Association of interleukin-6 with sarcopenia and its components in older adults: a systematic review and meta-analysis of cross-sectional studies

Observational studies have documented increased serum IL-6 levels in elderly individuals afflicted with sarcopenia. Nevertheless, the relationship between serum IL-6 concentrations and sarcopenia prevalence in the aging population is yet to be defined. We executed a systematic review and meta-analysis of cross-sectional studies that scrutinized serum IL-6 levels in older adults with and without sarcopenia. Relevant studies were sourced from PubMed, Scopus, Embase, Cochrane Library, and Web of Science from inception until 10 September 2023. The standard mean differences (SMDs) in serum IL-6 levels between studies were synthesized using a random-effects model. To examine the influence of demographic and clinical factors on these outcomes, we performed subgroup analyses and meta-regression, focusing on variables such as sex, age, and body mass index (BMI). We also assessed the relationship between serum IL-6 levels and the defining components of sarcopenia: muscle mass, muscle strength, and physical performance. We used Fisher’s Z transformation to standardize the interpretation of effect sizes from these relationships. The transformed values were then converted to summary correlation coefficients (r) for a clear and unified summary of the results. We included twenty-one cross-sectional studies involving 3,902 participants. Meta-analysis revealed significantly elevated serum IL-6 levels in older adults with sarcopenia compared with those without sarcopenia (SMD = 0.31; 95% CI 0.18, 0.44). The difference was highly pronounced in the subgroups of male and those with female percentage below 50% or a mean BMI below 24 kg/m². Serum IL-6 levels were inversely correlated with muscle mass (summary r = −0.18; 95% CI −0.30, −0.06), but not with handgrip strength (summary r = −0.10; 95%CI: −0.25, 0.05) or gait speed (summary r = −0.09; 95%CI: −0.24, 0.07). This meta-analysis establishes a link between increased serum IL-6 levels and sarcopenia in the elderly, particularly in relation to decreased muscle mass. Several studies have demonstrated elevated serum IL-6 levels in elderly individuals with sarcopenia, while the relationship between serum IL-6 levels and sarcopenia remains unclear. This is a systematic review and meta-analysis of 21 cross-sectional studies for the relationship between serum IL-6 levels and sarcopenia. Elevated serum IL-6 levels appear to be associated with sarcopenia in older adults, especially in relation to reduced muscle mass.

已有观察性研究证实，罹患肌少症（sarcopenia）的老年个体血清白细胞介素-6（IL-6）水平升高。然而，老年人群中血清IL-6浓度与肌少症患病率之间的关联尚未明确。本研究针对伴或不伴肌少症的老年人群血清IL-6水平开展了横断面研究的系统评价与meta分析。检索时限自建库起至2023年9月10日，检索数据库包括PubMed、Scopus、Embase、Cochrane图书馆及Web of Science。研究间血清IL-6水平的标准化均数差（SMD）采用随机效应模型进行合并分析。为探讨人口学与临床因素对研究结果的影响，我们针对性别、年龄、体质量指数（BMI）等变量进行了亚组分析与meta回归分析。本研究同时分析了血清IL-6水平与肌少症核心诊断指标——肌肉量、肌肉力量及躯体功能之间的关联。我们采用费希尔Z变换（Fisher’s Z transformation）对上述关联的效应量进行标准化处理，随后将变换后的值转换为合并相关系数（r），以实现研究结果的清晰统一汇总。本研究共纳入21项横断面研究，涉及3902名研究对象。Meta分析结果显示，与非肌少症老年人群相比，肌少症老年人群的血清IL-6水平显著升高（SMD=0.31；95%置信区间CI：0.18~0.44）。在男性亚组、女性占比低于50%的亚组以及平均BMI低于24kg/m²的亚组中，上述差异尤为显著。血清IL-6水平与肌肉量呈负相关（合并相关系数r=-0.18；95%CI：-0.30~-0.06），但与握力（合并相关系数r=-0.10；95%CI：-0.25~0.05）及步速（合并相关系数r=-0.09；95%CI：-0.24~0.07）无显著关联。本项meta分析证实，老年人群血清IL-6水平升高与肌少症存在关联，尤其与肌肉量减少相关。已有多项研究证实肌少症老年个体的血清IL-6水平升高，但血清IL-6水平与肌少症之间的关联仍不明确。本研究为针对血清IL-6水平与肌少症关联的系统评价与meta分析，共纳入21项横断面研究。结果显示，老年人群血清IL-6水平升高与肌少症存在关联，尤其与肌肉量减少密切相关。