FRAX, which is used to assess fracture probability, considers body mass index (BMI), but BMI may not reflect individual variation in body composition and distribution. We examined the effect of BMI-discordant abdominal thickness on FRAX-derived fracture probability for major osteoporotic fracture (MOF) and hip fracture. We studied 73,105 individuals, mean age 64.2 years. During mean 8.7 years, 7048 (9.6%) individuals sustained incident MOF, including 2155 (3.0%) hip fractures. We defined abdominal thickness index (ATI) as the difference between abdominal thickness measured by dual-energy X-ray absorptiometry (DXA) and thickness predicted by BMI using sex-stratified regression. ATI was categorized from lower (<−2 cm, −2 to −1 cm) to higher (1–2 cm, >+2 cm) with referent around zero (−1 to +1 cm). Adjusted for FRAX probability, increasing ATI was associated with incident MOF and hip fracture (p < 0.001). For the highest ATI category, MOF risk was increased (hazard ratio [HR] = 1.23, 95% confidence interval [CI] 1.12–1.35) independent of FRAX probability. Similar findings were noted for hip fracture probability (HR = 1.28, 95% CI 1.09–1.51). There was significant age-interaction with much larger effects before age 65 years (HR = 1.44, 95% CI 1.23–1.69 for MOF; 2.29, 95% CI 1.65–3.18 for hip fracture). In contrast, for the subset of individuals with diabetes, there was also increased risk for those in the lowest ATI category (HR = 1.73, 95% CI 1.12–2.65 for MOF; 2.81, 95% CI 1.59–4.97 for hip fracture). Calibration plots across ATI categories demonstrated deviation from the line of identity in women (calibration slope 2.26 for MOF, 2.83 for hip fracture). An effect of ATI was not found in men, but this was inconclusive as the sex-interaction terms did not show significant effect modification. In conclusion, these data support the need to investigate increased abdominal thickness beyond that predicted by BMI and sex as a FRAX-independent risk factor for fracture. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

中文翻译：

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BMI 不一致的腹部组织厚度对骨折概率的影响：一项基于登记的研究

用于评估骨折概率的 FRAX 考虑了体重指数 (BMI)，但 BMI 可能无法反映身体成分和分布的个体差异。我们研究了 BMI 不一致的腹部厚度对 FRAX 衍生的主要骨质疏松性骨折 (MOF) 和髋部骨折的骨折概率的影响。我们研究了 73,105 人，平均年龄 64.2 岁。在平均 8.7 年期间，有 7048 人 (9.6%) 发生 MOF，其中包括 2155 人 (3.0%) 髋部骨折。我们将腹部厚度指数 (ATI) 定义为通过双能 X 射线吸收测定法 (DXA) 测量的腹部厚度与使用性别分层回归通过 BMI 预测的腹部厚度之间的差异。ATI 被分类为从较低（<-2 cm，-2 至 -1 cm）到较高（1-2 cm，>+2 cm），参考值约为 0（-1 至 +1 cm）。根据 FRAX 概率进行调整后，ATI 增加与 MOF 和髋部骨折事件相关（p  < 0.001）。对于最高的 ATI 类别，MOF 风险增加（风险比 [HR] = 1.23，95% 置信区间 [CI] 1.12–1.35），与 FRAX 概率无关。髋部骨折概率也有类似的发现（HR = 1.28，95% CI 1.09–1.51）。65 岁之前存在显着的年龄交互作用，影响更大（MOF 的 HR = 1.44，95% CI 1.23–1.69；髋部骨折为 2.29，95% CI 1.65–3.18）。相比之下，对于糖尿病患者来说，最低 ATI 类别的患者风险也增加（MOF 的 HR = 1.73，95% CI 1.12–2.65；髋部骨折 2.81，95% CI 1.59–4.97）。跨 ATI 类别的校准图显示女性与身份线存在偏差（MOF 的校准斜率 2.26，髋部骨折的校准斜率 2.83）。在男性中没有发现 ATI 的影响，但这还不确定，因为性别相互作用项没有显示出显着的影响修改。总之，这些数据支持需要调查超出 BMI 和性别预测的腹部厚度增加作为与 FRAX 无关的骨折危险因素。© 2023 作者。《Journal of Bone and Mineral Research》由 Wiley periodicals LLC 代表美国骨与矿物研究学会 (ASBMR) 出版。