Abbreviated Injury Scale does not reflect the added morbidity of multiple lower extremity fractures

To determine if patients with multiple lower extremity fractures have worse outcomes than do patients with isolated femur fractures, and to determine if the Abbreviated Injury Scale (AIS) should distinguish between single and multiple lower extremity fractures.

A retrospective study.

All blunt trauma patients at least 15 years of age treated at a level 1 trauma center from January 1990 through December 1993. Three groups of patients were selected. Group 1 included 50 patients whose only significant injury was a diaphyseal femur fracture. They had no other long bone fractures, minimal injuries to other body areas, and an Injury Severity Score (ISS) < or = 14. Group 2 was consisted of 29 patients with a femur fracture, at least one other diaphyseal lower extremity fracture, and also an ISS < or = 14. Group 3 consisted of 23 patients who had fracture patterns similar to those of group 2, but also had more severe nonextremity injuries (ISS > or = 15). Hospital morbidity and mortality rates were compared with t tests or chi-square analysis. Type 1 error probability was established at p < 0.05.

Compared with patients in group 1, patients in group 2 had an identical ISS (10.1 vs. 10.6, respectively), but had higher transfusion requirements (0.3 vs. 3.9 units), more days in the intensive care unit (ICU) (0.02 vs. 1.4), a higher incidence of adult respiratory distress syndrome (ARDS) (0 vs. 14%), longer hospital stays (6.0 vs. 14.8 days), greater disability at discharge (disability score 2.2 vs. 3.2), and a higher mortality rate (0 vs. 3.4%; p < 0.05 all variables). Patients in group 3 had worse outcomes than the other two groups: ISS = 30.1; transfusions = 11.9 units; ICU days = 9.1; ARDS incidence = 26%; hospital days = 29.9; disability score = 3.9; mortality = 26% (p < 0.05).

Although AIS and ISS appropriately reflect the impact of extraskeletal injuries in patients with femur fractures, they do not adequately reflect the increased morbidity associated with multiple lower extremity fractures. The AIS-Extremity Score may need to be upgraded for multiple long bone fractures of the lower extremities.