目的

       了解江苏省成人超重、肥胖与骨密度异常的患病情况，并探讨不同肥胖指标与跟骨骨密度的关联。

方法

       使用多阶段整群随机抽样法，2023年10月-11月在江苏省南京市、无锡市、苏州市、淮安市、南通市和宿迁市开展流行病学现场调查，针对在当地居住5年以上的≥20周岁居民进行问卷调查、体格检查、实验室检测。使用法国Medilink公司生产的Pegasus超声跟骨骨密度仪测量调查对象右脚骨密度。描述江苏省成年居民超重、肥胖以及骨密度异常的患病情况，基于江苏省2023年人口年龄结构数据，通过直接标化法对男女患病率进行比较，另外分析跟骨骨密度随不同肥胖指标变化的趋势。采用多元线性回归方法，分别探讨五种肥胖指标(体质指数[BMI]、体脂率[BFP]、腰围[WC]、腰臀比[WHR]、内脏脂肪指数[VAI])与跟骨骨密度的线性关联；利用非条件logistic回归方法，分别探讨全身肥胖、中心性肥胖与跟骨骨密度异常的关联。根据不同性别、年龄、绝经状况和腰围测量情况，进行亚组分析，同时利用限制性立方样条法，分别探讨不同肥胖指标与跟骨骨密度的剂量反应关系。另外，利用线性回归模型探讨右腿脂肪量与跟骨骨密度的关联。使用主成分分析归纳饮食模式，并纳入模型，探讨其对肥胖与跟骨骨密度关联的调节作用。计算中国人内脏脂肪指数（CVAI），并进行敏感性分析。

结果

       本次调查最终有5786人完成有效的跟骨骨密度测量，其中男性2265（39.15%）人，女性3521（60.85%）人。江苏省成年居民超重率、肥胖率分别为40.0%、15.6%；男性超重率、肥胖率分别为44.1%、19.6%；女性超重率、肥胖率分别为37.4%、13.1%，男女超重率、肥胖率之间存在显著性差异（P ＜0.05）。而江苏省成人中，骨量减少、骨质疏松症的患病率分别为19.8%、2.3%；男性骨量减少、骨质疏松症患病率分别为24.7%和2.8%；女性骨量减少、骨质疏松症患病率分别为16.7%、1.9%，经统计学检验，男女骨量减少、骨质疏松症患病率之间有显著差异（P ＜0.05）。将患病率标化后，男性超重、肥胖、骨量减少和骨质疏松症的患病率仍然高于女性。多元线性回归分析的结果显示，BMI（β=0.40，95%CI：0.22-0.57）、BFP（β=0.18，95%CI：0.07-0.28）增加与跟骨骨密度提高显著相关，而没有发现WC、WHR和VAI与跟骨骨密度存在关联（P ＞0.05）。非条件logistic回归显示，全身肥胖是跟骨骨密度异常的保护因素，而中心性肥胖与跟骨骨密度异常没有统计学关联。通过亚组分析发现，BMI、BFP与跟骨骨密度的关联仅在女性、≥50岁人群中存在，测量腰围组和未测量腰围组肥胖指标与跟骨骨密度的关联具有一致性。BMI、BFP与跟骨骨密度存在剂量反应关系，随着BMI、BFP的增加，跟骨骨密度不断增加，而WC、WHR、VAI未发现剂量反应关系。右腿脂肪量与跟骨骨密度正相关，右腿脂肪量提高与跟骨骨密度增加密切相关。经过主成分分析提取了三种主要的膳食模式，仅有动物蛋白及水果膳食模式（β=0.77，95%CI：0.31-1.23）频率增加与跟骨骨密度增加显著相关，但与肥胖不存在交互作用。敏感性分析显示，尽管VAI和CVAI计算方法不同，但与跟骨骨密度的关联结论是一致的，两者都未发现与跟骨骨密度存在关联。

结论

       江苏省成年居民超重和肥胖率超50%，而江苏省成人跟骨骨量减少和骨质疏松症患病率较低。跟骨骨密度随BMI、BFP增加不断增加，而与WC、WHR、VAI无关。超重、肥胖与跟骨骨密度异常患病风险降低密切相关，尤其在女性与中老年人群中，全身肥胖对于跟骨有着较好的保护作用，而没有发现中心性肥胖与跟骨骨密度存在关联。右腿脂肪量增加能够提高跟骨骨密度水平。饮食摄入频率的增多能够有效增加跟骨骨密度，尤其是增加奶制品和水果的摄入，可以有效保护跟骨避免骨量流失。BMI、BFP与跟骨骨密度的关联相对独立，不受饮食因素的影响。

Objective

To investigate the prevalence of overweight, obesity, and abnormal bone mineral density (BMD) among adults in Jiangsu Province, and to explore the associations between different obesity indicators and calcaneal BMD.

