Department of Health Science & Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
Center for Nutrition and Bowel Disease, Department of Gastroenterology and Hepatology, Aalborg University Hospital, Denmark.
Clin Nutr ESPEN. 2021 Jun;43:522-531. doi: 10.1016/j.clnesp.2021.01.040. Epub 2021 Feb 9.
BACKGROUND & AIMS: Assessment of body composition is an important aspect of disease management in patients with intestinal insufficiency (INS) or intestinal failure (IF). However, in daily clinical settings most body composition methods are too expensive or impractical, leaving body composition to be assessed by less reliable methods such as skin fold thickness. The aim of this study was to investigate and validate the use of an equation for the estimation of fat-free mass (FFM) with bioelectrical impedance analysis (BIA) as reference method.
A literature search for identification of urinary creatinine-based FFM-prediction equations was carried out a long side the creation of an equation by multiple linear regression. The correlation of each equation with FFM (measured by BIA in 277 patients with either INS or IF) was done by Pearson's correlation. Further investigation and validation of performance was done for the equations with the strongest correlation by Bland-Altman analysis, determination of root mean square error (RMSE), and intraclass correlation (ICC). The validation was carried out in a new group of 37 patients with either INS or IF.
A total of 11 prediction equations were correlated with FFM measured by BIA. The equation called FFMmultiple and FFM-5 had the strongest correlation (r = 0.969, p < 0.01 and r = 0.950, p < 0.01, respectively). FFMmultiple was superior to FFM-5 regarding Bland-Altman analysis, RMSE, and ICC in the study group (Mean bias ± Standard Deviation = 0.042 ± 2.352 versus 0.309 ± 3.196; 95% limits of agreement = [-4.568; 4.651] versus [-5.955; 6.578]; RMSE = 0.158 versus 0.236; ICC = 0.969 versus 0.948). Cross-validation resulted in a Bland-Altman analysis with a statistically significant difference between FFMmultiple and FFM by BIA. FFM-5 showed wide 95% limits of agreement ([-6.977; 6.421]).
Two urinary creatinine-based equations (FFMmultiple and FFM-5) showed promising results as possible substitutes to BIA, however further investigation and cross validation revealed inauspicious results. Thus, the present study cannot recommend the use of a prediction equation instead of BIA for the assessment of FFM in patients with INS and IF.
评估身体成分是肠功能不全（INS）或肠衰竭（IF）患者疾病管理的重要方面。然而，在日常临床环境中，大多数身体成分方法过于昂贵或不切实际，导致身体成分只能通过皮肤褶皱厚度等不太可靠的方法进行评估。本研究旨在探讨并验证使用生物电阻抗分析（BIA）作为参考方法的基于尿肌酐的去脂体重（FFM）估计方程的适用性。
通过多元线性回归创建方程的同时，进行了文献检索以确定基于尿肌酐的 FFM 预测方程。通过 Pearson 相关分析，将每个方程与通过 BIA 测量的 277 例 INS 或 IF 患者的 FFM 进行相关性分析。通过 Bland-Altman 分析、均方根误差（RMSE）和组内相关系数（ICC），对相关性最强的方程进行进一步研究和验证。在另一组新的 INS 或 IF 患者中进行验证。
共有 11 个预测方程与 BIA 测量的 FFM 相关。FFMmultiple 和 FFM-5 方程与 FFM 的相关性最强（r = 0.969，p < 0.01 和 r = 0.950，p < 0.01）。在研究组中，FFMmultiple 在 Bland-Altman 分析、RMSE 和 ICC 方面优于 FFM-5（平均偏差 ±标准差= 0.042 ± 2.352 与 0.309 ± 3.196；95% 一致性范围= [-4.568; 4.651] 与 [-5.955; 6.578]；RMSE = 0.158 与 0.236；ICC = 0.969 与 0.948）。交叉验证导致 FFMmultiple 和 BIA 之间的 Bland-Altman 分析存在统计学差异。FFM-5 的 95% 一致性范围较宽（[-6.977; 6.421]）。
两种基于尿肌酐的方程（FFMmultiple 和 FFM-5）作为 BIA 的替代方法具有良好的效果，但进一步的研究和交叉验证显示出不理想的结果。因此，本研究不建议在 INS 和 IF 患者中使用预测方程代替 BIA 来评估 FFM。
