|Year : 2011 | Volume
| Issue : 4 | Page : 446-449
|Evaluation of trauma and prediction of outcome using TRISS method
Jaspal Singh1, Gulzar Gupta2, Ramneesh Garg3, Ashish Gupta3
1 Department of General Surgery, Dayanand Medical College and Hospital, Ludhiana, Punjab, India
2 Department of Neuro Surgery, Dayanand Medical College and Hospital, Ludhiana, Punjab, India
3 Department of Plastic Surgery, Dayanand Medical College and Hospital, Ludhiana, Punjab, India
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|Date of Submission||12-Jul-2010|
|Date of Acceptance||15-Mar-2011|
|Date of Web Publication||24-Oct-2011|
| Abstract|| |
Introduction: Trauma and injury severity score (TRISS), introduced in 1981 is a combination index based on revised trauma score (RTS), injury severity score (ISS) and patient's age. In this study we have used TRISS method to predict the outcome in trauma cases. Materials and Methods : 1000 consecutive cases of trauma of adult age group admitted in casualty of Dayanand Medical College and Hospital Ludhiana, from 1/7/2000 onwards. Revised Trauma Score, Injury Severity Score and Age Index were recorded from which TRISS was determined. The performance of TS, ISS and TRISS as predictors of survival was evaluated using the misclassification rate, the information gain and the relative information gain. Results : The majority of the patients were men (83.7%) and in the age group of 20-50 years. Road traffic collisions (72%) were the most common cause of trauma. The mortality rate was 4.1%. Using PER method, the TRISS method was found to have information gain of 0.049 and a relative information gain of 0.41. Conclusions : The revised trauma score (RTS) ranged from 2.746 to 7.8408.There was a graded increase in mortality with decreasing RTS score.
Keywords: Injury severity score, revised trauma score, trauma and injury severity score
|How to cite this article:|
Singh J, Gupta G, Garg R, Gupta A. Evaluation of trauma and prediction of outcome using TRISS method. J Emerg Trauma Shock 2011;4:446-9
| Introduction|| |
Traumatic injury is defined as damage to the body caused by an exchange with environmental energy that is beyond the body's resilience. 
Trauma is a global phenomenon and a major cause of morbidity and mortality throughout the world. It is the disease of young and the leading cause of death in the first four decades of life.  India has the 4 th highest rate of road accident  in the world with a reported mortality rates of severely injured patients ranging from 7-45%.  This variants could reflect real differences in therapeutic results or rely on differences concerning injury severity or age. In view of differences in prognostic variables, an instrument is necessary that considers these differences. 
Trauma score systems try to translate the severity of injury into a number. The scores enable physicians to translate different severity of injuries into a common language. Quantitative characterizations of injury are essential for research  and meaningful evaluation of patient outcome, quality improvement, and prevention programs. The development of trauma severity indices has been foremost task of trauma investigators. There are around 50 score systems published for the classification of trauma patients. These large number of score systems indicate not only the need for such scoring systems but also their shortcomings to meet all requirements.
Trauma and injury severity score (TRISS), introduced in 1981, is a combination index based on Trauma Score (RTS), Injury Severity Score (ISS), and patient's age.  Champion et al. (1981) showed that the physiological index in combination with anatomic index and age is a powerful predictor of outcome in trauma patients. They combined the trauma score and injury severity score with age to give a new index called TRISS (TS, ISS, Age combination index).
The TRISS methodology offers a standard approach for tracking and evaluating outcome of trauma care. Anatomic, physiologic, and age characteristics are used to quantify probability of survival as it relate to severity of injury. In this study we have used TRISS method to predict the outcome in trauma cases.
| Materials and Methods|| |
One thousand consecutive cases of trauma of adult age group admitted in casualty of Dayanand Medical College and Hospital Ludhiana, from 1/7/2000 onwards.
- Associated systemic diseases, e.g., Congestive heart failure, chronic obstructive pulmonary disease etc. as these co-morbid diseases may affect final outcome.
- Patients below the age of 15 years.
Patient was clinically assessed and managed as per the ABC protocol. After stabilizing the patient, detailed history was recorded and general physical/systemic examination was done. The following were determined for calculating TRISS. 
TRISS determines the probability of survival (PS) of a patient from the ISS and RTS.
The revised trauma score is made up of a combination of results from three categories; Glasgow Coma Scale, Systolic blood pressure, and respiratory rate.The score ranges from 0-12.
Weights for revised trauma score
GCS - 0.9368
Systolic B.P - 0.7326
Respiratory rate - 0.2908
The sum of these three products is the revised trauma score (RTS).
RTS = 0.9368 (GCSc) + 0.8326 (SBPc) + 0.2908 (RRc)
The Injury severity score as calculated by abbreviated injury score (AIS) is a simple numerical method for grading and comparing injury by severity. The AIS is a consensus derived, anatomically based system of grading injuries on an ordinal scale ranging from 1 (minor injury) to 6 (Lethal injury). 
The ISS is defined as the sum of squares of the highest AIS grade in the 3 most severely injured body regions. Six body regions are defined, as follows: The thorax, abdomen and visceral pelvis, head and neck, face, bony pelvis and extremities, and external structures. Only one injury per body region is allowed. The ISS ranges from 1-75, and an ISS of 75 is assigned to anyone with AIS of 6.
The performance of TS, ISS and TRISS as predictors of survival was evaluated using the misclassification rate, the information gain and the relative information gain. This methodology is known as the PER method. 
