Post-traumatic stress symptom clusters in acute whiplash associated disorder and their prediction of chronic pain-related disability

INTRODUCTION: The presence of post-traumatic stress disorder (PTSD) symptoms has been found to be associated with an increased risk of persisting neck pain and disability in motor vehicle crash (MVC) survivors with whiplash injuries. The findings are mixed as to which PTSD symptom(s) best predicts recovery in this population. OBJECTIVES: The aims were (1) to explore the factor structure of the Post-traumatic Stress Diagnostic Scale (PDS) in a sample of acute whiplash-injured individuals following a MVC and (2) to identify the PTSD-symptom clusters that best predict long-term neck pain-related disability in this population as measured by the Neck Pain Disability Index (NDI). METHODS: A sample (N = 146) of whiplash-injured individuals completed the NDI and the PDS at baseline (<1 month) and at 6 months follow-up. RESULTS: Principal component analyses generated 2 symptom clusters: re-experiencing/avoidance and hyperarousal/numbing. Nine trauma-related PTSD symptoms loaded exclusively on the re-experiencing/avoidance cluster and 7 nonspecific PTSD symptoms loaded exclusively on the hyperarousal/numbing cluster. One PTSD symptom (ie, inability to recall an important aspect of the trauma) had no salient loading on either clusters. Structural equation modelling analysis indicated that there was a significant positive relationship between the hyperarousal/numbing symptom cluster and long-term neck pain-related disability, while no significant relationship was found between the re-experiencing/avoidance symptom cluster and long-term neck pain-related disability. CONCLUSION: Given that only the hyperarousal/numbing symptom cluster predicted long-term neck pain-related disability, this finding may have implications in terms of diagnosis, assessment, and management of the psychological impact of whiplash-injured individuals following a MVC.