Associations of the magnesium depletion score with the prevalence and mortality of chronic respiratory diseases

Chronic respiratory diseases (CRDs) remain a substantial global health burden. The magnesium depletion score (MDS) integrates clinical factors associated with magnesium loss, but its associations with CRD prevalence and mortality remain unclear. We examined these associations in a nationally representative sample of US adults. We conducted a cross-sectional prevalence analysis and a prospective mortality analysis using data from the National Health and Nutrition Examination Survey (NHANES) 2003-2018. CRDs were defined by self-reported physician diagnoses of asthma, chronic obstructive pulmonary disease, chronic bronchitis, or emphysema. Survey-weighted logistic and Cox regression examined CRD prevalence and all-cause mortality, respectively. Additional analyses included subgroup analyses, receiver operating characteristic (ROC) curves, and survival Shapley additive explanations. Among 30,044 participants, 5588 had CRDs. Compared with MDS = 0, the fully adjusted odds ratios for CRD prevalence were 1.17 (95% confidence interval [CI], 1.04-1.32), 1.27 (95% CI, 1.10-1.48), and 1.34 (95% CI, 1.11-1.62) for MDS = 1, MDS = 2, and MDS ≥3, respectively. Exploratory interaction tests were significant for race, systemic immune-inflammation index, and poverty-income ratio. Among 5581 participants with CRDs, MDS ≥3 was associated with higher all-cause mortality (hazard ratio, 1.59; 95% CI, 1.06-2.37), whereas lower MDS categories were not. MDS alone yielded time-dependent area under the curves ranging from 0.734 to 0.778, while its contribution within the multivariable survival model showed an overall increasing trend across MDS values. Higher MDS was associated with greater CRD prevalence, and MDS ≥3 was associated with higher all-cause mortality among participants with CRDs. Prospective studies incorporating direct measures of magnesium status and clinically validated respiratory outcomes are needed to confirm these findings.