Higher Serum Magnesium Is a Survival Advantage in Maintenance Hemodialysis Patients

Abstract

Introduction: Elevated serum magnesium is common and associated with survival in maintenance hemodialysis (MHD) patients by observational studies. However, the results of these studies were underpowered and inconclusive. This work was designed to explore the predictive value of serum magnesium on the mortality of patients with MHD. Methods: We retrospectively analyzed mortality rates in 267 patients with MHD. The collected parameters included anthropometrics and laboratory parameters. Serum magnesium included baseline serum magnesium (BS-Mg) and average serum magnesium (AS-Mg). Receiver operator characteristic (ROC) curves were drawn, and multivariate Cox proportional hazards models were applied to identify the predictive value of serum magnesium on patient mortality. Results: During the 64-month follow-up period, 121 (45.3%) all-cause and 75 (28.1%) cardiovascular disease (CVD) deaths were recorded. The predictability of death of AS-Mg yielded results similar to those of serum albumin, secondary only to age, and superior to those of the high-sensitivity C-reactive protein (Hs-CRP), BS-Mg, by ROC curves. There were significant differences in all-cause and CVD mortality between the four groups (by quartile). Kaplan-Meier survival analyses revealed that the lowest 25th percentile had the poorest prognosis for both all-cause mortality (p < 0.001) and CVD mortality (p = 0.011). Finally, multivariate Cox proportional hazards models showed that increased age, increased Hs-CRP, decreased serum albumin, and AS-Mg were independent predictors of all-cause and CVD mortality. The hazard ratios of AS-Mg (per 0.01 mmol/L) were 0.925 (95% confidence interval, 0.884–0.968, p = 0.001) for all-cause mortality and 0.976 (95% confidence interval, 0.954–0.999, p = 0.040) for CVD mortality. Conclusion: AS-Mg was a good indicator for assessing all-cause and CVD mortality in patients with MHD in China. Higher serum magnesium had a survival advantage. Further studies with larger sample sizes should be needed to clarify the best reference value for maximizing the beneficial effects of magnesium.