Abstract: Objective  To explore the correlation between serum magnesium level and all-cause mortality, cardio-cerebrovascular mortality and non-cardio-cerebrovascular mortality in maintenance hemodialysis (MHD) patients.  Methods  Patients who underwent MHD in The Second Affiliated Hospital of Chongqing Medical University from January 1, 2014 to January 1, 2020 were enrolled in this study. The baseline data before dialysis and clinical follow-up data every 3 months after dialysis were collected and analyzed. The patients were grouped by the quartile of average serum magnesium value: Q1 (Mg≤0.98mmol/L), Q2 (Mg>0.98≤1.06mmol/L), Q3 (Mg >1.06 ≤1.13mmol/L), Q4 (Mg >1.13mmol/L). Combined with the Restricted Cubic Spline model, Q2 and Q3 were combined into Qi group (Mg >0.98 ≤1.13mmol/L), and Q1 and Q4 were combined into Qo group. Kaplan-Meier method was used to survival analysis. COX regression model was used to analyze the influencing factors for mortality.   Results  A total of 182 MHD patients were enrolled, including 46 patients in group Q1, 45 patients in group Q2, 46 patients in group Q3, and 45 patients in group Q4. Kaplan-Meier survival analysis showed that there was a statistical difference in total survival rate among the four groups (Log-rank χ2=9.024, P=0.029). There were statistical differences in total survival rate and non-cardio-cerebrovascular survival rate between groups Qi and Qo (Log-rank  χ2=8.892, P=0.003; Log-rank χ2=7.385, P=0.007). Cox regression model found that the risk of all-cause mortality and non-cardio-cerebrovascular mortality increased in patients in group Qo when patients in group Qi were used as the controls. After adjusting for confounders, the risk of all-cause mortality in the Qo group increased by 88.7%, as compared with that in the Qi group (HR=1.887, 95% CI： 1.012～3.519, P=0.046).  Conclusions  This study found that serum magnesium level was associated with all-cause mortality in MHD patients. Our results also suggest that the all-cause mortality is lower in patients with the serum magnesium between 0.98 and 1.13mmol/L.

Key words: Maintenance hemodialysis, Serum magnesium, Mortality, Influencing factor