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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Published in Kidney Int 82: 204-211; advance online publication, March 14, 2012; doi:10.1038/ki.2012.42