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Modification and Validation of the Phosphate Removal Model: A Multicenter Study.
Zhang, W, Du, Q, Xiao, J, Bi, Z, Yu, C, Ye, Z, Wang, M, Chen, J
Kidney & blood pressure research. 2021;(1):53-62
Abstract
BACKGROUND Our research group has previously reported a noninvasive model that estimates phosphate removal within a 4-h hemodialysis (HD) treatment. The aim of this study was to modify the original model and validate the accuracy of the new model of phosphate removal for HD and hemodiafiltration (HDF) treatment. METHODS A total of 109 HD patients from 3 HD centers were enrolled. The actual phosphate removal amount was calculated using the area under the dialysate phosphate concentration time curve. Model modification was executed using second-order multivariable polynomial regression analysis to obtain a new parameter for dialyzer phosphate clearance. Bias, precision, and accuracy were measured in the internal and external validation to determine the performance of the modified model. RESULTS Mean age of the enrolled patients was 63 ± 12 years, and 67 (61.5%) were male. Phosphate removal was 19.06 ± 8.12 mmol and 17.38 ± 6.75 mmol in 4-h HD and HDF treatments, respectively, with no significant difference. The modified phosphate removal model was expressed as Tpo4 = 80.3 × C45 - 0.024 × age + 0.07 × weight + β × clearance - 8.14 (β = 6.231 × 10-3 × clearance - 1.886 × 10-5 × clearance2 - 0.467), where C45 was the phosphate concentration in the spent dialysate measured at the 45th minute of HD and clearance was the phosphate clearance of the dialyzer. Internal validation indicated that the new model was superior to the original model with a significantly smaller bias and higher accuracy. External validation showed that R2, bias, and accuracy were not significantly different than those of internal validation. CONCLUSIONS A new model was generated to quantify phosphate removal by 4-h HD and HDF with a dialyzer surface area of 1.3-1.8 m2. This modified model would contribute to the evaluation of phosphate balance and individualized therapy of hyperphosphatemia.
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Optimal Phosphate Control Related to Coronary Artery Calcification in Dialysis Patients.
Isaka, Y, Hamano, T, Fujii, H, Tsujimoto, Y, Koiwa, F, Sakaguchi, Y, Tanaka, R, Tomiyama, N, Tatsugami, F, Teramukai, S
Journal of the American Society of Nephrology : JASN. 2021;(3):723-735
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BACKGROUND In patients on maintenance dialysis, cardiovascular mortality risk is remarkably high, which can be partly explained by severe coronary artery calcification (CAC). Hyperphosphatemia has been reported to be associated with the severity of CAC. However, the optimal phosphate range in patients on dialysis remains unknown. This study was planned to compare the effects on CAC progression of two types of noncalcium-based phosphate binders and of two different phosphate target ranges. METHODS We conducted a randomized, open-label, multicenter, interventional trial with a two by two factorial design. A total of 160 adults on dialysis were enrolled and randomized to the sucroferric oxyhydroxide or lanthanum carbonate group, with the aim of reducing serum phosphate to two target levels (3.5-4.5 mg/dl in the strict group and 5.0-6.0 mg/dl in the standard group). The primary end point was percentage change in CAC scores during the 12-month treatment. RESULTS The full analysis set included 115 patients. We observed no significant difference in percentage change in CAC scores between the lanthanum carbonate group and the sucroferric oxyhydroxide group. On the other hand, percentage change in CAC scores in the strict group (median of 8.52; interquartile range, -1.0-23.9) was significantly lower than that in the standard group (median of 21.8; interquartile range, 10.0-36.1; P=0.006). This effect was pronounced in older (aged 65-74 years) versus younger (aged 20-64 years) participants (P value for interaction =0.003). We observed a similar finding for the absolute change in CAC scores. CONCLUSIONS Further study with a larger sample size is needed, but strict phosphate control shows promise for delaying progression of CAC in patients undergoing maintenance hemodialysis. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER Evaluate the New Phosphate Iron-Based Binder Sucroferric Oxyhydroxide in Dialysis Patients with the Goal of Advancing the Practice of EBM (EPISODE), jRCTs051180048.
