High subcutaneous adipose, not visceral adipose, attenuates negative effects of low muscle mass on prognosis in abdominal trauma patients.

Background: Association between obesity and clinical prognosis of trauma patients remains controversial. Routine clinical practice of computed tomography of abdominal trauma patients provides a unique opportunity to assess the association between body composition and clinical outcomes.

Objective: This study aimed to investigate whether high adipose tissue can mitigate the adverse prognostic effects induced by low skeletal muscle mass in trauma patients.

Methods: We used a retrospective cohort including 542 patients with abdominal trauma from January 2010 to April 2023. We first categorized the patients into low and high skeletal muscle index (SMI) groups using cutoffs of 42.0 cm/m for men and 32.9 cm/m for women. Patients with low SMI were further divided into low- and high-adiposity groups based on the median values of visceral, subcutaneous and total fat index (VFI, SFI, TFI), respectively. Kaplan-Meier survival curves and Cox regression analyses were used to assess the associations of SMI and adiposity index with 28-day, 6-month, and 1-year mortality.

Results: The trauma patients were 50 ± 14 years of age, and 82.3 % (446/542) were males. The 28-day, 6-month, and 1-year mortality were 5.5 %, 12.7 % and 14.4 %, respectively. Compared to high SMI group, the hazard ratios for 6-month mortality were 2.73 (95 % confidence interval (CI), 1.49-5.00), 2.15 (95%CI, 1.27-3.65) and 2.19 (95%CI, 1.26-3.82) for low SMI patients with high VFI, with low SFI and with low TFI, respectively. No statistically significant differences were found when comparing mortality of high SMI group to low SMI group with low VFI, high SFI and high TFI. The results were robust for 1-year mortality.

Conclusions: High subcutaneous adipose, not visceral adipose, appears to alleviate medium- and long-term negative prognosis in trauma patients with low SMI. Our findings might inform personalized nutritional and lifestyle interventions in trauma patients.