Reciprocal associations of pain and post-traumatic stress symptoms after whiplash injury: A longitudinal, cross-lagged study

BackgroundThe objectives of the current study were to investigate (1) the longitudinal, reciprocal associations between pain and post-traumatic stress symptoms as proposed by the mutual maintenance model, and (2)to assess the predictive value of the three clusters of post-traumatic stress, where the model revealed that post-traumatic stress symptoms maintained pain in a consecutive cohort of whiplash-injured. MethodsParticipants (n=253; 66.4% women) were people with WAD grades I-III following motor vehicle crashes in Australia. Pain and post-traumatic stress symptoms were assessed by questionnaires over the course of a year (at baseline (<4weeks), 3, 6 and 12months post-injury). The objectives were tested using auto-regressive cross-lagged modelling and two additional structural equationmodels. ResultsThe analyses revealed that post-traumatic stress symptoms at baseline predicted an increase in pain between baseline and 3months and that post-traumatic stress symptoms at 6months predicted an increase in pain between 6 and 12months, beyond the stability of pain over time. Furthermore, hyperarousal at baseline significantly predicted pain at 3months and hyperarousal at 6months significantly predicted pain at 12months with 16 and 23% explained variance, respectively. [Correction added on 2 March 2018 after first online publication: the explained variance for hyperarousal symptoms at 6 months was previously given incorrectly and has been corrected to 23% in this version.] ConclusionsThe results point to a temporal main effect of post-traumatic stress symptoms on pain over and above the stability of pain itself within the first 3months post-injury and again in the chronic phase from 6 to 12months with hyperarousal symptoms driving these effects. From 3 to 6months, there was a slip in the maintenance patterns with no cross-lagged effects. SignificanceInvestigating mutual maintenance of pain and PTSS in whiplash, the present study found evidence suggesting a maintaining effect of PTSS on pain within the first 3months post-injury and from 6 to 12months driven by hyperarousal, highlighting the importance of addressing PTSS.