Methods

A multi-stage cluster random sampling method was employed to conduct an epidemiological field survey from October to November 2023 in Nanjing, Wuxi, Suzhou, Huaian, Nantong, and Suqian in Jiangsu province. Participants aged 20 years and older who had resided in the local area for more than five years were targeted for questionnaire surveys, physical examinations and laboratory tests. The calcaneal BMD of right foot of the participants was measured using a Pegasus ultrasound calcaneal bone densitometer manufactured by Medilink in France. The prevalence of overweight, obesity, and abnormal BMD among adult residents in Jiangsu province was described. Comparison of prevalences between males and females using the direct standardization method. And the study explored the distribution of calcaneal BMD across different obesity indicators. Utilizing multivariable linear regression to explore linear associations between five obesity indicators (body mass index [BMI], body fat percentage [BFP], waist circumference [WC], waist-to-hip ratio [WHR], visceral adiposity index [VAI]) and calcaneal BMD. Unconditional logistic regression was used to evaluate associations of general obesity, central obesity and visceral obesity with abnormal BMD, respectively. Subgroup analyses were stratified by sex, age, menopausal status, and waist measurement status. Additionally, restricted cubic spline methods explored the dose-response relationships. Furthermore, a linear regression model was employed to investigate the association between right-leg fat mass and calcaneal BMD. Principal component analysis identified dietary patterns, which were then incorporated into the model to assess their moderating effects on the relationship between obesity and calcaneal BMD. Calculate the Chinese Visceral Adiposity Index (CVAI) and perform a sensitivity analysis.

Results

The study ultimately included 5786 individuals who completed valid calcaneal bone mineral density measurements, comprising 2265 (39.15%) males and 3521 (60.85%) females. The overall prevalence of overweight and obesity was 40.0% and 15.6%, respectively, with significant sex differences (male: 44.1% overweight, 19.6% obesity; female: 37.4% overweight, 13.1% obesity; P＜0.05). Furthermore, among adults in Jiangsu province, the prevalence of osteopenia and osteoporosis was 19.8% and 2.3%, respectively, also differing by sex (male: 24.7% osteopenia, 2.8% osteoporosis; female: 16.7% osteopenia, 1.9% osteoporosis; P<0.05). After standardization, the prevalences of overweight, obesity, osteopenia, and osteoporosis in males remained higher than those in females. The results of multivariable linear regression revealed positive linear associations between BMI, BFP and calcaneal BMD (P<0.05), whereas no linear associations with WC, WHR, or VAI. Unconditional logistic regression analysis identified that overweight/obesity as protective factors against abnormal BMD, while central obesity and visceral obesity showed no association. Subgroup analyses indicated associations between BMI, BFP and calcaneal BMD were significant only in females and individuals aged ≥50 years. The associations obesity indicators with calcaneal BMD between the group with WC measured and the group without WC measured were consistent. A dose-response relationship was observed between BMI, BFP and calcaneal BMD, with calcaneal BMD increasing as BMI and BFP increased. However, WC, WHR and VAI showed no dose-response trends with calcaneal BMD. And a positive linear correlation exists between right-leg fat mass and calcaneal BMD. Three major dietary patterns were extracted through principal component analysis, with the "animal protein and fruit" pattern significantly associated with BMD but no interaction with obesity. The sensitivity analysis revealed that despite differences in the calculation methods between VAI and CVAI, their associations with calcaneal BMD were consistent—no significant association was found for either index.

Conclusion

The prevalences of overweight and obesity in Jiangsu among adults exceeded 50%, whereas the prevalences of osteopenia and osteoporosis was lower. Calcaneal BMD increases progressively with higher BMI and BFP, but shows no significant association with WC, WHR, and VAI. General obesity is significantly associated with a reduced risk of calcaneal abnormal BMD, particularly among women and older adults, where it demonstrates a protective effect on the calcaneus. No significant association was observed between central obesity and calcaneal BMD. Increased fat mass in the right leg may enhance calcaneal BMD levels. Higher dietary intake frequency, especially increased consumption of dairy products and fruits, effectively elevates calcaneal BMD and helps prevent bone loss in the calcaneus. The associations between BMI, BFP and calcaneal BMD remain relatively independent and are not influenced by dietary factors.