title: Validating the absolute reliability of a fat free mass estimate equation in hemodialysis patients using near-infrared spectroscopy.
abstract: The assessment of nutritional states using fat free mass (FFM) measured with near-infrared spectroscopy (NIRS) is clinically useful. This measurement should incorporate the patient's post-dialysis weight ("dry weight"), in order to exclude the effects of any change in water mass. We therefore used NIRS to investigate the regression, independent variables, and absolute reliability of FFM in dry weight. The study included 47 outpatients from the hemodialysis unit. Body weight was measured before dialysis, and FFM was measured using NIRS before and after dialysis treatment. Multiple regression analysis was used to estimate the FFM in dry weight as the dependent variable. The measured FFM before dialysis treatment (Mw-FFM), and the difference between measured and dry weight (Mw-Dw) were independent variables. We performed Bland-Altman analysis to detect errors between the statistically estimated FFM and the measured FFM after dialysis treatment. The multiple regression equation to estimate the FFM in dry weight was: Dw-FFM = 0.038 + (0.984 × Mw-FFM) + (-0.571 × [Mw-Dw]); R(2)  = 0.99). There was no systematic bias between the estimated and the measured values of FFM in dry weight. Using NIRS, FFM in dry weight can be calculated by an equation including FFM in measured weight and the difference between the measured weight and the dry weight.
authors: Department of Rehabilitation, Aichi Medical College, Kiyosu City, Aichi, Japan.
authors: Kenichi
authors: http://orcid.org/0000-0002-6498-7161
authors: K
authors: Kono
authors: Department of Rehabilitation, Seirei Christopher University, Hamamatsu City, Shizuoka, Japan.
authors: Yusuke
authors: Y
authors: Nishida
authors: Wellness Center, Nagoya Kyoritsu Hospital, Nagoya City, Aichi, Japan.
authors: Yoshihumi
authors: Y
authors: Moriyama
authors: Hemodialysis Center, Meiko Kyoritsu Clinic, Nagoya City, Aichi, Japan.
authors: Masahiro
authors: M
authors: Taoka
authors: Hemodialysis Center, Meiko Kyoritsu Clinic, Nagoya City, Aichi, Japan.
authors: Takashi
authors: T
authors: Sato
mesh_terms: D000368:Aged; D001823:Body Composition / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D015596:Nutrition Assessment; D009752:Nutritional Status / Q000502:physiology*; D010045:Outpatients; D012044:Regression Analysis; D006435:Renal Dialysis; D015203:Reproducibility of Results; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
keywords: Dry weight; Fat free mass; Hemodialysis; Near-infrared spectroscopy; Reliability