Supplementary Material for: Impact of dysmagnesemia on atrial fibrillation in maintenance hemodialysis patients: a nationwide study

Introduction: The dose-response relationship between serum magnesium (sMg) and atrial fibrillation (AF) and the contribution of dysmagnesemia to AF among hemodialysis patients remain unknown. Hence, we examined the dose-response correlation between sMg and AF and estimated the extent of the contribution of dysmagnesemia to AF in this population.
Methods: This was a nationwide cross-sectional study on the Japanese Society for Dialysis Therapy registry, also known as Japanese Renal Data Registry (JRDR), encompassing a nationwide population of dialysis centers, as of the end of 2019. Eligible participants were adult patients undergoing hemodialysis three times per week. The main exposure was sMg, categorized into seven categories (≤1.5, >1.5–≤2, >2–≤2.5, >2.5–≤3, >3–≤3.5, >3.5–≤4, and ≥4.0 mg/dL). The outcome was AF reported by dialysis facilities. The independent contribution to AF was assessed via logistic regression to generate population-attributable fractions, assuming a causal relationship between sMg and AF.
Results: Total 165,926 patients from 2,549 facilities were investigated. AF prevalence was 7.9%. Compared with the reference (>2.5–≤3 mg/dL), lower sMg was associated with increased AF (adjusted odds ratios [ORs] [95% confidence interval, CI] of 1.49 [1.19–1.85], 1.24 [1.17–1.32], and 1.11 [1.06–1.16] for sMg of ≤1.5, >1.5–≤2.0, and >2.0–≤2.5 mg/dL categories, respectively). Elevated sMg was associated with fewer AF (adjusted OR 0.87 [95% CI, 0.79–0.96] for sMg of >3.0–≤3.5 mg/dL). The adjusted population-attributable fraction of lower sMg and higher and lower sMg for AF was 7.4% and 6.9%, respectively. An association did indeed exist between lower sMg and AF, with the lowest percentages of AF at sMg levels above the reference range for the general population.
Conclusion: Dysmagnesemia may be an important contributor to AF among adult hemodialysis patients. Further longitudinal studies are warranted to determine whether sMg correction reduces the AF incidence.