A Systematic Review and Meta-Analysis: Hyponatremia Predicted All-Cause and Cardiovascular Mortality in Dialysis Population

BACKGROUND: Hyponatremia is one of the most common disorders of electrolytes. Some research studies reported that hyponatremia was closely associated with mortality in patients with dialysis. However, this viewpoint remains controversial. OBJECTIVE: We aimed to do a systematic review and meta-analysis to assess the influence of hyponatremia on mortality in patients with dialysis. METHODS: We identified the eligible studies that investigated the association between hyponatremia and mortality risk in patients under dialysis by searching systematically a series of databases including PubMed, Embase, Cochrane, Web of science, and Ovid from January 2011 to June 2020. Adjusted hazard ratios (HRs) with 95% confidence intervals (95% CIs) were pooled. RESULTS: From 1,116 records identified, 12 studies including prospective and retrospective cohort studies met our inclusion criteria. We found hyponatremia both at baseline (HR: 1.50 and 95% CI: 1.41-1.59) and in time-varying (HR: 1.63 and 95% CI: 1.44-1.84) were significantly correlated to all-cause mortality after multivariable adjusted. By the subgroup analysis, the same results were presented in hemodialysis (HR: 1.48 and 95% CI: 1.38-1.59) or peritoneal dialysis patients (HR: 1.52 and 95% CI: 1.37-1.70). We also observed that lower serum sodium was independently associated with cardiovascular death. CONCLUSIONS: Hyponatremia was independently associated with all-cause and cardiovascular mortality, and it might predict adverse outcomes of patients under dialysis.