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The predictive role of serum calprotectin on mortality in hemodialysis patients with high phosphoremia.
Kanki, T, Kuwabara, T, Morinaga, J, Fukami, H, Umemoto, S, Fujimoto, D, Mizumoto, T, Hayata, M, Kakizoe, Y, Izumi, Y, et al
BMC nephrology. 2020;(1):158
Abstract
BACKGROUND The inflammatory mediator calprotectin (CPT, myeloid-related protein 8/14) is known as an endogenous ligand contributing to pathophysiology in inflammatory diseases. Serum CPT reportedly became a potential biomarker in these conditions, though there is no report predicting the prognosis in hemodialysis patients. The aim of this study is to investigate the predictive role of serum CPT on mortality in hemodialysis patients. METHODS We conducted a multicenter, observational cohort study of 388 Japanese subjects undergoing hemodialysis. Serum CPT were measured using an ELISA. The potential associations between serum CPT and clinical variables were cross-sectionally examined. Multivariate Cox regression was used to estimate the association between serum CPT, high-sensitivity C reactive protein (hs-CRP), white blood cell (WBC) count and mortality. Median follow-up was 6.6 years. RESULTS The median CPT level was 6108 ng/ml (median in healthy subjects, 2800) at baseline. Serum CPT positively correlated with WBC count (ρ = 0.54, P < 0.001) and hs-CRP values (ρ = 0.35, P < 0.001). In multivariate analysis, hs-CRP was an independent predictor of all-cause mortality after adjusting confounding factors (middle vs. low: hazard ratio [HR] 2.09, 95% confidence interval [CI] 1.23-3.66; high vs. low: 2.47, 1.40-4.47). In the analysis by stratum of phosphate levels, elevated CPT levels were significantly associated with all-cause mortality in the highest tertile (18.1; 3.15-345.9) among the high-phosphate group, but not among the low-phosphate group. CONCLUSIONS Serum CPT would become a potential predictive marker on mortality in hemodialysis patients with high-phosphate levels.
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Efficacy and Safety of Tenapanor in Patients with Hyperphosphatemia Receiving Maintenance Hemodialysis: A Randomized Phase 3 Trial.
Block, GA, Rosenbaum, DP, Yan, A, Chertow, GM
Journal of the American Society of Nephrology : JASN. 2019;(4):641-652
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BACKGROUND Guidelines recommend reducing elevated serum phosphate in patients with CKD. Tenapanor, a minimally absorbed inhibitor of gastrointestinal sodium/hydrogen exchanger 3 (NHE3), reduces paracellular phosphate transport. METHODS In this phase 3 randomized, double-blind trial, we randomly assigned patients with hyperphosphatemia receiving maintenance hemodialysis to receive twice-daily oral tenapanor (3, 10, or 30 mg [the latter down-titrated, if needed]) for 8 weeks. Patients were then rerandomized 1:1 to receive either their previously assigned dose or placebo for a 4-week 'withdrawal' period. We measured serum phosphate levels over the course of the trial. The primary end point was mean change in serum phosphate over the 4-week withdrawal period for the tenapanor group (using pooled data) versus the placebo group. RESULTS Of 219 patients randomized, 152 completed both study phases. During the initial 8-week treatment period, all three treatment groups experienced significant decreases in mean serum phosphate (reductions of 1.00, 1.02, and 1.19 mg/dl, corresponding to the 3, 10, and 30 mg [down-titrated] dose groups, respectively). Tenapanor also showed a significant benefit over placebo during the withdrawal period, with a mean increase of 0.85 mg/dl in the placebo group versus a mean increase of 0.02 mg/dl in the pooled tenapanor group. Adverse events were largely limited to softened stool and a modest increase in bowel movement frequency, resulting from increased stool sodium and water content, stemming from tenapanor's mechanism of action. CONCLUSIONS Tenapanor significantly reduced elevated serum phosphate in patients with hyperphosphatemia receiving maintenance hemodialysis. Adverse effects were limited to those induced by its known mechanism of action, which increases stool sodium and water content.
