Low Skeletal Muscle Area Measured by CT Is Associated with Osteoporosis in Patients on Hemodialysis

Background: There are few studies to address the association of muscle and bone in dialysis patients and most of the previous studies assessed skeletal muscle mass with BIA and DXA. Whereas, we selected abdominal CT scans as assement tools for SMA because of an advantage of guaranteeing high accuracy and reproducibility. Thus, the purpose of this study is to examine the association between SMA measured by abdominal CT and BMD, and to investigate the risk of occurrence of osteoporosis with low measured SMA values. Methods: We included 87 patients who underwent abdominal CT and BMD within 3 months after initial HD date at Daejeon St. Mary’s hospital between January 2018 and September 2021. We used an abdominal CT image exported at the upper endplate of L3 transverse section and SMA was calculated by the open-source software program developed by Samsung Medical center of Korea in 2018. The BMD was measured by DEXA. All patients were divided into four SMA groups according to the interquartile ranges of measured SMA values to compare the impact of SMA groups on the osteoporosis occurrence. Results: The mean SMA in all patients was 122.92 cm2, and significantly higher in men (137.22 ± 26.48) than in women (106.88 ± 22.98). The positively correlated factors with both BMD were Sex(male), BMI, SMA, VFA. In multivariate regression analysis, the independent factor that most significantly affected with each BMD was the SMA (β = 0.314, β = 0.974). The risk for osteoporosis more increased as the subjects belong to the lower SMA groups (Very low SMA group; OR = 40.11, p < 0.001). Conclusion: Low skeletal muscle area assessed by abdominal CT independently increases risk of osteoporosis occurrence in hemodialysis patients.