Abbreviated injury scale scoring in traffic fatalities: comparison of computerized tomography and autopsy

Abstract

Objectives: The purpose of this investigation is to evaluate the value of postmortem computerized tomography (CT) for Abbreviated Injury Scale (AIS) scoring and Injury Severity Scoring (ISS) of traffic fatalities.

Material: This is a prospective investigation of a consecutive series of 52 traffic fatalities from Southern Denmark that were CT scanned and autopsied. The AIS and ISS scores based on CT and autopsy (AU) were registered in a computer database and compared. Kappa values for reproducibility of AIS-severity scores and ISS scores were calculated.

Results: On an average, there was a 94% agreement between AU and CT in detecting the presence or absence of lesions in the various anatomic regions, and the severity scores were the same in 90% of all cases (range, 75-100%). When different severity scoring was obtained, CT detected more lesions with a high severity score in the facial skeleton, pelvis, and extremities, whereas AU detected more lesions with high scores in the soft tissues (especially in the aorta), cranium, and ribs. The kappa value for reproducibility of AIS scores confirmed that the agreement between the two methods was good. The lowest kappa values (>0.6) were found for the facial skeleton, cerebellum, meninges, neck organs, lungs, kidneys, and gastrointestinal tract. In these areas, the kappa value provided moderate agreement between CT and AU. For all other areas, there was a substantial agreement between the two methods. The ISS scores obtained by CT and by AU were calculated and were found to be with no or moderate variation in 85%. Rupture of the aorta was often overlooked by CT, resulting in too low ISS scoring.

Discussion: The most precise postmortem AIS and ISS scorings of traffic fatalities was obtained by a combination of AU and CT. If it is not possible to perform an AU, then CT may be used as an acceptable alternative for AIS scoring. We have identified one important obstacle for postmortem ISS scoring, namely that aorta ruptures are not easily detected by post mortem CT.