Using Bioelectrical Impedance Analysis For Estimation Of Appendicular Skeletal Muscle Mass In Hemodialysis Patient

Objective:The aims of the current study were to investigate the prevalence of sarcopenia and the application value of the SARC-F scale in screening sarcopenia in chronic kidney disease（CKD）and maintenance hemodialysis（MHD）patients,find out risk factors of sarcopenia and explore the correlation between sarcopenia and osteoporosis in MHD patients,futher to develope a predictive equation（PE）by using bioelectrical impedance analysis（BIA）to evaluate appendicular skeletal muscle mass（ASM）in MHD patients.Methods:1.CKD and MHD patients were enrolled from Ruijin Hospital,Shanghai Jiao Tong University School of Medicine from March 2019 to November 2019 in accordance with inclusive criteria.Based on the diagnostic criteria proposed by the European Working Group on Sarcopenia in Older People met again in 2018（EWGSOP2）,grip strength（GS）was measured by the Jamar dynamometer and ASM was measured by dual energy X-ray absorptiometry（DXA）,and the prevalence of sarcopenia was evaluated.The application value of SARC-F scale in screening sarcopenia was evaluated by calculating the sensitivity and specificity.2.MHD patients receiving treatment in our center from March 2019 to November 2019were included.Laboratory measurement results,clinical data,dialysis prescriptions and medication regimen were collected during enrollment period.Multivariate logistic regression was used to explore the risk factors of sarcopenia in MHD patients.And the relationship between sarcopenia and osteoporosis was analyzed.3.Multi-frequency bioelectrical impedance analysis（MF-BIA）was performed on selected MHD patients to obtain human body composition and electrical impedance results.ASM measured by DXA was used as the reference standard,and stepwise multiple linear regression was employed to establish a PE to estimate the ASM in MHD patients.Bland-Altman analysis and root mean square error（RMSE）were used to evaluate the consistency of ASM between published BIA prediction equations（PEs）and DXA.Finally,using the ROC curve analysis and calculating the specificity and sensitivity of each prediction equation to test the efficacy of diagnosing low appendicular skeletal muscle mass index（ASMI）using DXA as the reference.Results:1.In total,105 CKD patients and 125 MHD patients were enrolled in the study,and the prevalence of sarcopenia were 5.7%and 31.2%,respectively.Among them,there were21（16.8%）MHD patients with severe sarcopenia and no CKD patients with severe sarcopenia.Compared with CKD,the risk of sarcopenia in MHD was increased（OR=7.48,95%CI:3.02-18.53）and decreased after age adjustment（OR=5.34,95%CI:2.09-13.63）.The specificity of SARC-F scale in CKD,MHD,MHD patients younger than 65years old and MHD patients not less than 65 years old were 98.0%,89.5%,98.2%and74.2%,respectively,and the sensitivity were 16.7%,48.7%,45.5%and 50%,respectively.2.A total of 125 MHD patients were enrolled,and 39 of them were suffering from sarcopenia.Compared with those without sarcopenia,patients with sarcopenia were older（69 years vs 56 years,p<0.001）,having higher TNF-α（15.4 pg/m L vs 13.2 pg/m L,p=0.025）and v WF（206.59±22.86%vs 179.61±32.27%,p<0.001）and lower pre-ALB（249.0 mg/L vs 276.5 mg/L,p=0.008）,ALB（34.31±3.42 g/L vs 36.06±3.57 g/L,p=0.011）,exercise frequency（12（30.8%）vs 58（67.4%）,p<0.001）and CO₂（21.60±2.58 mmol/L vs23.40±2.58 mmol/L）,P<0.001).Multivariate logistic analysis showed that CO₂（OR=0.717,95%CI:0.576-0.892,p=0.003）,v WF（OR=1.037,95%CI:1.016-1.058,p<0.001）and exercise frequency（OR=0.309,95%CI:0.118-0.810,p=0.017）were independently associated with sarcopenia in MHD patients.Correlation analysis indicated that there were positive correlations between bone mineral density T score（BMDTs）and skeletal muscle mass（r=0.52,p<0.001）or skeletal muscle strength（r=0.54,p<0.001）in MHD patients.3.A total of 102 MHD patients were enrolled,and the following BIA PE was established to estimate ASM in MHD patients:ASM（kg）=24.884+（0.292×Ht²/Z50）+（-24.520×Z250/Z5）+（0.043×Dry weight）+（-3221.333×1/Z50）+(0.999×sex（men=1,women=0）.In addition,we compared four published BIA PEs,including Peniche,Kim,Yoshida and Yamada equations,The ASM estimated by BIA PEs(ASM_PEs)had strong correlations with the ASM measured by DXA(ASM_DXA)（r>0.90）.However,by Bland-Altman analysis and RMSE,the bias was large and degree of fitting was poor,with the bias of（1.64±2.01）kg,（-3.51±1.91）kg,（4.12±2.01）kg and（4.80±2.53）kg and RMSE of 2.59kg,3.99 kg,4.58 kg and 5.42 kg,respectively.ROC curve analysis showed that the areas under the curves（AUC）of the four published BIA PEs were smaller than the newly created PE.By calculating the sensitivity and specificity,the newly created PE showed moderate to high consistency with DXA in the diagnosis of low ASMI,and the Kappa values of men and women were 0.478 and 0.570,respectively.Conclusion:1.The prevalence of sarcopenia in CKD and MHD patients was high,especially in MHD patients.The SARC-F scale had low sensitivity but high specificity and low misdiagnosis rate in the diagnosis of sarcopenia among CKD and MHD,and it can be used for rapid and simple clinical initial diagnosis of sarcopenia.The follow-up objective indicators can be measured to confirm sarcopenia of the patients with the SARC-F scale≥4 points,which can realize the optimal combination diagnosis.2.Reduced activity,metabolic acidosis,and inflammation status were independent risk factors of sarcopenia and there was a positive correlation between sarcopenia and BMDTs in MHD patients.In the future,further follow-up of this population will be necessary to observe whether it is related to the risk of falls and poor prognosis,and to find a new direction of intervention in the treatment of sarcopenia.3.BIA is a simple and feasible method to evaluate ASM.The published BIA PEs were not applicable to the MHD patients in our center.In this study,a newly BIA PE was established to evaluate ASM in MHD patients,however,large sample sizes of MHD population are needed for further verification and looking for a BIA PE which is suitable for the MHD patients in China.