***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    ***EXAMPLES*** 
    Input: Background and Aims : Calcium-containing phosphate binders have been shown to increase the progression of vascular calcification in hemodialysis patients . This is a prospect i ve study that compares the effects of calcium acetate and sevelamer on coronary calcification ( CAC ) and bone histology . Methods : 101 hemodialysis patients were r and omized for each phosphate binder and su bmi tted to multislice coronary tomographies and bone biopsies at entry and 12 months . Results : The 71 patients who concluded the study had similar baseline characteristics . On follow-up , the sevelamer group had higher levels of intact parathyroid hormone ( 498 ± 352 vs. 326 ± 236 pg/ml , p = 0.017 ) , bone alkaline phosphatase ( 38 ± 24 vs. 28 ± 15 U/l , p = 0.03 ) and deoxypyridinoline ( 135 ± 107 vs. 89 ± 71 nmol/l , p = 0.03 ) and lower LDL cholesterol ( 74 ± 21 vs. 91 ± 28 mg/dl , p = 0.015 ) . Phosphorus ( 5.8 ± 1.0 vs. 6 ± 1.0 mg/dl , p = 0.47 ) and calcium ( 1.27 ± 0.07 vs. 1.23 ± 0.08 mmol/l , p = 0.68 ) levels did not differ between groups . CAC progression ( 35 vs. 24 % , p = 0.94 ) and bone histological diagnosis at baseline and 12 months were similar in both groups . Patients of the sevelamer group with a high turnover at baseline had an increase in bone resorption ( eroded surface , ES/BS = 9.0 ± 5.9 vs. 13.1 ± 9.5 % , p = 0.05 ) , whereas patients of both groups with low turnover at baseline had an improvement in bone formation rate ( BFR/BS = 0.015 ± 0.016 vs. 0.062 ± 0.078 , p = 0.003 for calcium and 0.017 ± 0.016 vs. 0.071 ± 0.084 μm3/μm2/day , p = 0.010 for sevelamer ) . Conclusions : There was no difference in CAC progression or changes in bone remodeling between the calcium and the sevelamer groups Hyperphosphatemia is highly prevalent among patients with end-stage renal disease ( ESRD ) and is associated with increased mortality risk in hemodialysis ( HD ) patients . The mechanism through which this mortality risk is mediated is unclear . Data from two national r and om sample s of HD patients ( n = 12,833 ) was used to test the hypothesis that elevated serum PO(4 ) contributes mainly to cardiac causes of death . During a 2-yr follow-up , the cause-specific relative risk ( RR ) of death for patients was analyzed separately for several categories of cause of death , including coronary artery disease ( CAD ) , sudden death , and other cardiac causes , cerebrovascular and infection . Cox regression models were fit for each of the eight cause of death categories , adjusting for patient demographics and non-cardiovascular comorbid conditions . Time at risk for each cause-specific model was censored at death that result ed from any of the other causes . Higher mortality risk was seen for patients in the high PO(4 ) group ( > 6.5mg/dl ) compared with the lower PO(4 ) group ( < or = 6.5mg/dl ) for death result ing from CAD ( RR 1.41 ; P < 0.0005 ) , sudden death ( RR 1.20 ; P < 0.01 ) , infection ( RR 1.20 ; P < 0.05 ) , and unknown causes ( RR 1.25 ; P < 0.05 ) . Patients in the high PO(4 ) group also had non-significantly increased RR of death from other cardiac and cerebrovascular causes of death . The RR of sudden death was also strongly associated with elevated Ca x PO(4 ) product ( RR 1.07 per 10 mg(2)/dl(2 ) ; P < 0.005 ) and serum parathyroid hormone levels greater than 495 pg/ml ( RR 1.25 ; P < 0.05 ) . This study identifies strong relationships between elevated serum PO(4 ) , Ca x PO(4 ) product , and parathyroid hormone and cardiac causes of death in HD patients , especially deaths result ing from CAD and sudden death . More vigorous measures to reduce the prevalence of these factors in HD patients may result in improved survival BACKGROUND Sevelamer hydrochloride was recently proposed as a phosphate binder to prevent hypercalcaemia in place of calcium alkaline salts in dialysis patients . So far , it has been