Survival predictability of time-varying indicators of bone disease in maintenance hemodialysis patients

Randomized trial of two maintenance doses of vitamin D in children with chronic kidney disease

BACKGROUND

Correction of nutritional vitamin deficiency is recommended in children with chronic kidney disease (CKD). The optimal daily dose of vitamin D to achieve or maintain vitamin D sufficiency is unknown.

METHODS

We conducted a phase III, double-blind, randomized trial of two doses of vitamin D₃ in children ≥ 9 years of age with CKD stages 3-5 or kidney transplant recipients. Patients were randomized to 1000 IU or 4000 IU of daily vitamin D₃ orally. We measured 25-hydroxvitamin D (25(OH)D) levels at baseline, 3 months and 6 months. The primary efficacy outcome was the percentage of patients who were vitamin D replete (25(OH)D ≥ 30 ng/mL) at 6 months.

RESULTS

Ninety-eight patients were enrolled: 49 randomized into each group. Eighty (81.6%) patients completed the study and were analyzed. Baseline plasma 25(OH)D levels were ≥ 30 ng/mL in 12 (35.3%) and 12 (27.3%) patients in the 1000 IU and 4000 IU treatment groups, respectively. At 6 months, plasma 25(OH)D levels were ≥ 30 ng/mL in 33.3% (95% CI: 18.0-51.8%) and 74.4% (95% CI: 58.8-86.5%) in the 1000 IU and 4000 IU treatment groups, respectively (p = 0.0008). None of the patients developed vitamin D toxicity or hypercalcemia.

CONCLUSIONS

In children with CKD, 1000 IU of daily vitamin D₃ is unlikely to achieve or maintain a plasma 25(OH)D ≥ 30 ng/mL. In children with CKD stages 3-5, a dose of vitamin D₃ 4000 IU daily was effective in achieving or maintaining vitamin D sufficiency.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01909115.

Cardiac valve calcification is associated with mortality in hemodialysis patients: a retrospective cohort study

Background

Cardiac valve calcification (CVC) is common in end-stage renal disease (ESRD). We investigated the effect of CVC on all-cause and cardiovascular (CV) mortality in maintenance hemodialysis (MHD) patients.

Methods

A retrospective cohort study was conducted on 434 hemodialysis patients who underwent echocardiography for qualitative assessment of valve calcification with complete follow-up data from January 1, 2014, to April 30, 2021. The baseline data between the CVC and non-CVC groups were compared. The Kaplan–Meier method was used to analyse all-cause and cardiovascular mortality. The association of CVC with all-cause and cardiovascular mortality was evaluated using multivariate Cox regression analysis.

Results

Overall, 27.2% of patients had mitral valve calcification (MVC), and 31.8% had aortic valve calcification (AVC) on echocardiography. Patients with CVC showed significantly higher all-cause (log-rank P < 0.001) and cardiovascular (log-rank P < 0.001) mortality rates than patients without CVC. In multivariate regression analyses, MVC (HR: 1.517, P = 0.010) and AVC (HR: 1.433, P = 0.028) were significant factors associated with all-cause mortality. MVC (HR: 2.340, P < 0.001) and AVC (HR: 2.410, P < 0.001) were also significant factors associated with cardiovascular mortality.

Conclusions

MVC and AVC increased the risk of all-cause and cardiovascular mortality in MHD patients. Regular follow-up with echocardiography could be a useful method for risk stratification in MHD patients.

Parathyroidectomy Versus Cinacalcet for the Treatment of Secondary Hyperparathyroidism in Hemodialysis Patients

Background

Secondary hyperparathyroidism in patients with end stage renal disease on dialysis is associated with bone pain and fractures in addition to cardiovascular morbidity. Cinacalcet is the most commonly used drug to treat such patients, but it has never been compared to surgery. The goal of this study is to compare the long-term outcomes and survival between cinacalcet and parathyroidectomy in the treatment of secondary hyperparathyroidism in hemodialysis patients.

Methods

Adult patients on hemodialysis who were treated with cinacalcet or parathyroidectomy in the United States Renal Data System were included. Patients treated with surgery (n = 2023) were compared using 1:1 propensity score matching ratio to a cohort of patients treated with cinacalcet. A Cox regression analysis was conducted to compare the overall mortality.

Results

The propensity score matching successfully created two groups with similar demographics. Patients in the surgery group had a higher mean peak PTH level prior to therapy (2066.8 vs 1425.4, P < 0.001). No difference was observed in the development of new-onset coronary artery disease (7.7% vs 7.9%, P = 0.8) or cerebrovascular disease (7% vs 6.7%, P = 0.8). Surgical patients had a higher rate of pathologic fractures (27.8% vs 24.9%, P = 0.04). Survival analysis showed that patients undergoing surgery had a better 5-year survival (65.6% vs 57.8%) and were less likely to die within the study period (HR 0.77, 95% CI 0.7–0.85, P < 0.0001).

Conclusions

Patients on dialysis undergoing parathyroidectomy for the treatment of secondary hyperparathyroidism have a better overall survival than those treated with cinacalcet.

Adynamic bone disease: Revisited

The bone and mineral disorders form an integral part of the management of a chronic kidney disease (CKD) patient. Amongst various types of bone pathologies in chronic kidney disease-mineral bone disorder (CKD-MBD), the prevalence of adynamic bone disease (ABD) is increasing. The present review discusses the updated pathophysiology, risk factors, and management of this disorder.

Association Between Treatment of Secondary Hyperparathyroidism and Posttransplant Outcomes

BACKGROUND

Secondary hyperparathyroidism (SHPT) affects nearly all patients on maintenance dialysis therapy. SHPT treatment options have considerably evolved over the past 2 decades but vary in degree of improvement in SHPT. Therefore, we hypothesize that the risks of adverse outcomes after kidney transplantation (KT) may differ by SHPT treatment.

METHODS

Using the Scientific Registry of Transplant Recipients and Medicare claims data, we identified 5094 adults (age ≥18 y) treated with cinacalcet or parathyroidectomy for SHPT before receiving KT between 2007 and 2016. We quantified the association between SHPT treatment and delayed graft function and acute rejection using adjusted logistic models and tertiary hyperparathyroidism (THPT), graft failure, and death using adjusted Cox proportional hazards; we tested whether these associations differed by patient characteristics.

RESULTS

Of 5094 KT recipients who were treated for SHPT while on dialysis, 228 (4.5%) underwent parathyroidectomy, and 4866 (95.5%) received cinacalcet. There was no association between treatment of SHPT and posttransplant delayed graft function, graft failure, or death. However, compared with patients treated with cinacalcet, those treated with parathyroidectomy had a lower risk of developing THPT (adjusted hazard ratio, 0.56; 95% confidence interval, 0.35-0.89) post-KT. Furthermore, this risk differed by dialysis vintage (Pinteraction = 0.039). Among patients on maintenance dialysis therapy for ≥3 y before KT (n = 3477, 68.3%), the risk of developing THPT was lower when treated with parathyroidectomy (adjusted hazard ratio, 0.43; 95% confidence interval, 0.24-0.79).

CONCLUSIONS

Parathyroidectomy should be considered as treatment for SHPT, especially in KT candidates on maintenance dialysis for ≥3 y. Additionally, patients treated with cinacalcet for SHPT should undergo close surveillance for development of tertiary hyperparathyroidism post-KT.

Reduced Plasma Ascorbate and Increased Proportion of Dehydroascorbic Acid Levels in Patients Undergoing Hemodialysis

Ascorbate functions as an electron donor and scavenges free radicals. Dehydroascorbic acid (DHA), the oxidized form of ascorbate, is generated as a result of these reactions. While low plasma ascorbate levels have been reported in hemodialysis patients worldwide, no studies have measured DHA because it is not generalized. In this study, we aimed to clarify whether plasma ascorbate levels are low in dialysis patients and whether plasma ascorbate levels fluctuate before and after dialysis. Moreover, we applied our previously established method to measure the plasma ascorbate and DHA levels in chronic kidney disease (CKD) stage G3–G5 non-hemodialysis-dependent patients, and pre- and post-dialysis plasma ascorbate and DHA levels in CKD stage G5D hemodialysis patients. The sample size was calculated using G-power software. The pre-dialysis plasma total ascorbate levels, including DHA, were significantly (56%) lower in hemodialysis patients than in non-hemodialysis-dependent CKD patients. After dialysis, there was a 40% reduction in the plasma total ascorbate levels. Hemodialysis increased the post-dialysis plasma proportions of DHA from 37% to 55%. The study results demonstrated lower plasma total ascorbate levels in hemodialysis patients compared with in non-hemodialysis-dependent CKD patients; these low levels in hemodialysis patients were further reduced by hemodialysis and increased DHA proportion.

