Exploratory Diagnostic Performance of Salivary Cortisol for Initial Assessment of Recent Exposure to Interpersonal Physical Violence: A Preliminary Study

Background/Objectives: Enhancing the objectivity of the assessment of interpersonal physical violence has become a challenge in modern forensic sciences. The use of biomarker assessments, such as cortisol, has become a promising diagnostic tool. Moreover, this hormone can be assessed non-invasively by measuring its concentration in saliva. This preliminary study evaluated salivary cortisol concentrations following recent interpersonal physical violence and assessed their apparent exploratory diagnostic performance for distinguishing violence-exposed individuals from controls. Methods: A study group (n = 26) was recruited from individuals referred by the Police for forensic medical examination within 48 h of the violent incident. Samples were taken between 8:30 and 10:30 a.m. A medical interview and physical examination preceded sample collection. Saliva was collected using the passive drool method. Samples were centrifuged, and morning salivary cortisol concentrations were determined using ELISA. The control group (n = 26) was recruited concurrently from healthy volunteers. Results: Salivary cortisol concentrations were approximately 4.7-fold higher in individuals exposed to physical violence than in matched controls (110.33 ± 54.41 vs. 23.49 ± 6.29 ng/mL; p < 0.001), and this difference remained significant after adjustment for age, sex, BMI, and sample collection time (p < 0.001). ROC analysis demonstrated near-perfect apparent discrimination between violence-exposed individuals and controls, with an AUC of 0.991 (95% CI: 0.962–1.000; p < 0.0001). The optimal cut-off of >35.45 ng/mL yielded a sensitivity of 92.31% (95% CI: 74.9–99.1%) and specificity of 100% (95% CI: 86.8–100.0%). Bootstrap analysis yielded a 95% CI for the optimal cut-off ranging from >32.17 to >35.45 ng/mL. Conclusions: Salivary cortisol demonstrated strong apparent discriminatory performance for recent exposure to interpersonal physical violence in this preliminary cohort. However, the proposed threshold should be regarded as exploratory and requires prospective external validation before any forensic or clinical application.