定量CT参数联合血生化指标对体检肺气肿人群骨密度的评估

Assessment of bone mineral density in persons with radiographic emphysema using quantitative CT and serum biochemical parameters

目的:搜集在健康体检中CT发现的肺气肿患者,探讨肺气肿分型及程度、血生化指标、定量CT(QCT)参数与骨密度(BMD)的关系,并建立BMD的评估模型。方法:276例体检胸部CT发现的肺气肿患者(肺气肿组)被分为BMD正常组与异常组,按性别和年龄1:1匹配体检CT未发现肺气肿的健康受试者(对照组)。比较肺气肿组与对照组、肺气肿组中BMD正常组与异常组之间的一般资料、血生化指标及QCT参数的差异,评估BMD与肺气肿分型及程度的关系,利用Logistic回归分析肺气肿人群BMD异常的危险因素,并建立预测模型。结果:与对照组相比,肺气肿组患者的体质指数(BMI)(P<0.001)、BMD(P=0.001)和内脏脂肪面积(P=0.004)较低,而骨骼肌面积(SMA)(P=0.022)较高、总胆固醇(TC)(P=0.012)、高密度脂蛋白(P<0.001)及白蛋白(P=0.009)均较低。肺气肿人群中BMD异常组的BMI低于BMD正常组(P=0.001)。BMD异常组的肺气肿程度(LAA%)显著高于BMD正常组(P<0.001),且与BMD呈负相关(r=-0.283;P<0.001),而其分型在两组间的差异无统计学意义(P=0.506)。除各脂肪面积及空腹血糖外,余QCT参数和血生化指标在两组间的差异均有统计学意义(P值均<0.05)。年龄(OR=1.087;P<0.001)、TC(OR=1.735;P=0.001)和LAA%(OR=1.056;P=0.023)是BMD异常的危险因素,而BMI(OR=0.885;P=0.042)和SMA(OR=0.992;P=0.015)是其保护因素。基于年龄、TC、LAA%、BMI、SMA建立的预测模型,其ROC曲线下面积为0.806,阈值为0.503时,敏感度为0.742,特异度为0.761。结论:健康体检CT发现肺气肿人群的BMD受LAA%影响,而与肺气肿分型无关。基于年龄、BMI、TC、LAA%和SMA建立的模型能较好地预测肺气肿人群的BMD异常。

Objectives:To investigate the correlation among bone mineral density(BMD)and the subtypes and severity of emphysema,the parameters of serum biochemistry and quantitative CT(QCT)in persons with radiographic emphysema,and to establish the model for BMD evaluation.Methods:276 subjects with radiographic emphysema were divided into normal BMD and low BMD group.An age-and gender-matched control without emphysema for each case was included.The differences of all parameters between cases and controls,and different BMD groups of cases were compared.The correlation among BMD and subtypes and severity of emphysema was analyzed.Logistic regression was used to analyze the risk factors of low BMD in controlled group and to establish the model.Results:For subjects with emphysema,the lower body mass index(BMI)(P<0.001),BMD(P=0.001)and visceral fat area(P=0.004),with higher skeletal muscle area(SMA)(P=0.022),the lower in whom total cholesterol(TC)(P=0.012),high-density lipoprotein cholesterol(P<0.001)and albumin(P=0.009).BMI in low BMD group was slightly lower than that in normal BMD group(P=0.001).Severity of emphysema(LAA%)was significant higher in low BMD group(P<0.001)with a negative correlation with BMD(r=-0.283;P<0.001).There was no significant difference for subtypes of emphysema(P=0.506).Except for all fat area and fasting plasma glucose,there was significant difference of QCT and serum biochemical parameters between two groups(all P<0.05).Age(OR=1.087;P<0.001),TC(OR=1.735;P=0.001)and LAA%(OR=1.056;P=0.023)were risk factors for low BMD,while BMI(OR=0.885;P=0.042)and SMA(OR=0.992;P=0.015)were protective factors.The area under the ROC curve was 0.806.When the threshold value was assigned as 0.503,the sensitivity and the specificity were 0.742 and 0.761,respectively.Conclusions:Severity rather than subtypes of emphysema has effects on BMD significantly.It is of value to predict low BMD in persons with radiographic emphysema based on the model combining age,BMI,TC,LAA%and SMA.