50岁以上男性体质量指数、体质成分、骨密度的变化特征及其相关性分析

Relationship among aging,body composition,body mass index,and bone mass density in elderly men over 50-year-old

目的探讨50岁以上老年男性随增龄,体质成分(body composition)、体质量指数(body mass index,BMI)和骨密度(bone mineral density,BMD)的变化趋势及其相互关系。方法分析中国人民解放军总医院2009-2011年度门诊358例50岁以上老年男性患者的体质成分及BMD测定资料,根据年龄和BMI分组,比较各年龄组间体质成分的差别,分析体质成分的变化对BMD的影响。结果 (1)该人群身高、体质量随增龄而降低(P=0.000),但BMI各组间差异无统计学意义(P>0.05);瘦体质量指数(lean mass index,LMI)及非脂肪体质量指数(fat free mass index,FFMI)随增龄而下降(P均=0.000),而脂肪体质量指数(fat mass index,FMI)随增龄而增加(P=0.015);骨矿含量(bone mass content,BMC)及瘦体质量(lean mass,LM)的绝对值随增龄而降低(P=0.003,P=0.000),而脂肪含量(fat mass,FM)各年龄组间差异无统计学意义(P>0.05);从体质成分比例上看,随增龄%FM升高,而%LM降低(P均=0.000)。(2)随增龄股骨颈(femoral neck,FN)和全髋骨(total hip,TH)BMD降低(P=0.000,P=0.003),而腰椎1-4(L1-4)BMD无明显变化。(3)按BMI分组,随着BMI增加,各部位BMD增高(P均<0.01),而骨质疏松症及骨量减少的检出率相应减少(P均<0.01)。(4)将20≤BMI<24 kg/m2设为1,以骨质疏松症检出率为结局,采用回归分析,提示BMI降低是骨量减少及骨质疏松症的独立危险因素,BMI增加是BMD的保护因素。(5)分别以FMI、LMI和FFMI四分位统计,随FMI增高,L1-4部位BMD增高(P=0.000),而FN和HP的BMD则随着LMI和FFMI的增加而增加(P均=0.000)。结论 50岁以上老年男性,BMI过低更易患骨质疏松症,而体质成分中FMI是腰椎的保护因素,LMI和FFMI是髋部BMD的保护因素。

Objective To investigate the aged-related changes in body composition, body mass index （BMI）, and bone mineral density （BMD）, and to analyze the relationship between body composition and BMD in elderly men over 50-year-old. Methods The present study was a retrospective analysis of the body composition, BMI, and BMD of 358 Chinese male outpatients over 50 years of age who were recruited from our hospital between 2009 and 2011. Qualified subjects were stratified according to age and BMI. To compare the differences of body composition among different groups, and to analyze the impact of BMD according to the changes of body composition. Results Although there were no significant differences in BMI among the age groups, there was a significant decline in height and weight according to age （ both P=0.000）. The LMI （Lean mass index） and FFMI （Fat free mass index） also declined with age （both P = 0.000） whereas the FMI increased （ P = 0.015 ）. Although the absolute values of BMC and LM declined with age （P=0.003 and P=0.000, respectively）, there was no significant difference in FM. There was an increase in%FM （P=0.000） and a decrease in % LM （P= 0.000） with age. The femoral neck （FN） and total hip （TH） BMD significantly declined with age （P= 0.000 and P=0.003, respectively）. BMD increased at all sites （all P〈0.01） as BMI increased but there were declines in the detection rates of osteoporosis and osteopenia （both P= 0.000）. Logistic regression revealed that a decline in BMI was an independent risk factor of osteoporosis or osteopenia, while an increase in BMI was a protective factor for BMD. At the same time, BMD in L1.4 exhibited a significant positive correlation with FMI （P=0.000） and the femoral neck and total hip BMDs had significant positive correlation with FFMI and LMI, respectively （both P=0.000）. Conclusion These data indicated that in elderly males older than 50 years, an increased BMI was protective for BMD while FMI were protective for BMD in L1-4, LMI and FFMI were protective for BMD in the femoral neck and total hip.