Supplementary Material for: Association of remnant cholesterol with rapid kidney function decline in middle-aged and older adults with normal kidney function

Introduction Emerging evidence suggests a potential association between dyslipidemia and renal dysfunction. Remnant cholesterol, defined as the cholesterol content of triglyceride-rich lipoproteins, has not been thoroughly investigated in relation to rapid renal function decline in individuals with preserved kidney function. Therefore, our study aimed to clarify this association in a nationwide Chinese cohort. Methods Our study used data from the 2011 and 2015 waves of the China Health and Retirement Longitudinal Study. Remnant cholesterol level was derived using the following equation: total cholesterol minus low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol. The study outcomes were rapid kidney function decline or the progression to chronic kidney disease (CKD). To determine the associations between remnant cholesterol and CKD outcomes, we used multivariable logistic regression, subgroup analyses, restricted cubic spline models, and receiver operating characteristic curve analysis. Results A total of 4039 individuals (59 ± 8.7 years, 52.5% female) were enrolled in our study. Over a 4-year follow-up, 195 (4.8%) individuals experienced rapid renal function decline, and 367(9.1%) individuals experienced progression to CKD. Elevated remnant cholesterol levels were strongly linked to an elevated risk of rapid renal function decline (OR=1.89, 95%CI: 1.59-2.26, P-value < 0.001) and the progression to CKD (OR=1.76, 95%CI: 1.51-2.04, P-value < 0.001). The restricted cubic spline analysis revealed that these associations were nonlinear. Additionally, subgroup analysis demonstrated that this relationship was more evident in individuals with LDL-C ＞ 2.6 mmol/L than those in LDL-C ≤ 2.6 mmol/L. Conclusion Our study demonstrated elevated remnant cholesterol concentrations were associated with a higher risk of rapid renal function decline among middle-aged and older Chinese adults. These findings suggest that remnant cholesterol may serve as a valuable biomarker for identifying individuals at elevated risk for renal dysfunction.引言 越来越多的证据表明，血脂异常与肾功能不全之间可能存在潜在关联。残粒胆固醇（remnant cholesterol）被定义为富含甘油三酯的脂蛋白中的胆固醇含量，目前针对肾功能保留人群的快速肾功能下降与残粒胆固醇的关联尚未得到充分研究。因此，本研究旨在中国全国性队列中明确二者的关联。 研究方法 本研究采用中国健康与养老追踪调查2011年与2015年两轮调查的数据。残粒胆固醇水平通过以下公式计算：总胆固醇减去低密度脂蛋白胆固醇（low-density lipoprotein cholesterol, LDL-C）与高密度脂蛋白胆固醇。本研究的结局指标为快速肾功能下降或进展为慢性肾脏病（chronic kidney disease, CKD）。为探究残粒胆固醇与CKD结局的关联，我们使用了多变量logistic回归、亚组分析、限制性立方样条模型以及受试者工作特征曲线分析。 研究结果 本研究共纳入4039名受试者，平均年龄为（59±8.7）岁，女性占比52.5%。经过4年随访，195例（4.8%）受试者出现快速肾功能下降，367例（9.1%）进展为慢性肾脏病。残粒胆固醇水平升高与快速肾功能下降风险升高显著相关（比值比OR=1.89，95%置信区间CI: 1.59-2.26，P<0.001），同时与慢性肾脏病进展风险升高亦存在显著关联（OR=1.76，95%CI: 1.51-2.04，P<0.001）。限制性立方样条分析显示，此类关联呈非线性特征。此外，亚组分析表明，在低密度脂蛋白胆固醇＞2.6mmol/L的人群中，这种关联较LDL-C≤2.6mmol/L者更为显著。 结论 本研究证实，中国中老年人群中残粒胆固醇浓度升高与快速肾功能下降风险升高显著相关。上述研究结果提示，残粒胆固醇或可作为识别肾功能不全高危个体的有效生物标志物。