Forensic life-threat assessments using trauma scoring in single stabs to the trunk

Introduction. Forensic assessments of whether an injury would have been life-threatening often rely on empirical knowledge rather than evidence-based criteria. To address this gap, we applied the validated trauma scoring system New Injury Severity Score (NISS) to estimate mortality risk along the natural course of single stab injuries to the trunk. Methods and materials. We included 408 survivors and 139 fatalities with single stab injuries to the trunk, using data from registries maintained by the Swedish National Board of Forensic Medicine. Organ and vessel damage in survivors, stratified by intervention complexity; and fatalities, stratified by time until death, were presented. The predictive performance of NISS was estimated using logistic regression and Receiver Operating Characteristic (ROC) analysis. Results. NISS was strongly associated with intervention complexity among survivors and demonstrated excellent performance in predicting fatal outcomes without lifesaving treatment (AUC = 0.94, 95% CI 0.92–0.96), with optimal discrimination at NISS ≥ 20 (Youden’s Index = 0.72). Discussion and conclusion. To increase the evidence base in forensic life-threat assessment, we suggest applying NISS as a complement to expert opinion, as it offers potential for establishing a transparent and systematic tool that strengthens the rule of law. However, the tool needs to be validated in other settings and for multiple injuries.