Association Between Admission Serum Phosphate Level and All-Cause Mortality Among Patients with Spontaneous Intracerebral Hemorrhage

Background

Hypophosphatemia was reported to frequently occur in patients with nontraumatic intracranial hemorrhage (ICH); however, the correlation between hypophosphatemia and outcomes of ICH remains unclear. This study aimed to examine the association between admission serum phosphate and all-cause mortality among patients with mild–moderate spontaneous ICH (sICH).

Methods

A total of 851 patients with sICH were enrolled. Serum phosphate was acquired within 24 hours on admission, and participants were divided according to phosphate quartiles. The primary outcome was all-cause mortality within 90 days, and univariate and multivariate models were employed to estimate the mortality risk.

Results

There were significant differences among sICH patients with different phosphate quartiles in terms of age, diastolic blood pressure (DBP), activated partial thromboplastin time (APTT), platelet count, and incidence of respiratory failure events on admission (P < 0.05). Log rank test showed a significant difference in the mortality risk among sICH patients with each phosphate quartile. Univariate Cox regression analysis revealed that age, smoking, DBP, APTT, NIH stroke scale (NIHSS) score, hematoma volume and serum phosphate might be associated with the 90-day all-cause mortality in patients with sICH (P < 0.05). Multivariable Cox regression analysis showed that the crude mortality was 4.3-fold greater in sICH patients with serum phosphate Q1 than those with Q4 (P < 0.001), and remained 3.18-fold higher after adjusting for age, smoking, DBP, APTT, NIHSS score, hematoma volume and early withdrawal of life-sustaining therapy (P = 0.011). Representative operating curve (ROC) analysis showed that admission serum phosphate was predictable for all-cause mortality within 90 days in patients with sICH (area under the ROC = 0.628, P < 0.001).

Conclusion

Low admission serum phosphate is strongly associated with a high risk of mortality in patients with mild–moderate sICH, and hypophosphatemia may be a prognostic marker for all-cause mortality in patients with mild–moderate sICH.

Serum phosphorus and calcium levels, and kidney disease progression in immunoglobulin A nephropathy

BACKGROUND

Disorders of calcium and phosphorus metabolism have been reported to be associated with all-cause and cardiovascular mortality in patients requiring long-term dialysis therapy. However, its role in disease progression is not well established in patients without dialysis, especially in immunoglobulin A (IgA) nephropathy. We aim to evaluate the association of serum phosphorus and calcium and progression of IgA nephropathy.

METHODS

We assessed 2567 patients with IgA nephropathy at the First Affiliated Hospital, College of Medicine, Zhejiang University. Serum phosphorus and calcium were collected at the time of kidney biopsy and at each visit. The associations of serum phosphorus and serum calcium with composite kidney disease progression events, defined as 50% estimated glomerular filtration rate (eGFR) decline and kidney failure, were examined using Cox models and restricted cubic splines.

RESULTS

During a median follow-up of 31.9 months, 248 (10%) patients reached composite kidney disease progression events. A linear relationship was observed between serum phosphorus and composite kidney disease progression events. With higher levels of phosphorus, the risk of kidney disease progression events increased {hazard ratio [HR] 3.54 [95% confidence interval (CI) 1.37-9.12]; P = 0.009}. Compared with the first quartile group, the HR of kidney disease progression events was 1.66 (95% CI 0.91-301) for the second quartile, 1.67 (95% CI 0.91-3.08) for the third and 2.62 (95% CI 1.44-4.77) for the fourth (P for trend = 0.002). The association between serum phosphorus and kidney disease progression was detectable [HR 8.94 (95% CI 2.33-34.21); P = 0.001] within the subgroup with eGFR <60 mL/min/1.73 m2 but not among patients with eGFR ≥60 mL/min/1.73 m2 [HR 0.87 (95% CI 0.17-4.44); P = 0.87]. After adjustment for traditional risk factors, a higher level of serum calcium was not associated with kidney disease progression events [HR 0.33 (95% CI 0.10-1.09)].

CONCLUSIONS

Higher serum phosphorus rather than serum calcium was independently associated with kidney disease progression in IgA nephropathy.

Association between serum potassium and risk of all-cause mortality among chronic kidney diseases patients: A systematic review and dose-response meta-analysis of more than one million participants

We aimed to perform a meta-analysis, using prospective cohort studies, to test the association between serum potassium and all-cause mortality among chronic kidney diseases (CKD) patients. A systematic search was performed using PubMed-MEDLINE and Scopus, up to July 2020. Prospective cohort studies which reported risk estimates of all-cause mortality in CKD patients with different serum potassium levels were included in the present meta-analysis. Thirteen studies were included in the analysis. A nonlinear dose-response meta-analysis suggested that there is a J-shaped association between serum potassium levels and the risk of all-cause mortality, with a nadir at serum potassium of 4.5 mmol/L. Subgroup analyses indicated that the strength and shape of the association between serum potassium and all-cause mortality may be influenced by age. Our meta-analysis provides supportive evidence that there is a J-shape association between serum potassium and all-cause mortality among CKD patients.

Cinacalcet and gastrointestinal bleeding risk in patients receiving hemodialysis

PURPOSE

Secondary hyperparathyroidism (SHPT) is common among dialysis patients, and calcimimetics are a mainstay of treatment. This study assessed whether cinacalcet use is associated with gastrointestinal bleeding in a large hemodialysis cohort.

METHODS

A linked database of clinical records and medical claims for patients receiving hemodialysis in a large dialysis organization, 2007-2010, was used. A nested case-control study was performed among patients aged ≥18 years who had received hemodialysis for ≥90 days, had Medicare Parts A, B, and D coverage for ≥1 year, and had clinical evidence of SHPT (parathyroid hormone >300 pg/mL). Cases were those who experienced death or hospitalization caused by gastrointestinal bleeding. Each case was matched to up to four controls. Exposure was measured by any cinacalcet use, current use, past use, cumulative exposure days, and cumulative dosage. Conditional logistic models were used to assess the association.

RESULTS

Of 48 437 patients included, 2570 experienced gastrointestinal bleeding events (2498 non-fatal, 72 fatal), and 2465 (2397 non-fatal, 68 fatal) were matched to 9500 controls; 17.2% of cases and 15.8% of controls had cinacalcet exposure and 11.1% of both cases and controls had current use. The adjusted odds ratios (95% CI) of gastrointestinal bleeding for any use, current use, and past use of cinacalcet were 1.04 (0.91-1.19), 0.97 (0.83-1.13), and 1.22 (0.99-1.50), respectively, with no use as the reference.

CONCLUSION

The results do not suggest an elevated risk of gastrointestinal bleeding resulting in hospitalization or death for hemodialysis patients exposed to cinacalcet.

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.

Phosphate Control: The Next Frontier in Dialysis Cardiovascular Mortality

BACKGROUND

Cardiovascular disease (CVD) is a major cause of death in patients with chronic kidney disease (CKD) on dialysis. Mortality rates are still unacceptably high even though they have fallen in the past 2 decades. Hyperphosphatemia (elevated serum phosphate levels) is seen in almost all patients with advanced CKD and is by far the largest remaining modifiable contributor to CKD mortality.

SUMMARY

Phosphate retention drives multiple physiological mechanisms linked to increased risk of CVD. Fibroblast growth factor 23 and parathyroid hormone (PTH) levels, both of which have been suggested to have direct pathogenic CV effects, increase in response to phosphate retention. Phosphate, calcium, and PTH levels are linked in a progressively worsening cycle. Maladaptive upregulation of phosphate absorption is also likely to occur further exacerbating hyperphosphatemia. Even higher phosphate levels within the normal range may be a risk factor for vascular calcification and, thus, CV morbidity and mortality. A greater degree of phosphate control is important to reduce the risk of CV morbidity and mortality. Improved phosphate control and regular monitoring of phosphate levels are guideline-recommended, established clinical practices. There are several challenges with the current phosphate management approaches in patients with CKD on dialysis. Dietary restriction of phosphate and thrice-weekly dialysis alone are insufficient/unreliable to reduce phosphate to <5.5 mg/dL. Even with the addition of phosphate binders, the only pharmacological treatment currently indicated for hyperphosphatemia, the majority of patients are unable to achieve and maintain phosphate levels <5.5 mg/dL (or more normal levels) [PhosLo® gelcaps (calcium acetate): 667 mg (prescribing information), 2011, VELPHORO®: (Sucroferric oxyhydroxide) (prescribing information), 2013, FOSRENAL®: (Lanthanum carbonate) (prescribing information), 2016, AURYXIA®: (Ferric citrate) tablets (prescribing information), 2017, RENVELA®: (Sevelamer carbonate) (prescribing information), 2020, RealWorld dynamix. Dialysis US: Spherix Global Insights, 2019]. Phosphate binders do not target the primary pathway of phosphate absorption (paracellular), have limited binding capacity, and bind nonspecifically [PhosLo® gelcaps (calcium acetate): 667 mg (prescribing information). 2013, VELPHORO®: (Sucroferric oxyhydroxide) (prescribing information), 2013, FOSRENAL®: (Lanthanum carbonate) (prescribing information), 2016, AURYXIA®: (Ferric citrate) tablets (prescribing information), 2017, RENVELA®: (Sevelamer carbonate) (prescribing information) 2020]. Key Messages: Despite current phosphate management strategies, most patients on dialysis are unable to consistently achieve target phosphate levels, indicating a need for therapeutic innovations [RealWorld dynamix. Dialysis US: Spherix Global Insights, 2019]. Given a growing evidence base that the dominant mechanism of phosphate absorption is the intestinal paracellular pathway, new therapies are investigating ways to reduce phosphate levels by blocking absorption through the paracellular pathway.

