Penetrating abdominal trauma index: Sensitivity and specificity for morbidity and mortality by ROC analysis

Background: When developed in 1981 by Moore and colleagues the Penetrating Abdominal Trauma Index (PATI) was used to identify trauma patients at risk of postoperative complications. Methods of trauma quantification have been extensively developed but their outcome evaluations have been naïve, subject only to basic statistical analyses. The accuracy of PATI was assessed by means of Receiver Operating Characteristics (ROC) curve analysis. Aims: To evaluate PATI by means of ROC curve analysis and establish its sensitivity and specificity for predicting the morbidity and mortality in penetrating abdominal trauma. Settings and design: Patients who attended the University hospital trauma unit; prospective cohort study. Methods: This was a prospective study over an 11-month period, patients with penetrating abdominal trauma who underwent laparotomy were enrolled. Initial assessment of the patients was done following the ATLS guidelines. Patients were stratified on the basis of those who developed complications, no complications and postoperative mortality. PATI was calculated based on operative findings and the outcomes were measured on the basis of complications or mortality in the postoperative period. Statistical analysis: Receiver Operating Characteristics curve analysis and Logistic regression analysis using PATI as independent variable. Results: Eighty-nine consecutive patients underwent laparotomy for abdominal trauma, 49 for stab wounds and 40 for gunshot wounds. Patients with complications scored a mean PATI of 21.47; those who died scored a mean PATI of 25.29. ROC curve analysis of PATI scores in patients who developed complications showed results of 42.1% sensitivity and 91.4% specificity. Sensitivity and specificity for mortality prediction was 42.9% and 91.5% respectively. Conclusion: The statistical evaluation of trauma scores should be performed using an adequate methodology to avoid naive evaluations. ROC curve evaluation of this trauma score index allows a comprehensive study of the instrument’s performance, avoids data simplification and permits cross-analysis of different trauma score indexes.