Low dietary sodium intake increases the death risk in peritoneal dialysis

Abstract

Background and objectives: To explore the correlation between dietary sodium intake and cardiovascular and overall mortality, and then determine whether this correlation can be explained by protein and energy intake paralleled with sodium intake in dialysis patients.

Design, setting, participants, & measurements: This single-center retrospective cohort study enrolled 305 incident patients who started peritoneal dialysis in our unit from July 2002 to February 2007. All patients were followed until death or until being censored in February 2008. Demographic data were collected at baseline. Biochemical, dietary, and nutrition data were examined at baseline and thereafter at regular intervals to calculate the average values throughout the study.

Results: Participants with the highest average sodium intake were more likely to be younger, male, and overweight. Patients in the high tertile of average sodium intake had higher albumin, prealbumin, and lean body mass levels, and more nutrient intakes paralleling with sodium intake. Low average sodium intake independently predicted the increased risk for overall and cardiovascular death after adjusting for recognized confounders. Further adjustment for dietary protein, energy, and other nutrient intakes individually had minimal impact on the association between average sodium intake and overall death, with hazard ratios varying between 0.35 and 0.44, and cardiovascular death, with hazard ratios varying between 0.06 and 0.11.

Conclusions: This study revealed that low dietary sodium intake independently predicts the high overall and cardiovascular mortality in dialysis patients. This correlation could not be entirely explained by deficient protein and energy intake.

Figure 1.

Multivariate hazard ratio of average dietary sodium intake for all-cause mortality and the impact of adjustment for dietary nutrients. Base model was adjusted for age, gender, body mass index, DM, the history of CVD, averaged variables including mean arterial pressure, Ca × P, hemoglobin, albumin, LDL, TKt/V, and Tccr. Other models were adjusted for covariates included in base model, sequentially added dietary nutrients including dietary protein, energy, carbohydrate, fat, fiber, and potassium intake. The P values for HRs of average dietary sodium intake for all-cause mortality in these models were less than 0.05.

Figure 2.

Multivariate hazard ratio of average dietary sodium intake for CVD mortality and the impact of adjustment for dietary nutrients. Base model was adjusted for age, gender, body mass index, DM, the history of CVD, averaged variables including mean arterial pressure, Ca × P, hemoglobin, albumin, LDL, TKt/V, and Tccr. Other models were adjusted for covariates included in base model, sequentially added dietary nutrients including dietary protein, energy, carbohydrate, fat, fiber, and potassium intake. The P values for HRs of average dietary sodium intake for CVD mortality in these models were less than 0.05.