Department of Medicine, School of Clinical Sciences at Monash Health, Monash University, Clayton, Victoria, Australia.
Department of Medicine, School of Clinical Sciences at Monash Health, Monash University, Clayton, Victoria, Australia.
Bone. 2020 Nov;140:115546. doi: 10.1016/j.bone.2020.115546. Epub 2020 Jul 27.
The aim of this study was to determine and compare risk factors associated with incident fractures in older adults with and without obesity, defined by both body mass index (BMI) and body fat percentage.
1,099 older adults (mean ± standard deviation age = 63.0 ± 7.5) years, participated in this prospective cohort study. Obesity status at baseline was defined by BMI (≥30 kg/m) obtained by anthropometry and body fat percentage (≥30% for men and ≥40% for women) assessed by dual-energy X-ray absorptiometry (DXA). Total hip and lumbar spine areal bone mineral density (aBMD) were assessed by DXA up to five years. Incident fractures were self-reported up to 10 years.
Prevalence of obesity was 28% according to BMI and 43% according to body fat percentage. Obese older adults by BMI, but not body fat percentage, had significantly higher aBMD at the total hip and spine compared with non-obese (both p-value<0.05). Obese older adults by body fat percentage had significantly higher likelihood of all incident fractures (OR: 1.71; CI:1.08, 2.71) and non-vertebral fractures (OR: 1.88; CI:1.16, 3.04) compared with non-obese after adjusting for confounders. Conversely, obese older adults by BMI had a significantly lower likelihood (OR: 0.54; CI:0.31, 0.94) of non-vertebral fractures although this was no longer significant after adjustment for total hip aBMD (all p-value > 0.05). Mediation analysis confirmed that aBMD meditated the effects of BMI, but not body fat percentage, on all incident fractures. Higher baseline falls risk score was the only consistent predictor of increased likelihood of incident fracture in obese individuals only, according to both BMI and body fat percentage (both p-value<0.05).
Obesity defined by body fat percentage is associated with increased likelihood of incident fractures in community-dwelling older adults, whereas those who are obese according to BMI have reduced likelihood of incident fracture which appears to be explained by higher aBMD. Falls risk assessment may improve identification of obese older adults at increased risk of incident fractures.
本研究旨在确定和比较肥胖（通过体重指数（BMI）和体脂百分比定义）与非肥胖老年人发生骨折的相关因素。
这项前瞻性队列研究纳入了 1099 名年龄在 63.0±7.5 岁的老年人。基线肥胖状态由人体测量法获得的 BMI（≥30kg/m）和双能 X 射线吸收法（DXA）评估的体脂百分比（男性≥30%，女性≥40%）定义。通过 DXA 评估全髋和腰椎骨矿物质密度（aBMD），随访时间长达 5 年。通过自我报告评估 10 年内的骨折事件。
根据 BMI，肥胖的患病率为 28%，根据体脂百分比，肥胖的患病率为 43%。与非肥胖者相比，BMI 定义的肥胖老年人全髋和脊柱的 aBMD 显著更高（均 p 值<0.05）。然而，体脂百分比定义的肥胖老年人全髋和非椎骨骨折的发生风险显著更高（OR：1.71；95%CI：1.08，2.71）和非椎骨骨折（OR：1.88；95%CI：1.16，3.04），调整混杂因素后差异仍有统计学意义。相反，BMI 定义的肥胖老年人全髋和非椎骨骨折的发生风险显著降低（OR：0.54；95%CI：0.31，0.94），但在调整全髋 aBMD 后，差异无统计学意义（均 p 值>0.05）。中介分析证实，aBMD 中介了 BMI 但不是体脂百分比对所有骨折事件的影响。根据 BMI 和体脂百分比，较高的基线跌倒风险评分是肥胖个体发生骨折事件的唯一一致预测因子（均 p 值<0.05）。
体脂百分比定义的肥胖与社区居住的老年人骨折发生风险增加相关，而 BMI 定义的肥胖者骨折发生风险降低，这似乎与更高的 aBMD 有关。跌倒风险评估可能会提高识别肥胖老年人骨折风险增加的能力。
