Association between the number of individuals injured in a traumatic event and posttraumatic stress disorder among hospitalized trauma patients.

Posttraumatic stress disorder (PTSD) often occurs following mass casualty events, yet the connection between the number of individuals injured in an event and PTSD risk in smaller-scale events (i.e., involving one or several injured persons) remains unclear. We conducted a registries-based study cross-referencing three databases across the continuum of care for military trauma patients hospitalized for traumatic injuries. The study population was categorized into three groups based on the number of injured individuals involved (i.e., single injured person, two to four [2-4] injured people, and five or more [≥ 5] injured people), and PTSD prevalence was assessed using long-term disability claim diagnoses. Overall, 4,030 military personnel were included (age at injury: Mdn = 20 years), and 18.3% were subsequently diagnosed with PTSD, with the highest prevalence in events involving ≥ 5 injured individuals (35.8%). Regression analyses adjusted for potential confounders revealed that being injured in an event with 2-4 injured persons, OR = 1.68, 95% CI [1.31, 2.15], or ≥ 5 injured persons, OR = 2.36, 95% CI [1.79, 3.13], was associated with increased odds of developing PTSD compared to being the sole injured person. The findings suggest a direct association between the number of injured individuals in an event and PTSD prevalence among traumatic injury survivors. The results underscore the importance of early diagnosis and interventions to prevent PTSD in individuals injured in multicasualty and mass casualty events.