卫生研究

目的 依据中国现行体质指数(BMI)切点,探讨中国成年人群体脂率的最佳截断值,并与WHO体脂率标准进行比较。方法 于2017年9—12月采用分层多阶段整群抽样法,收集国内四大区(东西南北)共40家医院中46618例体成分测量数据。应用生物电阻抗法测量BMI和体脂率等指标,并以中国肥胖问题工作组制订的BMI切点为标准,绘制ROC曲线寻找适宜的体脂率截断值。通过计算检出率、灵敏度、特异度、kappa值等,比较最佳截断值与WHO体脂率标准评价超重和肥胖的效果。通过偏相关分析、曲线估计、模型回归以探讨体脂率和BMI间的关系。结果研究对象的男女性平均BMI分别为(24.07±3.16)和(23.76±3.38),体脂率男女性分别为(21.57%±9.16%)和(27.65%±9.94%)。通过体脂率判断肥胖的最佳截断值分别为男性27.4%和女性34.3%。最佳截断值与WHO体脂率相比,检出率和灵敏度下降而特异度和诊断一致性相对提高。体脂率法与BMI法诊断肥胖时,差异均有统计学意义(P<0.05)。BMI与体脂率的偏相关系数r=0.637,二次曲线模型比线性模型拟合效果更好。结论 与BMI法相比,体脂率法评价肥胖率的准确度和一致率较差。BMI法会漏诊较多低体重脂肪超标者,尤其是老年男性。

OBJECTIVE To discuss the optimum cut-off of body fat percentage among Chinese adult people according to current BMI cut-off, and compare with WHO standard of body fat percentage. METHODS A cross-sectional survey included plenty of hospitals throughout the country from September to December 2017, a total of 46618 residents' body composition data. BMI and BF% were measured by biological impedance analysis, took BMI established by WGOC as reference standard,and ROC curve analysis was used to determine the optimum BF% cut-off. Comparison between optimum cut-off and WHO standard was made by relevance rate, sensitivity, specificity and kappa index. Partial correlation, curve estimation and regression model were used to discuss the relationship between BMI and BF%. RESULTS The average BMI and BF% was(24.07±3.16) and(21.57±9.16)% in males, and(23.76±3.38) and(27.65±9.94)% in females. The optimum BF% cut-off to evaluate obesity were 27.4% in males, and 34.3% in females. Compared with WHO standard, the optimum BF% cut-off above had a lower relevance rate and sensitivity, and a higher specificity and consistency. There was a statistical difference between BMI and BF% method when diagnosing obesity(P<0.05). The partial correlation index r=0.637, and curvilinear model was much suitable than linear model. CONCLUSION Compared with BMI, BF% had poor accuracy and consistency to predict obesity. BMI method may cause more people to escape diagnosis, especially in aging males.