Severity of traumatic injuries predicting psychological outcomes: A surprising lack of empirical evidence

Despite widespread beliefs that trauma severity is related to levels of posttraumatic stress symptoms (PTSS), the empirical evidence to support such beliefs is lacking. In the current study we examined Injury Severity Score (ISS), a medical measure of event severity for physical injuries, in a sample of 460 patients admitted to a Level 1 Trauma Center. Results revealed no significant relationship between ISS and PTSS, depression, pain, and general physical and mental health at baseline, three months, and six months post-injury. However, at 12 months post-injury, ISS significantly predicted depression, pain, and physical health, but was unrelated to PTSS. The effect sizes of these relationships were small and would not remain significant if any adjustments for multiple comparisons were employed. We conclude that the relationship between ISS and PTSS is, at best, weak and inconsistent. The results are discussed in the broader picture of event severity and psychological outcomes.