower all-cause mortality. To recommend protein intake liberalization in parallel with phosphate management by physicians may be a critical practice for better nutritional status and outcomes in HD patients.

Kt/V: achievement, predictors and relationship to mortality in hemodialysis patients in the Gulf Cooperation Council countries: results from DOPPS (2012-18)

BACKGROUND

Dialysis adequacy, as measured by single pool Kt/V, is an important parameter for assessing hemodialysis (HD) patients' health. Guidelines have recommended Kt/V of 1.2 as the minimum dose for thrice-weekly HD. We describe Kt/V achievement, its predictors and its relationship with mortality in the Gulf Cooperation Council (GCC) (Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates).

METHODS

We analyzed data (2012-18) from the prospective cohort Dialysis Outcomes and Practice Patterns Study for 1544 GCC patients ≥18 years old and on dialysis >180 days.

RESULTS

Thirty-four percent of GCC HD patients had low Kt/V (<1.2) versus 5%-17% in Canada, Europe, Japan and the USA. Across the GCC countries, low Kt/V prevalence ranged from 10% to 54%. In multivariable logistic regression, low Kt/V was more common (P < 0.05) with larger body weight and height, being male, shorter treatment time (TT), lower blood flow rate (BFR), greater comorbidity burden and using HD versus hemodiafiltration. In adjusted Cox models, low Kt/V was strongly related to higher mortality in women [hazard ratio (HR) = 1.91, 95% confidence interval (CI) 1.09-3.34] but not in men (HR = 1.16, 95% CI 0.70-1.92). Low BFR (<350 mL/min) and TT (<4 h) were common; 41% of low Kt/V cases were attributable to low BFR or TT (52% for women and 36% for men).

CONCLUSION

Relatively large proportions of GCC HD patients have low Kt/V. Increasing BFR to ≥350 mL/min and TT to ≥4 h thrice weekly will reduce low Kt/V prevalence and may improve survival in GCC HD patients-particularly among women.

Serum biomarkers of iron stores are associated with worse physical health-related quality of life (HRQoL) in non-dialysis dependent chronic kidney disease (NDD-CKD) patients with or without anemia

Background

Iron deficiency (ID) is a common condition in nondialysis-dependent chronic kidney disease (NDD-CKD) patients that is associated with poorer clinical outcomes. However, the effect of ID on health-related quality of life (HRQoL) in this population is unknown. We analyzed data from a multinational cohort of NDD-CKD Stages 3–5 patients to test the association between transferrin saturation (TSAT) index and ferritin with HRQoL.

Methods

Patients from Brazil (n = 205), France (n = 2015) and the USA (n = 293) in the Chronic Kidney Disease Outcomes and Practice Patterns Study (CKDopps, 2013–2019) were included. We evaluated the association of TSAT and ferritin (and functional and absolute ID, defined as TSAT ≤20% and ferritin ≥300 or <50 ng/mL) on pre-specified HRQoL measures, including the 36-item Kidney Disease Quality of Life physical component summary (PCS) and mental component summary (MCS) as the primary outcomes. Models were adjusted for confounders including hemoglobin (Hb).

Results

TSAT ≤15% and ferritin <50 ng/mL and ≥300 ng/mL were associated with worse PCS scores, but not with MCS. Patients with composite TSAT ≤20% and ferritin <50 or ≥300 ng/mL had lower functional status and worse PCS scores than those with a TSAT of 20–30% and ferritin 50–299 ng/mL. Patients with a lower TSAT were less likely to perform intense physical activity. Adjustment for Hb only slightly attenuated the observed effects.

Conclusions

Low TSAT levels, as well as both low TSAT with low ferritin and low TSAT with high ferritin, are associated with worse physical HRQoL in NDD-CKD patients, even after accounting for Hb level. Interventional studies of iron therapy on HRQoL among NDD-CKD individuals are needed to confirm these findings.

Improving data quality in observational research studies: Report of the Cure Glomerulonephropathy (CureGN) network

Background

High data quality is of crucial importance to the integrity of research projects. In the conduct of multi-center observational cohort studies with increasing types and quantities of data, maintaining data quality is challenging, with few published guidelines.

