Do pre-hospital anaesthesiologists reliably predict mortality using the NACA severity score? A retrospective cohort study
Methods: All missions completed by one helicopter service during January 1999 to December 2009 were reviewed. One thousand eight hundred forty-one patients were assessed by the NACA score. Pre-hospital and in-hospital interventions were collected from patient records. The relationship between NACA score and the outcome measures was assessed using receiver operating characteristic (ROC) curves.
Results: A total of 1533 patients were included in the analysis; uninjured and dead victims were excluded per protocol. Overall mortality rate of the patients with NACA score 1–6 was 5.2%. Trauma patients with NACA score 1–6 had overall mortality rate of 1.9% (12/625) and non-trauma patients 7.4% (67/908). The NACA score’s ability to predict mortality was assessed by using ROC area under curve (AUC) and was 0.86 for all, 0.82 for non-trauma and 0.98 for trauma patients. The NACA score’s ability to predict a need for respiratory therapy within 24 h revealed an AUC of 0.90 for all patients combined.
Conclusion: The NACA score had good discrimination for predicting mortality and need for respiratory therapy. It is thus useful as a tool to measure overall severity of the patient population in this kind of emergency medicine system.