Serum Alkaline Phosphatase Levels and Increased Risk of Brain Hemorrhage in Hemodialysis Patients: The Q-Cohort Study

Aim: Elevated serum alkaline phosphatase (ALP) levels have been associated with increased risks of all-cause and cardiovascular mortality in patients receiving hemodialysis. However, little is known about the impact of serum ALP levels on the development of stroke, such as brain hemorrhage and infarction.

Methods: A total of 3,497 patients receiving maintenance hemodialysis registered in the multicenter observational Q-Cohort Study were analyzed. The primary outcomes were the incidences of brain hemorrhage and infarction. The covariate of interest was serum ALP levels. Patients were divided into tertiles based on their serum ALP levels (U/L) at baseline (T1, ＜69.3; T2, 69.3–98.4; T3, ＞98.4). The risks of brain hemorrhage, brain infarction, and composite stroke were estimated using Cox proportional hazards models and competing risk models with all-cause death as a competing risk.

Results: A total of 89 patients developed brain hemorrhage and 195 patients developed brain infarction during the 4-year follow-up period. The risk of brain hemorrhage in the highest tertile (T3) was significantly higher than that in the lowest tertile (T1) (multivariable-adjusted hazard ratio [95% confidence interval], 1.93 [1.12–3.35], subdistribution hazard ratio, 1.91 [1.10–3.30]). However, there was no significant association between serum ALP levels and the risk of brain infarction or composite stroke.

Conclusions: Higher serum ALP levels are associated with an increased risk of brain hemorrhage, but not brain infarction, in patients receiving maintenance hemodialysis. High serum ALP level is thus an important risk factor for brain hemorrhage in hemodialysis patients.

Design and Rationale of HiLo: A Pragmatic, Randomized Trial of Phosphate Management for Patients Receiving Maintenance Hemodialysis

RATIONALE & OBJECTIVE

Hyperphosphatemia is a risk factor for poor clinical outcomes in patients with kidney failure receiving maintenance dialysis. Opinion-based clinical practice guidelines recommend the use of phosphate binders and dietary phosphate restriction to lower serum phosphate levels toward the normal range in patients receiving maintenance dialysis, but the benefits of these approaches and the optimal serum phosphate target have not been tested in randomized trials. It is also unknown if aggressive treatment that achieves unnecessarily low serum phosphate levels worsens outcomes.

STUDY DESIGN

Multicenter, pragmatic, cluster-randomized clinical trial.

SETTING & PARTICIPANTS

HiLo will randomize 80-120 dialysis facilities operated by DaVita Inc and the University of Utah to enroll 4,400 patients undergoing 3-times-weekly, in-center hemodialysis.

INTERVENTION

Phosphate binder prescriptions and dietary recommendations to achieve the "Hi" serum phosphate target (≥6.5 mg/dL) or the "Lo" serum phosphate target (<5.5 mg/dL).

OUTCOMES

Primary outcome: Hierarchical composite outcome of all-cause mortality and all-cause hospitalization. Main secondary outcomes: Individual components of the primary outcome.

RESULTS

The trial is currently enrolling.

LIMITATIONS

HiLo will not adjudicate causes of hospitalizations or mortality and does not protocolize use of specific phosphate binder classes.

CONCLUSIONS

HiLo aims to address an important clinical question while more generally advancing methods for pragmatic clinical trials in nephrology by introducing multiple innovative features including stakeholder engagement in the study design, liberal eligibility criteria, use of electronic informed consent, engagement of dietitians to implement the interventions in real-world practice, leveraging electronic health records to eliminate dedicated study visits, remote monitoring of serum phosphate separation between trial arms, and use of a novel hierarchical composite outcome.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov with study number NCT04095039.

Serum phosphate and mortality in incident dialysis patients in Australia and New Zealand

AIM

Hyperphosphataemia is associated with increased adverse outcomes, including mortality. Re-examining this association using up-to-date data reflecting current and real-world practices, across different global regions and in both haemodialysis and peritoneal dialysis patients, is important.

METHODS

We describe the association between serum phosphate and all-cause and cardiovascular mortality in incident dialysis patients between 2008 and 2018 using the Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry. Time-dependent Cox proportionate hazards models were used. Models were adjusted for available covariates and fitted for the overall cohort, and also each dialysis modality.

RESULTS

31 989 patients were followed over 97 122 person-years at risk (mean age at first dialysis 61 years, 38% female, 67% haemodialysis). We observed a U-shaped association between serum phosphate and all-cause mortality. In the fully adjusted model, categories of serum phosphate above and below 1.25-1.99 mmol/L were associated with progressively higher risk, reaching a hazard ratio of 2.13 (95% CI 1.93-2.36, p < .001) for serum phosphate ≥2.75 mmol/L, and 1.56 (95% CI 1.44-1.69, p < .001) for serum phosphate <1.00 mmol/L. Low and high levels of serum phosphate were also associated with increased risk of cardiovascular mortality, however the association with high serum phosphate was more pronounced ("J-shaped relationship"). The associations were consistent across sub-analyses of patients receiving haemodialysis and peritoneal dialysis treatment.

CONCLUSION

In this large contemporary dialysis cohort, both high and low levels of serum phosphate were independently associated with increased risk of mortality. Future studies are required to determine whether treatment of abnormal serum phosphate levels improves mortality.

Association Between Alkaline Phosphatase and Muscle Mass, Strength, or Physical Performance in Patients on Maintenance Hemodialysis

Introduction: Alkaline phosphatase (ALP) is an indicator for checking liver or bone disorders, but recent studies have shown the possibility of an additive indicator beyond the simple mineral-bone status in dialysis patients. The aim of the study was to evaluate the ALP level and various indicators for malnutrition, physical performance, or hospitalization in patients on hemodialysis (HD).

Methods: This study was an observational study (n = 84). We included all patients undergoing HD with the following criteria: age ≥ 20 years, duration of dialysis ≥ 6 months, ability to ambulate without an assistive device, ability to communicate with the interviewer, and no hospitalization within the last 3 months before enrollment. Furthermore, none of the patients had liver disease. We recommended abstinence of alcohol for ≥ 1 month for the duration of the study. The patients were divided into tertiles based on the ALP level. Muscle mass [appendicular muscle mass index using dual-energy X-ray absorptiometry (ASM/Ht²), thigh muscle area index using computed tomography (TMA/Ht²)], strength [handgrip strength (HGS)], and physical performance [gait speed (GS), sit-to-stand for 30-s test (STS30), 6-min walk test (6-MWT), or Short Physical Performance Battery test (SPPB)] were evaluated. The number of hospitalizations was also evaluated.

Results: The ALP level in the low, middle, and high tertiles was 50.5 ± 7.5, 69.8 ± 5.4, and 113.3 ± 47.3 IU/l, respectively. The high tertile group showed the poorest trends in ASM/Ht², TMA/Ht², HGS, GS, STS30, and 6-MWT compared to the other tertile groups. Logistic regression analysis showed that the high tertile group for low HGS, low GS, or low SPPB had a higher odds ratio compared to the other tertiles. Subgroup analyses according to age, sex and diabetes mellitus showed similar trends as in the total cohort. Hospitalization-free survival rates after 300 days in the high tertile and the other tertiles were 53.8 and 77.2%, respectively (P = 0.105).

Conclusion: The present study demonstrated that ALP is associated with muscle mass, strength, and physical performance in patients on maintenance HD. In addition, the trend showed better hospitalization-free survival in the low or middle tertiles than in the high tertile. ALP can be considered as a simple and useful indicator to detect malnutrition, physical performance, or hospitalization in patients on HD.

