Effect of body mass index on bone mineral density is age-specific

Background and aimsObesity and osteoporosis are two important and growing public health problems worldwide. Body mass index (BMI) has been found to be inversely related to the risk of osteoporotic fracture. We aimed to assess the association of BMI with thoracic vertebral bone mineral density (BMD) measured from a quantitative computed tomography (QCT).Methods and resultsWe retrospectively evaluated the data from 15,758 consecutive patients (5675 females and 10,083 males) between age 20–90 years, who underwent Coronary Artery Calcium (CAC) scoring. Quantitative data analyses of thoracic trabecular BMD (mg/cm³) was performed with a phantom system or phantomless using validated software. The gender-specific subgroup was divided based on age (<45, 45–55, 55–65, >65 yrs in females; <40,40–60,>60 yrs in Males) and weight by BMI (kg/m²) as < 25 (normal or low weight), >25 - <30 (overweight) and >30 (obesity). Analysis of variance (ANOVA) and Scheffe's post hoc procedure tested the association of body weight/BMI on BMD. A significant positive association between the body weight and BMD existed in obese population in elder groups in both genders (p < 0.05). There was no significant difference in BMD in 40–60 years in men and <55 years in women with normal or low weight compared to overweight or obese cohorts.ConclusionsWe concluded that the effect of weight on BMD is age-specific and the BMD should be monitored routinely with a cardiac CT scan in the senile population.     

体重、体重指数对健康绝经后妇女骨密度的影响

目的探讨体重和体重指数（BMI）对健康绝经后妇女骨密度（BMD）的影响。方法采用双能X线骨密度仪测量591例健康绝经后女性不同部位的BMD，按BMI不同分为低体重组、正常体重组和肥胖组进行分析。结果各部位的BMD随BMI的增加而增高（P〈0．01）。BMD随年龄的增长而降低（P〈0．01）。肥胖组各部位BMD均比正常体重组和低体重组高（P〈0．05或P〈0．01）。年龄和体重是决定BMD变异的主要因素，年龄与BMD呈负相关，体重与BMD呈正相关，绝经年龄与腰椎正位BMD呈正相关；BMI与BMD无相关性。结论体重是影响绝经后妇女BMD的重要因素。对低体重的绝经后妇女定期监测BMD，有助于早期干预。     

降压药对老年女性高血压患者骨密度的影响

目的 探讨目前常用降压药对老年女性高血压患者骨密度（bone mineral density,BMD）的影响.方法 回顾性分析,同济大学附属同济医院在2007年-2009年间收治的512例60～85岁患者的BMD.其中高血压患者378例,非高血压者134例.高血压患者分为5组：噻嗪类利尿剂组63例,钙通道阻滞剂组（calcium-channel blocker,CCB）113例,血管紧张素转换酶抑制剂（angiotensin converting enzyme inhibitor,ACEI）和血管紧张素Ⅱ受体拈抗剂组（angiotensinⅡreceptorblocker,ARB）92例,联合用药组56例,高血压未用药组（54例）.采用美国Lunar公司生产的DEXA骨密度测量仪,测定非优势侧股骨近端Femur Neck、Troch、Ward＇s 三角和L1～4的BMD.结果 非高血压组与其他各组相比腰椎的BMD最低.非高血压组LIBMD值与ACEI/ARB组和高血压未用药组相比差异有统计学意义（P〈0.05、P〈0.05）.非高血压组L2、L3、L4、Neck、Troch的BMD与ACEI/ARB组相比差异有统计学意义（P〈0.05）.高血压患者各组问腰椎与髋部BMD差异均无统计学意义.结论 ACEI/ARB降压药可能对老年女性高血压患者的BMD有一定的保护作用.年龄对BMD有一定的影响且为负性作用,而BMI与BMD有正相关性.     

Association of bone mineral density and body mass index in a cohort of Pakistanis: Relation to gender,menopause and ethnicity

Aim of the work

To assess association of body mass index (BMI) with bone mineral density (BMD) in a sample of Pakistanis and explore their relation with age, gender, menopausal status and ethnicity.

