Overhydration as a modifiable cardiovascular risk factor in patients undergoing hemodialysis

Introduction: Cardiovascular mortality in patients with end-stage renal disease (ESRD) remains high despite advances in dialysis techniques. This can be attributed to several traditional and nontraditional risk factors. Overhydration seems to be one of the promising cardiovascular risk factors that could be targeted to improve survival. Objectives: We aimed to assess the effect of chronic overhydration as well as changes in the degree of overhydration over time on cardiovascular and all-cause morbidity and mortality in patients undergoing hemodialysis. Patients and methods: We enrolled 511 patients with ESRD undergoing hemodialysis. The hydration status was assessed with whole-body bioimpedance spectroscopy. Patients were divided into 4 subgroups according to baseline hydration status. Additionally, patients with at least 2 follow-up visits (n = 277) were classified into 4 subgroups according to changes in the hydration status over time. Results: Statistical analysis showed that male sex (P <⁠0.001), diabetes (P <⁠0.001), cardiac insufficiency (P <⁠0.001), smoking (P = 0.049), and cerebrovascular events (P = 0.007) were significant risk factors for overhydration. Cardiovascular toxicity of overhydration was reflected by elevated levels of N-terminal pro-B-type natriuretic peptide (P <⁠0.001) and cardiac troponin T (P <⁠0.001). Albumin and total cholesterol levels were the lowest in patients with severe overhydration (P <⁠0.001). Mortality was lower in patients with normal hydration status and mild overhydration (P <⁠0.001) as well as in those with stable low or descending overhydration pattern (P = 0.002). Conclusions: We showed that the degree of overhydration is significantly associated with the incidence of cardiovascular complications and prognosis in patients with ESRD undergoing hemodialysis.