Association between serum alkaline phosphatase and renal outcome in patients with type 2 diabetes mellitus

This retrospective study included 299 patients with type 2 diabetes mellitus and biopsy-confirmed diabetic nephropathy (DN) to investigate the prognostic value of alkaline phosphatase (ALP) for renal outcome. Cox proportional hazards models were used to estimate the hazard ratios (HRs) for the serum ALP level on renal outcome, which was defined as end-stage renal disease (ESRD) or a 50% decline in estimated glomerular filtration rate (eGFR) from baseline. The median baseline ALP was 80 IU/L with an interquartile range of 64–97 IU/L. Serum ALP was negatively associated with eGFR but positively associated with proteinuria and renal interstitial fibrosis. During a median follow-up period of 23 months, ESRD or a 50% declined in the eGFR occurred in 156 (52.2%) patients. The highest quartile of ALP was significantly associated with poor renal outcome, as defined above (HR 2.38, 95% confidence interval [CI] 1.09–5.17), when adjusted for sociodemographics, baseline eGFR, proteinuria, liver function parameters, parathyroid hormone levels, and renal pathological findings. Each standard deviation higher in the natural log-transformed ALP was associated with a 25% increased risk for poor renal outcome. Additionally, there was a graded increase in the risk for poor renal outcome with higher ALP in patients with nephrotic-range proteinuria. However, no significant associations were observed between serum ALP levels and renal outcome in patients with non-nephrotic-range proteinuria. In conclusion, an elevated ALP level was independently associated with poor renal outcome in patients with type 2 diabetes mellitus and nephrotic-range proteinuria after multivariate adjustment.

Laboratory correlates of SARS-CoV-2 seropositivity in a nationwide sample of patients on dialysis in the U.S

Patients on dialysis are at high risk for death due to COVID-19, yet a significant proportion do survive as evidenced by presence of SARS-CoV-2 antibodies in 8% of patients in the U.S. in July 2020. It is unclear whether patients with seropositivity represent the subgroup with robust health status, who would be more likely to mount a durable antibody response. Using data from a July 2020 sample of 28,503 patients receiving dialysis, we evaluated the cross-sectional association of SARS-CoV-2 seropositivity with laboratory surrogates of patient health. In separate logistic regression models, we assessed the association of SARS-CoV-2 seropositivity with seven laboratory-based covariates (albumin, creatinine, hemoglobin, sodium, potassium, phosphate, and parathyroid hormone), across the entire range of the laboratory and in comparison to a referent value. Models accounted for age, sex, region, race and ethnicity, and county-level COVID-19 deaths per 100,000. Odds of seropositivity for albumin 3 and 3.5 g/dL were 2.1 (95% CI 1.9-2.3) and 1.3 (1.2-1.4) respectively, compared with 4 g/dL. Odds of seropositivity for serum creatinine 5 and 8 mg/dL were 1.8 (1.6-2.0) and 1.3 (1.2-1.4) respectively, compared with 12.5 mg/dL. Lower values of hemoglobin, sodium, potassium, phosphate, and parathyroid hormone were associated with higher odds of seropositivity. Laboratory values associated with poorer health status and higher risk for mortality were also associated with higher likelihood of SARS-CoV-2 antibodies in patients receiving dialysis.

Cardiovascular and Renal Disease in Chronic Critical Illness

With advances in critical care, patients who would have succumbed in previous eras now survive through hospital discharge. Many survivors suffer from chronic organ dysfunction and induced frailty, representing an emerging chronic critical illness (CCI) phenotype. Persistent and worsening cardiovascular and renal disease are primary drivers of the CCI phenotype and have pathophysiologic synergy, potentiating one another and generating a downward spiral of worsening disease and clinical outcomes manifest as cardio-renal syndromes. In addition to pharmacologic therapies (e.g., diuretics, beta adrenergic receptor blockers, angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, and blood pressure control), special consideration should be given to behavioral modifications that avoid the pitfalls of polypharmacy and suboptimal renal and hepatic dosing, to which CCI patients may be particularly vulnerable. Smoking cessation, dietary modifications (e.g., early high-protein nutrition and late low-sodium diets), and increased physical activity are advised. Select patients benefit from cardiac re-synchronization therapy or renal replacement therapy. Coordinated, patient-centered care bundles may improve compliance with standards of care and patient outcomes. Given the complex, heterogeneous nature of cardiovascular and renal disease in CCI and the dismal long-term outcomes, further research is needed to clarify pathophysiologic mechanisms of cardio-renal syndromes in CCI and develop targeted therapies.

Traditional and Non-traditional Risk Factors for Osteoporosis in CKD

Osteoporosis is a state of bone fragility with reduced skeletal resistance to trauma, and consequently increased risk of fracture. A wide range of conditions, including traditional risk factors, lifestyle choices, diseases and their treatments may contribute to bone fragility. It is therefore not surprising that the multi-morbid patient with chronic kidney disease (CKD) is at a particularly high risk. CKD is associated with reduced bone quantity, as well as impaired bone quality. Bone fragility in CKD is a composite of primary osteoporosis, accumulation of traditional and uremia-related risk factors, assaults brought on by systemic disease, and detrimental effects of drugs. Some risk factors are modifiable and represent potential targets for intervention. This review provides an overview of the heterogeneity of bone fragility in CKD.

The optimal range of serum intact parathyroid hormone for a lower risk of mortality in the incident hemodialysis patients

The serum intact parathyroid hormone (iPTH) is associated with the prognosis of hemodialysis (HD) patients, however, its optimal range for reducing mortality remains inconsistent. We designed a prospective cohort study of 346 incident HD patients to assess the association between different serum iPTH level and mortality. According to the Kidney Disease Outcomes Quality Initiative (K/DOQI) international guidelines (2003), we divided patients into three groups (iPTH < 150 pg/mL, 150–300 pg/mL and >300 pg/mL). During the median follow-up of 58 months, 157 patients (45.38%) died. Multivariate Cox regression analysis showed that iPTH < 150 pg/mL and >300 pg/mL were associated with all-cause and cardiovascular mortality. Then, we performed a sensitivity analysis of patients divided into 6 serum PTH levels groups according to the folds of the K/DOQI target range. Multivariate Cox regression analysis showed that patients with serum iPTH ≥750 pg/mL, 600–749 pg/mL, 450–599 pg/mL had significantly higher risk of all-cause and cardiovascular mortality compared with those with serum iPTH in the range of 150–299 pg/mL. The association between serum iPTH and mortality shows a U-shaped curve. The optimal serum iPTH level which confers the lowest risk of all-cause and cardiovascular mortality could range from 150 pg/mL to 450 pg/mL in this group of incident HD patients.

Adynamic bone disease: Revisited

The bone and mineral disorders form an integral part of the management of a chronic kidney disease (CKD) patient. Amongst various types of bone pathologies in chronic kidney disease-mineral bone disorder (CKD-MBD), the prevalence of adynamic bone disease (ABD) is increasing. The present review discusses the updated pathophysiology, risk factors, and management of this disorder.

Efficacy and Safety of a Novel Nicotinamide Modified-Release Formulation in the Treatment of Refractory Hyperphosphatemia in Patients Receiving Hemodialysis-A Randomized Clinical Trial

INTRODUCTION

Despite widespread use of phosphate binders (PBs), phosphate control is insufficient in many hemodialysis patients. Preliminary clinical observations suggest that nicotinamide may act synergistically with PBs to improve phosphate control.

METHODS

This multinational, randomized, double-blind, placebo-controlled study evaluated the efficacy and safety of nicotinamide modified release (NAMR) in combination with oral PB in a large cohort of hemodialysis patients with abnormal serum phosphate concentration (>4.5 mg/dl) despite treatment with PB. Patients entered a proof-of-efficacy phase (12 weeks [W12]) in which adjustments of relevant comedication were not permitted, followed by a safety extension phase for up to 52 weeks. Here, we report the results of the first phase.

RESULTS

The intention-to-treat (ITT) population consisted of 539 patients in the NAMR and 183 patients in the placebo group. NAMR and placebo were orally administered once daily (250-1500 mg/d). Mean age of patients was 61.8 years, and 63.0% were men. In the confirmatory analysis that estimated the difference in serum phosphate concentration after 12 weeks, NAMR proved superior over placebo with a significant difference of -0.51 mg/dl (95% confidence interval [CI] -0.72, -0.29; P < 0.0001). This effect was associated with significantly lower intact parathyroid hormone (iPTH) values (NAMR: 292.4±300.4 pg/ml vs. placebo: 337.0±302.7 pg/ml; P = 0.04) and an improved calcification propensity (T50 time; NAMR: 23.8±97.1 minutes vs. placebo: 2.3±100.7 minutes; P = 0.02). Diarrhea and pruritus were more frequent in the NAMR group.

CONCLUSION

NAMR combined with oral PB significantly improved phosphate control in hemodialysis patients.

