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Trauma and Injury Severity Score (TRISS) Coefficients 2009 Revision

Schluter, Philip J. PhD; Nathens, Avery MD, PhD; Neal, Melanie L. MSc; Goble, Sandra MSc; Cameron, Cate M. PhD; Davey, Tamzyn M. MPH; McClure, Roderick J. MBBS, PhD

The Journal of Trauma: Injury, Infection, and Critical Care: April 2010 - Volume 68 - Issue 4 - p 761-770
doi: 10.1097/TA.0b013e3181d3223b
Original Article

Background: Currently used Trauma and Injury Severity Score (TRISS) coefficients, which measure probability of survival (PS), were derived from the Major Trauma Outcome Study (MTOS) in 1995 and are now unlikely to be optimal. This study aims to estimate new TRISS coefficients using a contemporary database of injured patients presenting to emergency departments in the United States; and to compare these against the MTOS coefficients.

Methods: Data were obtained from the National Trauma Data Bank (NTDB) and the NTDB National Sample Project (NSP). TRISS coefficients were estimated using logistic regression. Separate coefficients were derived from complete case and multistage multiple imputation analyses for each NTDB and NSP dataset. Associated PS over Injury Severity Score values were graphed and compared by age (adult ≥15 years; pediatric <15 years) and injury mechanism (blunt; penetrating) groups. Area under the Receiver Operating Characteristic curves was used to assess coefficients’ predictive performance.

Results: Overall 1,072,033 NTDB and 1,278,563 weighted NSP injury events were included, compared with 23,177 used in the original MTOS analyses. Large differences were seen between results from complete case and imputed analyses. For blunt mechanism and adult penetrating mechanism injuries, there were similarities between coefficients estimated on imputed samples, and marked divergences between associated PS estimates and those from the MTOS. However, negligible differences existed between area under the receiver operating characteristic curves estimates because the overwhelming majority of patients had minor trauma and survived. For pediatric penetrating mechanism injuries, variability in coefficients was large and PS estimates unreliable.

Conclusions: Imputed NTDB coefficients are recommended as the TRISS coefficients 2009 revision for blunt mechanism and adult penetrating mechanism injuries. Coefficients for pediatric penetrating mechanism injuries could not be reliably estimated.

From the School of Public Health and Psychosocial Studies (P.J.S.), AUT University, Auckland, New Zealand; School of Nursing and Midwifery (P.J.S.), The University of Queensland, Brisbane, Australia; St. Michael’s Hospital (A.N.), Toronto, Canada; National Trauma Data Bank (NTDB) (M.L.N., S.G.), American College of Surgeons, Chicago, Illinois; School of Medicine (C.M.C.), Griffith University, Logan, Australia; National Trauma Registry Consortium (T.M.D.), Royal Australasian College of Surgeons, Brisbane, Australia; and Accident Research Centre (R.J.M.), Monash University, Melbourne, Australia.

Submitted for publication June 24, 2009.

Accepted for publication January 7, 2010.

Address for reprints: Philip Schluter, PhD, Akoranga Campus, 90 Akoranga Drive, Auckland 0627, New Zealand; email:

© 2010 Lippincott Williams & Wilkins, Inc.