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A New Weighted Injury Severity Scoring System: Better Predictive Power for Pediatric Trauma Mortality

Shi, Junxin, MD, PhDa,b; Shen, Jiabin, PhDa,b; Caupp, Sarah, MSa,b; Wang, Angelaa,b; Nuss, Kathryn E., MDc; Kenney, Brian, MDa,d; Wheeler, Krista K., MSa,b; Lu, Bo, PhDe; Xiang, Henry, MD, MPH, PhDa,b,f

Journal of Trauma and Acute Care Surgery: May 2, 2018 - Volume Publish Ahead of Print - Issue - p
doi: 10.1097/TA.0000000000001943
Original Article: PDF Only

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 injury severity scoring (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 (NTDB). The Nationwide Emergency Department Sample (NEDS) was used to validate our main results. Pediatric blunt trauma patients less 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 vs. 0.86 in ISS=1-74 and 0.77 vs. 0.64 in ISS=25-74 (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 versus 19.7 for ISS=1-74 and 10.9 versus 12.6 for ISS= 25-74). The wISS showed even better discrimination with the NEDS.

Conclusions 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

Level IV Prognostic/Epidemiological

aCenter for Pediatric Trauma Research, The Research Institute at Nationwide Children’s Hospital, Columbus, OH

bCenter for Injury Research and Policy, The Research Institute at Nationwide Children’s Hospital, Columbus, OH

cDepartment of Emergency Medicine, Nationwide Children’s Hospital, Columbus, OH

dDepartment of Pediatric Surgery, The Ohio State University College of Medicine, Columbus, OH

eThe Ohio State University College of Public Health, Division of Biostatistics, Columbus, OH

fThe Ohio State University College of Medicine, Columbus, OH

CORRESPONDING AUTHOR: Henry Xiang, MD, MPH, PhD, Center for Pediatric Trauma Research, The Research Institute at Nationwide Children’s Hospital, 700 Children’s Drive, Columbus, OH 43205; Email: Henry.Xiang@NationwideChildrens.org

Conflicts of Interest and Sources of Funding: The authors report no conflicts of interest. Sources of funding include: Agency for Healthcare Research and Quality (grant #1R01 HS24263-01) and Health Resources and Services Administration (grant #R40MC30759).

Key Points:

Question: Will a weighted injury severity score (wISS) have better predictive power in pediatric blunt trauma patients when compared with the traditional injury severity score (ISS)?

Findings: By weighting the abbreviated injury scores (AIS) from different body regions, we produced the wISS. The wISS showed better mortality discrimination and more accurate calibration than the ISS, especially in children with ISS=25-74.

Meaning: The wISS has a significantly better predictive power for mortality than the traditional ISS in critically injured children.

© 2018 Lippincott Williams & Wilkins, Inc.