Underweight adult burn survivors report significantly worse physical function and social participation: A Burn Model System Database Study

Burns can cause serious physical injury and psychosocial distress. Extremes of body weight can also impair physical recovery and exacerbate emotional distress. However, the impact of body mass index (BMI) on longitudinal self-reported outcomes is not well understood. We aimed to compare self-reported psychosocial and functional outcomes among adult burn survivors who were obese, normal weight, and underweight at discharge. Adult burn survivors participating in the Burn Model System (BMS) national database between 2010 - 2020 were included. Participants were divided into three groups: those who were obese (BMI ≥ 30), normal weight (BMI 18.5 - 29.9), and underweight (BMI < 18.5) at discharge. Survey responses using the PROMIS scales (Pain Interference, Anxiety, Depression, Fatigue, Ability to Participate in Social Roles, and Physical Function); PTSD Checklist for DSM-5; and Satisfaction with Life scale at 6-, 12-, and 24 months post-burn injury were analyzed. A total of 920 participants met inclusion criteria, of which 306 were obese, 579 normal weight, and 35 underweight. There were no significant differences across all self-reported outcomes between normal weight and obese participants. However, underweight participants reported significantly worse physical function (-4.2 pts, p = 0.005) and social participation (-3.49 pts, p = 0.041) compared to those with normal BMI. These findings indicate that underweight burn survivors may experience significantly worse physical function and social integration post-burn compared to normal weight survivors long-term. Our study suggests that low BMI status should be considered when discussing long-term physical and psychosocial recovery among adults living with burn injuries.