Association of serum calcium levels within the first hour of ER admission with 28-day mortality in sepsis: A retrospective ICU analysis

Sepsis poses a global health challenge, necessitating effective predictors for risk stratification and timely intervention. Serum calcium, involved in vital physiological processes, has shown potential associations with sepsis outcomes, but the evidence remains limited and conflicting. This retrospective study included 1000 sepsis patients admitted to the intensive care unit. Serum calcium levels were measured within 1 hour of emergency room (ER) admission. Clinical data, including demographics, comorbidities, vital signs, laboratory results, and severity scores, were collected. Logistic regression and receiver operating characteristic curve analyses were conducted to assess the association between serum calcium levels and 28-day mortality. Kaplan-Meier analysis assessed the effect of serum calcium on 28-day survival. Lower serum calcium levels within 1 hour of ER admission were significantly associated with higher 28-day mortality (adjusted odds ratio: 0.1097, 95% CI: 0.04024-0.2912, P < .0001), even after adjusting for confounders. The area under the curve for serum calcium in predicting 28-day mortality was 0.5885 (P < .0001). Combining serum calcium with other predictors, such as the Charlson comorbidity index, red cell distribution width, lactic acid levels, and Acute Physiology and Chronic Health Evaluation II score, improved predictive accuracy (area under the curve: 0.7245, P < .0001). Kaplan-Meier analysis demonstrated a significant association between lower serum calcium levels and reduced 28-day survival (P < .0001). Low serum calcium levels within 1 hour of ER admission are significantly associated with increased 28-day mortality in sepsis patients. It complements existing predictors, showcasing its potential role in a comprehensive prognostic framework.