Bone metabolism and bone mineral density of systemic lupus erythematosus at the time of diagnosis

Recent studies have shown that systemic lupus erythematosus (SLE) is associated with a loss of trabecular bone. However, these changes have not been not described in patients with SLE at the time of diagnosis. To investigate the markers of bone metabolism 20 female patients with a recently manifested clinical picture of SLE were selected. All patients included in this study met the ARA criteria (for classification) of SLE. For comparison, 35 female patients with SLE, which had previously manifested itself and which had been treated with glucocorticoids, were included in a second group. A control group (III) consisting of 20 healthy individuals of the same age was formed to compare the results obtained. Test parameters comprised both serum levels of osteocalcin (OC) as the marker for bone formation and crosslinks excretion (CE) in urine as a specific marker for bone resorption. The bone density (BMD) was examined by dual energy X-ray absorption (DEXA) of the vertebral column (L2–L4), femoral neck, Ward's triangle and trochanter. The patients under study received either no medication or nonsteroidal antirheumatic drugs. The BMD of the vertebral column was significantly lower than expected in SLE-afflicted subjects of group II when compared with the age-matched normal female controls. The reduction of BMD in female patients with SLE was related to the significantly increased excretion of urinary pyridinoline, to hypoparathyroidism, and to the decrease in serum OC. Bone loss in women with fresh manifestation of SLE (I) increases to a degree similar to that of patients in group II. Lowered BMD predicts an increased risk for bone fractures. Therefore, female premenopausal SLE patients should be monitored for osteoporosis. Received: 10 June 1998 / Accepted: 11 December 1998     

Risks factors for low bone mineral density in pre-menopausal Mexican women with systemic lupus erythematosus

The aim of this study was to determine the prevalence and risk factors for low bone mineral density (BMD) in women with systemic lupus erythematosus (SLE). A cross-sectional study was conducted among 100 pre-menopausal patients with SLE. Patients were evaluated using a questionnaire about the following variables: age, disease duration, disease activity, chronic disease damage, cumulative corticosteroid dose, and history of fracture. Lumbar spine and hip measurements of BMD were performed by dual absorptiometry. Univariate and multivariate statistical analyses were used to assess the relationship between risk factors and BMD. The mean age was 32.8 ± 8.7 years, and the median duration of SLE was 73.2 ± 65 months. The mean cumulative corticosteroid dose was 20.0 ± 21.3 g. The mean BMD was 1.09 ± .18 g/cm² in the lumbar spine and 1.0 ± .14 g/cm² in the hip. Osteopenia was present in 40% of patients and osteoporosis in 5%. In the multiple regression analysis, low BMD in the lumbar spine was associated with chronic disease damage and low body mass index (BMI). Low BMD in the hip was associated with cumulative corticosteroid dose and low BMI. Chronic disease damage, low BMI, and cumulative corticosteroid dose are risks factors for low BMD in pre-menopausal SLE patients. Osteopenia was found in 40% of patients, while osteoporosis was found in only 5%.     

绝经后女性骨密度与心血管疾病的关系

骨密度是评价骨量变化、预测骨质疏松骨折风险的最佳指标。骨组织受性激素调节,绝经后女性雌激素水平与骨密度下降及心血管疾病风险增加密切相关。但是,骨密度能否预测心血管疾病的风险,以及这一作用是否与内源性的雌激素相关尚无定论。本文对此方面的研究现状作简要介绍。     

Role of bone mineral density in the inverse relationship between body size and aortic calcification: Results from the Baltimore Longitudinal Study of Aging

Objective

There is a J-shaped relationship between body mass index (BMI) and cardiovascular outcomes in elderly patients (obesity paradox). Whether low BMI correlates with aortic calcification (AC) and whether this association is accounted for by bone demineralization is uncertain.

Methods

Presence of AC was evaluated in 687 community-dwelling individuals (49% male, mean age 67 ± 13 years) using CT images of the thoracic, upper and lower abdominal aorta, and scored from 0 to 3 according to number of sites that showed any calcification. Whole-body bone mineral density (BMD) was evaluated by dual-energy X-ray absorptiometry. Predictors of AC were assessed by logistic regression, and the role of BMD using mediation analysis.

