BACKGROUND: Posttraumatic stress disorder (PTSD) symptoms are highly prevalent after whiplash and associated with pain-related symptoms. While mutual maintenance between pain and PTSD has been suggested, knowledge on individual differences in the course of these symptoms is needed. The present study aimed to identify trajectories of PTSD symptoms following whiplash and test predictors and functional outcomes of such trajectories.

METHODS: In a prospective cohort design with assessments at baseline (<4 weeks), 3 months, and 6 months post-injury (n = 229, whiplash grade I-III), we identified PTSD-trajectories using Latent Growth Mixture Modeling. Predictors (pain, fear-avoidance-beliefs, pain-catastrophizing, depression, age, and gender) were tested using multinomial logistic regression, and group mean differences in physical and psychosocial pain-related disability at 6 months were tested as outcomes after controlling for baseline levels.

RESULTS: Three trajectories were identified: "Resilient" (75.1%) with little or no PTSD symptoms over time, "Recovering" (10.0%) with high initial PTSD symptom levels, then decreasing substantially, and "Chronic" (14.9%) with high initial PTSD symptom levels and a small increase over time. Initial higher pain and depression levels predicted the recovering and chronic trajectories, while the latter had more pain-related disability at 6 months compared to both other trajectories.

CONCLUSIONS: Three trajectories were identified, with the chronic trajectory suggesting that a significant subset of people does not recover from PTSD symptoms. This class also reported more pain-related disability. Pain and depression predicted membership, but did, however, not succeed in differentiating between the two high-starting trajectories, suggesting that targeting PTSD symptoms may be important to ensure recovery.

SIGNIFICANCE: Distinct recovery patterns after whiplash were identified with a significant subgroup reporting elevated and slightly increasing PTSD symptoms over time, highlighting both recovery variability and the presence of PTSD symptoms in a significant subgroup of individuals with whiplash. This subgroup also displayed enhanced pain-related disability over time compared to the recovering and resilient subgroups, thereby linking PTSD symptoms to functional pain outcomes over time. These findings suggest that clinicians should be attentive of potential PTSD symptoms in whiplash patients.