Methods

The Cure Glomerulonephropathy (CureGN) Network has established numerous quality control procedures to manage the 70 participating sites in the United States, Canada, and Europe. This effort is supported and guided by the activities of several committees, including Data Quality, Recruitment and Retention, and Central Review, that work in tandem with the Data Coordinating Center to monitor the study. We have implemented coordinator training and feedback channels, data queries of questionable or missing data, and developed performance metrics for recruitment, retention, visit completion, data entry, recording of patient-reported outcomes, collection, shipping and accessing of biological samples and pathology materials, and processing, cataloging and accessing genetic data and materials.

Results

We describe the development of data queries and site Report Cards, and their use in monitoring and encouraging excellence in site performance. We demonstrate improvements in data quality and completeness over 4 years after implementing these activities. We describe quality initiatives addressing specific challenges in collecting and cataloging whole slide images and other kidney pathology data, and novel methods of data quality assessment.

Conclusions

This paper reports the CureGN experience in optimizing data quality and underscores the importance of general and study-specific data quality initiatives to maintain excellence in the research measures of a multi-center observational study.

Citric Acid-Containing Dialysate and Survival Rate in the Dialysis Outcomes and Practice Patterns Study

Background

Metabolic acidosis is a common threat for patients on hemodialysis, managed by alkaline dialysate. The main base is bicarbonate, to which small amounts of acetic, citric, or hydrochloric acid are added. The first two are metabolized to bicarbonate, mostly by the liver. Citric acid-containing dialysate might improve dialysis efficiency, anticoagulation, calcification propensity score, and intradialytic hemodynamic stability. However, a recent report from the French dialysis registry suggested this dialysate increases mortality risk. This prompted us to assess whether citric acid-containing bicarbonate-based dialysate was associated with mortality in the international Dialysis Outcomes and Practice Patterns Study (DOPPS).

Methods

Detailed patient-based information on dialysate composition was collected in DOPPS phases 5 and 6 (2012-2017). Cox regression was used to model the association between baseline bicarbonate dialysate containing citric acid versus not containing citric acid and mortality among DOPPS countries and phases where citric acid-containing dialysate was used.

Results

Citric acid-containing dialysate was most commonly used in Japan, Italy, and Belgium (25%, 25%, 21% and of patients who were DOPPS phase 6, respectively) and used in <10% of patients in other countries. Among 11,306 patients in DOPPS country and phases with at least 15 patients using citric acid-containing dialysate, patient demographics, comorbidities, and laboratories were similar among patients using (14%) versus not using (86%) citric acid-containing dialysate. After accounting for case mix, we did not observe a directional association between citric acid-containing dialysate use (any versus none) and mortality (HR, 1.14; 95% CI, 0.97 to 1.34), nor did we find evidence of a dose-dependent relationship when parameterizing the citric acid concentration in the dialysate as 1, 2, and 3+ mEq/L.

Conclusions

The use of citric acid-containing dialysate was not associated with greater risk of all-cause mortality in patients on hemodialysis participating in DOPPS. Clinical indications for the use of citric acid-containing dialysate deserve further investigation.

The combination of malnutrition-inflammation and functional status limitations is associated with mortality in hemodialysis patients

The identification of malnutrition-inflammation-complex (MIC) and functional status (FS) is key to improving patient experience on hemodialysis (HD). We investigate the association of MIC and FS combinations with mortality in HD patients. We analyzed data from 5630 HD patients from 9 countries in DOPPS phases 4–5 (2009–2015) with a median follow-up of 23 [IQR 11, 31] months. MIC was defined as serum albumin < 3.8 g/dL and serum C-reactive protein > 3 mg/L in Japan and > 10 mg/L elsewhere. FS score was defined as the sum of scores from the Katz Index of Independence in Activities of Daily Living and the Lawton-Brody Instrumental Activities of Daily Living Scale. We investigated the association between combinations of MIC (+/−) and FS (low [< 11]/high [≥ 11]) with death. Compared to the reference group (MIC−/high FS), the adjusted hazard ratios [HR (95% CI)] for all-cause mortality were 1.82 (1.49, 2.21) for MIC−/low FS, 1.57 (1.30, 1.89) for MIC+/high FS, and 3.44 (2.80, 4.23) for MIC+/low FS groups. Similar associations were observed with CVD-related and infection-related mortality. The combination of MIC and low FS is a strong predictor of mortality in HD patients. Identification of MIC and poor FS may direct interventions to lessen adverse clinical outcomes in the HD setting.