Sevelamer Use, Vitamin K Levels, Vascular Calcifications, and Vertebral Fractures in Hemodialysis Patients: Results from the VIKI Study

Hyperphosphatemia is a risk factor for vascular calcifications (VCs), which are part of the chronic kidney disease-mineral and bone disorders (CKD-MBD). Vitamin K-dependent proteins such as matrix Gla protein (MGP) and bone Gla proteins (BGP, or osteocalcin) can inhibit VCs and regulate bone mineralization. In this analysis of the Vitamin K Italian (VIKI) study, the relationship between vitamin K status, vertebral fractures (VFs) and VCs in 387 hemodialysis (HD) patients with (N = 163; 42.1%) or without N = 224; 57.9%) sevelamer was evaluated. Levels of vitamin K vitamers K1 and K2 or menaquinones (MK; MK4-7), total and undercarboxylated (uc) forms for both BGP and MGP were determined. Although no differences in clinical characteristics were noted, lower levels of MK4 (0.45 versus 0.6 ng/mL, p = .01) and a greater MK4 deficiency was observed in sevelamer-treated patients (13.5% versus 5.4%, p = .005). Multivariate logistic regression revealed that MK4 deficiency was associated with sevelamer use (odds ratio [OR] = 2.64, 95% confidence interval [CI] 1.25-5.58, p = .011) and aortic calcification (OR = 8.04, 95% CI 1.07-60.26, p = .04). In the same logistic model, sevelamer amplified the effect of total BGP levels on the odds of VFs in patients with total BGP <150 μg/L compared with those with total BGP ≥150 μg/L (OR = 3.15, 95% CI 1.46-6.76, p = .003). In contrast, there was no such effect in those untreated (total BGP <150 μg/L versus total BGP ≥150 μg/L: OR = 1.21, 95% CI 0.66-2.23, p = .54]; p = .049 for effect modification by sevelamer). Sevelamer may interfere with MK4 levels in HD patients and interact with low BGP levels to increase bone fractures in CKD patients. © 2020 American Society for Bone and Mineral Research (ASBMR).

Dietary intake in adults on hemodialysis compared with guideline recommendations

Background

Clinical practice guidelines of dietary management are designed to promote a balanced diet and maintain health in patients undergoing haemodialysis but they may not reflect patients’ preferences. We aimed to investigate the consistency between the dietary intake of patients on maintenance haemodialysis and guideline recommendations.

Methods

Cross-sectional analysis of the DIET-HD study, which included 6,906 adults undergoing haemodialysis in 10 European countries. Dietary intake was determined using the Global Allergy and Asthma European Network (GA²LEN) Food Frequency Questionnaire (FFQ), and compared with the European Best Practice Guidelines. Consistency with guidelines was defined as achieving the minimum daily recommended intake for energy (≥ 30 kcal/kg) and protein (≥ 1.1 g/kg), and not exceeding the maximum recommended daily intake for phosphate (≤ 1000 mg), potassium (≤ 2730 mg), sodium (≤ 2300 mg) and calcium (≤ 800 mg).

Results

Overall, patients’ dietary intakes of phosphate and potassium were infrequently consistent with guidelines (consistent in 25% and 25% of patients, respectively). Almost half of the patients reported that energy (45%) and calcium intake (53%) was consistent with the guidelines, while the recommended intake of sodium and protein was consistent in 85% and 67% of patients, respectively. Results were similar across all participating countries. Intake was consistent with all six guideline recommendations in only 1% of patients.

Conclusion

Patients on maintenance haemodialysis usually have a dietary intake which is inconsistent with current recommendations, especially for phosphate and potassium.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40620-020-00962-3.

Hyperphosphatemia rather than hypophosphatemia indicates a poor prognosis in patients with sepsis

BACKGROUND

Sepsis is the leading cause of hospitalization and death in the intensive care unit. It is vital to identify high-risk patients with poor prognosis in the early stages of sepsis. We aimed to investigate the prognostic value of serum phosphorus levels for sepsis.

METHODS

The data of 4767 patients with sepsis were collected from the Multiparameter Intelligent Monitoring in Intensive Care III database. The Locally Weighted Scatterplot Smoothing technique and Kaplan-Meier analysis were used to test the crude relationship between serum phosphorus levels and mortality or overall survival. The multivariable logistic regression was used to further analyze the relationship between serum phosphorus levels and in-hospital mortality. The subgroup analysis was performed according to renal failure, use of vasopressin and the Sequential Organ Failure Assessment (SOFA) score.

RESULTS

Only hyperphosphatemia significantly correlated with in-hospital mortality [odds ratio (OR) 1.48; 95% confidence interval (CI) 1.19-1.85], while the correlation between hypophosphatemia and in-hospital mortality was not significant (OR 0.91; 95% CI 0.70-1.19). The interactions between serum phosphorus and renal failure, use of vasopressin or the SOFA score were not significant.

CONCLUSIONS

Hyperphosphatemia rather than hypophosphatemia indicates a poor prognosis in patients with sepsis.

Cardiovascular mortality in peritoneal dialysis: the impact of mineral disorders

Introduction:

Mineral and bone disorders (MBD) are associated with higher mortality in dialysis patients. The main guidelines related to the subject, Kidney Disease Outcomes Quality Initiative (KDOQI) and Kidney Disease: Improving Global Outcomes (KDIGO), were elaborated based on published information from hemodialysis participants. The aim of our study was to evaluate the impact of calcium (Ca), phosphorus (P), and parathyroid hormone (PTH) (according to guideline ranges from KDOQI and KDIGO) on the cardiovascular mortality of peritoneal dialysis (PD) patients.

Methods:

We used the BRAZPDII database, an observational multi-centric prospective study, which assessed participants on PD between December 2004 and January 2011. Amongst 9,905 participants included in this database, we analyzed 4424 participants who were on PD for at least 6 months. The appropriate confounding variables were entered into the model. Serum levels of Ca, P, and PTH were the variables of interest for the purposes of the current study.

Results:

We found a significant association between high P serum levels, categorized by KDOQI and KDIGO (P above 5.5 mg/dL), and cardiovascular survival (p < 0.01). Likewise, a compelling association was found between lower levels of PTH, categorized by guidelines (KDOQI and KDIGO - PTH less than 150 pg/mL, p < 0.01), and cardiovascular survival.

Conclusion:

In conclusion, levels of P above and PTH below the values proposed by KDOQI and KDIGO were associated with cardiovascular mortality in PD patients.

Dyselectrolytemia-management and implications in hemodialysis (Review)

Hemodialysis is a method for the renal replacement therapy followed by series of acute and chronic complications. Dyselectrolytemia appears in patients undergoing dialysis through mechanisms related to the chronic kidney disease and/or to the dialysis therapy and for this group of patients it is associated with an increase of morbidity and mortality. The dialysate has a standard composition, which can be modified according to the patient's characteristics. During hemodialysis patients are exposed to 18,000-36.000 litres of water/year, and the water purity along with the biochemical composition of the dialysate are essential. The individualization of the dialysis prescription is recommended for each patient and it has an important role in preventing the occurrence of dyselectrolyemia. The individualization of the treatment prescription according to the blood constants of each patient is the prerogative of the nephrologist and the association of the electrolyte imbalances with the patients cardiovascular mortality explains the importance of paying special attention to them.

Efficacy and safety of sucroferric oxyhydroxide in the treatment of hyperphosphataemia in chronic kidney disease in Asturias. FOSFASTUR study

Alterations in bone and mineral metabolism are very common in chronic kidney disease (CKD). The increase in phosphate levels leads to bone disease, risk of calcification and greater mortality, so any strategy aimed at reducing them should be welcomed. The latest drug incorporated into the therapeutic arsenal to treat hyperphosphataemia in CKD is Sucroferric Oxyhydroxide (SFO).

OBJECTIVE

To analyse the efficacy and safety of OSF in three cohorts of patients, one with advanced chronic kidney disease not on dialysis (CKD-NoD), another on peritoneal dialysis (PD) and the last on haemodialysis (HD), followed for six months.

METHODS

A prospective, observational, multicentre study in clinical practice. Clinical and epidemiological variables were analysed. The evolution of parameters relating to alterations in bone and mineral metabolism and anaemia was analysed.

RESULTS

Eighty-five patients were included in the study (62 ± 12 years, 64% male, 34% diabetic), 25 with CKD-NoD, 25 on PD and lastly, 35 on HD. In 66 patients (78%), SFO was the first phosphate binder; in the other 19, SFO replaced a previous phosphate binder due to poor tolerance or efficacy. The initial dose of SFO was 964 ± 323 mg/day. Overall, serum phosphate levels saw a significant reduction at three months of treatment (19.6%, P < 0.001). There were no differences in the efficacy of the drug when the different populations analysed were compared. Over the course of the study, there were no changes to levels of calcium, PTHi, ferritin, or the transferrin and haemoglobin saturation indices, although there was a tendency for the last two to increase. Twelve patients (14%) withdrew from follow-up, ten due to gastrointestinal adverse effects (primarily diarrhoea) and two were lost to follow-up (kidney transplant). The mean dose of the drug that the patients received increased over time, up to 1147 ± 371 mg/day.

