title: A comparison of Injury Severity Score and New Injury Severity Score after penetrating trauma: A prospective analysis.
abstract: BACKGROUND
  The Injury Severity Score (ISS) has been validated in numerous studies and has become one of the most common trauma scoring systems since its inception. The ISS equation was later modified to create the New Injury Severity Score (NISS). By using the three most severe injuries regardless of body region, the NISS seems well suited to describe patients of penetrating trauma, where injuries often cluster within a single body region. We hypothesized that NISS would better predict outcomes than ISS in penetrating trauma patients.
  
  
  METHODS
  An analysis (June 2008 to March 2009) of all severely injured (length of hospital stay ≥ 48 hours, intensive care unit admission, interhospital transfer, or death) penetrating trauma patients revealed final study sample of 256 patients. ISS and NISS were compared as predictors for both mortality and complications through area under the receiver operating characteristic curve, Hanley-McNeil test, multiple-variable logistic regression, and Hosmer-Lemeshow goodness-of-fit test analysis.
  
  
  RESULTS
  Of 256 study patients, 195 (76.2%) survived until discharge. The mean (ISS, 21.7 ± 21.1 vs. NISS, 27.4 ± 22.0; p < 0.001) and median (ISS, 14.0 vs. NISS, 21.0) ISS was lower than those of the NISS. Overall, 173 patients (67.6%) had discordant scores with 26% and 43% having scores greater than 25 (ISS and NISS, respectively, p < 0.01). The mortality area under the curve (AUC) for NISS was greater than the AUC for ISS in all penetrating patients (0.930 vs. 0.885, p = 0.008), those with penetrating torso injuries (NISS, 0.934 vs. ISS, 0.881, p < 0.001), and those with severe (score > 25) injuries (NISS, 0.845 vs. ISS, 0.761, p < 0.001). In patients surviving for more than 48 hours, the complications AUC for NISS was also greater than the AUC for ISS (NISS, 0.838 vs. ISS, 0.784; p = 0.023).
  
  
  CONCLUSIONS
  The NISS outperformed ISS as a predictor of both mortality and complications in civilian penetrating trauma patients. These results indicate that NISS is a superior scoring system for patients with penetrating injuries.
  
  
  METHODS
  Prognostic study, level III.
authors.affiliation: From the Division of Traumatology, Surgical Critical Care and Emergency Surgery (B.P.S., M.J.S.), Hospital of the University of Pennsylvania; and Section of Trauma (A.J.G.), Department of Surgery, Temple University School of Medicine, Philadelphia, Pennsylvania; and Research Institute (J.P.G.), Cooper University Hospital, Camden, New Jersey.
authors.forename: Brian P
authors.initials: BP
authors.lastname: Smith
authors.forename: Amy J
authors.initials: AJ
authors.lastname: Goldberg
authors.forename: John P
authors.initials: JP
authors.lastname: Gaughan
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Seamon
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D015601:Injury Severity Score; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D015599:Trauma Severity Indices; D014950:Wounds, Penetrating; D055815:Young Adult