Impact of longer term phosphorus control on cardiovascular mortality in hemodialysis patients using an area under the curve approach: results from the DOPPS

BACKGROUND

Serial assessment of phosphorus is currently recommended by the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines, but its additional value versus a single measurement is uncertain.

METHODS

We studied data from 17 414 HD patients in the Dialysis Outcomes and Practice Patterns Study, a prospective cohort study, and calculated the area under the curve (AUC) by multiplying the time spent with serum phosphorus >4.5 mg/dL over a 6-month run-in period by the extent to which this threshold was exceeded. We estimated the association between the monthly average AUC and cardiovascular (CV) mortality using Cox regression. We formally assessed whether AUC was a better predictor of CV mortality than other measures of phosphorus control according to the Akaike information criterion.

RESULTS

Compared with the reference group of AUC = 0, the adjusted hazard ratio (HR) of CV mortality was 1.12 [95% confidence interval (CI) 0.90-1.40] for AUC > 0-0.5, 1.26 (95% CI 0.99-1.62) for AUC > 0.5-1, 1.44 (95% CI 1.11-1.86) for AUC > 1-2 and 2.03 (95% CI 1.53-2.69) for AUC > 2. The AUC was predictive of CV mortality within strata of the most recent phosphorus level and had a better model fit than other serial measures of phosphorus control (mean phosphorus, months out of target).

CONCLUSIONS

We conclude that worse phosphorus control over a 6-month period was strongly associated with CV mortality. The more phosphorus values do not exceed 4.5 mg/dL the better is survival. Phosphorus AUC is a better predictor of CV death than the single most recent phosphorus level, supporting with real-world data KDIGO's recommendation of serial assessment of phosphorus to guide clinical decisions.

The risk of medically uncontrolled secondary hyperparathyroidism depends on parathyroid hormone levels at haemodialysis initiation

BACKGROUND

Optimal parathyroid hormone (PTH) control during non-dialysis chronic kidney disease (ND-CKD) might decrease the subsequent risk of parathyroid hyperplasia and uncontrolled secondary hyperparathyroidism (SHPT) on dialysis. However, the evidence for recommending PTH targets and therapeutic strategies is weak for ND-CKD. We evaluated the patient characteristics, treatment patterns and PTH control over the first year of haemodialysis (HD) by PTH prior to HD initiation.

METHODS

We studied 5683 incident HD patients from 21 countries in Dialysis Outcomes and Practice Patterns Study Phases 4-6 (2009-18). We stratified by PTH measured immediately prior to HD initiation and reported the monthly prescription prevalence of active vitamin D and calcimimetics over the first year of HD and risk of PTH >600 pg/mL after 9-12 months on HD.

RESULTS

The 16% of patients with PTH >600 pg/mL prior to HD initiation were more likely to be prescribed active vitamin D and calcimimetics during the first year of HD. The prevalence of PTH >600 pg/mL 9-12 months after start of HD was greater for patients who initiated HD with PTH >600 (29%) versus 150-300 (7%) pg/mL (adjusted risk difference: 19%; 95% confidence interval : 15%, 23%). The patients with sustained PTH >600 pg/mL after 9-12 months on HD were younger, more likely to be black, and had higher serum phosphorus and estimated glomerular filtration rates at HD initiation.

CONCLUSIONS

Increased PTH before HD start predicted a higher PTH level 9-12 months later, despite greater use of active vitamin D and calcimimetics. More targeted PTH control during ND-CKD may influence outcomes during HD, raising the need for PTH target guidelines in these patients.

Sex differences in chronic kidney disease awareness among US adults, 1999 to 2018

BACKGROUND

Chronic kidney disease (CKD) is less prevalent among men than women, but more men than women initiate kidney replacement therapy. Differences in CKD awareness may contribute to this gender gap, which may further vary by race/ethnicity. We aimed to investigate trends in CKD awareness and the association between individual characteristics and CKD awareness among US men versus women.

