Determinants of chronic pain 3 years after moderate or serious injury

Patients with pain 3 years after injury are at risk of lifetime pain. It is not known if the predictors of chronic pain at 3 years are the same as those for earlier time points or whether other factors become important. Clarifying these factors will aid our understanding of the development of long-term pain and further inform the development of models for screening and early intervention for pain in the aftermath of injury.

Patients admitted to two trauma centers underwent a comprehensive physical and psychological assessment of known and potential risk factors for chronic pain during their index admission. Three years after injury, these patients were assessed for the presence of chronic pain (score was ≥5 on an 11-point numerical rating scale during the last episode of pain, and present in the last month and at least two times in the past week) and pain-related disability. Logistic regression was used to identify independent risk factors for the presence of chronic pain and disability.

Two hundred and twenty patients (75.9% of the original cohort) were assessed at 3 years. Of these, 146 (66.7%) reported some pain and 52 (23.7%) reported chronic pain. Factors (present at the time of injury) that predicted chronic pain were lower socioeconomic status, pain severity, and injury severity. The predictive power of these combined factors was modest.

Three years after serious injury, almost a quarter of patients report chronic pain, and more than a third report at least moderate pain-related disability. The predicative power of measures taken in the acute setting is not enough to support discharge screening alone as a method of triaging high-risk patients to early intervention.