Background: The Injury Severity Score (ISS) accounts for only one injury in each body region. The New Injury Severity Score (NISS) considers all injuries in a body region. Despite a big difference between the two scores in patients with multiple injuries, the NISS does not offer significant improvement in mortality prediction. This paper hypothesizes that two injuries in different body regions are associated with higher mortality than two injuries in the same body region, independently of injury severity.
Methods: The population consisted of 15,200 patients with two or more injuries from the Quebec Trauma Registry, Canada, abstracted between 1998 and 2004. The two worst injuries were considered. Logistic regression analysis was used to assess the mortality odds ratio of having two worst injuries in different body regions (DR) compared with two worst injuries in the same body region (SR), while adjusting for the severity and the body region of the two worst injuries and age.
Results: A total of 5,869 patients (49%) had their worst injuries in DR. DR patients had 75% higher risk of mortality than SR patients (odds ratio = 1.75, 95% confidence interval = 1.42–2.15).
Conclusion: After accounting for differing injury severity, patients with their two worst injuries in different body regions have higher mortality than those with their two worst injuries in the same region. Results suggest that the observed effect is not due to a foible in the Abbreviated Injury Scale system but rather to physiologic, clinical, or organizational elements. The results of this study should be considered in the development of future injury severity instruments and may have implications for the care of patients with multiple injuries.
From the Departments of Social and Preventative Medicine (L.M., A.L.) and Emergency Medicine (N.L.), Centre hospitalier affilié universitaire de Québec, Enfant-Jésus Hospital, Laval University, Quebec City; Department of Surgery, McGill University (M.L.), Montreal; and the Department of Surgery, Sherbrooke University (E.B.), Sherbrooke, Canada.
Submitted for publication May 24, 2005.
Accepted for publication December 1, 2005.
This study was supported by the Fonds de la recherche en santé du Québec (grant number 015102).
Address for reprints: Lynne Moore, MSc, Unité de recherche en traumatologie, Centre hospitalier affilié universitaire de Québec, 1401, 18ème rue, Quebec City, Canada G1J 1Z4; email: Lynne.firstname.lastname@example.org.