CONCLUSIONS

SFO is an effective option for the treatment of hyperphosphataemia in patients with CKD both in the advanced phases of the disease and on dialysis. We found similar efficacy across the three groups analysed. The higher their baseline phosphate level, the greater the reduction in the serum levels. A notable reduction in phosphate levels can be achieved with doses of around 1000 mg/day. Diarrhoea was the most common side effect, although it generally was not significant.

CKD-MBD post kidney transplantation

Complications of chronic kidney disease-associated mineral and bone disorders (CKD-MBD) are frequently observed in pediatric kidney transplant recipients and are associated with high morbidity, including growth failure, leg deformities, bone pain, fractures, osteonecrosis, and vascular calcification. Post-transplant CKD-MBD is mainly due to preexisting renal osteodystrophy and cardiovascular changes at the time of transplantation, glucocorticoid treatment, and reduced graft function. In addition, persistent elevated levels of parathyroid hormone (PTH) and fibroblast growth factor 23 may cause hypophosphatemia, resulting in impaired bone mineralization. Patient monitoring should include assessment of growth, leg deformities, and serum levels of calcium, phosphate, magnesium, alkaline phosphatase, 25-hydroxyvitamin D, and PTH. Therapy should primarily focus on regular physical activity, preservation of transplant function, and steroid-sparing immunosuppressive protocols. In addition, adequate monitoring and treatment of vitamin D and mineral metabolism including vitamin D supplementation, oral phosphate, and/or magnesium supplementation, in case of persistent hypophosphatemia/hypomagnesemia, and treatment with active vitamin D in cases of persistent secondary hyperparathyroidism. The latter should be done using the minimum PTH-suppressive dosages aiming at the recommended CKD stage-dependent PTH target range. Finally, treatment with recombinant human growth hormone should be considered in patients lacking catch-up growth within the first year after transplantation.

NaPi-IIb Inhibition for Hyperphosphatemia in CKD Hemodialysis Patients

Introduction

Chronic kidney disease (CKD) has a prevalence of 9.1% globally, and frequently results in elevated serum phosphate, increasing cardiovascular morbidity and mortality risk in hemodialysis (HD) patients. DS-2330b, an oral NaPi-IIb inhibitor, reduced intestinal phosphate absorption in preclinical studies, but its effect in patients with CKD is unknown. This 2-part, randomized, placebo- and active-controlled, single- and repeated-dose, phase 1b study evaluated safety and efficacy of DS-2330b in patients with CKD on HD.

Methods

Part A, a 2-period, 2-way study, evaluated safety and pharmacokinetics of DS-2330b 250 mg in solution and tablet formulations. Part B assessed the safety of DS-2330b in solution (chosen based on results of part A) and its effect on serum phosphate. Patients were randomized to placebo 3 times daily (TID), DS-2330b 400 mg TID, DS-2330b 400 mg with sevelamer 1.6 g TID, and sevelamer 1.6 g with placebo TID for 14 days. Safety endpoints included adverse event (AE) monitoring.

Results

Six patients completed part A. Two patients experienced serious AEs considered unrelated to DS-2330b treatment. Thirty-two patients enrolled and completed part B. Serum phosphate mean change from baseline ± SD was −2.2±1.5 mg/dl versus −1.9 ± 1.1 mg/dl for DS-2330b monotherapy versus placebo. Patients receiving DS-2330b with sevelamer or sevelamer with placebo experienced the greatest serum phosphate decrease from baseline. Nine patients (28.1%) experienced ≥1 treatment-emergent AE (TEAE); 7 patients experienced drug-related TEAEs. The TEAE incidence was comparable between DS-2330b and control groups.

Conclusions

DS-2330b, alone or in combination with sevelamer, was safe and well tolerated but did not demonstrate clinically meaningful efficacy in HD patients.

Vitamin D and Kidney Diseases: A Narrative Review

Vitamin D (Vit. D) is among the most important elements of the human body that play pivotal roles in health and disease. It belongs to the fat-soluble secosteroid family, which is provided by either foods or direct exposure to sunlight that converts 7-hydroxycholesterol to the Vit. D precursor. An alternative step is bio-activation, which delivers an active form of Vit. D (Vit. D3), which participates in various noticeable functions including calcium regulation, bone remodeling, fertility, glucose control, and detoxification. The most recent literature is carefully reviewed (2049 articles) and the relative information was collected and discussed meticulously. Inclusion criteria were the articles that mentioned the relationship between Vit. D, adipokine, and kidney disease and exclusion criteria were nonrelevant articles. Vit. D plays several roles in the normal function of the kidney and metabolism. It has been revealed that Vit. D has a crucial impact on kidney disease and that its deficiency leads to kidney dysfunction and further renal disorder. Apart from the direct relationship of Vit. D with kidney disease, the association of adipocytes and adipokines with Vit. D and kidney function has also been studied. The noticeable role of Vit. D in kidney disease is investigated in various studies. It has been found that Vit. D has a pivotal role in kidney function and metabolism. Further study can reveal the better-detailed information about the exact relation of Vit. D and kidney disorders. The aim of the review was to provide a better insight into the exact role of Vit. D and adipokine in the kidney disease.

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.

Efficacy and safety of sucroferric oxyhydroxide in the treatment of hyperphosphataemia in chronic kidney disease. FOSFASTUR study

INTRODUCTION

Alterations in bone and mineral metabolism are very common in chronic kidney disease (CKD). The increase in phosphate levels leads to bone disease, risk of calcification and greater mortality, so any strategy aimed at reducing them should be welcomed. The latest drug incorporated into the therapeutic arsenal to treat hyperphosphataemia in CKD is sucroferric oxyhydroxide (SFO).

OBJECTIVE

To analyse the efficacy and safety of SFO in 3 cohorts of patients, one with advanced CKD not on dialysis, another on peritoneal dialysis and the last on haemodialysis, followed for 6 months.

METHODS

A prospective, observational, multicentre study in clinical practice. Clinical and epidemiological variables were analysed. The evolution of parameters relating to alterations in bone and mineral metabolism and anaemia was analysed.

RESULTS

Eighty-five patients were included in the study (62±12 years, 64% male, 34% diabetic), 25 with advanced CKD not on dialysis, 25 on peritoneal dialysis and lastly, 35 on haemodialysis. In 66 patients (78%), SFO was the first phosphate binder; in the other 19, SFO replaced a previous phosphate binder due to poor tolerance or efficacy. The initial dose of SFO was 964±323mg/day. Overall, serum phosphate levels saw a significant reduction at 3 months of treatment (19.6%; P<.001). There were no differences in the efficacy of the drug when the different populations analysed were compared. Over the course of the study, there were no changes to levels of calcium, PTHi, ferritin, transferrin saturation index or haemoglobin, although there was a tendency for the last 2 to increase. Twelve patients (14%) withdrew from follow-up, 10 due to gastrointestinal adverse effects (primarily diarrhoea) and 2 were lost to follow-up (kidney transplant). The mean dose of the drug that the patients received increased over time, up to 1,147±371mg/day.

CONCLUSIONS

SFO is an effective option for the treatment of hyperphosphataemia in patients with CKD both in the advanced phases of the disease and on dialysis. We found similar efficacy across the 3 groups analysed. The higher their baseline phosphate level, the greater the reduction in the serum levels. A notable reduction in phosphate levels can be achieved with doses of around 1,000mg/day. Diarrhoea was the most common side effect, although it generally was not significant.

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.

Parathyroidectomy for patients with secondary hyperparathyroidism in a changing landscape for the management of end-stage renal disease

BACKGROUND

The landscape of patients with end-stage renal disease is changing with the increasing availability of kidney transplantation. In the near future, a less aggressive approach to treat secondary hyperparathyroidism might be beneficial. We report outcomes of parathyroidectomy for end-stage renal disease-related hyperparathyroidism comparing the outcomes of limited, subtotal, and total parathyroidectomy.

METHODS

We performed a retrospective analysis of prospectively collected data. Patients were divided into 3 parathyroidectomy subgroups: limited (<3 glands removed), subtotal (3-3.5 glands), and total (4 glands) parathyroidectomy. Primary outcome was serum levels of parathyroid hormone. Secondary endpoints were serum levels of calcium, phosphate, and alkaline phosphatase, postoperative complications, and persistent or recurrent disease rates.

RESULTS

In total, 195 patients were included for analysis of whom 13.8% underwent limited parathyroidectomy, 46.7% subtotal parathyroidectomy, and 39.5% total parathyroidectomy. Preoperative parathyroid hormone levels (pg/mL) were 471 (210-868), 1,087 (627-1,795), and 1,070 (475-1,632) for the limited, subtotal, and total parathyroidectomy groups, respectively (P < .001). A decrease in serum parathyroid hormone was seen in all groups; however, postoperative levels remained greater in the limited parathyroidectomy group compared to the subtotal and total parathyroidectomy groups (P < .001). Serum calcium, phosphate, and alkaline phosphatase levels decreased in all groups to within the reference range. In the limited parathyroidectomy group, persistent disease and recurrence occurred more frequently (P = .02 and P = .07, respectively).

