PTSD symptoms, pain catastrophizing, and pain outcomes after acute orthopedic injury.

Background: PTSD is associated with greater incidence of chronic pain. Pain catastrophizing often accounts for this association. Less is known about these relationships during the acute phase (1-2 months) following orthopedic traumatic injuries. We sought to understand which orthopedic traumatic injury-related PTSD symptoms were associated with acute pain and physical dysfunction and whether pain catastrophizing accounted for these associations.

Methods: This secondary analysis uses baseline data from a multisite randomized controlled trial of an intervention for individuals with heightened pain catastrophizing or pain anxiety following acute orthopedic injury. We used partial correlations to examine associations between PTSD symptom clusters (re-experiencing, avoidance, negative alterations in cognitions and mood, and hyperarousal) and pain outcomes (pain intensity and physical dysfunction) controlling for pain catastrophizing. We used hierarchical regressions to evaluate unique associations between PTSD clusters and pain outcomes. In exploratory analysis, we examined the indirect effects of PTSD symptoms on pain outcomes through catastrophizing.

Results: Hierarchical linear regressions indicated that hyperarousal was uniquely associated with greater pain intensity with activity (β = 0.39, p < 0.001, ΔR2 =0.06) and physical dysfunction (β = 0.22, p = 0.04 ΔR2 =0.02). PTSD symptoms were still associated with pain with activity even with pain catastrophizing included in the models, and catastrophizing did not have a significant indirect effect on the relationship between PTSD and physical dysfunction (b=0.06, SEBoot=0.04, 95% CIBoot = [-0.003, 0.14]). Pain catastrophizing did largely account for the association between re-experiencing, avoidance, and negative alterations in cognitions and mood symptoms and pain at rest.

Conclusions: Pain catastrophizing interventions may be best suited for limiting the impact of PTSD symptoms on pain at rest, but catastrophizing alone may not fully explain the relationship between PTSD symptoms and physical dysfunction after acute orthopedic injury. To prevent the negative association of PTSD symptoms, especially hyperarousal, on physical outcomes in acute pain populations, interventions may require more than solely targeting pain catastrophizing.