Stress-related psychological symptoms contribute to axial pain persistence after motor vehicle collision: path analysis results from a prospective longitudinal study

Abstract

Posttraumatic stress disorder (PTSD) symptoms and pain after traumatic events such as motor vehicle collision (MVC) have been proposed to be mutually promoting. We performed a prospective multicenter study that enrolled 948 individuals who presented to the emergency department within 24 hours of MVC and were discharged home after evaluation. Follow-up evaluations were completed 6 weeks, 6 months, and 1 year after MVC. Path analysis results supported the hypothesis that axial pain after MVC consistently promotes the maintenance of hyperarousal and intrusive symptoms, from the early weeks after injury through 1 year. In addition, path analysis results supported the hypothesis that one or more PTSD symptom clusters had an influence on axial pain outcomes throughout the year after MVC, with hyperarousal symptoms most influencing axial pain persistence in the initial months after MVC. The influence of hyperarousal symptoms on pain persistence was only present among individuals with genetic vulnerability to stress-induced pain, suggesting specific mechanisms by which hyperarousal symptoms may lead to hyperalgesia and allodynia. Further studies are needed to better understand the specific mechanisms by which pain and PTSD symptoms enhance one another after trauma, and how such mechanisms vary among specific patient subgroups, to better inform the development of secondary preventive interventions.

Figure 1

FKBP5 risk haplotype was defined by the presence of one or more copies of the h2 or h3 haplotype (combined frequency 0.18). Reproduced from A.V. Bortsov et al. Pain 154.8 (2013): 1419-1426

Figure 2

Proportion of overlap between moderate/severe motor vehicle collision (MVC) related axial pain symptoms (MRAP), psychological distress (as measured by Peritraumatic Distress Inventory (PDI)) and post-traumatic distress disorder (PTSD) symptoms (as measured by the Impact of Event Scale-Revised (IES-R)) among study participants in the emergency department and at six weeks, six months and one-year follow-up timepoints.

Figure 3

Significant pathways between peritraumatic distress symptom cluster severity (assessed in the ED as life threat, helplessness, loss of control, and guilt/shame) and post-traumatic stress disorder symptom cluster severity (assessed at subsequent timepoints as intrusion, avoidance, and hyperarousal) and motor vehicle collision (MVC)-related axial pain severity across ED, 6 week, 6 month, and 1 year timepoints after MVC. *p < 0.05, **p<0.01

Figure 4

Among study participants with one or more copies of the FKBP5 risk haplotype (18%), hyperarousal symptoms had a greater influence on mediating the relationship between acute axial pain and axial pain at 6 months than among other participants (p=0.03)

Figure 5

Among study participants with substantial peritraumatic distress, hyperarousal symptoms had a lesser influence on mediating the relationship between axial pain at 6 weeks and axial pain at 1 year than among other participants (p=0.008), and avoidance symptoms had a greater influence on mediating the relationship between axial pain at 6 weeks and axial pain at 1 year (p < 0.001) than among other participants.