Results

Age and cardiovascular risk factors were positively associated while both BMI (r = −0.11, p < 0.01) and BMD (r = −0.17, p < 0.0001) were negatively associated with AC severity. In multivariate models, lower BMI (OR 0.96, 95%CI 0.92–0.99, p = 0.01), older age, higher systolic blood pressure, use of lipid-lowering drugs and smoking were independent predictors of AC. A nonlinear relationship between BMI and AC was noticed (p = 0.03), with decreased AC severity among overweight participants. After adjusting for BMD, the coefficient relating BMI to AC was reduced by 14% and was no longer significant, whereas BMD remained negatively associated with AC (OR 0.82, 95%CI 0.069–0.96, p = 0.01), with a trend for a stronger relationship in older participants.

Conclusion

Low BMI is associated with increased AC, possibly through calcium mobilization from bone, resulting in low BMD. Prevention of weight loss and bone demineralization with aging may help reducing AC.     

Bone mineral density changes in women with systemic lupus erythematosus

The aim of this study was to analyse the heterogeneity of bone mineral density (BMD) reduction across measurement sites in female systemic lupus erythematosus (SLE) patients on glucocorticoid (CS) treatment. The study population consisted of two subgroups: 32 women at a mean (SD) age of 43.2 (12.0) years, SLE duration of 13.4 (6.2) years, treated with a mean cumulative prednisone dose of 34.4 g; and 16 women at a mean age of 36.1 (9.0) years, SLE duration of 3.2 (2.0) years, never treated with glucocorticoids (control group). The participants underwent a standardised interview, medical record review, blood sampling and BMD examination of the lumbar spine, femoral neck and distal forearm by dual-energy X-ray absorptiometry. CS-treated participants were supplemented with daily calcium (1200 mg) and vitamin D (500 UI). During the study mean daily glucocorticoid dose was 10 mg prednisone equivalent. The controls did not receive either corticosteroids or calcium and vitamin D. BMD and laboratory parameters were re-examined at the end of the second year. At baseline 22 (68.7%) of the CS-treated participants had osteoporosis at least at one major site, compared to 18.8% of the controls. The BMD reduction was proportional to the trabecular bone content at the specific measurement site. At baseline mean T scores in the CS-treated group were the highest at the forearm (–1.03 ± 1.13), followed by the hip (–1.32 ± 1.26), AP spine (–1.87 ± 1.46) and lateral spine (–2.90 ± 1.50). At follow-up lateral spine bone loss was 5.54% per year, the total hip and the forearm lost 3.59% and 0.33%, respectively, compared to annual losses of 1.02% (AP spine), 1.30% (lateral spine), 0.83% (total hip) and 0.11% (forearm) in the control group. The heterogeneity of BMD reduction in our SLE population emphasises the need for the targeted use of bone densitometry in steroid-treated patients. Attention should be paid to trabecular-rich sites, and fracture risk should be specifically determined.     

社区人群中外周动脉病与体质量指数相关性的研究

目的:分析上海嘉定社区人群中外周动脉病(PAD)的患病率及其与体质量指数(BMI)的关系。方法:采用整群抽样的方法,选取上海嘉定区40岁以上的社区居民5 435名。所有受试者均接受口服75 g葡萄糖耐量试验(OGTT)、血脂的测定以及踝肱指数(ABI)的检测。将ABI0.05)。BMI正常组、超重组及肥胖组的PAD患病率分别为6.67%、6.83%和12.62%,肥胖组PAD的患病率显著高于BMI正常组以及超重组(均P     

The burden of cardiovascular disease associated with high body mass index in the Asia–Pacific region

Studying obesity in the Asia–Pacific region is difficult because of the diverse ethnic background and different stages of economic and nutrition transition. The burden of cardiovascular disease associated with overweight (defined as body mass index ≥25 kg m^?2) was previously estimated for countries within the region. However, using the conventional cut‐point of 25 kg m^?2 ignores the continuous association between body mass index and cardiovascular disease from approximately 20 kg m^?2. By estimating the proportion of cardiovascular disease that would be prevented if the theoretical mean body mass index in the population was shifted to 21 kg m^?2, nationally representative data from 15 countries suggested the population attributable fractions for cardiovascular disease were approximately three times higher than the previous estimates. Coronary heart disease attributable to body mass index other than 21 kg m^?2 ranged from 2% in India to 58% in American Samoa. Similarly, the population attributable fraction for ischaemic stroke ranged from 3% in India to 64% in American Samoa. If cardiovascular risk increases from 21 kg m^?2 applies to all populations, most countries in the region will need to aim towards substantially reducing their current population mean body mass index in order to lower the burden of cardiovascular disease associated with excess weight.     

