Prognostic Performance of the Lactate-to-Ionized Calcium Ratio for In-Hospital Mortality in Adult Major Trauma: A...

Background/Objectives: Early identification of adult major trauma patients at high risk of death remains challenging in the emergency department. Lactate reflects tissue hypoperfusion, whereas ionized calcium contributes to coagulation and cardiovascular function. This study evaluated the prognostic performance of the lactate-to-ionized calcium ratio (LiCa) for in-hospital mortality and compared it with established trauma scores. Methods: This single-center retrospective cohort study included adults with major trauma, defined as an Injury Severity Score (ISS) ≥ 16, who presented to a tertiary emergency department between May 2021 and April 2023. Demographic, clinical, laboratory, and outcome data were obtained from electronic records. LiCa was calculated as lactate divided by ionized calcium using the initial arterial blood gas sample obtained within 30 min of emergency department arrival. Factors associated with mortality were examined using multivariable logistic regression. Discrimination was assessed using receiver operating characteristic analysis and compared across LiCa, ISS, and Trauma and Injury Severity Score (TRISS) models. Results: A total of 236 patients were analyzed. In-hospital mortality occurred in 49 patients (20.8%). LiCa remained associated with in-hospital mortality after adjustment (adjusted odds ratio, 1.42; 95% confidence interval, 1.23-1.62; p < 0.001). LiCa showed good discrimination in this cohort, with an area under the curve of 0.93 (95% confidence interval, 0.88-0.97), compared with 0.94 for both TRISS 1995 and TRISS 2010 and 0.85 for ISS. At an exploratory threshold of ≥12.59, LiCa yielded 82% sensitivity, 94% specificity, a positive likelihood ratio of 12.72, and a negative likelihood ratio of 0.20. Conclusions: LiCa was independently associated with in-hospital mortality and showed good discrimination within this single-center retrospective cohort. As a rapidly available blood gas-derived measure, LiCa may provide exploratory adjunctive prognostic information at presentation, but it should not be interpreted as a replacement for validated trauma scoring systems. Prospective multicenter validation is needed before routine clinical use.