Obesity has been found to increase the risk of musculoskeletal pain (MSP) in other settings, but to our knowledge, the influence of increased body mass index on pain outcomes after common trauma exposures such as motor vehicle collision (MVC) has not been assessed. In addition, obesity results in biomechanical changes, as well as physiologic changes including reduced hypothalamic pituitary adrenal axis negative feedback inhibition, but mechanisms by which obesity may result in worse post-traumatic outcomes remain poorly understood. In this study, we evaluated the influence of body mass index on axial and overall MSP severity (0-10 numeric rating scale) 6 weeks, 6 months, and 1 year after MVC among 917 European Americans who presented to the emergency department for initial evaluation. After adjusting for an array of sociodemographic factors, obesity (particularly morbid obesity) was an independent risk factor for worse MSP after MVC (eg, RR 1.41 [95% CI 1.11, 1.80] for moderate or severe MSP 6 months after MVC among morbidly obese vs normal weight MVC survivors). Interestingly, substantial effect modification was observed between obesity risk and a genetic variant known to reduce hypothalamic pituitary adrenal axis negative feedback inhibition (FKBP5 rs9380526). (eg, 41% vs 16% increased risk of moderate or severe MSP at 6 months among obese individuals with and without the risk allele.) Further studies are needed to elucidate mechanisms underlying chronic pain development in obese trauma survivors and to develop interventions that will reduce chronic pain severity among this common, at-risk group.
Prospective, longitudinal study shows that morbid obesity predicts greater chronic pain severity after motor vehicle collision.
aDepartment of Anesthesiology, Institute for Trauma Recovery, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
bDepartment of Emergency Medicine, Oakland University William Beaumont School of Medicine, Royal Oak, MI, United States
cDepartment of Emergency Medicine, Massachusetts General Hospital, Boston, MA, United States
dDepartment of Emergency Medicine, Spectrum Health System, Grand Rapids, MI, United States
eDepartment of Emergency Medicine, Baystate Medical Center, Springfield, MA, United States
fDepartment of Emergency Medicine, North Shore University Hospital, Manhasset, NY, United States
gDepartment of Emergency Medicine, Saint Joseph Mercy Health System, Ypsilanti, MI, United States
hDepartment of Emergency Medicine, University of Florida, Jacksonville, FL, United States
Corresponding author. Address: Department of Anesthesiology, Institute for Trauma Recovery, The University of North Carolina at Chapel Hill, N2201 UNC Hospitals CB#7010, Chapel Hill, NC 27599-7010, United States. Tel.: 919.843.5353; fax: 919.966.7193. E-mail address: firstname.lastname@example.org (S.A. McLean).
Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article.
Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (www.painjournalonline.com).
Received July 10, 2018
Received in revised form October 15, 2018
Accepted November 05, 2018