The Clinical Impact of Sarcopenia and Delirium in Hospitalized Elderly Patients: An Analysis Using Muscle Ultrasound

BACKGROUND: Sarcopenia and delirium are two highly prevalent clinical syndromes among hospitalized elderly patients, both independently associated with adverse outcomes such as increased risk of falls, disability and mortality. Although a correlation between sarcopenia and delirium has been previously reported, past studies have often relied on less reliable surrogate markers for sarcopenia, leading to potential inaccuracies in diagnosis and assessment. This study aims to address these limitations by utilizing a more precise and reliable diagnostic tool for sarcopenia, specifically, muscle ultrasound (US) to measure the quadriceps femoris muscle and its pennation angle, to accurately evaluate the correlation between sarcopenia and delirium in acutely admitted geriatric patients. METHODS: We used muscle US to measure sarcopenia with reliable markers, specifically the Ultrasound Sarcopenia Index (USSI). This index evaluates the ratio between vastus lateralis thickness and fascicle length (L/f), offering a detailed view of muscle structure that is not affected by sex or body size. RESULTS: In 194 patients (mean age 86.5 years; 46.4% women; 81.4% with delirium), USSI correlated with MMSE (r = -0.619, p < 0.001), 4AT (r = 0.844, p < 0.001), ADL/IADL (r ≈ -0.32, p < 0.001), BMI, grip strength and muscle thickness (all p < 0.001). Women had higher USSI and worse cognitive/frailty scores; patterns were consistent across sexes. CONCLUSION: Our findings are expected to support the implementation of more targeted assessments and interventions, emphasizing the crucial role of accurate sarcopenia diagnosis in improving outcomes for elderly patients and highlighting its interconnectedness with delirium in comprehensive geriatric care.