CONCLUSION

Subtotal parathyroidectomy is the optimal strategy in an era with an increasing availability of kidney transplantation and improved regimens of dialysis. In this changing practice, the approach to parathyroid surgery, however, might shift to a less aggressive and patient-tailored approach.

Changes in 3-month mineral and bone disorder patterns were associated with all-cause mortality in prevalent hemodialysis patients with secondary hyperparathyroidism

BACKGROUND

There is limited evidence on the association between short-term changes in mineral and bone disorder parameters and survival in maintenance hemodialysis patients.

METHODS

We investigated the association between changing patterns of phosphorus, calcium and intact parathyroid hormone levels and all-cause mortality in hemodialysis patients with secondary hyperparathyroidism. Each parameter was divided into three categories (low [L], middle [M] and high [H]), and the changing patterns between two consecutive visits at 3-month intervals were categorized into nine groups (e.g., L-L and M-H). The middle category was defined as 4.0-7.0 mg/dL for phosphorous, 8.5-9.5 mg/dL for calcium and 200-500 pg/mL for intact parathyroid hormone. Adjusted incidence rates and rate ratios were analyzed by weighted Poisson regression models accounting for time-dependent exposures.

RESULTS

For phosphorus, shifts from low/high to middle category (L-M/H-M) were associated with a lower mortality compared with the L-L and H-H groups, whereas shifts from middle to low/high category (M-L/M-H) were associated with a higher mortality compared with the M-M group. For calcium, shifts from low/middle to high category (L-H/M-H) were associated with a higher mortality compared with the L-L and M-M groups, whereas shifts from high to middle category (H-M) were associated with a lower mortality compared with the H-H group. For intact parathyroid hormone, shifts from low to middle category (L-M) were associated with a lower mortality compared with the L-L group.

CONCLUSIONS

Changes in the 3-month patterns of phosphorus and calcium toward the middle category were associated with lower mortality. Our study also suggests the importance of avoiding hypercalcemia.

Higher-order clinical risk factor interaction analysis for overall mortality in maintenance hemodialysis patients

BACKGROUND AND AIMS

In Taiwan, approximately 90% of patients with end-stage renal disease receive maintenance hemodialysis. Although studies have reported the survival predictability of multiclinical factors, the higher-order interactions among these factors have rarely been discussed. Conventional statistical approaches such as regression analysis are inadequate for detecting higher-order interactions. Therefore, this study integrated receiver operating characteristic, logistic regression, and balancing functions for adjusting the ratio in risk classes and classification errors for imbalanced cases and controls using multifactor-dimensionality reduction (MDR-ER) analyses to examine the impact of interaction effects between multiclinical factors on overall mortality in patients on maintenance hemodialysis.

METERIALS AND METHODS

In total, 781 patients who received outpatient hemodialysis dialysis three times per week before 1 January 2009 were included; their baseline clinical factor and mortality outcome data were retrospectively collected using an approved data protocol (201800595B0).

RESULTS

Consistent with conventional statistical approaches, the higher-order interaction model could indicate the impact of potential risk combination unique to patients on maintenance hemodialysis on the survival outcome, as described previously. Moreover, the MDR-based higher-order interaction model facilitated higher-order interaction effect detection among multiclinical factors and could determine more detailed mortality risk characteristics combinations.

CONCLUSION

Therefore, higher-order clinical risk interaction analysis is a reasonable strategy for detecting non-traditional risk factor interaction effects on survival outcome unique to patients on maintenance hemodialysis and thus clinically achieving whole-scale patient care.

Association of changes in bone mineral parameters with mortality in haemodialysis patients: insights from the ARO cohort

BACKGROUND

There is little information in haemodialysis (HD) patients on whether temporal changes in serum calcium, phosphate or intact parathyroid hormone (iPTH) are associated with mortality.

METHODS

We analysed associations of phosphate, total calcium and iPTH with all-cause and cardiovascular mortality in 8817 incident HD patients from the European second Analyzing Data, Recognizing Excellence and Optimizing Outcomes (AROii) cohort enrolled in 2007-09, which were prospectively followed for a median of 3 years, using time-dependent Cox proportional hazards models. We evaluated changes in risk over time depending on changes in phosphate, calcium or iPTH.

RESULTS

The association of phosphate and iPTH with all-cause mortality was U-shaped, with the lowest risk ranges between 1.20 and 1.89 mmol/L for phosphate and between 239 and 710 ng/L for iPTH. For total calcium, the associations were J-shaped, with an increased risk for all-cause mortality at levels >2.36 mmol/L. Lowest risk ranges for cardiovascular mortality did not change markedly for all three parameters. If iPTH was below the lowest risk range at baseline (iPTH <239 ng/L), a subsequent increase in levels was associated with improved survival. For phosphate, an increase or decrease out of the lowest risk range was associated with increased mortality risk. For calcium, this was only the case when the values increased above the lowest risk range.

CONCLUSION

In the AROii cohort, the ranges of bone mineral biomarkers associated with the lowest mortality ranges were largely consistent with the current Kidney Disease: Improving Global Outcomes chronic kidney disease-mineral and bone disorder guideline recommendations. Allowing a suppressed iPTH to increase was associated with a lower mortality, whereas shifts of phosphate or calcium outside the lowest risk range increased mortality.

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.

Cinacalcet use in paediatric dialysis: a position statement from the European Society for Paediatric Nephrology and the Chronic Kidney Disease-Mineral and Bone Disorders Working Group of the ERA-EDTA

Secondary hyperparathyroidism (SHPT) is an important complication of advanced chronic kidney disease (CKD) in children, which is often difficult to treat with conventional therapy. The calcimimetic cinacalcet is an allosteric modulator of the calcium-sensing receptor. It has proven to be effective and safe in adults to suppress parathyroid hormone (PTH), but data on its use in children are limited. To date, studies in children only consist of two randomized controlled trials, nine uncontrolled interventional or observational studies, and case reports that report the efficacy of cinacalcet as a PTH-lowering compound. In 2017, the European Medical Agency approved the use of cinacalcet for the treatment of SHPT in children on dialysis in whom SHPT is not adequately controlled with standard therapy. Since evidence-based guidelines are so far lacking, we present a position statement on the use of cinacalcet in paediatric dialysis patients based on the available evidence and opinion of experts from the European Society for Paediatric Nephrology, Chronic Kidney Disease-Mineral and Bone Disorder and Dialysis Working Groups, and the ERA-EDTA. Given the limited available evidence the strength of these statements are weak to moderate, and must be carefully considered by the treating physician and adapted to individual patient needs as appropriate. Audit and research recommendations to study key outcome measures in paediatric dialysis patients receiving cinacalcet are suggested.

A Combination of Hemodialysis with Hemoperfusion Helped to Reduce the Cardiovascular-Related Mortality Rate after a 3-Year Follow-Up: A Pilot Study in Vietnam

AIMS

Moderate to severe hyperparathyroidism (parathyroid hormone [PTH] concentrations ≥600 pg/mL) may increase the risk of cardiovascular problems and bone disease. We assume that a combination of hemodialysis with hemoperfusion may reduce the cardiovascular-related mortality rate in maintenance hemodialysis.

SUBJECTS AND METHODS

From 625 maintenance hemodialysis patients, 93 people met with our inclusion criteria. Based on the level of serum PTH, the patients were divided into 2 groups: 46 patients who underwent a combination of hemodialysis and hemoperfusion (HD + HP group) for consecutive 3 years and 47 patients who used hemodialysis only (HD group).

RESULTS

During 3 years of follow-up, the ratio of mortality was 4.3% in the HD + HP group which was significantly lower than in the HD group (17%), p = 0.049. Based on Kaplan-Meier analysis of cardiovascular-related mortality, patients in the HD group (red line) exhibited a significantly higher death rate compared to the HD + HP group (violet line) (log-rank test, p = 0.049).

CONCLUSION

We demonstrated that a combination of hemodialysis and hemoperfusion for 3 years helped to reduce the cardiovascular-related mortality rate.

Estimation of homeostatic dysregulation and frailty using biomarker variability: a principal component analysis of hemodialysis patients

Increased intraindividual variability in several biological parameters is associated with aspects of frailty and may reflect impaired physiological regulation. As frailty involves a cumulative decline in multiple physiological systems, we aimed to estimate the overall regulatory capacity by applying a principal component analysis to such variability. The variability of 20 blood-based parameters was evaluated as the log-transformed coefficient of variation (LCV) for one year’s worth of data from 580 hemodialysis patients. All the LCVs were positively correlated with each other and shared common characteristics. In a principal component analysis of 19 LCVs, the first principal component (PC1) explained 27.7% of the total variance, and the PC1 score exhibited consistent correlations with diverse negative health indicators, including diabetes, hypoalbuminemia, hyponatremia, and relative hypocreatininemia. The relationship between the PC1 score and frailty was subsequently examined in a subset of the subjects. The PC1 score was associated with the prevalence of frailty and was an independent predictor for frailty (odds ratio per SD: 2.31, P = 0.01) using a multivariate logistic regression model, which showed good discrimination (c-statistic: 0.85). Therefore, the PC1 score represents principal information shared by biomarker variabilities and is a reasonable measure of homeostatic dysregulation and frailty.

