LOWER SERUM POTASSIUM LEVEL IS ASSOCIATED WITH MORTALITY AS CONFOUNDING EFFECT OF MALNUTRITION IN DIALYSIS PATIENTS

Abstract

Introduction: Obtaining normal serum potassium level is an important goal in maintenance hemodialysis patients. Hyperkalemia is known to be associated with mortality. In this study we aimed to assess the relationship between pre-dialysis potassium level, nutritional status and survival in dialysis patients. Materials and methods: This study used annual cohorts of hemodialysis patients with 36 months of follow-up. To determine the impact of potassium level on mortality, patients were followed from the first potassium measurement until death or a censoring event; hypokalemia was defined by potassium levels below median level - 5.5 mmol/l and albumin level below 35g/l was considered as an index for undernourished. Time-dependent Cox proportional hazards modeling was used to estimate the association between potassium level and mortality. Results: A total of 199 patients were included in the study. Mean age was approximately 56 years, about 59% were men and 23% had end-stage renal disease caused by diabetes. Albumin below 35 g/l was observed in 26 (13%) patients. In the follow-up period 53 (26%) patients died, consisting of 31 (31%) of the 101 hypokalemic and 22 (22%) of 98 hyperkalemic patients. The Kaplan-Meier survival rate was significantly better in the hyperkalemic population (34.300.71 vs. 31.061.16, p=0.051). Hypokalemia, when defined as serum potassium 5.5 mmol/l, was associated with all-cause mortality (hazards ratio (HR) 1.857, 95% CI 0.986-3.496, p = 0.051). The significance was lost in the model after adjustment for albumin level. Only albumin level determined mortality (p=0.03). Conclusion: Lower potassium level was associated with all-cause mortality, but only as a confounding effect of malnutrition in dialysis patients