Prediction and Validation of DXA‐Derived Appendicular Fat‐Free Adipose Tissue by a Single Ultrasound Image of the Forearm in Japanese Older Adults. (4th August 2017) - Abe, Takashi
Abstract : Objectives: To develop regression‐based equations for estimating dual‐energy x‐ray absorptiometry (DXA) derived appendicular fat‐free adipose tissue (FFAT) using a single ultrasound image in the forearm, and to investigate the validity of those equations to calculate FFAT‐free appendicular lean mass (aLM‐minus‐FFATappendicular ) in 311 Japanese adults aged 60 to 79 years. Methods: Subjects were randomly separated into two groups: 215 in the model‐development group (91 men and 124 women) and 96 in the cross‐validation group (42 men and 54 women). Appendicular fat mass and aLM were measured by the DXA, and subcutaneous adipose tissue (AT‐forearm) and muscle (MT‐ulna) thicknesses were measured by ultrasound. Appendicular FFAT was calculated based on the results of a previous study (appendicular FFAT = appendicular fat mass/0.85 x 0.15). The aLM was estimated from MT‐ulna using a previously published equation (aLM = 4.89 x MT‐ulna x body height – 9.15). Stepwise linear regression analysis was used to determine predictive models for DXA‐derived appendicular FFAT from AT‐forearm, sex, age, and anthropometrical variables. The best ultrasound prediction equation for estimation of appendicular FFAT was developed and then cross‐validated in a subsample of older adults. Results: There was no significant difference between the DXA‐derived and ultrasound‐predicted aLM‐minus‐FFATappendicular . A strong correlation was observed between the DXA‐derived and ultrasound‐predicted aLM‐minus‐FFATappendicular (r = 0.935, P < .001). Bland‐Altman analysis did not indicate a bias in the prediction of the aLM‐minus‐FFATappendicular for the validation group. Conclusions: Our results indicated that a single ultrasound forearm measurement can be used to accurately estimate DXA‐derived aLM‐minus‐FFATappendicular in Japanese older adults, which may be advantageous for community‐based physical examinations.