METHODS AND FINDINGS

We conducted a serial, cross-sectional analysis of 10 cycles (1999-2018) from the National Health and Nutrition Examination Survey (NHANES). Adult participants with CKD stages G3-G5 (estimated glomerular filtration rate [eGFR] <60 mL/min/1.73m2) were included, unless they were on dialysis or medical information was missing. Serum creatinine was measured during NHANES medical exams. CKD stage was classified by eGFR, based on the CKD-EPI formula. CKD awareness was assessed with the question: "Have you ever been told by a health care professional you had weak or failing kidneys", asked in standardized NHANES questionnaires on each survey. Using logistic regression models, we evaluated the association between sex and CKD awareness, adjusting for potential confounders including age, race/ethnicity and comorbidities. We stratified CKD awareness by 5 pre-defined calendar-year periods and conducted all analyses for the complete study population as well as the Caucasian and African American subpopulations. We found that among 101871 US persons participating in NHANES, 4411 (2232 women) had CKD in stages G3-G5. These participants were, on average, 73±10 years old, 25.3% reported diabetes, 78.0% reported hypertension or had elevated blood pressure during medical examinations and 39.8% were obese (percentages were survey-weighted). CKD awareness was more prevalent among those with higher CKD stage, younger age, diabetes, hypertension and higher body mass index. CKD awareness was generally low (<22.5%), though it increased throughout the study period, remaining consistently higher among men compared to women, with a decreasing gender gap over time (adjusted odds ratio [men-to-women] for CKD awareness = 2.71 [1.31-5.64] in period 1; = 1.32 [0.82-2.12] in period 5). The sex difference in CKD awareness was smaller in African American participants, in whom CKD awareness was generally higher. Using serum creatinine rather than eGFR as the CKD-defining exposure, CKD awareness increased with rising serum creatinine, in a close to identical fashion among both sexes during 1999-2008, while during 2009-2018, CKD awareness among women increased earlier than among men (i.e. with lower serum creatinine levels).

CONCLUSIONS

CKD awareness is lower among US women than men. The narrowing gap between the sexes in more recent years and the results on CKD awareness by serum creatinine indicate that health care professionals have previously been relying on serum creatinine to inform patients about their condition, but in more recent years have been using eGFR, which accounts for women's lower serum creatinine levels due to their lower muscle mass. Additional efforts should be made to increase CKD awareness among both sexes.

Combinations of mineral and bone disorder markers and risk of death and hospitalizations in the international Dialysis Outcomes and Practice Patterns Study

BACKGROUND

Prior studies have developed a chronic kidney disease-mineral and bone disorder (CKD-MBD) composite score based on combinations of calcium (Ca), phosphorus (P) and parathyroid hormone (PTH) that have been shown to be associated with an increased risk of clinical outcomes in the USA. We examined this association in a contemporary, international cohort of hemodialysis patients.

METHODS

We studied 19 313 patients surviving ≥12 months in the Dialysis Outcomes and Practice Patterns Study Phases 3-5 (2005-15) from Europe, Canada and the USA. The CKD-MBD composite score was defined as the number of markers above target levels (P, 3.5-5.5 mg/dL; Ca, 8.4-10.2 mg/dL; PTH, 150-600 pg/mL). Using Cox models, we estimated hazard ratios (HRs) for death and a composite event (death or hospitalization), contrasting MBD 2/3 (2-3 parameters above target) with MBD 0 (all in target), adjusted for a disease risk score (DRS).

RESULTS

MBD 2/3 above target was observed in 10-14% of patients across regions and was associated with greater DRS-adjusted mortality {HR 1.41 [95% confidence interval (CI) 1.10-1.82]} and composite events [HR 1.23 (95% CI 1.10-1.38)] in the USA compared with MBD 0; the mortality association was stronger for patients ≥ 65 years of age [HR 1.82 (95% CI 1.28-2.58)] compared with patients <65 years of age [HR 1.11 (95% CI 0.80-1.55)]. HRs observed in Canada and Europe were generally consistent but weaker. Estimates for MBD 2/3 outside target (above or below) were slightly lower in all regions.

CONCLUSIONS

Simultaneous consideration of Ca, P and PTH may help in identifying patients on dialysis with a higher risk of major clinical outcomes related to CKD-MBD.