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Serum Phosphate and the Risk of New-Onset Hyperuricemia in Hypertensive Patients.
Cao, J, Zhang, J, Li, Q, Jiang, C, Song, Y, Liu, C, Liu, L, Wang, B, Li, J, Zhang, Y, et al
Hypertension (Dallas, Tex. : 1979). 2019;(1):102-110
Abstract
The relationship of serum phosphate and new-onset hyperuricemia remains uncertain. We aimed to evaluate the relationship of serum phosphate with the risk of new-onset hyperuricemia, and to examine any possible effect modifiers in hypertensive patients. This is a post hoc analysis of the Uric Acid substudy of the CSPPT (China Stroke Primary Prevention Trial). A total of 10 612 participants with normal uric acid levels (<357 μmol/L [6 mg/dL]) at baseline were included in the current study. The primary outcome was new-onset hyperuricemia, which was defined as a uric acid concentration ≥417 μmol/L (7 mg/dL) in men or ≥357 μmol/L (6 mg/dL) in women. During a median follow-up of 4.4 years, 1663 (15.7%) participants developed new-onset hyperuricemia. Overall, there was a significant inverse association between serum phosphate and the risk of new-onset hyperuricemia (per SD increment; odds ratio, 0.71; 95% CI, 0.66-0.76). When serum phosphate was assessed as quartiles, a significantly lower risk of new-onset hyperuricemia was found in participants in quartile 4 (≥1.4 mmol/L; odds ratio, 0.48; 95% CI, 0.40-0.57) compared with those in quartile 1 (<1.2 mmol/L). Similar results were found in males and females. In summary, there was an inverse association between serum phosphate and the risk of new-onset hyperuricemia in hypertensive adults.
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A randomized controlled trial of different serum phosphate ranges in subjects on hemodialysis.
Bhargava, R, Kalra, PA, Hann, M, Brenchley, P, Hurst, H, Hutchison, AJ
BMC nephrology. 2019;(1):37
Abstract
BACKGROUND Hyperphosphataemia in dialysis subjects is associated with increased mortality. However cause and effect has not been proven, and the ideal phosphate target range is unknown despite KDOQI's call for studies over 12 years ago. The design and conduct of a randomized controlled trial is challenging because maintaining two groups within differing target ranges of serum phosphate has not been achieved over a long follow-up of 1 year, in a trial setting, before. The SPIRiT study examines the subject acceptance, recruitment and retention rates for such a study in which subjects were randomised to two distinct serum phosphate concentrations, then titrated and maintained over 12 months. METHODS A two center trial of 104 hemodialysis subjects randomized to lower range LRG 0.8-1.4 mmol/L or 2.5-4.3 mg/dL) and higher range (HRG 1.8-2.4 mmol/L or 5.6-7.4 mg/dL) serum phosphate groups. Two months' titration and ten months' maintenance phase. Interventions were non-calcium phosphate binders, self-help questionnaires, with blood tests at specified time intervals. RESULTS Thirteen percent of the eligible dialysis population were successfully recruited. A mean separation by serum phosphate of 1.1 mg/dL was achieved and maintained between the groups over 10 months. Drop-out rate was 27% with mortality 10%. Nine subjects in the HRG (17.6%) and two subjects in the LRG (3.8%) died during the study, however the study was not powered to detect significant differences in outcomes. CONCLUSION Randomizing dialysis subjects to separate treatment targets for serum phosphate can achieve a clinically significant sustained separation over 12 months. A large scale longer term study is required to examine outcomes including mortality. TRIAL REGISTRATION The trial registration number is ISRCTN24741445 - Date of registration 16th January, retrospectively registered.
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Effects of Nicotinamide and Lanthanum Carbonate on Serum Phosphate and Fibroblast Growth Factor-23 in CKD: The COMBINE Trial.
