Disability after injury: the cumulative burden of physical and mental health.

Context: Injury is one of the leading contributors to the global burden of disease. The factors that drive long-term disability after injury are poorly understood.

Objective: The main aim of the study was to model the direct and indirect pathways to long-term disability after injury. Specifically, the relationships between 3 groups of variables and long-term disability were examined over time. These included physical factors (including injury characteristics and premorbid disability), pain severity (including pain at 1 week and 12 months), and psychiatric symptoms (including psychiatric history and posttraumatic stress, depression, and anxiety symptoms at 1 week and 12 months).

Design, Setting, And Participants: A multisite, longitudinal cohort study of 715 randomly selected injury patients (from April 2004 to February 2006). Participants were assessed just prior to discharge (mean = 7.0 days, SD = 7.8 days) and reassessed at 12 months postinjury. Injury patients who experienced moderate/severe traumatic brain injury and spinal cord injury were excluded from the study.

Main Outcome Measure: The World Health Organization Disability Assessment Schedule 2.0 was used to assess disability at 12 months after injury.

Results: Disability at 12 months was up to 4 times greater than community norms, across all age groups. The development and maintenance of long-term disability occurred through a complex interaction of physical factors, pain severity across time, and psychiatric symptoms across time. While both physical factors and pain severity contributed significantly to 12-month disability (pain at 1 week: total effect [TE] = 0.2, standard error [SE] < 0.1; pain at 12 months: TE = 0.3, SE < 0.1; injury characteristics: TE = 0.3, SE < 0.1), the total effects of psychiatric symptoms were substantial (psychiatric symptoms 1 week: TE = 0.30, SE < 0.1; psychiatric symptoms 12 months: TE = 0.71, SE < 0.1). Taken together, psychiatric symptoms accounted for the largest proportion of the variance in disability at 12 months.

Conclusions: While the physical and pain consequences of injury contribute significantly to enduring disability after injury, psychiatric symptoms play a greater role. Early interventions targeting psychiatric symptoms may play an important role in improving functional outcomes after injury.