尿酸指数在体重指数与卒中关联中的作用研究：基于中国健康与养老追踪调查队列的中介与交互分析

The role of the uric acid index in the association between body mass index and stroke: mediation and interaction analyses based on the China Health and Retirement Longitudinal Study cohort

摘要:

目的 探讨尿酸指数（由尿酸、甘油三酯和空腹血糖构成的复合指标）与体重指数（BMI）对中老年人群卒中风险的影响、中介效应、交互作用及联合预测价值。方法 基于中国健康与养老追踪调查（CHARLS）的前瞻性队列数据，选取2011年基线时无卒中史的45岁及以上成年人共3 712名。采用Cox比例风险回归模型分析尿酸指数和BMI与卒中风险的关联。采用限制性立方样条（RCS）探索非线性关系。进行中介效应分析和交互作用评估（相乘与相加）。通过受试者操作特征（ROC）曲线及曲线下面积（AUC）评估联合指标的判别能力。结果 中位随访9年期间，共发生344例卒中事件。多因素调整后，尿酸指数最高四分位组相较于最低组的卒中风险比为1.81（95%CI：1.28～2.57）；BMI≥28 kg/m2组相较于BMI<24 kg/m2组的风险比为1.70（95%CI：1.25～2.32）。尿酸指数在BMI与卒中关联中起到44.4%的中介作用（95%CI：9%～80%）。未发现BMI与尿酸指数存在显著的相乘或相加交互作用。联合使用BMI和尿酸指数的AUC为0.609，略高于单一指标。结论 尿酸指数和BMI均是卒中的危险因素，且尿酸指数在BMI与卒中关联中具有部分中介作用。两者对卒中风险的影响主要为独立且相加，未发现协同放大效应。综合评估BMI与尿酸指数有助于更准确地识别卒中高危人群。

Abstract:

Objective To investigate the independent associations of the uric acid index （a composite measure of uric acid， triglycerides， and fasting glucose） and body mass index （BMI） with the risk of stroke in a middle-aged and elderly Chinese population， the mediating effect， the interactions of uric acid index and BMI， and the predictive value of BMI+uric acid index.Methods This prospective cohort study used data from the China Health and Retirement Longitudinal Study. A total of 3 712 participants aged ≥45 years without a history of stroke at baseline in 2011 were included. Cox proportional hazards model was used to assess the associations of uric acid index and BMI with the risk of stroke， and restricted cubic spline analysis was applied to explore their nonlinear relationships. Mediation analysis was conducted to evaluate the mediating role of the uric acid index， and multiplicative and additive interactions were assessed. The discriminative ability of the combined indicator was evaluated using the receiver operating characteristic curve and the area under the curve.Results During a median follow-up of 9 years， 344 stroke events occurred. After multivariable adjustment， the hazard ratio for stroke in the highest quartile of the uric acid index compared with the lowest quartile was 1.81 （95%CI： 1.28-2.57）. The hazard ratio for BMI≥28 kg/m² compared with BMI<24 kg/m² was 1.70 （95%CI： 1.25-2.32）. The uric acid index mediated 44.4% （95%CI： 9%-80%） of the association between BMI and stroke. No significant multiplicative or additive interaction was observed between BMI and the uric acid index. The combined indicator （BMI+uric acid index） had an area under the curve of 0.609， slightly higher than either measure alone.Conclusions Both the uric acid index and BMI are independent risk factors for stroke， with the uric acid index partially mediating the effect of BMI on the risk of stroke. Their effects on the risk of stroke are mainly independent and additive， and there is no synergistic amplification effect. A comprehensive assessment integrating BMI and the uric acid index helps to more accurately identify populations at high risk of stroke.