Prognostic value of admission serum magnesium and systemic inflammation indices in septic ICU patients aged 85 years and older: A retrospective observational study

This study aimed to investigate the prognostic value of admission serum magnesium levels and systemic inflammatory indices, including C-reactive protein (CRP), neutrophil-to-lymphocyte ratio, systemic immune-inflammation index (SII), and multiple inflammation index, for predicting key clinical outcomes in critically ill patients with sepsis aged ≥ 85 years. This retrospective observational study was conducted to evaluate the prognostic value of admission serum magnesium and systemic inflammatory indices in critically ill patients with sepsis aged ≥ 85 years. Patients were stratified by serum magnesium levels into hypomagnesemia (<1.8 mg/dL), normomagnesemia (1.8-2.4 mg/dL), and hypermagnesemia (>2.4 mg/d). The prognostic performance for intensive care unit (ICU) mortality, 28-day mortality, mechanical ventilation requirement, and prolonged ICU stay was assessed using receiver operating characteristic curve analysis and multivariable Cox proportional hazards models. Among 381 patients aged ≥ 85 years (mean age 89.2 ± 3.2; 59.3% male) admitted to the ICU with sepsis, the ICU and 28-day mortality rates were 33.1% and 37.8%, respectively. Hypermagnesemia (>2.4 mg/dL) was observed in 18.9% of patients and was associated with higher sequential organ failure assessment (sequential organ failure assessment) scores (9.2 ± 3.1), CRP (129.7 ± 84.6 mg/L), neutrophil-to-lymphocyte ratio (15.2 ± 10.8), and multiple inflammation index (564.3 × 10³), with an ICU mortality of 52.8% (P = .001) and 28-day mortality of 61.1% (P < .001). In ICU patients with sepsis aged ≥ 85 years, hypermagnesemia at admission was a strong and independent predictor of mortality.