Replicating Randomized Trial Results with Observational Data Using the Parametric g-Formula: An Application to Intravenous Iron Treatment in Hemodialysis Patients

BACKGROUND

Reproducibility of clinical and epidemiologic research is important to generalize findings and has increasingly been scrutinized. A recently published randomized trial, PIVOTAL, evaluated high vs low intravenous iron dosing strategies to manage anemia in hemodialysis patients in the UK. Our objective was to assess the reproducibility of the PIVOTAL trial findings using data from a well-established cohort study, the Dialysis Outcomes and Practice Patterns Study (DOPPS).

METHODS

To overcome the absence of randomization in the DOPPS, we applied the parametric g-formula, an extension of standardization to longitudinal data. We estimated the effect of a proactive high-dose vs reactive low-dose iron supplementation strategy on all-cause mortality (primary outcome), hemoglobin, two measures of iron concentration (ferritin and TSAT), and erythropoiesis-stimulating agent dose over 12 months of follow-up in 6325 DOPPS patients.

RESULTS

Comparing high- vs low-iron dose strategies, the 1-year mortality risk difference was 0.020 (95% CI: 0.008, 0.031) and risk ratio was 1.20 (95% CI: 1.07, 1.33), compared with null 1-year findings in the PIVOTAL trial. Differences in secondary outcomes were directionally consistent but of lesser magnitude than in the PIVOTAL trial.

CONCLUSION

Our findings are somewhat consistent with the recent PIVOTAL trial, with discrepancies potentially attributable to model misspecification and differences between the two study populations. In addition to the importance of our results to nephrologists and hence hemodialysis patients, our analysis illustrates the utility of the parametric g-formula for generalizing results and comparing complex and dynamic treatment strategies using observational data.

Fibroblast Growth Factor 23 and Mortality Among Prevalent Hemodialysis Patients in the Japan Dialysis Outcomes and Practice Patterns Study

INTRODUCTION

Elevated fibroblast growth factor 23 (FGF23) levels have been strongly associated with mortality in the predialysis and incident hemodialysis populations, but few studies have examined this relationship in a large cohort of prevalent hemodialysis patients and in particular among persons with high dialysis vintage. To address this, we analyzed data from the Japan Dialysis Outcomes and Practice Patterns Study (J-DOPPS).

METHODS

We included 1122 prevalent hemodialysis patients from the J-DOPPS phase 5 (2012-2015) who had FGF23 measurements. We evaluated the association of FGF23 levels with all-cause mortality and cardiovascular composite outcome using Cox regression adjusted for potential confounders.

RESULTS

At study enrollment, median dialysis vintage was 5.8 years (interquartile range, 2.7-12.4 years) and median FGF23 level was 2113 pg/ml (interquartile range, 583-6880 pg/ml). During 3-year follow-up, 154 of the 1122 participants died. In adjusted analyses, higher FGF23 was associated with a greater hazard of death (hazard ratio per doubling of FGF23, 1.12; 95% confidence interval, 1.03-1.21); however, the association became weaker as the dialysis vintage increased and finally disappeared in the highest tertile (>9.4 years). Similar patterns of effect modification by dialysis vintage were observed for cardiovascular composite outcome and in time-dependent models.

CONCLUSION

Elevated FGF23 was associated with mortality and cardiovascular events in prevalent hemodialysis patients, but the association was attenuated at longer dialysis vintages. This novel finding suggests that long-term hemodialysis patients may be less susceptible to the detrimental effects of FGF23 or correlated biological processes, and additional studies are needed to gain understanding of these possibilities.

Parathyroid Hormone Serum Levels and Mortality among Hemodialysis Patients in the Gulf Cooperation Council Countries: Results from the DOPPS (2012-2018)

BACKGROUND

The prospective Dialysis Outcomes and Practice Patterns Study (DOPPS) has collected data since 2012 in all six Gulf Cooperation Council (GCC) countries (Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and United Arab Emirates). We report the relationship of PTH with mortality in this largest GCC cohort of patients on hemodialysis studied to date.

METHODS

Data were from randomly selected national samples of hemodialysis facilities in GCC-DOPPS phases 5 and 6 (2012-2018). PTH descriptive findings and case mix-adjusted PTH/mortality Cox regression analyses were based on 1825 and 1422 randomly selected patients on hemodialysis, respectively.

