The Relationship Between Body Mass Index and Long-Term Outcomes Following Traumatic Injury

Introduction Little is known about the relationship between body mass index (BMI), a function of mass and height (mass(kg)/height(m)(2)) and long-term outcomes among traumatic injury survivors. In this prospective cohort study, we investigate the relationship between BMI and long-term health outcomes in the trauma population. Methods Adult trauma survivors with an injury severity score >= 9 admitted to one of three level 1 trauma centers, from January 1, 2015 to December 31, 2022, were surveyed via telephone between 6 and 12 mo postinjury. Participants were stratified into one of five groups by BMI at the time of trauma: L-BMI (BMI <18.5), N-BMI (BMI 18.5-24.9), H1-BMI (BMI 25-29.9), H2-BMI (BMI 30-34.9), and H3-BMI (BMI >= 35); N-BMI was used as the referent. Mental and physical health-related quality of life scores, pain, new functional limitations, and hospital readmissions were evaluated. Univariate and multivariate analyses were used to compare outcomes between study groups. Results 3830 patients were included. Of those, 124 were L-BMI (3.2%), 1495 N-BMI (39%), 1318 H1-BMI (34.4%), 541 H2-BMI (14.1%), and 352 H3-BMI (9.2%). L-BMI was associated with adverse physical (b = -3.13, CI = -5.71 to -0.55, P = 0.017) and mental health (b = -3.17, CI = -5.87 to -0.46, P = 0.022) outcomes 6-12 mo postinjury compared to the referent. H1-BMI and H2-BMI had higher odds of wo`rse physical outcomes (b = -1.47, CI = -2.42 to -0.52, P = 0.002; b = -3.11, CI = - 4.33 to -1.88, P <= 0.001, respectively) and chronic pain (adjusted odds ratio (aOR) = 1.24, CI = 1.04-1.47, P = 0.016; aOR = 1.52, CI = 1.21-1.90, P <= 0.001, respectively). Patients with H3-BMI had higher odds of worse physical outcomes compared to N-BMI (b = -4.82, CI = -6.28 to -3.37, P <= 0.001), chronic pain (aOR = 2.11, CI = 1.61-2.78, P <= 0.001), all-cause hospital readmissions (aOR = 1.62, CI = 1.10-2.34, P = 0.013), and new functional limitations (aOR = 1.39, CI = 1.08-1.79, P = 0.01). Conclusions BMI variance above or below N-BMI is associated with worse long-term outcomes following traumatic injury