Association between muscle mass,bone mineral density and osteoporosis in type 2 diabetes

Aims/IntroductionType 2 diabetes mellitus is associated with an increased incidence of osteoporosis and sarcopenia. However, the relationship between osteoporosis and sarcopenia in patients with type 2 diabetes mellitus remains to be unclear. Appendicular skeletal muscle was adjusted by height (appendicular skeletal muscle mass [ASM]/height²) as a marker of sarcopenia. This study aimed to explore the relationship between ASM/height², osteoporosis and bone mineral density (BMD) in this population.Materials and MethodsA total of 192 women and 225 men with type 2 diabetes mellitus were recruited. General information, laboratory and BMD data were collected. Spearman’s correlation, multiple regression analyses and receiver operating characteristic curve analysis were used to explore the correlation between ASM/height², BMD and bone metabolism markers.ResultsSpearman’s correlation analysis showed that ASM/height² had a positive correlation with serum calcium and BMD (r = 0.209–0.404, P < 0.01). In multivariate regression analysis, we found significant correlations between ASM/height² and total lumbar spine, hip and femur neck BMD. According to the receiver operating characteristic curve, ASM/height² was the best marker of osteoporosis, with a cut‐off value of 7.87 kg/m² for men and 5.94 kg/m² for women. When these cut‐off values were used to identify sarcopenia, the risk of osteoporosis increased 6.036‐fold in men and 4.079‐fold in women, respectively.ConclusionsIn patients with type 2 diabetes mellitus, ASM/height² was positively correlated with BMD, and negatively correlated with osteoporosis.     

Atherosclerosis biomarkers in female systemic lupus erythematosus patients with and without cardiovascular diseases

Background

Cardiovascular diseases (CVD) and atherosclerosis are over presented in patients with systemic lupus erythematosus (SLE).

Response to hydroxychloroquine in Japanese patients with lupus-related skin disease using the cutaneous lupus erythematosus disease area and severity index (CLASI)

Background

Hydroxychloroquine (HCQ) is not available in Japan. To design a clinical trial of HCQ, we evaluated the response to HCQ in Japanese patients with lupus-related skin disease using the cutaneous lupus erythematosus disease area and severity index (CLASI).

Methods

Twenty-seven patients with lupus-related skin disease who started HCQ at four hospitals were included. Patients were categorized into responders by the CLASI response criteria. The points and the rate of improvement in the CLASI activity score after 16 weeks of treatment were analyzed, focusing on six parameters: systemic lupus erythematosus (SLE), skin manifestations, disease duration, prednisolone, smoking, and severity.

Results

Twenty-seven patients, including 17 with SLE (6 with SLE/Sjögren’s syndrome), were analyzed retrospectively. Twenty-three patients (85 %) were categorized as responders. The mean CLASI activity score improved from 10.1 to 4.5 (p < 0.0001). The improvement rate did not differ in these parameters except for that of annular erythema (81.6 versus 34.3 %, p = 0.036). On multivariate analysis, the baseline CLASI activity score (CLASI ≥9) correlated with the greatest decrease in CLASI activity score (F = 69.7, p < 0.0001).

Conclusions

CLASI is a reliable indicator to evaluate the efficacy of the drug, and HCQ is an effective treatment for Japanese patients with lupus-related skin disease.     

成年人群功能性肠病与体质量指数的相关性研究

目的探讨成年人群功能性肠病与体质量指数的相关性。 方法回顾性分析2016年1月至2019年2月在宁夏回族自治区人民医院消化内科确诊的50例功能性肠病患者为病例组,同期行健康体检者50例为对照组。根据《中国成人超重和肥胖症预防控制指南》推荐的标准,以体质量指数作为不同体重分类依据,采用两独立样本t检验方法比较两者相关性。 结果病例组与对照组比较中,年龄、性别、民族、身高、体重比较差异无统计学意义(P>0.05),而吸烟、饮酒、睡眠情况及进食辛辣食物比较差异有统计学意义(P>0.05);体质量指数与功能性肠病无关(P>0.05),但女性患者功能性肠病的占比较男性多;功能性肠病患者体重过低组占比达20.0%,而健康体检人群超重/肥胖所占比例达44.0%。 结论成年人群功能性肠病与吸烟、饮酒、睡眠情况及进食辛辣食物有关,而与年龄、性别、民族、体质量指数不存在相关性。     

