ICISS: Dr. Rutledge’s Contribution to Trauma Care
Dr Rutledge: Inventor of ICISS (ICD based Injury Severity Score)

In 1993 Dr Rutledge published the first article describing the use of ICD-9 codes as a means of predicting injury severity. (1) At the time the standard means of injury severity scoring was the consensus derived ISS. Dr Rutledge’s invention was a data derived system based upon analysis of actual injury outcomes that were quantitated from actual trauma outcomes.

Although controversial at the time, (criticized by Champion, MacKenzie and others) now 17 years later the ICISS stands as simple, well validated and relatively inexpensive means of injury severity scoring, confirming Dr Rutledge’s initial findings.(2-51)

Over 10 years ago Dr. Rutledge wrote:

The Journal of Trauma: Injury, Infection, and Critical Care:
January 1998 – Volume 44 – Issue 1 – pp 41-49
The End of the Injury Severity Score (ISS) and the Trauma and Injury Severity Score (TRISS): ICISS, an International Classification of Diseases, Ninth Revision-Based Prediction Tool, Outperforms Both ISS and TRISS as Predictors of Trauma Patient Survival, Hospital Charges, and Hospital Length of Stay
Rutledge, Robert MD; Osler, Turner MD; Emery, Sherry PhD; Kromhout-Schiro, Sharon PhD
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Introduction: Since their inception, the Injury Severity Score (ISS) and the Trauma and Injury Severity Score (TRISS) have been suggested as measures of the quality of trauma care. In concept, they are designed to accurately assess injury severity and predict expected outcomes. ICISS, an injury severity methodology based on International Classification of Diseases, Ninth Revision, codes, has been demonstrated to be superior to ISS and TRISS. The purpose of the present study was to compare the ability of TRISS to ICISS as predictors of survival and other outcomes of injury (hospital length of stay and hospital charges). It was our hypothesis that ICISS would outperform ISS and TRISS in each of these outcome predictions.

Methods: “Training” data for creation of ICISS predictions were obtained from a state hospital discharge data base. “Test” data were obtained from a state trauma registry. ISS, TRISS, and ICISS were compared as predictors of patient survival. They were also compared as indicators of resource utilization by assessing their ability to predict patient hospital length of stay and hospital charges. Finally, a neural network was trained on the ICISS values and applied to the test data set in an effort to further improve predictive power. The techniques were compared by comparing each patient’s outcome as predicted by the model to the actual outcome.

Results: Seven thousand seven hundred five patients had complete data available for analysis. The ICISS was far more likely than ISS or TRISS to accurately predict every measure of outcome of injured patients tested, and the neural network further improved predictive power.

Conclusion: In addition to predicting mortality, quality tools that can accurately predict resource utilization are necessary for effective trauma center quality-improvement programs. ICISS-derived predictions of survival, hospital charges, and hospital length of stay consistently outperformed those of ISS and TRISS. The neural network-augmented ICISS was even better. This and previous studies demonstrate that TRISS is a limited technique in predicting survival resource utilization. Because of the limitations of TRISS, it should be superseded by ICISS.


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2. Rutledge R. Injury severity and probability of survival assessment in trauma patients using a predictive hierarchical network model derived from ICD-9 codes. J Trauma 1995;38(4):590-7; discussion 597.

3. Osler T, Rutledge R, Deis J, Bedrick E. ICISS: an international classification of disease-9 based injury severity score. J Trauma 1996;41(3):380-6; discussion 386.

4. Rutledge R, Hoyt DB, Eastman AB, Sise MJ, Velky T, Canty T, et al. Comparison of the Injury Severity Score and ICD-9 diagnosis codes as predictors of outcome in injury: analysis of 44,032 patients. J Trauma 1997;42(3):477-87; discussion 487.

5. Osler TM, Cohen M, Rogers FB, Camp L, Rutledge R, Shackford SR, et al. Trauma registry injury coding is superfluous: a comparison of outcome prediction based on trauma registry International Classification of Diseases-Ninth Revision (ICD-9) and hospital information system ICD-9 codes. J Trauma 1997;43(2):253-6; discussion 256.

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8. Rutledge R, Osler T, Kromhout-Schiro S. Illness severity adjustment for outcomes analysis: validation of the ICISS methodology in all 821,455 patients hospitalized in North Carolina in 1996. Surgery 1998;124(2):187-94; discussion 194.

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