gms | German Medical Science

Objectives: Rib fractures are commonly found in trauma patients and have a relevant mortality rate. Obesity is usually measured with the body mass index (BMI). Although it can predict all-cause mortality, there is only sparse literature whether it can predict rib fracture-mortality. This may be in part due to the fact that the BMI is often not available in (poly-)trauma patients. Since these patients often receive a computed tomography (CT) scan, it may be more feasible to use CT-based measures of obesity. The aim of this study was to assess whether rib fractures and CT-based measures of obesity are associated with mortality and abdominal injuries and to evaluate the correlation between local and global measures of obesity.

Methods: A retrospective cohort study included all inpatients with rib fractures in 2013 at a level 1 trauma center. The main exposure variable was the rib fracture score (RFS) (number of rib fractures, uni- or bilateral, age). Other exposure variables were the BMI and CT-based measures of obesity. The latter consisted of the subxiphoid outer abdominal fat (SOAF), subxiphoid peritoneal fat (SPF), umbilical outer abdominal fat (UOAF), and umbilical visceral fat (UVF) on axial planes of a CT scans (Figure 1 [Fig. 1]). The primary outcome was in-hospital mortality. Secondary outcome was abdominal injuries. Sex and comorbidities were adjusted for in a logistic regression model. Due to multiple testing, the significance level was lowered to 1%.

Results and Conclusion: Two hundred and fifty-nine patients (median age 55.0 [IQR 44.0-72.0] years, 66.4% males) were analyzed. The mortality rate was 8.5%. A RFS >4 was associated with 490% increased mortality (adjusted odds ratio (OR_adjusted)=5.9, 95% confidence interval (CI) 1.9-16.6, p=0.002). The BMI and CT-based measures of obesity were not associated with mortality, rib fractures or injury of the liver. The BMI and CT-based measures of obesity showed moderate correlations (e.g. umbilical outer abdominal fat: r=0.59, p< 0.001) (Table 1 [Tab. 1] ).

A RFS >4 was an independent risk factor for increased mortality. Global and local measures of obesity were not associated with mortality, rib fractures or liver injuries. If the BMI is not available in trauma patients, CT-based measures of obesity may be considered as a surrogate.

Acknowledgements: A similar version of this abstract has been submitted to a peer-reviewed journal, but not yet published or presented anywhere. The last two authors contributed equally to this study.