Influence of lean and fat mass on bone mineral density (BMD) in postmenopausal women with osteoporosis

Despite known positive association between body mass and bone mineral density (BMD), relative contribution of fat and lean tissue to BMD remains under debate. We aimed at investigating the effect of selected anthropometric parameters, including fat content and lean body mass (LBM) on BMD in postmenopausal, osteoporotic women with body mass index (BMI) > 20 kg/m². The study involved 92 never-treated women (mean age 69.5 ± 7.3). L1-L4 and femoral neck (FN) BMD were measured by dual energy X-ray absorptiometry (DEXA). Absolute (kg) and relative (%) fat and LBM were assessed by means of electric bioimpedance method. We showed both FN and L1-L4 BMD were positively correlated with body mass, waist circumference (WC), hip circumference (HC) and LBM (kg). Fat content correlated with FN BMD (r = 0.36, p < 0.001). Regression analysis revealed the only predictor of L1-L4 BMD was LBM (R² = 0.18, p < 0.05), for FN - both LBM and fat (R² = 0.18, p < 0.05 and p < 0.001, respectively). Of the women, 44.5% were overweight, 18.4% obese. Obese women displayed the highest BMD. Both L1-L4 and FN BMD were higher in women with WC > 80 cm. In postmenopausal osteoporotic women with BMI > 20 kg/m² both fat and lean tissue might contribute to BMD. Positive association between body mass and BMD does not make obesity and osteoporosis mutually exclusive.     

老年人身体脂肪分布与骨密度关系的研究

目的 研究中国宁波市老年人骨密度(BMD)与年龄、体质指数(BMI)、身体脂肪(体脂)、肌肉的关系. 方法 选择宁波市老年男性61例,用双能X线吸收法测量法(DXA)测定腰椎BMD、全身BMD和体脂、肌肉分布,并与63例老年女性进行对照. 结果 老年男性腰椎BMD与年龄呈负相关(r=-0.401,P<0.01),与BMI、全身肌肉比例、躯干肌肉比例、全身脂肪比例及躯干脂肪比例呈正相关(分别为r=0.560,P<0.01;r=0.249,P<0.05;r=0.214,P>0.05;r=0.276,P<0.05;r=0.217,P<0.01);全身BMD与年龄呈负相关(r=-0.423,P<0.01),与BMI、全身肌肉比例、躯干肌肉比例、全身脂肪比例和躯干脂肪比例呈正相关(分别为r=0.542,P<0.01;r=0.314,P<0.05;r=0.197,P>0.05;r=0.253,P<0.05;r=0.191,P>0.01).老年女性腰椎BMD及全身BMD与年龄(r=0.364,P<0.01;r=0.412,P<0.01)、BMI(r=0.413,P<0.01;r=0.49,P<0.01)、全身肌肉比例(r=0.246,P<0.05;r=0.246,P<0.01)、躯干肌肉比例(r=0.215,P<0.05;r=0.320,P<0.01)、全身脂肪比例(r=0.361,P<0.01;r=0.507,P<0.01)及躯干脂肪比例(r=0.434,P<0.01;r=0.422,P<0.01)呈正相关. 结论 老年女性体脂与BMD相关性较男性更为密切;躯干脂肪与腰椎BMD呈正相关,提示向心性肥胖可能对腰椎BMD有保护作用.     

