The influence of skeletal muscle and fat on 28-day mortality in patients with pneumonia-induced sepsis

Objective To establish a predictive model for 28-day mortality in pneumonia-induced sepsis patients and evaluate its predictive efficacy. Methods The study included patients with pneumonia-induced sepsis admitted to the Emergency Department of Chaoyang Hospital, Capital Medical University, between January 1, 2024, and November 31, 2024. Patients were randomly divided into training and test cohort in a 7:3 ratio. The 28-day survival status of the patients was recorded. Univariate and multivariate Logistic regression analyses were conducted to screen the risk factors of 28-day mortality, and a nomogram was constructed based on these factors. The model was then verified in the test cohort. Results A total of 560 patients were enrolled in the study, with 392 in the training set and 168 in the internal validation set. Multivariate Logistic regression analysis revealed that the cross-sectional area of the erector spinal muscle at the T12 level ( OR =0.998, 95%CI : 0.997-0.999), SOFA score ( OR =1.173, 95%CI : 1.032-1.334), LAR( lactate-to-albumin ) ratio ( OR =44.174, 95%CI : 1.156- 1687.954) were independent predictors of 28-day mortality. There was a significant difference in the subcutaneous fat thickness at the umbilical level between the survival and death groups ( P = 0.02), but it was not an independent risk factor for 28-day mortality after being included in the Logistic regression analysis. A nomogram was established based on these independent risk factors, and evaluations using time-dependent area under the curve, calibration curves, and decision curve analysis demonstrated good calibration and discrimination of the model in both sets. Conclusion The cross-sectional area of the erector spinae muscle at the T12 level, SOFA score and LAR ratio were identified as independent factors for 28-day mortality in pneumonia-induced sepsis patients. Among these, the cross-sectional area of the erector spinae muscle at T12 served as a protective factor, while SOFA score and LAR ratio were identified as risk factors.However, subcutaneous fat thickness at the navel is not an independent risk factor. However, the thickness of subcutaneous fat at the umbilicus is not an independent risk factor. The nomogram constructed based on these risk factors exhibits good predictive performance and provides guidance for clinicians in the early assessment of pneumonia-induced sepsis patient prognosis.