One thousand cases of trauma admitted through the emergency department of Dayanand Medical College and Hospital, Ludhiana have been studied. The probability of survival was calculated using TRISS methodology. The estimated probability of survival was compared with actual survival. The epidemiology of trauma, patient`s characteristics, and their relation to mortality have also been studied:
- Age and Sex: Age distribution ranged from 15-86 years of age with majority of patients in 20-50 years age group. There were 837 males and 163 females thereby indicating male preponderance. The male to female ratio was 5.134:1 with P value of <0.01 and t value of 3.45.
- Mechanism of injury: Road traffic collisions were responsible for 721 (72%) of the total cases, this was followed by 120 (12%) cases of fall.
- Time of arrival: Out of 1000 patients, 383 (38.3%) reached between 4-12 hrs after sustaining injury of which 21 patients died. Some 251 (25.1%) reached 2-4 hrs following injury of which 10 patients died, and 136 (13.6%) reached between 1-2 hrs following injury of which 8 patients died. Only 94 patients (<10%) reached within 1 hr of sustaining injury indicating some delay in receiving medical aid [Figure 1]. Of these 2 patients died.
- Region affected by injury: Head and neck was the most commonly injured region. Injuries of the head and neck region along with orthopedic injuries constituted more than 76% of the total cases [Figure 2].
- Mortality: Out of 1000 patients 959 patients were discharged alive, while 41 patients expired. Mortality was maximum inpatients of age group >50 yrs [Table 1].
- TRISS index: [Table 2].
Misclassification rate = 0.056
False positive rate = 2.50%
False negative rate = 78.05%
Specificity = 97.50%
Sensitivity = 21.95%
The cut off for prediction was taken at PS = 0.6.
Using PER method, the TRISS method was found to have information gain of 0.049 and a relative information gain of 0.41 [Table 3].
The negative values of Z statistic and W statistic indicate that number of survivors predicted from the base line subset is more than the observed survivors in the study subset [Table 4]. The M statistic evaluates the match of injury severity between the study group and the base line group. The value above 0.88 indicates a good match. Hence, the study subset and the baseline subset have a good severity match.
[Table 5] compares the performance of three indices as assessed by PER method. It can be seen that that RTS and TRISS has performed better than ISS.
[Table 6] depicts the comparative performance of the three indices with regard to miscalculation rate sensitivity and specificity with cut off taken at PS = 0.6
| Discussion|| |
Evaluation of 1000 cases of trauma to rate the severity of injury has been done. A physiologic RTS and an anatomic ISS index have been used for this purpose.The probability of survival has been calculated using TRISS index (RTS, ISS, and age combination index). The comparison between the predicted and actual outcome and various systems of evaluation has been made.
Several factors useful in studying the epidemiology of trauma cases were also studied.
- Age and Sex: It is a well-known fact that trauma principally affects the young population. ,, In our study 50% of the patients were between the age group 20-40 years. There is a marked male preponderance in all communities of the world among trauma victims (WHO 1975). In our study, males comprised 83.7% of the patients. The results are comparable with another study done in India. 
- Cause of injury: In most of the studies on epidemiology of trauma, majority of the cases are due to road side collisions. ,,, Motor vehicles were responsible for 76.4% and 73.4% injuries in two Canadian centers. In our study, traffic collisions were responsible for 71% of cases.
- Time of arrival: The recognition of fact that time lapse between the time of injury and start of definitive treatment is vital to the outcome has been recognized for a long time.  In our study, we found that there was a graded increase in mortality with increase in delay in arrival. In a developing country like India, trauma care centres are limited to big cities only and common man does not have easy access to these centres.
- Region affected by injury: Head and neck accounted for 43.7% of injured patients followed by lower limb injuries (33.8%). The findings are comparable to the results of other studies. ,
- Mortality: The analysis of affect of age on mortality in our study brought forward the fact that mortality increase with age, which was comparable to results by other studies. , Copes et al. (1988) in a large study showed that mortality becomes nearly double for patients over 50 yrs of age for the same degree of injury severity as compared to patients below 50 yrs of age.  Champion et al. (1990) also reported similar findings.
- TRISS index: In our study, the value of Z was −3.95 while W was −5.345. These negative values are indicative of higher mortality observed in our study than predicted according to the MTOS norm. The M statistic was 0.967 and it represents a good severity match of the patient with MTOS baseline subset. TRISS has a better combination of low misclassification rate with high specificity and better sensitivity. With regards to comparison by PER method, RTS and TRISS performed better than ISS. Guzzo et al. in their study used area under the ROC curve of sensitivity versus 1-specificity to asses predictive ability and measured discrimination of the models. They found their model to be superior to ISS and comparable to RTS and TRISS. 
Kalaycioglu et al. in their study have found the scoring system to be a valuable tool for assessing the clinical outcome. , Hariharan et al. in their study on 326 trauma patients found a considerable disparity between predicted and observed outcomes when trauma patients were evaluated using TRISS scoring system. 
| Conclusions|| |
Numerous scoring systems are available, each having its own shortcomings.  In this study, 1000 trauma patients were evaluated using TRISS methodology for the severity of injury and outcome.
- The RTS ranged from 2.746 to 7.8408. There was a graded increase in mortality with decreasing RTS score.
- There was a graded increase in mortality with increasing ISS scores.
- The TRISS index also revealed similar probability of survival as expected from above values.
- Definitive analysis of TRISS revealed Z values of 3.95, W 5.345, and M +0.967.
- Comparison of RTS, ISS and TRISS by the PER method showed that ISS gave the poorest gain in information, while RTS and TRISS were comparable.
- Comparable performances of the RTS, ISS, and TRISS again showed ISS as the poorest index, while the results of RTS and TRISS were comparable.
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Department of Plastic Surgery, Dayanand Medical College and Hospital, Ludhiana, Punjab
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]
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