老年人骨骼健康与肌少型肥胖症的关系

Relationship between bone health and sarcopenic obesity in elderly adults

目的探讨与老年人骨骼健康和平衡相关的肌少型肥胖症的特征性指标。方法收集168名50岁以上的社区老年人,通过双能X线骨密度仪测定全身骨骼面积骨密度(areal bone mineral density,aBMD)、总体脂和四肢瘦组织量(appendicular lean mass,ALM)。通过外周定量计算机断层扫描评估小腿肌肉密度、体积骨密度(volumetric bone mineral density,vBMD)、面积、厚度和强度应变指数(strength-strain index,SSI)等,并测量手握力和平衡路径长度,通过Pearson、多元线性回归等比较各项身体成分与胫骨参数的相关性。结果较高的小腿肌肉密度与男性(r=-0.36,P=0.008)和女性(r=-0.40,P=0.003)较低的平衡路径长度有关。受试者体质量指数(body mass index,BMI)≥30 kg/m^2即为肥胖人群,其全身aBMD、胫骨近端骨皮质面积、厚度和SSI均高于BMI正常的受试者。在多元回归分析中,肥胖受试者的小腿肌肉密度与胫骨近端骨皮质vBMD(β=2.91,95%CI:0.02～5.80,P=0.004)和面积(β=2.70,95%CI:0.06～5.33,P=0.001)呈正相关。结论在各项身体成分中,较高的ALM是反映骨骼健康状况的较好指标,低肌肉密度可严重影响老年人的骨质健康与平衡。

Objective To investigate the characteristics of sarcopenic obesity related to bone health and balance in the elderly. Methods A total of 168 elderly people aged over 50 years were recruited and their whole body areal bone mineral density(aBMD), body fat percentage and appendicular lean mass(ALM) were assessed by dual-energy X-ray absorptiometry. Peripheral quantitative computed tomography was used to assess muscle density and cortical volumetric BMD(vBMD), area, thickness and strength-strain index(SSI) at the 66% tibial length. Hand grip strength(dynamometry) and balance path length(computerized posturography) were assessed. Pearson correlation and multivariate linear regression were used to compare associations of characteristics of sarcopenic obesity and bone healthy parameters. Results Higher lower-leg muscle density was associated with lower balance path length in males(r=-0.36, P=0.008) and females(r=-0.40, P=0.003). Obese subjects with a BMI≥30 kg/m^2 had higher whole-body aBMD, and greater cortical area, thickness and SSI at the proximal tibia than those with normal BMI. In multivariate regression analysis, in obese subjects lower-leg muscle density had positive association with proximal tibial cortical vBMD(β=2.91, 95% CI: 0.02-5.80, P=0.004) and area(β=2.70, 95% CI: 0.06-5.33, P=0.001), respectively. Conclusion Among the body composition index, higher ALM is a good indicator of bone health, and low muscle density could seriously affect bone health and balance of the elderly.