Approximately 6 million Americans present to US Emergency Departments (ED) each year for care after motor vehicle collision (MVC). More than 90% of these individuals do not have serious physical injury and are discharged to home after ED evaluation. Persistent musculoskeletal pain develops in 10-20% of European Americans (EA) who experience such MVCs, with an economic impact of $29 billion per year in the US alone. The incidence of chronic pain development in African Americans (AA) experiencing MVC has never been reported. However, substantial evidence (and the investigator's pilot data) indicate that AA experience an increased burden of chronic pain. Reasons for this increased burden are poorly understood. Mechanisms of chronic musculoskeletal pain pathogenesis after MVC are described in biopsychosocial models, most notably Vlaeyen's fear-avoidance model (FAM), which is supported by substantial research. Experiences of discrimination may influence FAM processes and contribute to an increased incidence of chronic pain in AA experiencing MVC via a number of mechanisms. For example, discrimination experiences may: (1) cause stress-induced physiologic changes which increase initial pain in response to MVC, (2) increase subsequent depression and disability, and (3) increase chronic pain vulnerability in response to disability and depression. In addition, past adverse outcomes related to discrimination may increase negative expectations after MVC, which in turn may worsen pain-related outcomes. Available data suggest that the strength of an individual's ethnic identification may moderate these discrimination influences. To date, the FAM has never been evaluated in a cohort of AA transitioning to recovery vs. persistent pain, and the influence of discrimination and ethnic identity on FAM mechanisms has never been assessed. In addition, the influence of genetic vulnerability factors on FAM concepts and processes has rarely been evaluated, and never in AA. Evaluating genetic factors which influence the function of a physiologic system affecting FAM processes can advance our understanding of how constitutional factors interact with cognitive, psychological, and experiential factors to shape pain outcomes. The adrenergic nervous system is an excellent physiologic system to assess in this regard, because of its importance in pain perception, its critical role in the stress response, and its demonstrated interaction with FAM processes during chronic pain development. The proposed study will recruit one thousand AA presenting to a research network of ED sites after minor MVC. Participants will receive initial ED evaluation and follow-up interviews at 6 weeks and 6 and 12 months. Structural equation modeling will be used to test the multivariate predictive relationships described in the FAM. The influence of experiences of discrimination and ethnic identity on specific FAM concepts and processes will also be assessed, as will the influence of genetic factors affecting adrenergic system function. Together, the results of these analyses will substantially advance our knowledge of chronic pain pathogenesis in AA.
Chronic pain after motor vehicle collision (MVC) is common in European Americans, but to date no studies have been performed in African American cohorts, and the incidence and mechanisms of chronic post-MVC pain development in African Americans are unknown. The proposed study will provide new knowledge regarding mechanisms of persistent post-MVC musculoskeletal pain development in African Americans. Understanding the etiology of musculoskeletal pain disorders is important to the public's health because these disorders are common, cause significant pain and suffering, and are very costly to society.