Increased dietary sodium is independently associated with greater mortality among prevalent hemodialysis patients - PubMed (original) (raw)

Randomized Controlled Trial

doi: 10.1038/ki.2012.42. Epub 2012 Mar 14.

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Randomized Controlled Trial

Increased dietary sodium is independently associated with greater mortality among prevalent hemodialysis patients

Finnian R Mc Causland et al. Kidney Int. 2012 Jul.

Abstract

Dietary sodium is thought to play a major role in the pathogenesis of hypertension, hypervolemia, and mortality in hemodialysis patients; hence, sodium restriction is almost universally recommended. Since the evidence upon which to base these assumptions is limited, we undertook a post-hoc analysis of 1770 patients in the Hemodialysis Study with available dietary, clinical, and laboratory information. Within this cohort, 772 were men, 1113 black, and 786 diabetic, with a mean age of 58 years and a median dietary sodium intake of 2080 mg/day. After case-mix adjustment, linear regression modeling found that higher dietary sodium was associated with a greater ultrafiltration requirement, caloric and protein intake; sodium to calorie intake ratio was associated with a greater ultrafiltration requirement; and sodium to potassium ratio was associated with higher serum sodium. No indices were associated with the pre-dialysis systolic blood pressure. Cox regression modeling found that higher baseline dietary sodium and the ratio of sodium to calorie or potassium were each independently associated with greater all-cause mortality. No association between a prescribed dietary sodium restriction and mortality were found. Thus, higher reported dietary sodium intake is independently associated with greater mortality among prevalent hemodialysis patients. Randomized trials will be necessary to determine whether dietary sodium restriction improves survival.

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Figures

Figure 1

Figure 1

Distribution of daily dietary sodium intake (mg/day; Panel A), sodium:calorie intake ratio (mg/kcal/day; Panel B), sodium:potassium intake ratio (mg/mg/day; Panel C) and prescribed dietary sodium intake (mg/day; Panel D) at baseline.

Figure 1

Figure 1

Distribution of daily dietary sodium intake (mg/day; Panel A), sodium:calorie intake ratio (mg/kcal/day; Panel B), sodium:potassium intake ratio (mg/mg/day; Panel C) and prescribed dietary sodium intake (mg/day; Panel D) at baseline.

Figure 2

Figure 2

Hazard ratios (95% CIs) between measures of daily sodium intake and all-cause mortality. Sodium was considered as total intake (mg/day), sodium:calorie intake ratio (Na:Cal; mg/kcal/day) and sodium:potassium intake ratio (Na:K; mg/mg/day). Unadjusted estimates are indicated by circles. Estimates from Model 1 (squares) were adjusted for age, sex, race (black vs non-black), HEMO Study Kt/V and flux group assignments, post-dialysis weight, sex-by post-weight cross product terms, access (fistula, graft, catheter), congestive heart failure status (none, mild, moderate/severe), presence/ absence of diabetes and ischemic heart disease, urine volume (≤200mL/day, >200mL/day) and dialysis session length (≤180, 181-209, 210-239, ≥240min). Estimates from Model 2 (triangles) were additionally adjusted for serum sodium, albumin (≤3.5, 3.5-4.0 and >4.0 g/dL), phosphorus, creatinine and ultrafiltration requirement. All models were stratified on clinical center.

Figure 3

Figure 3

Hazard ratios (95% CIs) for all-cause mortality according to quartiles (Q; referent Q1) of reported daily dietary sodium intake (mg/day; Panel A), daily sodium:calorie intake ratio (mg/kcal/day; Panel B), and sodium:potassium intake ratio (mg/mg/day; Panel C). Estimates from Model 1 were adjusted for age, sex, race (black vs non-black), HEMO Study Kt/V and flux group assignments, post-dialysis weight, sex-by post-weight cross product terms, access (fistula, graft, catheter), congestive heart failure status (none, mild, moderate/severe), presence/ absence of diabetes and ischemic heart disease, urine volume (≤200mL/day, >200mL/day) and dialysis session length (≤180, 181-209, 210-239, ≥240min). Estimates from Model 2 were additionally adjusted for serum sodium, albumin (≤3.5, 3.5-4.0 and >4.0 g/dL), phosphorus, creatinine and ultrafiltration requirement. All models were stratified on clinical center.

Figure 3

Figure 3

Hazard ratios (95% CIs) for all-cause mortality according to quartiles (Q; referent Q1) of reported daily dietary sodium intake (mg/day; Panel A), daily sodium:calorie intake ratio (mg/kcal/day; Panel B), and sodium:potassium intake ratio (mg/mg/day; Panel C). Estimates from Model 1 were adjusted for age, sex, race (black vs non-black), HEMO Study Kt/V and flux group assignments, post-dialysis weight, sex-by post-weight cross product terms, access (fistula, graft, catheter), congestive heart failure status (none, mild, moderate/severe), presence/ absence of diabetes and ischemic heart disease, urine volume (≤200mL/day, >200mL/day) and dialysis session length (≤180, 181-209, 210-239, ≥240min). Estimates from Model 2 were additionally adjusted for serum sodium, albumin (≤3.5, 3.5-4.0 and >4.0 g/dL), phosphorus, creatinine and ultrafiltration requirement. All models were stratified on clinical center.

Figure 4

Figure 4

Associations between liberal (>2g/day) versus restrictive (≤2g/day; referent group; HR=1, not shown) prescribed sodium restriction and all-cause mortality. Estimates from Model 1 were adjusted for age, sex, race (black vs non-black), HEMO Study Kt/V and flux group assignments, post-dialysis weight, sex-by post-weight cross product terms, access (fistula, graft, catheter), congestive heart failure status (none, mild, moderate/severe), presence/ absence of diabetes and ischemic heart disease, urine volume (≤200mL/day, >200mL/day) and dialysis session length (≤180, 181-209, 210-239, ≥240min). Estimates from Model 2 were additionally adjusted for serum sodium, albumin (≤3.5, 3.5-4.0 and >4.0 g/dL), phosphorus, creatinine and ultrafiltration requirement. All models were stratified on clinical center.

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