Prescribed Dietary Phosphate Restriction and Survival among Hemodialysis Patients

Abstract

SummaryBackground and objectives 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.Design, setting, participants, & measurements We conducted a post hoc analysis of data from the Hemodialysis Study (n ϭ 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 Յ870, 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.

Interaction of Time-Varying Albumin and Phosphorus on Mortality in Incident Dialysis Patients

“…In the same study similar results were observed when serum albumin was used as a surrogate for the nutritional status in multiple regression analysis. Moreover, in a recent post hoc analysis from the Hemodialysis (HEMO) study a more liberal phosphate prescription was associated with greater survival in prevalent hemodialysis patients (35). A decline in serum phosphorus observed over time should prompt a nutritional evaluation, and, if serum albumin has concurrently fallen, the patient might face a greater mortality risk.…”

Managing serum phosphate in haemodialysis patients: time for an innovative approach?

“…Increased level of phosphate restriction may be associated with greater mortality in some subgroups of patients. 4 Several studies have highlighted the lack of knowledge as a contributory factor to poor phosphate control. Cupisti et al 5 found that phosphate nutrition knowledge of HD patients was much lower than that of the dialysis nurses, and patients with hyperphosphataemia had similar knowledge levels to those with normal serum phosphate.…”

Gastrointestinal Inhibition of Sodium-Hydrogen Exchanger 3 Reduces Phosphorus Absorption and Protects against Vascular Calcification in CKD

“…5,6 Restrictions of dietary P to offset the effects of declining kidney function are no longer endorsed by Kidney Disease Improving Global Outcomes, because a recent study showed that dietary P was positively coupled to protein content and nutritional status in patients with ESRD and that liberal dietary P would actually increase survival. 7 Pharmacologic agents capable of selectively decreasing dietary P absorption, such as P binders, continue to be the first line of treatment of P disorders in those patients. Orally administered P binders prevent systemic absorption of dietary phosphate by converting it to an insoluble form that is eliminated in the feces.…”