慢性阻塞性肺疾病患者体质量指数与肺功能及HRCT气道重塑参数的相关性研究

目的探讨低体质量指数（bodymassindex,BMI）cOPD患者肺功能受损程度、临床及影像学特征。方法选取COPD急性加重期患者62例,根据BMI分为4组：低体重组（BMI％18．5kg／m2）、正常体重组（BMI18．5～23．9kg／m2）、超重组（BMI24．0H27．9kg／m2）、肥胖组（BMI≥28kg／m2）。所有患者进行慢性阻塞性肺疾病自我评估测试（COPDassessmenttest,CAT）问卷、肺功能检测及高分辨CT（highresolutionCT,HRcT）检查,并同时应用HRCT相关软件测定肺气肿评分、气道壁厚度及管腔面积等气道重塑指标。观察各组上述指标的变化,并研究其与BMI的相关性。结果①所有患者中低体重组患者12例,正常体重组患者30例,超重组患者7例,肥胖组患者13例,各组患者的年龄、性别、吸烟指数差异无统计学意义;②与正常体重、超重及肥胖患者比较,低体重患者FEV。％pred、MVV、Dt．co／VA％pred、FEV,／FVC均下降（P〈0．05）,而RV／TLc增高（P〈0．05）;③与正常体重、肥胖患者比较,低体重患者CAT评分增高（Pd0．05）;④与正常体重、超重及肥胖组患者比较,低体重组患者肺气肿评分高（Pd0．05）;⑤低体重患者管壁面积百分比（WA％pred）、壁厚与外径比率（TDR％pred）与各组间差异无统计学意义（P〉0．05）;⑥BMI与CAT评分、肺气肿评分、RV／TLC均呈负相关（r=-0．351,P〈0．05;r=-0．628,P〈0．05;r=-0．256,P〈0．05）,而与WA％pred、TDR％pred无相关性（P〉0．05）;BMI与FEV1／FVC、DLCO／VA％pred呈正相关（r=0．387,P〈0．05;r=0．549,P〈0．05）。结论低BMI的COPD患者肺气肿程度严重,通气及弥散功能明显下降,这对临床综合评估COPD病情的严重程度有一定帮助。     

老年炎症性肠病患者的骨代谢和骨密度分析

目的 探讨老年炎症性肠病（inflammatory bowel disease,IBD）患者的骨代谢和骨密度情况与健康对照者的差异,为临床防治IBD引起的骨质疏松提供依据.方法 纳入复旦大学附属华东医院IBD患者20例为IBD组,同期健康体检者20例为对照组.记录并比较两组的年龄、病程、病变部位、糖皮质激素（Glucocorticoids,GCs）应用、骨代谢相关血清学指标检查结果以及髋关节和股骨颈骨密度T值.结果 溃疡性结肠炎组髋关节骨量减少的发生率高于对照组,差异有统计学意义（64.3％ vs 30.0％,P=0.048）.UC组的血清25-羟维生素D[25-hydroxyvitamin D,25-（OH） D]浓度低于对照组（t=0.036,P=-2.100）,IBD组的血清β-CTX浓度高于对照组（UC：=0.003,P=2.975; CD：t=0.024,P=2.253）.结论 老年UC患者髋关节骨量减少的发生率增加,25-（OH）D浓度降低;IBD患者血清β-CTX浓度升高.     

低体质指数的慢性阻塞性肺疾病患者临床和实验室研究

目的 探讨低体质指数(BMI)的慢性阻塞性肺疾病(COPD)患者的临床特征及与COPD患者BMI相关的因素. 方法 选取中、重度稳定期COPD患者38例,测量身高、体质量,按BMI分为低体质量组:16例,BMI<20}正常体质量组22例,20≤BMI<26.所有患者行肺功能检查;记录吸烟指数;测6 min步行距离(6MWD);采用英国医学研究委员会呼吸困难量表(MRC)记录气促分级并评分;St George's呼吸问卷(SGRQ)和一般健康状况调查问卷(SF-36)评价生活质量,用酶联免疫吸附试验(ELISA)测定血清瘦素、格列林的水平. 结果 低体质量组与正常体质量组比较,深吸气量(IC)明显降低(P<0.01);第1秒用力呼气量(FEVl)、肺活量(VC)、最大通气量(MVV)、最大呼气峰值流速(PEF)均下降(P<0.05);残气量与肺总量比值(RV/TLC)明显增高(P<0.01).低体质量组吸烟指数增加,6MWD减少(P<0.05),MRC气促评分增高(P<0.01).低体质量组SGRQ评分中活动分、影响分与总均分增高(P<0.05),SF-36量表中情感职能、社会功能评分明显减低(P<0.05).低体质量组瘦素水平明显降低(P<0.01),格列林水平增高(P<0.05).经多元逐步回归分析发现,与BMI独立相关的因素分别是:IC、SF-36量表的精神健康和生理机能、瘦索、6MWD、吸烟指数. 结论 低BMI COPD患者肺功能、营养状况、运动能力及生活质量较正常BMI患者下降;IC与BMI关系最密切,患者的精神健康、运动能力、血清瘦素水平、吸烟指数均与BMI独立相关;纠正低BMI应为COPD综合治疗的重要组成部分.