title: Prescribed dietary phosphate restriction and survival among hemodialysis patients.
abstract: OBJECTIVE
  Hyperphosphatemia is common among hemodialysis patients. Although prescribed dietary phosphate restriction is a recommended therapy, little is known about the long-term effects on survival.
  
  
  METHODS
  We conducted a post hoc analysis of data from the Hemodialysis Study (n = 1751). Prescribed dietary phosphate was recorded at baseline and annually thereafter. Marginal structural proportional hazard models were fit to estimate the adjusted association between dietary phosphate restriction and mortality in the setting of time-dependent confounding.
  
  
  RESULTS
  At baseline, prescribed daily phosphate was restricted to levels ≤ 870, 871 to 999, 1000, 1001 to 2000 mg, and not restricted in 300, 314, 307, 297, and 533 participants, respectively. More restrictive prescribed dietary phosphate was associated with poorer indices of nutritional status on baseline analyses and a persistently greater need for nutritional supplementation but not longitudinal changes in caloric or protein intake. On marginal structural analysis, there was a stepwise trend toward greater survival with more liberal phosphate prescription, which reached statistical significance among subjects prescribed 1001 to 2000 mg/d and those with no specified phosphate restriction: hazard ratios (95% CIs) 0.73 (0.54 to 0.97) and 0.71 (0.55 to 0.92), respectively. Subgroup analysis suggested a more pronounced survival benefit of liberal dietary phosphate prescription among nonblacks, participants without hyperphosphatemia, and those not receiving activated vitamin D.
  
  
  CONCLUSIONS
  Prescribed dietary phosphate restriction is not associated with improved survival among prevalent hemodialysis patients, and increased level of restriction may be associated with greater mortality particularly in some subgroups.
authors.affiliation: Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Lynch
authors.forename: Rebecca
authors.initials: R
authors.lastname: Lynch
authors.forename: Gary C
authors.initials: GC
authors.lastname: Curhan
authors.forename: Steven M
authors.initials: SM
authors.lastname: Brunelli
mesh_terms: D000368:Aged; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D054559:Hyperphosphatemia / Q000178:diet therapy* / Q000209:etiology / Q000401:mortality; D053208:Kaplan-Meier Estimate; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D010710:Phosphates / Q000008:administration & dosage / Q000009:adverse effects*; D016226:Phosphorus, Dietary / Q000008:administration & dosage / Q000009:adverse effects*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D006435:Renal Dialysis / Q000009:adverse effects / Q000401:mortality*; D018570:Risk Assessment; D012307:Risk Factors; D015996:Survival Rate; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology
chemical_list: D010710:Phosphates; D016226:Phosphorus, Dietary