Injury severity scoring and length of stay in hospital of war casualties--demonstration of an association and possible selection bias.

The Injury Severity Score (ISS) is a widely used measure of anatomical injury. It is the sum of squares of the highest scores on the Abbreviated Injury Scale (AIS) in each of the three most severely injured body regions. This study was designed to describe the relationship between ISS and length of stay (LOS) in hospital. The ISS was independently determined by four physicians who studied 491 war casualties, excluding dead on arrival and non-trauma patients. The study demonstrates non-linear and non-homogeneous relationships between ISS and LOS. Exclusion of fatalities resulted in biased (higher) estimates of LOS among those with ISS scores of 25-66. The patients could be grouped into five categories according to their maximal AIS (MAIS): (1) Slight injury--i.e. those with injuries appropriate for AIS scores 1 or 2 that lead to an LOS of median 5 days; (2) Moderate injury--i.e. those with injuries appropriate to AIS scores of 3, with an expected median LOS of 10 days; (3) Severe injuries--i.e. those with injuries appropriate to AIS scores of 4, with expected median LOS of about 17 days; (4) Very severe injuries--i.e. those with one injury appropriate to an AIS score of 5; and (5) Multiple severe injuries--those who are severely wounded in two or more body regions, i.e. those with two or more injuries appropriate to AIS scores of 5 and 4, with a median LOS of 39 days.(ABSTRACT TRUNCATED AT 250 WORDS)