PREDICTORS OF SURVIVAL IN PEDIATRIC TRAUMA:
A COMPARISON OF THE INTERNATIONAL CLASSIFICATION INJURY SEVERITY
SCORE (ICISS) TO EXISTING INJURY SCORING TOOLS
Casey J. Allen, MD, Jonathan P. Meizoso, MD, William M Hannay, BS, Juliet J Nissan, MD,
Carl I. Schulman, MD, PhD, Alan S. Livingstone MD, Juan E. Sola, MD, Nicholas Namias, MD,
and Kenneth G. Proctor, PhD
Dewitt-Daughtry Department of Surgery, Divisions of Trauma and Surgical Critical Care and
University of Miami Miller School of Medicine, Miami, FL 33136, USA
Supported in part by: Grants #N140610670 from the Office of Naval Research and #09078015
from U.S. Army Medical Research & Materiel Command
None of the authors have declared conflicts of interest.
BACKGROUND
Traditional injury scoring systems for adults are not as reliable in pediatrics due to altering
physiologies, disproprotionate organ sizes, and unique injury patterns. The International
Classification Injury Severity Score (ICISS) predicts survival as calculated from the product of
survival risk ratios (SRRs) for a patient's 3 worst injuries. SRRs are derived as the proportion of
fatalities for every International Classification of Diseases, Ninth Edition (ICD-9) in a
"benchmark" population. In adults, previous studies have demonstrated that ICISS predicts
outcome more accurately than ISS. In pediatrics, the value of ICISS has been less well defined.
One study validated ICISS as objective metrics for determining performance using the National
Surgical Quality Improvement Program (NSQIP) methodology. Another study demonstrated that
ICISS simplified determination of expected mortality necessary to compute the expected
component of NSQIP. Analysis of expected to observed mortality demonstrates variance among
centers, defines performance against peers using the same benchmarks, and can drive
performance improvement based on the objective evidence of injury diagnoses actually
encountered. To our knowledge, the ICISS has never been compared to existing injury scoring
tools in predicting survival in pediatric trauma at a single institution.
OBJECTIVES
To assess the utility of the ICISS in predicting survival compared to existing injury scoring tools
in pediatric trauma at a single institution, we provide a demographic analysis and survival
analysis from over a decade of experience of a level 1 pediatric trauma center. We evaluate the
use of ICISS based on probabilities of survival by ICD-9 coding from the Florida Agency for
Health Care Administration (AHCA) discharge dataset from 1991 to 2010. We hypothesize that
the ICISS survival prediction model derived from the Florida AHCA dataset will accurately
predict survival in our independent sample, and that this algorithm better predicts survival than
existing injury scoring tools at a single level 1 pediatric trauma center.
Ryder Trauma Center, 1800 NW 12th Avenue, T-242, Miami, FL 33136 | (305) 585-1280
c.allen7@med.miami.edu
METHODS
From January 2000 to December 2012, consecutive pediatric admissions (≤17y) at a Level I
pediatric trauma center were retrospectively reviewed for demographics, mechanisms of injury
(MOI), Injury Severity Score (ISS), Revised Trauma Score (RTS), Trauma Score – Injury
Severity Score (TRISS), length of stay (LOS), and survival.
The ICISS survival probabilities were calculated for all admitted patients using SRRs computed
from all pediatric admissions from 1991 to 2010 in the Florida AHCA dataset (236,317 total
pediatric injury codes, with 6,907 mortalities). Receiver operator characteristic (ROC) analysis
was used to independently assess and compare the predictive capability of ICISS, ISS, RTC, and
TRISS. Data are represented as mean  standard deviation if normally distributed, or median
(interquartile range) if not. Student’s t, Fisher’s exact, or non-parametric tests were used as
appropriate. Significance was assessed at p=0.05.
RESULTS
The study population was comprised of 1,928 pediatric trauma admissions (Table 1) with an ISS
of 13±12, RTS of 7.84(0.29), TRISS of 0.981(0.011), and ICISS of 0.981(0.011). Subsequent
overall survival was 96.6%.
The independent predictive capabilities of ICISS, ISS, RTC, and TRISS are detailed in Table 2.
ICISS accurately predicts survival (area under ROC: 0.970) in the overall population, however
the existing scoring tools are better predictors even in separate age groups.
CONCLUSIONS
ICISS is an accurate predictor of survival in patients at this trauma center, but it is inferior when
compared to existing scoring tools. This may reveal the poor utility of a tool derived from
outcomes at various levels of trauma centers across the nation/state in predicting outcomes in
those treated at a large volume level 1 pediatric trauma center with inherently different systems
and capabalities.
Table 1: Population. n=1,928
Male
70%
Sex
Female
30%
Age, years
MOI
Blunt
Penetrating
ISS
RTS
TRISS
ICISS
LOS, days
Survival
11±6
76%
24%
13±12
7.84(0.29)
0.981(0.011)
0.903(0.168)
3(7)
96.6%
Table 2: AUROC of injury scoring models on survival, separate age groups. n=1,928
0-5y
6-11y
12-17y
All pediatric
ISS
0.978
0.939
0.940
0.992
RTS
0.972
0.970
0.889
0.982
TRISS
0.999
0.982
0.992
0.992
ICISS
0.892
0.850
0.878
0.970