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A new weighted injury severity scoring system: Better predictive power for pediatric trauma mortality

Shi, Junxin, MD, PhD; Shen, Jiabin, PhD; Caupp, Sarah, MS; Wang, Angela; Nuss, Kathryn E., MD; Kenney, Brian, MD; Wheeler, Krista K., MS; Lu, Bo, PhD; Xiang, Henry, MD, PhD

Journal of Trauma and Acute Care Surgery: August 2018 - Volume 85 - Issue 2 - p 334–340
doi: 10.1097/TA.0000000000001943
Original Articles

BACKGROUND An accurate injury severity measurement is essential for the evaluation of pediatric trauma care and outcome research. The traditional Injury Severity Score (ISS) does not consider the differential risks of the Abbreviated Injury Scale (AIS) from different body regions nor is it pediatric specific. The objective of this study was to develop a weighted ISS (wISS) system for pediatric blunt trauma patients with better predictive power than ISS.

METHODS Based on the association between mortality and AIS from each of the six ISS body regions, we generated different weights for the component AIS scores used in the calculation of ISS. The weights and wISS were generated using the National Trauma Data Bank. The Nationwide Emergency Department Sample (NEDS) was used to validate our main results. Pediatric blunt trauma patients younger than 16 years were included, and mortality was the outcome. Discrimination (areas under the receiver operating characteristic curve, sensitivity, specificity, positive predictive value, negative predictive value, concordance) and calibration (Hosmer-Lemeshow statistic) were compared between the wISS and ISS.

RESULTS The areas under the receiver operating characteristic curves from the wISS and ISS are 0.88 versus 0.86 in ISS of 1 to 74 and 0.77 versus 0.64 in ISS of 25 to 74 (p < 0.0001). The wISS showed higher specificity, positive predictive value, negative predictive value, and concordance when they were compared at similar levels of sensitivity. The wISS had better calibration (smaller Hosmer-Lemeshow statistic) than the ISS (11.6 vs. 19.7 for ISS = 1–74 and 10.9 vs. 12.6 for ISS = 25–74). The wISS showed even better discrimination with the Nationwide Emergency Department Sample.

CONCLUSION By weighting the AIS from different body regions, the wISS had significantly better predictive power for mortality than the ISS, especially in critically injured children.

LEVEL OF EVIDENCE AND STUDY TYPE Prognostic/epidemiological, level IV.

From the Center for Pediatric Trauma Research (J.S., J.S., S.C., A.W., B.K., K.K.W., H.X.), Center for Injury Research and Policy (J.S., J.S., S.C., A.W., K.K.W., H.X.), The Research Institute at Nationwide Children’s Hospital; Department of Emergency Medicine (K.E.N.), Nationwide Children’s Hospital; Department of Pediatric Surgery, Nationwide Children's Hospital (B.K.); The Ohio State University College of Public Health, Division of Biostatistics (B.L.); and Department of Pediatrics, The Ohio State University College of Medicine (H.X.), Columbus, Ohio.

Submitted: January 18, 2018, Revised: April 4, 2018, Accepted: April 6, 2018, Published online: May 22, 2018.

Address for reprints: Henry Xiang, MD, PhD, Center for Pediatric Trauma Research, The Research Institute at Nationwide Children's Hospital, 700 Children's Dr, Columbus, OH 43205; email: Henry.Xiang@NationwideChildrens.org.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text, and links to the digital files are provided in the HTML text of this article on the journal’s Web site (www.jtrauma.com).

© 2018 Lippincott Williams & Wilkins, Inc.