J Korean Med Sci.  2008 Aug;23(4):700-705. 10.3346/jkms.2008.23.4.700.

The Value of Initial Ionized Calcium as a Predictor of Mortality and Triage Tool in Adult Trauma Patients

• Choi YC
• Hwang SY

• KMID: 1785832
• DOI: http://doi.org/10.3346/jkms.2008.23.4.700

Abstract

Ionized hypocalcemia is a common finding in critically ill patients, but the relationship between ionized hypocalcemia and mortality risk in trauma patients has not been well established. The aim of this study was to assess the usefulness of initial ionized calcium (iCa) in predicting mortality in the trauma population, and evaluate its superiority over the three other triage tools: base deficit, systemic inflammatory response syndrome (SIRS) score, and triage-revised trauma score (t-RTS). A proand retrospective study was performed on 255 consecutive trauma patients admitted to our Emergency Medical Center from January to December, 2005, who underwent arterial blood gas analysis. Multivariate logistic regression analysis confirmed iCa (< or =0.88 mM/L), low Glasgow coma scale score, and a large transfusion amount to be significant risk factors associated with mortality (p<0.05). The sensitivities of iCa, base deficit, SIRS score, and t-RTS were 82.9%, 76.4%, 67.1%, and 74.5%, and their specificities were 41.0%, 64.1%, 64.1%, and 87.2%, respectively. Receiver operating characteristic curve analysis determined the areas under the curves of these parameters to be 0.607+/-0.062, 0.736+/-0.056, 0.694+/-0.059, and 0.875 +/-0.043, respectively (95% confidence interval). Although initial iCa (< or =0.88 mM/L) was confirmed as a significant risk factor associated with mortality, it exhibited a poorer discriminative power for mortality prediction than other predictors, especially t-RTS.

Keyword

Trauma; Hypocalcemia; Mortality; Triage

MeSH Terms

Adolescent
Adult
Aged
Aged, 80 and over
Area Under Curve
Calcium/*blood
Female
Humans
Male
Middle Aged
Prospective Studies
Retrospective Studies
Systemic Inflammatory Response Syndrome/blood/mortality
*Triage
Wounds and Injuries/*blood/mortality

Figure

• 

  Fig. 1 Interactive dot diagram of trauma patients relative to ionized calcium levels. The horizontal line indicates the cut-off point with the best separation (minimized false negative and false positive results) between the two groups. The cut-off point of ionized calcium level was 0.88 mM/L. The corresponding test characteristics of sensitivity and specificity were 82.9% and 41.0%, respectively.

• 

  Fig. 2 The receiver operating characteristic curves of ionized calcium, base deficit, systemic inflammatory response syndrome (SIRS) score, and triage-revised trauma score (t-RTS) in predicting mortality. The areas under the curves (AUC) of these indicators were 0.607±0.062, 0.736±0.056, 0.694±0.059, and 0.875±0.043, respectively (95% confidence interval). The AUC of iCa was not different from that of SIRS, but smaller than those of the other predictors (p<0.05). The AUC of t-RTS was the largest (p<0.01).

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