Predictive value of calf circumference, prealbumin, and serum calcium for 28-day mortality in male sepsis patients with nutritional risk: a retrospective study

Background Sepsis is a life-threatening organ-dysfunction syndrome driven by infection. A substantial proportion of septic patients present with nutritional risk, a combination that worsens prognosis. Easily accessible early prognostic tools for this high-risk subset are lacking. Objective To identify early risk factors for 28-day clinical death in sepsis patients with nutritional risk. Methods A retrospective analysis of sepsis patients in the intensive care unit (ICU) at the Affiliated Hospital of Inner Mongolia Medical University (Jan 2022 to Jan 2025). Patients were categorized by 28-day outcome. Univariate and multivariate logistic regression identified risk factors; receiver operating characteristic (ROC) curves evaluated predictive performance. Results Among 231 patients, 154 were male (mortality 13.0%) and 77 female (mortality 11.7%). In males, multivariate analysis identified calf circumference, serum prealbumin (PA), and serum calcium (Ca 2+ ) as independent risk factors. ROC analysis showed areas under the curve: calf circumference (AUC: 0.837), PA (AUC: 0.822), and Ca 2+ (AUC: 0.724). Subgroup analysis using cutoffs (calf circumference ≤ 30 cm, PA ≤ 10.3 mg/dL, Ca 2+ ≤ 1.94 mmol/L) showed associations with higher sequential organ failure assessment (SOFA) score and acute physiology and chronic health evaluation II (APACHE II) score, and 28-day mortality (all p < 0.05). For female patients, only univariate comparisons of baseline characteristics were performed, and significant between-group differences were identified (upper arm circumference, calf circumference, abdominal circumference, APACHE II score, SOFA score, red blood cell count, hemoglobin, prealbumin, prothrombin time, international normalized ratio, serum sodium), while multivariable regression was not conducted due to the small number of outcome events. Conclusions Calf circumference, PA, and Ca 2+ are early independent risk factors for 28-day mortality in male sepsis patients with nutritional risk. Values below the specified cutoffs should prompt consideration of earlier, more aggressive interventions. These single-center findings require validation in larger, multi-center prospective studies.