Association of metabolic syndrome with inflammatory markers in a sample of community-dwelling older adults

The study aimed to identify the cutoff points for inflammatory markers that best discriminate the occurrence of metabolic syndrome in community-dwelling older adults. Baseline data were used from the elderly cohort in the city of Bambuí, Minas Gerais State, Brazil. The target exposure was presence of metabolic syndrome, defined according to the Adult Treatment Panel III criterion, and the outcomes included the following inflammatory markers: cytokines (IL-1β, IL-6, IL-10, IL-12 e TNF), chemokines (CXCL8, CXCL9, CCL2, CXCL10, and CCL5), and C-reactive protein (CRP). Definition of the cutoff points for the inflammatory markers was based on the Classification and Regression Tree (CART) method. The associations between these markers and metabolic syndrome were estimated by logistic regression models, obtaining odds ratios and 95% confidence intervals, considering adjustment for confounding factors. Prevalence of metabolic syndrome was 49.1%, and IL-1β, IL-12, and TNF levels were not associated statistically with this exposure. After adjustment, presence of metabolic syndrome was associated with higher IL-6 and CRP levels and lower CXCL8 and CCL5. Significant associations were also observed with intermediate serum CXCL9 and CXCL10 levels. The combination of markers also showed a significant and consistent association with metabolic syndrome. In addition to demonstrating an association between metabolic syndrome and a wide range of biomarkers (some not previously described in the literature), the results highlight that this association occurs at much lower levels than previously demonstrated, suggesting that metabolic syndrome plays an important role in the inflammatory profile of the older adults.

本研究旨在确定可最佳区分社区居住老年人群代谢综合征（metabolic syndrome）发病风险的炎症标志物截断值。研究数据取自巴西米纳斯吉拉斯州班布伊市的老年队列基线资料。本研究的暴露因素为代谢综合征的存在，其诊断依据美国成人治疗小组第三次指南（Adult Treatment Panel III）标准；研究结局指标涵盖以下炎症标志物：细胞因子（cytokines）：IL-1β、IL-6、IL-10、IL-12及TNF，趋化因子（chemokines）：CXCL8、CXCL9、CCL2、CXCL10及CCL5，以及C反应蛋白（C-reactive protein, CRP）。炎症标志物截断值的确定采用分类与回归树（Classification and Regression Tree, CART）法。通过logistic回归模型分析上述标志物与代谢综合征的关联，计算比值比（odds ratios）及95%置信区间（confidence intervals），并对混杂因素进行校正。本研究人群代谢综合征患病率为49.1%，IL-1β、IL-12及TNF水平与该暴露因素无统计学关联。校正混杂因素后，代谢综合征的存在与IL-6、CRP水平升高及CXCL8、CCL5水平降低显著相关。血清CXCL9及CXCL10的中等水平也与代谢综合征存在显著关联。多种标志物联合检测也与代谢综合征存在显著且稳定的关联。本研究不仅证实代谢综合征与多种生物标志物（其中部分此前未见文献报道）存在关联，还发现该关联发生于远低于既往研究报道的标志物水平，提示代谢综合征在老年人群的炎症特征中发挥重要作用。