Assessment of trauma scoring systems in patients subjected to exploratory laparotomy

Objective: to assess the epidemiological profile of patients undergoing exploratory trauma laparotomy based on severity and prognosis criteria, and to determine the predictive accuracy of trauma scoring systems in terms of morbidity and mortality. Methods: retrospective cohort study and review of medical records of patients undergoing exploratory laparotomy for blunt or penetrating trauma at the Hospital de Pronto Socorro de Porto Alegre, from November 2015 to November 2019. Demographic data, mechanism of injury, associated injuries, physiological (RTS and Shock Index), anatomical (ISS, NISS and ATI) and combined (TRISS and NTRISS) trauma scores, intraoperative findings, postoperative complications, length of stay and outcomes. Results: 506 patients were included in the analysis. The mean age was 31 ± 13 years, with the majority being males (91.3%). Penetrating trauma was the most common mechanism of injury (86.2%), predominantly by firearms. The average RTS at hospital admission was 7.5 ± 0.7. The mean ISS and NISS was 16.5 ± 10.1 and 22.3 ± 13.6, respectively. The probability of survival estimated by TRISS was 95.5%, and by NTRISS 93%. The incidence of postoperative complications was 39.7% and the overall mortality was 12.8%. The most accurate score for predicting mortality was the NTRISS (88.5%), followed by TRISS, NISS and ISS. Conclusion: the study confirms the applicability of trauma scores in the studied population. The NTRISS seems to be the best predictor of morbidity and mortality.


INTRODUCTION
T rauma scores are classification systems quantified by numerical values that stratify the severity of injuries resulting from trauma, allowing a prognostic estimation in terms of morbidity and mortality 1   The NISS has the same ISS calculation criteria, but it scores the three most severe injuries, regardless of the affected region 9 . The ATI score was based on the severity classification of the anatomical injury attributed to each intra-abdominal organ during laparotomy 10 . Chi-square and the Fisher's exact tests were applied in the analysis of categorical variables. Binary logistic regression analysis was performed to assess risk factors, with description of the sensitivity, specificity and accuracy of the predictive models using the ROC curve.
The significance level of 5% (p < 0.05) was considered statistically significant.  ATI was greater than 25 in 15% (n = 78) of cases. All scores analyzed but ATI showed a statistically significant difference when stratified by the mechanism of injury, blunt trauma being more severe ( Table 2).
The rate of postoperative complications was 39.7% (n = 201), and infectious ones were the most common, mainly due to intracavitary abscesses, bronchopneumonia, and surgical site infections.
Most complications were classified as minor (grade II, according to the adapted Clavien-Dindo classification 5 ) and, therefore, managed only with supportive measures and pharmacological treatment, without the need for an invasive approach. There was no statistically significant difference between the incidence of Fonseca Assessment of trauma scoring systems in patients subjected to exploratory laparotomy complications and mechanism of injury. Patients with ATI > 25 (15%; n = 78) developed a significantly higher rate of complications (51.3% and 37.6%, respectively; p = 0.03). The overall mortality was 12.8% (n = 65), with no significant difference between blunt and penetrating trauma. The outcomes are presented in detail in Table 3.
The multivariate analysis of the baseline and operative characteristics and outcomes stratified by survival established risk factors for mortality in the studied population, as shown in Table 4. Variables such as age, injury to more than two intra-abdominal organs,      In contrast, international series differ from Brazilian findings regarding the proportion between sexes, age groups, and the most prevalent mechanism of injury.
Van Gool et al. 14  The intraoperative findings and most affected abdominal organs described in Table 1 are in accordance   with the literature 1,16 and the Institution's historical series 13 , with emphasis on hollow viscera, liver and spleen injuries.
The combined negative and non-therapeutic laparotomies corresponded to 14% of the cases, which is very similar to that reported in other series (Kruel et al. 16  Among the anatomical scores, ATI had the worst performance, with a predictive accuracy of 73.1%, versus AUC > 0.8 for ISS and NISS. Furthermore, it was the only of the analyzed scores whose results did not display a statistical difference between blunt and penetrating trauma. Blunt trauma usually involves the dissipation and distribution of energy over a relatively larger surface area, and is therefore associated with potentially more serious injuries. ATI does not consider injuries in body segments other than the abdomen that can significantly contribute to morbidity and mortality 1 . Nevertheless, it was a good predictor of postoperative complications; values above the cutoff of 25 points were related to a higher incidence of complications, with statistical significance. NISS values were higher than the ISS ones in more than half of cases (56%), being an even better predictor of survival than the ISS. The latter ignores more than one potentially serious injury in the same body segment, to the detriment of less relevant injuries in other regions. This can underestimate the severity of certain patients with injuries restricted to one body region 1 . The NISS has the practical advantage of easier calculation, as it does not require the division of the body into regions, in addition to giving priority to injury severity, regardless of the affected area. Both indexes had an average value greater than 15, underlining anatomical injuries considered severe.
The probability of survival greater than or equal to 50%, which corresponds to preventable deaths, was estimated at 86.9% and 86.3% by TRISS and NTRISS, respectively, very similar to the 87.1% survival observed in the study. Mixed scores had the best predictive accuracy among all the other evaluated ones; the NTRISS had a slightly superior performance. The difference is only due to the higher anatomical score 19 , given that the physiological parameters and coefficients adjusted for age and mechanism of injury remain the same in the calculation.
Despite the better results of NTRISS suggested by several studies 1,19 , the community is still reluctant to adopt it, and TRISS remains the most used mixed index in the literature.
The main limitations of this study are its retrospective nature and those inherent to the use of medical records as a data source. Inconsistent documentation of vital signs and anatomical injuries may represent biases for the proper calculation of trauma scores. As an example, the RR did not have a statistically significant difference between the survival and death groups, despite being an early indicator of severity in the traumatized patient when altered.
In the context of trauma care, it is essential to train health professionals on the calculation and interpretation of severity scores as tools for therapeutic planning and service quality assessment. The improvement of instruments or the development of new ones that overcome the limitations of current systems is still an object of study.