DXA腰椎和股骨局部脂肪测量推算全身脂肪含量的研究

Assessment of total body fat percentage from regional spine and femur DXA measurements

目的探讨DXA测量正位腰椎、股骨局部脂肪含量评估腹部、髋部和全身脂肪含量的可行性。方法成年受试者共833例，其中男性203人，女性630人。所有受试者分为两组：回归方程组和验证组。采用双能X线骨密度仪测量所有受试者全身、腹部Android区域（A区）、髋部Gynoid区域（G区）、正位腰椎（L1～L4）和双侧股骨的脂肪体重百分比（％fat）。回归方程组受试者按性别分组，分析正位腰椎和双侧股骨％fat与A区、G区和全身％fat的相关性，并建立局部％fat与A区、G区和全身％fat的多元线性回归方程。验证组受试者实际测量值用来验证回归方程的准确性。结果①男、女性正位腰椎和双侧股骨的％fat与A区％fat、G区％fat和TBF％之间均具有显著正相关（r=0．72～0．94，P〈0．001）。②腰椎、股骨、年龄和BMI的共同作用对全身％fat的预测贡献最大（男性R^2=0．88，女性R^2=0．84）。③根据多元线性回归方程从正位腰椎、股骨局部％fat得到的男、女性A区％fat、G区％fat和TBF％的预测值和实测值之间具有显著正相关（r=0．72～0．96，P〈0．001）。结论可以根据DXA腰椎和股骨局部脂肪测量评估腹部、髋部和全身的脂肪含量。

Objective This study was aimed to investigate the correlation between regional body composition and total body fat percentage, as measured by dual-energy X-ray absorptiometry （DXA）. Methods Men （ n = 203） and women （n = 630）, aged 20-87 yr, were assessed for height, weight, and body mass index （BMI） and for total body, lumbar spine （ L1 - L4 ）, and left and right proximal femur fat percentage （ % fat） using DXA. All subjects were subdivided randomly into 2 groups： regression equation group and checking group. Subjects in regression equation group were used to 1 ）analyze the correlation between spine % fat, the left and right femur% fat and total body%fat, 2）establish the multiple linear regression equation. Subjects in checking group were used to verify the accuracy of the equation. Results 1 ） For all subjects, the total body % fat derived from the total body scan was strongly correlated with spine%fat and the left and right femur%fat （ r ： 0.72 - 0.94, P 〈 0.001 ）, as obtained from regional scans. 2） In stepwise regression, total body% fat was best assessed by spine% fat, left femur% fat, age, and BMI for both genders （ male ： R^2 = 0.88 ; female R^2 = 0.84） . 5 ） The accuracy of all prediction equations was high in both males and females. Conclusion Clinicians can assess total body% fat using data obtained from DXA regional scans.