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

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.

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).

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.

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

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.

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.