Ix, JH, Isakova, T, Larive, B, Raphael, KL, Raj, DS, Cheung, AK, Sprague, SM, Fried, LF, Gassman, JJ, Middleton, JP, et al
Journal of the American Society of Nephrology : JASN. 2019;(6):1096-1108
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BACKGROUND Higher serum phosphate and fibroblast growth factor-23 (FGF23) levels may be modifiable to prevent cardiovascular disease in CKD. Short-term studies have reported modest efficacy in phosphate and FGF23 reduction with intestinal phosphate binders in CKD. METHODS To investigate effects of lanthanum carbonate (LC; a phosphate binder) and/or nicotinamide (NAM; an inhibitor of active intestinal phosphate transport) on serum phosphate and FGF23 in stage 3b/4 CKD, we conducted a randomized trial among individuals with eGFR 20-45 ml/min per 1.73 m2 to NAM (750 mg twice daily) plus LC (1000 mg thrice daily), NAM plus LC placebo, LC plus NAM placebo, or double placebo for 12 months. Dual primary end points were change from baseline in serum phosphate and intact FGF23 concentrations. RESULTS Mean eGFR for the 205 participants was 32ml/min per 1.73 m2. At baseline, serum phosphate was 3.7 mg/dl and median FGF23 was 99 pg/ml (10th, 90th percentiles: 59, 205). Mean rates of change in phosphate increased slightly over 12 months in all groups and did not differ significantly across arms. Similarly, percent changes in FGF23 per 12 months increased for all arms except LC plus placebo, and did not differ significantly across arms. Gastrointestinal symptoms limited adherence. Adverse events rates were similar across arms. CONCLUSIONS LC and/or NAM treatment did not significantly lower serum phosphate or FGF23 in stage 3b/4 CKD over 12 months. Although these agents appeared safe, intestinal symptoms limited adherence. Reducing phosphate and FGF23 in nondialysis CKD will require new approaches.
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Can we IMPROVE cardiovascular outcomes through phosphate lowering in CKD? Rationale and protocol for the IMpact of Phosphate Reduction On Vascular End-points in Chronic Kidney Disease (IMPROVE-CKD) study.
Lioufas, N, Toussaint, ND, Pedagogos, E, Elder, G, Badve, SV, Pascoe, E, Valks, A, Hawley, C, ,
BMJ open. 2019;(2):e024382
Abstract
INTRODUCTION Patients with chronic kidney disease (CKD) are at heightened cardiovascular risk, which has been associated with abnormalities of bone and mineral metabolism. A deeper understanding of these abnormalities should facilitate improved treatment strategies and patient-level outcomes, but at present there are few large, randomised controlled clinical trials to guide management. Positive associations between serum phosphate and fibroblast growth factor 23 (FGF-23) and cardiovascular morbidity and mortality in both the general and CKD populations have resulted in clinical guidelines suggesting that serum phosphate be targeted towards the normal range, although few randomised and placebo-controlled studies have addressed clinical outcomes using interventions to improve phosphate control. Early preventive measures to reduce the development and progression of vascular calcification, left ventricular hypertrophy and arterial stiffness are crucial in patients with CKD. METHODS AND ANALYSIS We outline the rationale and protocol for an international, multicentre, randomised parallel-group trial assessing the impact of the non-calcium-based phosphate binder, lanthanum carbonate, compared with placebo on surrogate markers of cardiovascular disease in a predialysis CKD population-the IM pact of P hosphate R eduction O n V ascular E nd-points (IMPROVE)-CKD study. The primary objective of the IMPROVE-CKD study is to determine if the use of lanthanum carbonate reduces the burden of cardiovascular disease in patients with CKD stages 3b and 4 when compared with placebo. The primary end-point of the study is change in arterial compliance measured by pulse wave velocity over a 96-week period. Secondary outcomes include change in aortic calcification and biochemical parameters of serum phosphate, parathyroid hormone and FGF-23 levels. ETHICS AND DISSEMINATION Ethical approval for the IMPROVE-CKD trial was obtained by each local Institutional Ethics Committee for all 17 participating sites in Australia, New Zealand and Malaysia prior to study commencement. Results of this clinical trial will be published in peer-reviewed journals and presented at conferences. TRIAL REGISTRATION NUMBER ACTRN12610000650099.
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Serum Alkaline Phosphatase, Phosphate, and In-Hospital Mortality in Acute Ischemic Stroke Patients.
