Measuring the severity of injury.

Attempts have been made to improve the Injury Severity Score (ISS) system of Baker et al. (1974) using plasma lactate data obtained from 277 patients shortly after injury and before treatment. The ISS is based on the Abbreviated Injury Scale (AIS) values of the individual injuries, being the sum of the squares of the values for the three most severely injured regions. Log (plasma lactate concentration) is positively related to ISS over its whole range. It was not possible to vary the AIS values, either on clinical grounds or using a computer, in such a way that the variance of the log (plasma lactate concentration) about its regression line with ISS was significantly reduced. With a score based on the sum of the squares of the AIS values for all the patient's injuries, some improvement to the AIS values could be made but it was not statistically significant. At the present time Baker's ISS method would seem to be the best way of grading injuries for acute studies.