我国成人适宜体重指数切点的前瞻性研究

目的 分析我国成人队列基线体重指数（BMI）和随访期间总死亡率以及心血管病发病率的关系。为超重和肥胖的切点提供验证。方法 汇总我国现有队列人群的前瞻性研究数据。分析按BMI分层的年龄调整总死亡率，以显示基线BMI和总死亡的关系。以方差倒数加权平均方法求出在控制其他危险因素后BMI对于冠心病和脑卒中发病的综合Cox回归系数，以分析BMI对于冠心病和脑卒中发病是否有独立的作用以及其作用强度。结果 汇总分析4组队列人群共76227人，合计随访745346人年，结果表明，按BMI分层的年龄调整总死亡率呈“U”形曲线，在除外随访前3年内死亡之后和仅在不吸烟者，这种“U”形关系仍然存在，在BMI18.5以下和28以上死亡率升高，Cox回归分析结果显示BMI对于冠心病和脑卒中发病有独立于其他危险因素的作用，BMI每增加2kg/m^2，冠心病，总脑卒中和缺血型卒中发病的相对危险分别增高15.4%,6.1%和18.8%，将BMI控制在24以下男性可能减少冠心病和缺血型卒中发病11%和15%，女性可能减少二者发病各22%。结论 在中国成年人群以BMI18.5为体重过低，28为肥胖切点是适宜的。

Prospective study for cut-off points of body mass index in Chinese adults

OBJECTIVE: To verify the optimal cut-off point for overweight and obesity in Chinese adults based on the relationship of body mass index (BMI) to all-cause mortality and incidence of coronary heart disease (CHD) and stroke from pooled data of Chinese cohorts. METHODS: Pooling the data of four Chinese cohorts, to analyze the age-adjusted all-cause mortality by strata of BMI, and to repeat the analyses after excluding deaths within the first three years of follow-up and after excluding the smokers. Analyzing the age-adjusted incidence of CHD and stroke by strata of BMI. Pooling the Cox regression coefficients of BMI to incidence of CHD or stroke of different cohorts using the method of weighting by inverse of variance. RESULTS: All together 76,227 people from 4 cohorts were enrolled, with 745,346 person-year of follow-up. All-cause mortality by strata of BMI showed a U shaped curve, even after excluding deaths from the first three years and the smokers. Age-adjusted all-cause mortality increased when BMI was lower than 18.5 and higher than 28. Incidence rates of CHD and stroke increased when the level of BMI was increasing. Results of Cox regression showed that BMI was an independent risk factor for both CHD and stroke. Each amount of 2 kg/m(2) increase in baseline BMI might cause 15.4%, 6.1% and 18.8% in incidence of CHD, stroke and ischaemic stroke. Reduction of increased BMI to the level of under 24 might prevent incidence of CHD by 11% and that of stroke by 15% for men and 22% CHD and stroke for women in the population. CONCLUSION: Attempt to define the levels of BMI < 18.5 for underweight, 24 to 27.9 for overweight and > or = 28 for obesity seemed to be appropriate cut-off points for Chinese adults.