Supplementary Material for: Association of high-density lipoprotein cholesterol with sarcopenia in Chinese community-dwelling middle-aged and older adults: Evidence from 4-year longitudinal study from the CHARLS

Introduction There is inconsistent evidence on the associations between high-density lipoprotein cholesterol (HDL-C) and risk of sarcopenia. To determine the evidence existing between HDL-C and sarcopenia in Chinese middle-aged and older adults. Methods We used a panel study design of the China Health and Retirement Longitudinal Study (CHARLS), with 7,415 participants (mean age 57.5 years) from 2011, 2013, and 2015. HDL-C was measured by colormetric test of venous serum samples. Sarcopenia was defined as low muscle mass, plus low muscle strength, or low physical performance. Muscle mass was estimated by anthropometric measures. Muscle strength was measured by handgrip strength using dynamometer. Physical performance was measured by 5-time chair stand test, gait speed test, and short physical performance battery. Results With 961 (13.0%) sarcopenia cases, each 1-unit increase (1 SD = 15.4 mg/dL) of HDL-C levels was associated with 42% increased odds of incident sarcopenia [OR = 1.42, 95% confidence interval (CI) = 1.28 – 1.58] at 4 years follow up. Females with high HDL-C levels (HDL-C > 60 mg/dL) had a higher risk of sarcopenia [OR = 2.49, 95% CI = 1.76 - 3.52]. A J-shaped association between HDL-C and risk of sarcopenia in females. HDL-C was negatively associated with muscle mass [ = -0.23, 95% CI = -0.27 – -0.20] and hand grip strength [ = -0.05, 95% CI = -0.19 – 0.09]. Conclusion High HDL-C levels were associated with higher risk of sarcopenia among middle-aged and older Chinese adults, and appropriate control of its high levels informs the management of sarcopenia.

研究背景
目前关于高密度脂蛋白胆固醇（high-density lipoprotein cholesterol, HDL-C）与肌少症（sarcopenia）发病风险之间的关联，尚无一致的研究证据。本研究旨在明确中国中老年人群中HDL-C与肌少症之间的关联证据。

研究方法
本研究采用中国健康与养老追踪调查（China Health and Retirement Longitudinal Study, CHARLS）的队列研究设计，纳入2011、2013及2015年随访的7415名受试者（平均年龄57.5岁）。HDL-C水平通过静脉血清样本的比色法检测获取。肌少症的定义为肌肉量低下合并肌肉力量低下，或身体活动能力低下。肌肉量通过人体测量学指标进行估算；肌肉力量采用握力计（dynamometer）测定握力来评估；身体活动能力则通过5次坐立试验（5-time chair stand test）、步速试验（gait speed test）以及简易体能状况量表（short physical performance battery）进行测定。

研究结果
本研究共纳入961例肌少症患者（占比13.0%）。在4年随访期间，HDL-C水平每升高1个标准差单位（1个标准差=15.4 mg/dL），新发肌少症的比值比（odds ratio, OR）升高42%[OR=1.42，95%置信区间（95% confidence interval, 95%CI）=1.28~1.58]。HDL-C水平高于60 mg/dL的女性受试者，其肌少症发病风险更高[OR=2.49，95%CI=1.76~3.52]；女性人群中，HDL-C与肌少症发病风险呈现J型关联。此外，HDL-C水平与肌肉量[偏回归系数β=-0.23，95%CI=-0.27~-0.20]及握力[偏回归系数β=-0.05，95%CI=-0.19~0.09]呈负相关。

研究结论
中国中老年人群中，较高的HDL-C水平与肌少症发病风险升高显著相关；对HDL-C水平进行合理管控，可为肌少症的临床管理提供参考依据。