# Chest CT-derived body composition parameters for outcome prediction in sepsis patients with pneumonia

## TL;DR

This study shows that body composition measured from chest CT scans can predict severe outcomes in pneumonia patients with sepsis.

## Contribution

The study demonstrates that CT-derived body composition parameters are effective predictors of adverse events in sepsis patients.

## Key findings

- Low skeletal muscle area at T4 and L1, and high abdominal circumference at L1 are linked to ICU admission and mortality.
- High intramuscular adipose tissue at L1 correlates with worse oxygenation during hospitalization.
- CT-based body composition models perform as well as standard scores in predicting sepsis outcomes.

## Abstract

We aim to evaluate the potential contribution of chest computed tomography (CT)-derived body composition parameters in predicting adverse events in sepsis patients with pneumonia.

A retrospective study was conducted on sepsis with pneumonia cases who visited Shengjing Hospital of China Medical University from January 2023 to September 2024. We used chest CT scans to quantify skeletal muscle area (SMA) at the fourth thoracic vertebra (T4) and the first lumbar vertebra (L1) levels, as well as abdominal circumference (AC), subcutaneous adipose tissue (SAT), and intramuscular adipose tissue (IMAT) at the L1 level.

A total of 303 patients (203 men; median age 70 years, interquartile range 63–79) were included in the study. Fully adjusted models identified low SMAT4, low SATL1, and high ACL1 as independent risk factors for medical intensive care unit (MICU) admission, with odds ratios (ORs) of 0.795, 0.897, and 2.095, respectively. Low SMAT4 (OR 0.880, 95% confidence interval [CI] 0.800–0.967, p = 0.008) and high ACL1 (OR 1.527, 95% CI 1.122–2.079, p = 0.007) were both independently associated with in-hospital mortality. High IMATL1 (β: −2.360, p = 0.003) was associated with a greater decrease in the PaO2/FiO2 ratio during hospitalization. Models using chest CT-derived body composition parameters to predict MICU admission, septic shock, and in-hospital mortality in patients with sepsis were as effective as sequential organ failure assessment scores.

The assessment of frailty status and visceral obesity, determined by chest CT measurements of low thoracic muscle mass and elevated AC, is independently correlated with an increased risk of admission to the MICU and mortality among sepsis patients with pneumonia. This underscores the significance of CT-derived body composition as a critical imaging biomarker that reflects the physiological reserve of sepsis patients and their associated risk of adverse events.