Goran M I, Toth M J, Poehlman E T
Department of Nutrition Sciences, University of Alabama at Birmingham 35294, USA.
J Am Geriatr Soc. 1997 Jul;45(7):837-43. doi: 10.1111/j.1532-5415.1997.tb01511.x.
To cross-validate existing equations in the literature for their accuracy and precision for estimating body fat in older people from anthropometric measures and height2/resistance, using the 4-compartment model as a criteria method, and to propose new practical equations with improved accuracy and precision.
Measurement of body composition in a cross-sectional cohort of healthy men and women and comparison by cross-validation techniques against existing prediction equations.
The study was performed on subjects admitted to a General Clinical Research Center.
The subjects were 41 healthy women (68.2 +/- 6.6 years; 64.1 +/- 10.2 kg) and 41 healthy men (70.2 +/- 7.0 years; 74.9 +/- 11.0 kg).
The criteria method for total body composition was the 4-compartment model based on measurement of total body density by underwater weight, total body water by isotope dilution, and total bone mineral from dual energy X-ray absorptiometry. The other techniques examined for accuracy and validity were body fat estimates derived by skinfolds using the Durnin and Womersley Equations; waist circumference and age using the Lean Equations; and bio-electrical resistance using five published equations, including two derived in the older population.
When compared with data derived from the 4-compartment model, the skinfold equation of Durnin and Womersley was cross-validated successfully in women but not in men. The Baumgartner equation was the only bioelectrical resistance equation that met the criteria for successful cross-validation in men and women, although in women the intercept (4.0 +/- 2.1 kg) was close to significantly different from zero (P = .06). Error in the estimates of body fat using the Durnin and Womersley and the Baumgartner equations was significantly and inversely related to fat mass (r = -.39 to r = -.56). In our data, the significant predictors of fat mass were hip circumference, calf skinfold, gender, body weight, height2/resistance, and biceps skinfold, explaining 84% of the variance.
The Durnin and Womersley equation is accurate for women and the Baumgartner equation is accurate for both men and women if a correction of +4 kg is made in women; however, for both equations the error in the estimate is inversely related to fat mass. We suggest new anthropometric equations for estimating body fat in older people, which may improve accuracy and precision. The new equations will need to be tested in independent cross-validation studies.
以四室模型作为标准方法，交叉验证文献中现有的通过人体测量指标和身高²/电阻来估算老年人身体脂肪的方程的准确性和精确性，并提出准确性和精确性更高的实用新方程。
对健康男性和女性的横断面队列进行身体成分测量，并通过交叉验证技术与现有的预测方程进行比较。
研究在一家综合临床研究中心收治的受试者中进行。
受试者为41名健康女性（68.2±6.6岁；64.1±10.2千克）和41名健康男性（70.2±7.0岁；74.9±11.0千克）。
全身成分的标准方法是四室模型，该模型基于水下称重测量全身密度、通过同位素稀释测量全身水含量以及通过双能X线吸收法测量总骨矿物质。检查准确性和有效性的其他技术包括使用杜宁和沃姆斯利方程通过皮褶厚度估算体脂；使用利恩方程通过腰围和年龄估算体脂；以及使用五个已发表的方程通过生物电阻抗估算体脂，其中两个方程是在老年人群中推导得出的。
与四室模型得出的数据相比，杜宁和沃姆斯利的皮褶厚度方程在女性中成功进行了交叉验证，但在男性中未成功。鲍姆加特纳方程是唯一在男性和女性中都符合成功交叉验证标准的生物电阻抗方程，不过在女性中，截距（4.0±2.1千克）接近显著异于零（P = 0.06）。使用杜宁和沃姆斯利方程以及鲍姆加特纳方程估算体脂的误差与脂肪量显著负相关（r = -0.39至r = -0.56）。在我们的数据中，脂肪量的显著预测因素是臀围、小腿皮褶厚度、性别、体重、身高²/电阻以及肱二头肌皮褶厚度，可解释84%的方差。
杜宁和沃姆斯利方程对女性准确，鲍姆加特纳方程对男性和女性均准确，前提是女性需加上4千克的校正值；然而，对于这两个方程，估算误差均与脂肪量负相关。我们提出了用于估算老年人身体脂肪的新人体测量方程，这可能会提高准确性和精确性。新方程需要在独立的交叉验证研究中进行测试。
