Association of serum magnesium level with all-cause mortality in maintenance hemodialysis patients / 中华肾脏病杂志

ABSTRACT

Objective To investigate the association of serum magnesium (Mg) level with all-cause mortality in maintenance hemodialysis patients. Methods A multicenter retrospective cohort study was conducted in seven hemodialysis centers of Guizhou province. The adult outpatients who underwent hemodialysis for more than 3 months were included from June 2015 to June 2016. Demographics, baseline clinical and laboratory test results were collected. All patients were followed up until June 30, 2018. Patients were divided into 4 groups according to their baseline serum Mg levels (interquartile range). Kaplan-Meier method was used to compare the survival rates of the four group. Cox regression model was used to analyze the association of Mg with all-cause mortality. Logistic regression was used to analyze the influencing factors of low Mg level. Results A total of 868 hemodialysis dialysis patients with baseline Mg data were enrolled in this study, with age of (55.47± 16.17) years old, among whom 59.4% were male. There were 11 (1.3%) patients with hypomagnesemia (Mg＜0.7 mmol/L), 432(49.8% ) patients with hypermagnesemia (Mg＞1.05 mmol/L), and 16(1.8% ) patients with Mg＞2.0 mmol/L. Median Mg was 1.05 mmol/L and interquartile range was 0.95-1.24 mmol/L. The comparison between Mg quartile groups showed that the difference in age, hemoglobin, serum albumin, serum calcium, parathyroid hormone (PTH), serum creatinine, uric acid and urea nitrogen was statistically significant (all P＜0.05). After a median follow-up of 24 months, 207 patients died. Kaplan-Meier curves showed higher all-cause mortality in patients with Mg≤0.95 mmol/L (Q1 group) (Log - rank test χ2=15.11, P=0.002). However, after adjusting for age, comorbidities and biochemical indicators(especially albumin), there was no statistically significant difference in the hazard ratio for all-cause death among the four groups. Multiple logistic regression analysis results showed that low serum albumin (OR=0.946, 95%CI 0.913-0.979, P=0.002) and low serum uric acid (OR=0.994, 95% CI 0.992-0.997, P＜0.001) were the risk factors for baseline Mg≤0.95 mmol/L. Conclusions Hypomagnesemia is rare in MHD patients, while hypermagnesemia is more common. Baseline serum Mg≤0.95 mmol/L in MHD patients is correlated with increased risk of all-cause death, but it may be not an independent risk factor. Baseline serum Mg≤0.95 mmol/L that occurred is associated with low levels of albumin and serum uric acid.