Association between hypocalcemia and mortality in trauma patients: a systematic review and meta-analysis.

Background: The trauma triad of death, consisting of hypothermia, acidosis, and coagulopathy, has long been recognized as a major cause of mortality in trauma patients. Recently, hypocalcemia has emerged as a fourth component that plays a critical role in the prognosis of these patients. The objective of this meta-analysis is to evaluate the association between hypocalcemia and mortality among trauma patients. Methods: The authors systematically reviewed studies published in English from OVID, EMBASE, and Cochrane databases between January 1, 2000 and October 31, 2024. Randomized controlled trials and cohort studies reporting mortality rates among trauma patients with hypocalcemia were included. A meta-analysis was conducted using random effects models. The methodological quality of the studies was assessed using the Cochrane risk of bias tool. Results: Of the 4,209 studies identified, 20 were included in the meta-analysis. Trauma patients with hypocalcemia had a statistically significant increase in mortality (OR 2.79; 95% CI 2.01 to 3.89). This increase in mortality was also observed in subgroup analysis based on the timing of calcium level measurement: before blood transfusion (OR 2.45; 95% CI 1.75 to 3.43; I2=59%), before or after blood transfusion (OR 1.61; 95% CI 1.26 to 2.05; I2=0%), and no available data on the timing of calcium level measurement (OR 3.97; 95% CI 2.24 to 7.02; I2=78%). Notably, hypocalcemia was associated with increased mortality regardless of whether calcium levels were measured before or after blood transfusion. In terms of hypocalcemia severity, we found that more severe hypocalcemia was associated with higher mortality. Conclusions: Hypocalcemia in trauma patients is associated with increased mortality. We suggest that hypocalcemia should be closely monitored regardless of the transfusion history. Trial registration number: INPLASY number, 202330116.