Muscle mass evaluation using psoas muscle mass index by computed tomography imaging in hemodialysis patients.

BACKGROUND AND AIMS: The use of the psoas muscle mass index (PMI) using computed tomography (CT) has become a marker of interest to evaluate whole body muscle mass. However, in hemodialysis (HD) patients, reports about the clinical significance of psoas muscle evaluation are limited. We aimed to clarify the association between PMI and skeletal muscle mass index (SMI) using bioelectrical impedance analysis (BIA), and to investigate factors affecting PMI in HD patients. METHODS: In this prospective observational study, to evaluate muscle mass, SMI was measured using BIA after HD, and PMI was measured by the manual trace method on routinely available CT scans. PMI measurement was assessed twice by two physicians to compute intra-rater and inter-rater reliability. The correlations between PMI and the clinical factors were evaluated using Pearson's correlation coefficient and a linear regression analysis. Variables with a p-value < 0.05 in the simple linear regression analysis were included in the multivariable linear regression analysis to identify the factors that affected PMI of the HD patients. RESULTS: Fifty HD patients were recruited (31 males and 19 females; HD duration, 9.0 ± 8.8 years). The SMI was 6.10 ± 1.20 kg/m2, and the PMI was 4.79 ± 1.61 cm2/m2. Regarding the reliability of PMI measurements, intra-rater reliability [intra-class correlation (ICC) = 0.999] and inter-rater reliability (ICC = 0.998) were high in this study. The mean PMI of male patients was 5.40 ± 1.62 cm2/m2, while that of female patients was significantly lower (3.78 ± 0.98 cm2/m2; p < 0.001). The PMI was significantly and positively correlated with SMI (r = 0.630, p < 0.001), in addition to HD duration, body mass index (BMI), serum phosphate and serum creatinine (Cr). In the multivariate linear regression analysis by two models using SMI or BMI, they were respectively extracted as an independent factor associating with PMI, in addition to serum Cr and the difference of sex. CONCLUSIONS: PMI assessed with CT positively correlated with SMI measured using BIA. PMI might be one of the methods for evaluating the muscle mass in HD patients, when CT scans are taken as part of routine care.

Skeletal Muscle Mass Index Is Positively Associated With Bone Mineral Density in Hemodialysis Patients.

Background: Patients with chronic kidney disease (CKD) are at risk for bone loss and sarcopenia because of associated mineral and bone disorders (MBD), malnutrition, and chronic inflammation. Both osteoporosis and sarcopenia are associated with a poor prognosis; however, few studies have evaluated the relationship between muscle mass and bone mineral density (BMD) in hemodialysis (HD) patients. The present study examined the association between skeletal muscle mass index (SMI) and BMD in the lumbar spine and femoral neck in HD patients. Methods: Fifty HD patients (mean age, 69 ± 10 years; mean HD duration, 9.0 ± 8.8 years) in Minami-Uonuma City Hospital were evaluated. BMD was measured by dual-energy X-ray absorptiometry, and SMI was measured by bioelectrical impedance analysis (InBodyTM) after HD. The factors affecting lumbar spine and femoral neck BMD were investigated, and multivariate analysis was performed. Results: In simple linear regression analysis, the factors that significantly affected the lumbar spine BMD were sex, presence of hypertension, presence of diabetes mellitus, body mass index, triglyceride level, grip strength, and SMI; the factors that significantly affected the femoral neck BMD were sex, HD duration, serum creatinine level, tartrate-resistant acid phosphatase 5b level, undercarboxylated osteocalcin (ucOC) level, N-terminal propeptide of type I procollagen level, grip strength, and SMI. In multivariate analysis, SMI (standardized coefficient: 0.578) was the only independent factor that affected the lumbar spine BMD; the independent factors that affected the femoral neck BMD were SMI (standardized coefficient: 0.468), ucOC (standardized coefficient: -0.366) and sex (standardized coefficient: 0.231). Conclusion: SMI was independently associated with the BMD in the lumbar spine and femoral neck in HD patients. The preservation of skeletal muscle mass could be important to prevent BMD decrease in HD patients, in addition to the management of CKD-MBD.