Outcomes after traffic injury: mental health comorbidity and relationship with pain interference
Abstract Background Mental health symptoms, like depressive mood (DM) and post-traumatic stress (PTS), and pain-related disability, known as pain interference (PI) often co-occur following traffic injury and their comorbidity can complicate recovery. Clarification is required on mental health comorbidity and relationships with PI, to enhance care and outcomes after a traffic injury. Methods 2019 adults sustaining minor-to-moderate traffic injury were recruited within 28 days post-injury and assessed using phone interviews at 1, 6 and 12-months post-injury. Trajectories of DM, PTS and PI were established and relationships between DM, PTS and PI trajectories were explored using dual trajectory modelling. Predictors of mental health trajectories were also investigated. Results Up to five typical post-trauma trajectories were identified for DM, PTS and PI. Most people were in a resilient mental health trajectory (over 60%, DM or PTS), or in a chronic pain disability trajectory (almost 60%, PI) 12 months post-injury. While recovery/resilient mental health trajectories were strongly interrelated (73.4% joint probability and >94% conditional probabilities), DM/PTS comorbidity in chronic trajectories was not straightforward, suggesting a possibly asymmetric relationship. That is, persistent DM was more likely associated with persistent PTS (90.4%), than vice versa (31.9%), with a 22.5% probability that persistent PTS was associated with none or milder depression (i.e. following a recovery/resilient DM trajectory). An asymmetrical relationship was also found between mental health and PI. The majority of those with persistent PI were likely to be in a recovery/resilient DM/PTS trajectory (almost 70%), but those in a non-resilient DM/PTS trajectory showed a high risk of persistent PI. Predictors of non-resilient mental health trajectories included poorer pre-injury health and social support, and shared factors like acute psychological distress and pain catastrophizing. Conclusions Strong interrelations were confirmed between mental health problems and pain disability following traffic injury. However, persistent depression was more strongly linked to persistent post-traumatic stress, than vice versa. Persistent pain disability was only linked with persistent mental health symptoms in vulnerable subgroups. Early psychiatric/psychological interventions should target elevated psychological distress and negative appraisals in vulnerable individuals, to reduce mental health morbidity/comorbidity and chronic pain disability.