Zhong, C, You, S, Chen, J, Zhai, G, Du, H, Luo, Y, Dong, X, Cao, Y, Liu, CF, Zhang, Y
Journal of stroke and cerebrovascular diseases : the official journal of National Stroke Association. 2018;(1):257-266
Abstract
BACKGROUND The clinical impacts of serum alkaline phosphatase (ALP) and phosphate on early death are not fully understood in patients with acute ischemic stroke. We examined the associations between serum ALP, phosphate, and in-hospital mortality after ischemic stroke. METHODS Serum ALP and phosphate were measured in 2944 ischemic stroke patients from 22 hospitals in Suzhou City from December 2013 to May 2014. Cox proportional hazard models and restricted cubic splines were used to estimate the relationships between serum ALP and phosphate (both as categorical and continuous variables) and risk of in-hospital mortality. RESULTS During hospitalization, 111 patients (3.7%) died from all causes. After multivariable adjustment, the hazard ratio (HR) of the highest quartile compared with the lowest quartile of ALP was 2.19 (95% confidence interval [CI], 1.20-4.00) for early death. Restricted cubic spline analysis indicated a significant linear association between ALP and death (P-linearity = .017). A U-shaped association of phosphate with in-hospital mortality was observed (P-nonlinearity = .011). Compared with the third quartile of phosphate (1.08-1.21 mmol/L), HRs of the lowest and highest quartiles for early death were 2.17 (1.15-4.08) and 1.70 (.88-3.30), respectively. Sensitivity analyses further confirmed our findings. CONCLUSIONS We observed a graded relationship between serum ALP levels and risk of early death in patients with acute ischemic stroke. There was a U-shaped association between phosphate and all-cause mortality with significantly increased risk among patients with lower phosphate levels.
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Impact of using two dialyzers in parallel on phosphate clearance in hemodialysis patients: a randomized trial.
Thompson, S, Manns, B, Lloyd, A, Hemmelgarn, B, MacRae, J, Klarenbach, S, Unsworth, L, Courtney, M, Tonelli, M
Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association. 2017;(5):855-861
Abstract
BACKGROUND Dietary restriction and phosphate binders are the main interventions used to manage hyperphosphatemia in people on hemodialysis, but have limited efficacy. Modifying conventional dialysis regimens to enhance phosphate clearance as an alternative approach remains relatively unstudied. METHODS This was a 10-week, 2-arm, randomized crossover study. Participants were prevalent dialysis patients ( n = 32) with consecutive serum phosphate levels >1.6 mmol/L and on stable doses of a phosphate binder. Following a 2-week run-in period, participants were randomized to initiate dialysis using two high flux dialyzers in parallel (blood flow ≥350 mL/min, dialysate flow 800 mL/min) or standard dialysis using one high flux dialyzer (blood flow ≥350 mL/min, dialysate flow of 800 mL/min). Each regimen was 3 weeks in duration. After a 2-week washout period, participants received the alternate regimen. The primary outcome was the mean difference in phosphate clearance by dialyzer strategy. Secondary outcomes were phosphate removal and pre-dialysis serum phosphate. RESULTS Phosphate clearance for the double dialyzer strategy did not differ significantly from the single dialyzer strategy [mean difference 7.5 mL/min (95% confidence interval, 95% CI, -6.1, 21.0), P = 0.28]. There was no difference in total phosphate removal and pre-dialysis phosphate between the double and single dialyzer strategies [total phosphate removal mean difference -0.2 mmol (95% CI -4.1, 3.7), P = 0.93; pre-dialysis mean difference 0.01 mmol/L (95% CI -0.18, 0.21), P = 0.88]. There was no difference in the proportion of participants who experienced at least one episode of intradialytic hypotension (32 versus 47%, P = 0.13). A limitation of the study was frequent protocol deviations in the dialysis prescription. CONCLUSIONS In this study, the use of two dialyzers in parallel did not increase phosphate clearance, phosphate removal or pre-dialysis serum phosphorus when compared with a standard dialysis treatment strategy. Future studies should continue to evaluate novel methods of phosphate removal using conventional hemodialysis.