evaluated only in patients receiving calcitriol , without comparison with CaCO(3 ) alone , although the latter was found to be as effective as the combination of calcitriol and Al(OH)(3 ) in suppressing parathyroid hormone ( PTH ) without inducing hypercalcaemia and to have a better lowering effect on serum phosphate . Moreover , this bile salt binder may decrease serum 25-OH vitamin D. Therefore , we compared for 5 months two strategies for controlling moderate hyperparathyroidism : CaCO(3 ) alone vs sevelamer in conjunction with measures to increase calcium balance . METHODS Forty-two patients were r and omized : 21 continued their treatment with 4.8 g/day CaCO(3 ) and 21 were switched to sevelamer ( initial dose : 2.4 g/day , increased to 4.4 g/day ) . Each month , when serum-corrected calcium decreased below 2.30 mmol/l , dialysate calcium was increased or alphacalcidol was given at each dialysis session , according to serum PO(4 ) levels . The following parameters were monitored : serum Ca , PO(4 ) , bicarbonate and protein , weekly ; and serum PTH , 25-OH vitamin D and total , LDL and HDL cholesterol monthly . RESULTS Except for higher serum phosphate at month 1 , lower serum bicarbonate at month 2 and lower LDL cholesterol at month 5 in the sevelamer group , no difference was found between the two groups . Compared with baseline levels , PTH increased and 25-OH vitamin D decreased significantly in both groups , these two parameters being inversely correlated . CONCLUSIONS Given comparable control of plasma calcium , phosphate and 25-OH vitamin D , PTH control is comparable in both strategies . Sevelamer does not induce greater vitamin D depletion than CaCO(3 ) . The transient decrease of serum bicarbonate after discontinuation of CaCO(3 ) in the sevelamer group suggests a less optimal prevention of acidosis . The sevelamer-induced decrease in LDL cholesterol gives this drug a potential advantage in cardiovascular prevention The risk of death in hemodialysis patients treated with calcium-containing phosphate binders or sevelamer  is not known . We assessed all-cause  mortality in 127 patients new to hemodialysis assigned to calcium-containing binders or sevelamer after a median follow-up of 44 months from r and omization . This was a predetermined secondary end point of a r and omized clinical trial design ed to assess progression of coronary artery calcium ( CAC ) scores in the two treatment arms . Thirty-four deaths occurred during the follow-up period : 23 in subjects r and omized to calcium-containing phosphate binders and 11 in subjects r and omized to sevelamer .  Baseline CAC score was a significant predictor of mortality after adjustment for age , race , gender , and diabetes with increased mortality proportional to baseline score ( P=0.002 ) . Mortality was borderline significantly lower in subjects r and omized to sevelamer ( 5.3/100 patient years , confidence interval ( CI ) ( 2.2 - 8.5 ) compared to those r and omized to calcium-containing binders ( 10.6/100 patient years , CI 6.3 - 14.9 ) ( P=0.05 ) . The greater risk of death for patients treated with calcium-containing phosphate binders  persisted after full multivariable adjustment ( P=0.016 , hazard ratio 3.1 , CI 1.23 - 7.61 ) . In subjects new to hemodialysis baseline CAC score was a significant predictor of all-cause mortality . Treatment with sevelamer was associated with a significant survival benefit as compared to the use of calcium-containing phosphate binders BACKGROUND Cardiovascular disease is frequent and severe in patients with end-stage renal disease . Disorders of mineral metabolism may contribute by promoting cardiovascular calcification . METHODS We conducted a r and omized clinical trial comparing sevelamer , a non-absorbed polymer , with calcium-based phosphate binders in 200 hemodialysis patients . Study outcomes included the targeted concentrations of serum phosphorus , calcium , and intact parathyroid hormone ( PTH ) , and calcification of the coronary arteries and thoracic aorta using a calcification score derived from electron beam tomography . RESULTS Sevelamer and calcium provided equivalent control of serum phosphorus ( end-of- study values 5.1 + /- 1.2 and 5.1 + /- 1.4 mg/dL , respectively , P = 0.33 ) . Serum calcium concentration was significantly higher in the calcium-treated group ( P = 0.002 ) , and hypercalcemia was more common ( 16 % vs. 5 % with sevelamer , P = 0.04 ) . More subjects in the calcium group had end-of- study intact PTH below the target of 150 to 300 pg/mL ( 57 % vs. 30 % , P = 0.001 ) . At study completion , the median absolute calcium score in the coronary arteries and aorta increased significantly in the calcium treated subjects but not in the sevelamer-treated subjects ( coronary arteries 36.6 vs. 0 , P = 0.03 and aorta 75.1 vs. 0 , P = 0.01 , respectively ) . The median percent change in coronary artery ( 25 % vs. 6 % , P = 0.02 ) and aortic ( 28 % vs. 5 % , P = 0.02 ) calcium score also was significantly greater with calcium than with sevelamer . CONCLUSIONS Compared with calcium-based phosphate binders , sevelamer is less likely to cause hypercalcemia , low levels of PTH , and progressive coronary and aortic calcification in hemodialysis patients BACKGROUND Elevated serum phosphorus and calcium are associated with arterial calcification and mortality in dialysis patients .  Sevelamer , a phosphate-binding polymer , attenuates the progression of arterial calcification ; it is unknown whether this improves outcomes . PATIENTS AND INTERVENTIONS A r and omized comparison of sevelamer and calcium-based phosphate binders was performed in hemodialysis patients treated up to 45 months . The primary endpoint was mortality . Secondary endpoints included cause-specific mortality and hospitalization ;  2103 patients were r and omized , 2040 received treatment , and 1065 completed treatment . RESULTS Overall mortality was not significantly reduced by sevelamer ( adjusted relative risk = 0.92 ; 95 % confidence interval , 0.78 to 1.09 ; log-rank P = .40 ) . Among patients > or = 65 years of age , sevelamer reduced the risk of death ( adjusted relative risk = 0.77 ; 95 % confidence interval , 0.62 to 0.97 ; log-rank P = .02 ) . Sevelamer patients had a trend toward fewer hospitalizations ( P = .06 ) and fewer hospital days ( P = .09 ) . CONCLUSIONS A statistically significant reduction in mortality in the overall study population was not observed . Sevelamer was associated with a survival benefit among patients > or = 65 years of age BACKGROUND Abnormalities in serum calcium , phosphorus , and parathyroid hormone ( PTH ) concentrations are common in patients with chronic kidney disease and have been associated with increased morbidity and mortality . No clinical trials have been conducted to clearly identify categories of calcium , phosphorus , and PTH levels associated with the lowest mortality risk . Current clinical practice guidelines are based largely on expert opinions , and clinical ly relevant differences exist among guidelines across countries . We sought to describe international trends in calcium , phosphorus , and PTH levels during 10 years and identify mortality risk categories in the Dialysis Outcomes and Practice Patterns Study ( DOPPS ) , an international study of hemodialysis practice s and associated outcomes . STUDY DESIGN Prospect i ve cohort study . PARTICIPANTS 25,588 patients with end-stage renal disease on hemodialysis therapy for longer than 180 days at 925 facilities in DOPPS I ( 1996 - 2001 ) , DOPPS II ( 2002 - 2004 ) , or DOPPS III ( 2005 - 2007 ) . PREDICTORS Serum calcium , albumin-corrected calcium ( Ca( 
    Output:
    
Despite the trends observed , we did not find a statistically significant difference in cardiovascular mortality and coronary artery calcification in patients receiving calcium-based phosphate binders compared to non-calcium-based phosphate binders .