RESULTS

Mean patient age was 55 years (median dialysis vintage, 2.1 years). Median PTH ranged from 259 pg/ml (UAE) to 437 pg/ml (Kuwait), with 22% having PTH <150 pg/ml, 24% with PTH of 150-300 pg/ml, 34% with PTH 301-700 pg/ml, and 20% with PTH >700 pg/ml. Patients with PTH >700 pg/ml were younger; on dialysis longer; less likely to be diabetic; have urine >200 ml/d; be prescribed 3.5 mEq/L dialysate calcium; had higher mean serum creatinine and phosphate levels; lower white blood cell counts; and more likely to be prescribed cinacalcet, phosphate binders, or IV vitamin D. A U-shaped PTH/mortality relationship was observed with more than two- and 1.5-fold higher adjusted HR of death at PTH >700 pg/ml and <300 pg/ml, respectively, compared with PTH of 301-450 pg/ml.

CONCLUSIONS

Secondary hyperparathyroidism is highly prevalent among GCC patients on hemodialysis, with a strong U-shaped PTH/mortality relationship seen at PTH <300 and >450 pg/ml. Future studies are encouraged for further understanding this PTH/mortality pattern in relationship to unique aspects of the GCC hemodialysis population.

Peritoneal Dialysis and Mortality, Kidney Transplant, and Transition to Hemodialysis: Trends From 1996-2015 in the United States

Rationale & Objective

Transitions between dialysis modalities can be disruptive to care. Our goals were to evaluate rates of transition from peritoneal dialysis (PD) to in-center hemodialysis (HD), mortality, and transplantation among incident PD patients in the US Renal Data System from 1996 to 2015 and identify factors associated with these outcomes.

Study Design

Observational registry-based retrospective cohort study.

Setting & Participants

Medicare patients incident to end-stage renal disease (ESRD) from January 1, 1996, through December 31, 2011 (for adjusted analyses; through December 31, 2014, for unadjusted analyses), and treated with PD 1 or more days within 180 days of ESRD incidence (n = 173,533 for adjusted analyses; n = 219,787 for unadjusted analyses).

Exposure & Predictors

Exposure: 1 or more days of PD. Predictors: patient- and facility-level characteristics obtained from Centers for Medicare & Medicaid Services Form 2728 and other data sources.

Outcomes

Patients were followed up for 3 years until transition to in-center HD, death, or transplantation.

Analytical Approach

Multivariable Cox regression was used to estimate hazards over time and associations with predictors.

Results

Compared with earlier cohorts, recent incident PD patient cohorts had lower rates of death (48% decline) and transition to in-center HD (13% decline). Among many other findings, we found that: (1) rates of transition to in-center HD and death were lowest in the 2008 to 2011 cohort, (2) longer time receiving PD was associated with higher mortality risk but lower risk for transition to in-center HD, and (3) larger PD programs (≥25 vs ≤6 patients) displayed lower risks for death and transition to in-center HD.

Limitations

Data collected on Form 2728 are only at the time of ESRD incidence and do not provide information at the time of transition to in-center HD, death, or transplantation.

Conclusions

Rates of transition from PD to in-center HD and death rates for PD patients decreased over time and were lowest in PD programs with 25 or more patients. Implications of the observed improved technique survival warrant further investigation, focusing on modifiable factors of center-level performance to create opportunities for improved patient outcomes.

Management of Anemia in Nondialysis Chronic Kidney Disease: Current Recommendations, Real-World Practice, and Patient Perspectives

In nondialysis CKD (ND-CKD), anemia is a multifactorial and complex condition in which several dysfunctions dynamically contribute to a reduction in circulating hemoglobin (Hb) levels in red blood cells. Anemia is common in CKD and represents an important and modifiable risk factor for poor clinical outcomes. Importantly, symptoms related to anemia, including reduced physical functioning and fatigue, have been identified as high priorities by patients with CKD. The current management of anemia in ND-CKD (i.e., parameters to initiate treatment, Hb and iron indexes targets, choice of therapies, and effect of treatment on clinical and patient-reported outcomes) remains controversial. In this review article, we explore the epidemiology of anemia in ND-CKD and revise current recommendations and controversies in its management. Exploring data from real-world clinical practices, particularly from the Chronic Kidney Disease Outcomes and Practice Patterns Study (CKDopps), we highlight the current challenges to translating current recommendations to clinical practice, providing patients' perspectives of anemia and how it affects their quality of life. Finally, we summarize recent advances in the field of anemia that may change the way this condition will be managed in the future.