A comparative analysis of the efficacy and safety of paricalcitol versus other vitamin D receptor activators in patients undergoing hemodialysis: A systematic review and meta-analysis of 15 randomized controlled trials

Paricalcitol, a new vitamin D receptor activator (VDRA), is reported to be more effective than other VDRAs in reducing calcium and phosphorus levels in patients undergoing hemodialysis. However, the efficacy and safety of paricalcitol remain controversial. This analysis compares paricalcitol with other VDRAs in patients undergoing hemodialysis. We searched the Cochrane Library, PubMed, EMBASE, Web of Science, and CNKI up to April 22, 2019. Standardized mean difference (SMD), risk ratio (RR) and 95% confidence interval (CI) values were estimated to compare the outcomes of the groups. Two reviewers extracted data and assessed trial quality independently. All statistical analyses were performed using the standard statistical procedures of RevMan 5.2 and Stata 12.0. Fifteen studies (N = 110,544) were included in this meta-analysis. Of these studies, 11 were randomized controlled trials (RCTs) and 4 were non-randomized studies of interventions (NRSIs). Patients receiving paricalcitol experienced better overall survival (OS) than patients receiving other VDRAs, with a pooled hazard ratio of 0.86 (95% CI 0.80–0.91; P < 0.00001). Intact parathyroid hormone (iPTH) levels were significantly reduced in the paricalcitol group compared to the group receiving other VDRAs, with a pooled SMD of -0.53 (95% CI -0.89– -0.16; P = 0.004). There was a significant increase in serum calcium levels from baseline in the paricalcitol group compared to the other VDRAs group when limiting the analysis to RCTs, with a pooled SMD of 2.14 (95% CI 0.90–3.38; P = 0.0007). Changes in serum calcium levels were significantly lower in the paricalcitol group when the analysis was limited to NRSIs, with a pooled SMD of -0.85 (95% CI -1.34–-0.35; P = 0.0008). The NSRI analysis also showed a significant reduction in serum phosphorus levels in the paricalcitol group, with a pooled SMD of -0.57 (95% CI -1.00–-0.13; P = 0.01). No significant differences were observed in the incidence of hypercalcemia, hyperphosphatemia, or adverse events. Generally, paricalcitol seems superior to other VDRAs in reducing mortality and iPTH levels in patients undergoing hemodialysis. However, the comparative effectiveness of paricalcitol in reducing serum calcium and phosphorus levels needs further exploration. No significant difference was found in the rate of adverse events.

High alkaline phosphatase and low intact parathyroid hormone associate with worse clinical outcome in peritoneal dialysis patients

OBJECTIVE

Alkaline phosphatase (ALP) is used as a biomarker to monitor the chronic kidney disease-mineral bone disorder (CKD-MBD) and high levels of parathyroid hormone (PTH) that were reported to be related to increased mortality in CKD patients. Therefore, we conducted this longitudinal cohort study to evaluate the relations between ALP and intact PTH (iPTH) and the associations with all-cause and cardiovascular mortality in peritoneal dialysis (PD) patients.

METHODS

In 1276 incident PD patients (median age 50 years, 56% males), baseline serum ALP, iPTH, and metabolic biomarkers potentially linked to CKD-MBD were analyzed in relation to mortality during follow-up period of up to 60 months. All-cause and cardiovascular mortality risk of ALP and iPTH were analyzed with competing-risks regression models with transplantation as competing risk adjusting for all covariates.

RESULTS

After adjustments for confounders by logistic regression model, older age, higher change level to levels of iPTH, S-albumin, calcium, alanine transaminase (ALT), and lower level of phosphorus were associated with higher ALP level (>79 U/L), and female gender, non-diabetes mellitus, younger age, lower calcium, higher ALT, total bilirubin, phosphorus, and ALP were associated with higher iPTH level (>300 pg/mL). During 60 months (median 44 months) of follow-up, the all-cause mortality rate was 16%, and 91 (46%) of the 199 deaths were caused by cardiovascular disease. In competing-risks regression analysis, "high ALP + low iPTH" was independently associated with all-cause and cardiovascular mortality after adjustment for age, gender, presence of diabetes, and cardiovascular disease, the calendar year of recruitment and vitamin D therapy in PD patients. The subhazard ratio (sHR) of group "high ALP + low iPTH" was 1.96 times and 3.35 times higher than sHR of group "low ALP + high iPTH" for all-cause mortality and cardiovascular mortality, respectively.

CONCLUSIONS

The combination of high ALP and low iPTH was independently associated with increased all-cause and cardiovascular mortality in PD patients, suggesting that ALP and iPTH have the potential to predict clinical outcomes and might be useful risk assessment tools in PD patients. Further studies exploring the observed association between combination of ALP with iPTH and mortality are warranted.

Functional impairment attenuates the association between high serum phosphate and mortality in dialysis patients: a nationwide cohort study

BACKGROUND

Both functional impairment and abnormalities in mineral and bone disorder (MBD) parameters are well-known predictors of mortality in dialysis patients. However, previous studies have not evaluated whether functional impairment modifies the association between MBD parameters and mortality.

METHODS

A nationwide prospective cohort study was conducted using data from the Japanese Society for Dialysis Therapy Renal Data Registry collected at the end of 2009 and 2010. The Eastern Cooperative Oncology Group performance status (PS) was used to assess functional status. Cox proportional hazards models were used to assess the associations of baseline functional status, serum phosphate, albumin-corrected calcium and intact parathyroid hormone (PTH) with 1-year all-cause mortality.

RESULTS

By 31 December 2010, 18 447 of 220 054 prevalent dialysis patients (8.4%) had died. Mortality significantly increased with worsening PS grade. PS grade modified the association of serum phosphate levels with mortality (Pinteraction = 0.001). Worsening PS grade attenuated the association of hyperphosphatemia (≥7.4 mg/dL) with mortality, and hyperphosphatemia was no longer significant on mortality among patients with the worst PS grade (hazard ratio = 1.1, 95% confidence interval 0.88-1.39), compared with the level between 3.5 and 4.7 mg/dL. In contrast, hypophosphatemia (<3.5 mg/dL) had a greater adjusted risk of mortality irrespective of PS grade. Serum-corrected calcium (Pinteraction = 0.26) and intact PTH (Pinteraction = 0.17) showed consistent associations with mortality irrespective of PS grade. Findings were robust in several sensitivity analyses.

CONCLUSIONS

Functional impairment was significantly associated with 1-year mortality and attenuated the effect of hyperphosphatemia on mortality among prevalent dialysis patients.

Hidden Hypocalcemia as a Risk Factor for Cardiovascular Events and All-Cause Mortality among Patients Undergoing Incident Hemodialysis

Lower corrected calcium (cCa) levels are associated with a better prognosis among incident dialysis patients. However, cCa frequently overestimates ionized calcium (iCa) levels. The prognostic importance of the true calcium status defined by iCa remains to be revealed. We conducted a retrospective cohort study of incident hemodialysis patients. We collected data of iCa levels immediately before the first dialysis. We divided patients into three categories: apparent hypocalcemia (low iCa; <1.15 mmol/L and low cCa; <8.4 mg/dL), hidden hypocalcemia (low iCa despite normal or high cCa), and normocalcemia (normal iCa). The primary outcome was the composite of all-cause death and cardiovascular diseases after hospital discharge. Among the enrolled 332 patients, 75% of the patients showed true hypocalcemia, defined as iCa <1.15 mmol/L, 61% of whom showed hidden hypocalcemia. In multivariate Cox models including other potential risk factors, true hypocalcemia was a significant risk factor (hazard ratio [HR], 2.34; 95% confidence interval [CI], 1.03–5.34), whereas hypocalcemia defined as corrected calcium <8.4 mg/dL was not. Furthermore, hidden hypocalcemia was significantly associated with an increased risk of the outcome compared with normocalcemia (HR, 2.56; 95% CI, 1.11–5.94), while apparent hypocalcemia was not. Patients with hidden hypocalcemia were less likely to receive interventions to correct hypocalcemia, such as increased doses of active vitamin D or administration of calcium carbonate, than patients with apparent hypocalcemia (odds ratio, 0.45; 95% CI, 0.23–0.89). Hidden hypocalcemia was a strong predictor of death and cardiovascular events, suggesting the importance of measuring iCa.