The usefulness of a trauma probability of survival model for forensic life-threatening danger assessments

Abstract

Clinical forensic medical examinations constitute an increasing proportion of our institution's tasks, and, concomitantly, the authorities are now requesting forensic life-threatening danger assessments based on our examinations. The aim of this retrospective study was to assess if a probability of survival (PS) trauma score could be useful for these forensic life-threatening danger assessments and to identify a cut-off PS score as a supporting tool for the forensic practice of assessing life-threatening danger. We compared a forensic database and a trauma database and identified 161 individuals (aged 15 years or older) who had both a forensic life-threatening danger assessment and a PS score. The life-threatening danger assessments comprised the following statements: was not in life-threatening danger (NLD); could have been in life-threatening danger (CLD); or was in life-threatening danger (LD). The inclusion period was 2012-2016. A statistically significant difference was found in the PS scores between NLD, CLD and LD (chi-square test: p < 0.0001). The usefulness of the PS score for categorizing life-threatening danger assessments was determined by a receiver-operator characteristic (ROC) curve. The area under the curve was 0.76 (95% CI, 0.69 to 0.84) and the ROC curve revealed that a cut-off PS score of 95.8 would appropriately identify LD. Therefore, a PS score below 95.8 would indicate life-threatening danger. We propose a further exploration of how the evidence-based PS score, including a cut-off value, might be implemented in clinical forensic medical statements to add to the scientific strength of these statements.

Keywords: AUC-ROC; Clinical forensic medicine; Life-threatening danger assessment; Objective injury severity; Penetrating injury.

Fig. 1

Flowchart for patient inclusion. Patients with a probability of survival (PS) score, a life-threatening danger assessment and penetrating injuries who underwent clinical forensic medical (CFM) examinations at Copenhagen University Hospital (CUH) from 2012 to 2016. Abbreviations: Trauma Audit and Research Network (TARN), cases registered in the TARN database (TARN ID), no assessment of life-threatening danger (NA), not possible to reassess the life-threatening danger (NP), died shortly after the CFM examination (D), was not in life-threatening danger (NLD), could have been in life-threatening danger (CLD), was in life-threatening danger (LD)

Fig. 2

Boxplots of the forensic life-threatening danger assessments and PS scores. a The distribution of PS scores for NLD, CLD and LD, b the distribution of PS scores for NLD and CLD on upper 5% of the y-axis. Abbreviations: Was not in life-threatening danger (NLD), could have been in life-threatening danger (CLD), and was in life-threatening danger (LD)

Fig. 3

Receiver-operator characteristic curve. The probability of survival after trauma in relation to the forensic life-threatening danger assessment with cutpoints. The diagonal red line illustrates the uninformative model with an AUC = 0.5, and the dashed grey line represents the shortest distance to the upper-left corner of the graph. Abbreviations: Highest correct classification rate (C), minimum distance to upper-left corner (D), minimum absolute difference between sensitivity and specificity (=), area under the curve (AUC)