The Military Injury Severity Score (mISS): A better predictor of combat mortality than Injury Severity Score (ISS)

Tuan D. Le, Jean A. Orman, Zsolt T. Stockinger, Mary Ann Spott, Susan A. West, Elizabeth A. Mann-Salinas, Kevin K. Chung, Kirby R. Gross

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

Background: TheMilitary Injury Severity Score (mISS) was developed to better predict mortality in complex combat injuries but has yet to be validated. METHODS: US combat trauma data from Afghanistan and Iraq from January 1, 2003, to December 31, 2014, from the US Department of Defense Trauma Registry (DoDTR) were analyzed.Military ISS, a variation of the ISS, was calculated and compared with standard ISS scores. Receiver operating characteristic curve, area under the curve, and Hosmer-Lemeshow statisticswere used to discriminate and calibrate between mISS and ISS. Wilcoxon-Mann-Whitney, t test and X2 tests were used, and sensitivity and specificity calculated. Logistic regression was used to calculate the likelihood of mortality associated with levels of mISS and ISS overall. RESULTS: Thirty thousand three hundred sixty-four patients were analyzed. Most were male (96.8%). Median age was 24 years (interquartile range [IQR], 21-29 years). Battle injuries comprised 65.3%. Penetrating (39.5%) and blunt (54.2%) injury types and explosion (51%) and gunshot wound (15%) mechanisms predominated. Overall mortality was 6.0%. Median mISS and ISS were similar in survivors (5 [IQR, 2-10] vs. 5 [IQR, 2-10]) but different in nonsurvivors, 30 (IQR, 16-75) versus 24 (IQR, 9-23), respectively (p < 0.0001). Military ISS and ISS were discordant in 17.6% (n = 5,352), accounting for 56.2% (n = 1,016) of deaths. Among cases with discordant severity scores, the median difference between mISS and ISS was 9 (IQR, 7-16); range, 1 to 59. Military ISS and ISS shared 78% variability (R2 = 0.78). Area under the curve was higher in mISS than in ISS overall (0.82 vs. 0.79), for battle injury (0.79 vs. 0.76), non-battle injury (0.87 vs. 0.86), penetrating (0.81 vs. 0.77), blunt (0.77 vs. 0.75), explosion (0.81 vs. 0.78), and gunshot (0.79 vs. 0.73), all p < 0.0001. Higher mISS and ISS were associated with higher mortality. Compared with ISS, mISS had higher sensitivity (81.2 vs. 63.9) and slightly lower specificity (80.2 vs. 85.7). CONCLUSION: Military ISS predicts combat mortality better than does ISS.

Original languageEnglish (US)
Pages (from-to)114-121
Number of pages8
JournalJournal of Trauma and Acute Care Surgery
Volume81
Issue number1
DOIs
StatePublished - 2016
Externally publishedYes

Keywords

  • Combat mortality
  • mAIS
  • Military Abbreviated Injury Scale
  • Military Injury Severity Score
  • mISS

ASJC Scopus subject areas

  • Critical Care and Intensive Care Medicine
  • Surgery

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    Le, T. D., Orman, J. A., Stockinger, Z. T., Spott, M. A., West, S. A., Mann-Salinas, E. A., Chung, K. K., & Gross, K. R. (2016). The Military Injury Severity Score (mISS): A better predictor of combat mortality than Injury Severity Score (ISS). Journal of Trauma and Acute Care Surgery, 81(1), 114-121. https://doi.org/10.1097/TA.0000000000001032