Parathyroid Hormone Serum Levels and Mortality among Hemodialysis Patients in the Gulf Cooperation Council Countries: Results from the DOPPS (2012–2018)

Background

The prospective Dialysis Outcomes and Practice Patterns Study (DOPPS) has collected data since 2012 in all six Gulf Cooperation Council (GCC) countries (Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and United Arab Emirates). We report the relationship of PTH with mortality in this largest GCC cohort of patients on hemodialysis studied to date.

Methods

Data were from randomly selected national samples of hemodialysis facilities in GCC-DOPPS phases 5 and 6 (2012–2018). PTH descriptive findings and case mix–adjusted PTH/mortality Cox regression analyses were based on 1825 and 1422 randomly selected patients on hemodialysis, respectively.

Results

Mean patient age was 55 years (median dialysis vintage, 2.1 years). Median PTH ranged from 259 pg/ml (UAE) to 437 pg/ml (Kuwait), with 22% having PTH <150 pg/ml, 24% with PTH of 150–300 pg/ml, 34% with PTH 301–700 pg/ml, and 20% with PTH >700 pg/ml. Patients with PTH >700 pg/ml were younger; on dialysis longer; less likely to be diabetic; have urine >200 ml/d; be prescribed 3.5 mEq/L dialysate calcium; had higher mean serum creatinine and phosphate levels; lower white blood cell counts; and more likely to be prescribed cinacalcet, phosphate binders, or IV vitamin D. A U-shaped PTH/mortality relationship was observed with more than two- and 1.5-fold higher adjusted HR of death at PTH >700 pg/ml and <300 pg/ml, respectively, compared with PTH of 301–450 pg/ml.

Conclusions

Secondary hyperparathyroidism is highly prevalent among GCC patients on hemodialysis, with a strong U-shaped PTH/mortality relationship seen at PTH <300 and >450 pg/ml. Future studies are encouraged for further understanding this PTH/mortality pattern in relationship to unique aspects of the GCC hemodialysis population.

Association of erythropoietin resistance and fibroblast growth factor 23 in dialysis patients: Results from the Japanese Dialysis Outcomes and Practice Patterns Study

BACKGROUND

Fibroblast growth factor 23 (FGF23) plays an important role in chronic kidney disease (CKD)-related mineral and bone disorders. High FGF23 levels are associated with increased risk of anaemia in non-haemodialysis CKD patients. FGF23 also negatively regulates erythropoiesis in mice. We hypothesized that higher FGF23 levels are associated with increased erythropoietin hyporesponsiveness among haemodialysis patients.

METHODS

The study included 1044 patients from the Japanese Dialysis Outcomes and Practice Patterns Study (J-DOPPS) phase 5 (2012-2015). The outcome was erythropoiesis-stimulating agent hyporesponsiveness (ESA-hypo), defined as mean Hgb <10 g/dL and standardized mean ESA dose >6000 u/week over 4 months following FGF23 measurement. The association between ESA-hypo and FGF23 was estimated using multivariable-adjusted logistic generalized estimating equation regression models.

RESULTS

Patients with higher levels of FGF23 were younger and had higher levels of serum albumin, creatinine, albumin-corrected calcium, phosphorus, PTH, 25(OH)-vitamin D, and had higher percentages of intravenous (IV) iron, IV vitamin D and cinacalcet use. ESA-hypo was present in 144 patients (13.8%). Compared with the third quintile of FGF23 levels, the odds ratio (95% CI) of ESA-hypo was 2.14 (0.99, 4.62) and 1.74 (0.74, 4.11) for the first and fifth quintiles, respectively.

CONCLUSION

The lowest and highest levels of FGF23 were associated with higher odds of ESA-hypo in patients on maintenance haemodialysis, although the associations were not statistically significant. The relationship between FGF23 and anaemia, and particularly the increased risks of ESA-hypo at low FGF23 levels which might be the result of energy saving, must be confirmed in larger clinical studies.