Sarcopenia as Manifested by L3SMI Is Associated with Increased Long-Term Mortality amongst Internal Medicine Patients-A Prospective Cohort Study

Background: Sarcopenia and Frailty are syndromes that affect the clinical outcomes of patients suffering from a wide range of diseases. The use of Computed Tomography (CT) is well established for Sarcopenia evaluation via estimation of the Skeletal Muscle Index (SMI) at the level of the third lumbar vertebra (L3SMI). Nevertheless, the association of more readily available biomarkers of Sarcopenia and clinical outcomes is desired. Recent studies have associated low Alanine amino-transferase ALT (SGPT) levels with Sarcopenia and frailty. The current study aimed to establish the association between low L3SMI and the aforementioned indices of Sarcopenia, frailty and poor clinical outcomes. Methods: A cohort study of patients admitted to the internal medicine department at a tertiary medical center. Sarcopenia was determined as L3SMI, lower than 53 cm(2)/m(2) in men and 41 cm(2)/m(2) in women. Clinical and mortality data was collected from the medical record. Results: Of the 187 patients recruited (mean age 70.4 +/- 9.2, 59% males), 116 (62%) had Sarcopenia, based on L3SMI values. Sarcopenic patients were older, predominantly male, had lower BMI, lower mid-arm muscle circumference (MAMC) and low ALT values upon admission. L3SMI values significantly correlated with age and MAMC among males (R = -0.38, p < 0.001, R = 0.35, p < 0.001, respectively). Sarcopenia was associated with higher, one-year mortality (HR = 2.60, 95% CI 1.06-6.37, p = 0.036) and shorter all-time survival (HR = 2.91, 95% CI 1.35-6.29, p = 0.007). The association with all-time survival remained after adjusting for age and sex (HR = 2.38, 95% CI 1.07-5.29, p = 0.034). Conclusion: As defined by low L3SMI value, Sarcopenia is a poor prognostic factor for the general internal ward patient population. As part of personalized medicine, physicians may benefit from measuring L3SMI value, as indicated by commonly performed CT scans, to objectively assess their patient's risk of suffering from Sarcopenia and frailty-associated complications.