Impact of the quantity and quality of erector spinae muscles on the short-term prognosis of elderly patients with aspiration pneumonia in Japan.

Background: Whether muscle mass and muscle quality affect the prognosis of elderly patients with aspiration pneumonia is unclear. This study aimed to evaluate the relationship between erector spinae muscle mass and muscle quality on the 30-day prognosis of elderly patients with aspiration pneumonia.

Methods: Two hundred fifty-eight patients who were diagnosed with aspiration pneumonia and admitted to Sanuki Municipal Hospital for pulmonary rehabilitation intervention were included. The cross-sectional area (ESM/BSA) and CT values (ESM) of the erector spinae muscles at the 12th thoracic vertebra were measured on chest CT images to represent muscle mass and quality, respectively. The primary outcome was defined as 30-day survival.

Results: Twenty-six patients died within 30 days after hospitalization. The ESM/BSA ratio was significantly greater in the survival group than in the nonsurvival group (p = 0.001). The cutoff values for 30-day survival were calculated as follows: the ESM/BSA was 11.046 cm/m in male patients and 9.600 cm/m in female patients; the ESM was 26.85 HU in male patients and 8.00 HU in female patients. A higher ESM/BSA significantly improved 30-day survival, while ESM did not show a significant difference. Cox proportional hazards regression analysis revealed that the ESM/BSA was independently associated with 30-day short-term prognosis (hazard ratio 0.34, p = 0.034).

Conclusion: The short-term prognosis of elderly patients with aspiration pneumonia may be more strongly influenced by muscle mass than by the muscle quality of the erector spinae muscles.