Rectus femoris and vastus intermedius muscle thickness as a predictor of mortality in elderly patients with pneumonia.

OBJECTIVES

The high mortality rate among elderly patients with community-acquired pneumonia (CAP) underscores the need for the early identification of high-risk individuals. Sarcopenia has been demonstrated to be associated with mortality in various infectious diseases. In this study, we compared the roles of rectus femoris (RF) muscle thickness, vastus intermedius (VI) muscle thickness, paraspinal muscle area, and the CURB-65 score (which includes confusion, urea level, respiratory rate, blood pressure, and age ≥ 65 years) and the Pneumonia Severity Index (PSI) in predicting 30-day mortality in elderly patients with pneumonia.

METHODS

This single-center, prospective observational cohort study included patients aged 65 years and older who were diagnosed with CAP in the emergency department between February and March 2025, and who underwent thoracic computed tomography (CT) imaging within 48 h before or after hospital admission. Baseline characteristics and laboratory data were collected upon presentation. Rectus femoris (RF) and vastus intermedius (VI) muscle thicknesses were assessed via ultrasound and these measurements were then divided by the square of the subjects' height, in order to obtain the RF index (RFI) and VI index (VII). Additionally, paraspinal muscle areas were measured from thoracic CT images to calculate the paraspinal muscle index. The prognostic predictive power of these measurements was evaluated using Receiver Operating Characteristic (ROC) curve analysis. De Long test was used to compare area under the curve (AUC).

RESULTS

Of the 118 patients included in the study, 25 (21.2 %) died within 30 days. The AUC for predicting mortality was 0.770 for RFI, 0.778 for the VII and 0.871 for the reference test, the paraspinal muscle index. There were no statistically significant differences among these values. In comparison, the AUC values for the CURB-65 and PSI scores in predicting 30-day mortality were 0.647 and 0.662, respectively.

CONCLUSION

The sarcopenia markers RFI and VII were found to be superior to the CURB-65 and PSI scores in predicting 30-day mortality in geriatric patients with CAP. Furthermore, the RFI and VII indices evaluated by ultrasonography do not differ from the paraspinal index assessed by CT, which is considered the gold standard in diagnosing sarcopenia, in terms of their predictive capability for mortality.