The NACA-scale. Construct and predictive validity of the NACA-scale for prehospital severity rating in trauma patients

The NACA-scale is used in many Austrian, German and Swiss emergency medical systems for demographic description of emergency patients. Little attentio n has been payed to the evaluation of its construct and predictive validity . In 427 consecutive trauma patients rescued in primary mission the NACA-Sc ale and the Injury Severity Score (ISS) were determined. Outcome data were obtained from medical charts and by written or telephone requests. Data wer e analysed with Spearman-Rank-Correlation. NACA-Grade and ISS-values showed only a moderate correlation with a considerably large spread (Rho=0.721). Both severity scores demonstrated a good correlation to mortality (Rho=0.97 6/0.994) and to transfer to an ICU (Rho=0.964/0.943), as well a moderate co rrelation to the duration of ICU-stay (Rho=0.722/0.756) and of hospital sta y (Rho=0.558/0.694). The NACA-scale adequately describes life threat in tra uma victims and correlates well with morbidity a nd mortality. Thus, it is a valuable tool for demographic purposes in emergency medical systems. For more precise prehospital severity rating in trauma patients, the NACA-scale should be supplemented or replaced by a physiologically based prehospital severity score.