Department of Physical and Environmental Sciences, University of Toronto, Toronto, Ontario, Canada
School of Nursing, Queen's University, Kingston, Ontario, Canada.
BMJ Open. 2021 Jan 27;11(1):e043166. doi: 10.1136/bmjopen-2020-043166.
High blood pressure (BP) is a risk factor for cardiovascular disease. Examining the role of inflammatory mediators on BP is important since vitamin D (VD) is a modifiable risk factor, which possibly modulates inflammatory cytokines. This study simulated what are known as average 'controlled direct effects (CDE)' of inflammatory markers, C reactive protein (CRP), tumour necrosis factor-α (TNF-α), and interlukin-6 (IL-6) on continuous BP measures, while fixing VD, an intermediate variable to specific level.
Cross-sectional study.
We analysed data from the Multi-Community Environment-and-Health Study, 2005-2009, conducted in , Quebec, Canada.
This study recruited 1425 study Indigenous Cree participants from seven Cree communities. Only adults with serum VD levels, inflammatory markers and BP measures were included in this data analysis.
Inflammatory markers examined the top 25th exposure percentiles. VD 'insufficiency' (ie, 25-hydroxyvitamin-D levels<50 nmol/L) defined by the Institute of Medicine. CDE for each inflammatory marker in the presence and absence of population VD insufficiency simulated the average direct effect change for systolic and diastolic BP (SBP and DBP) measures. All models were adjusted for exposure-and-mediator outcome relationship.
Among 161 participants, 97 (60 %) were female. The prevalence of VD insufficiency was 32%. CDE estimates show in the presence and absence of population vitamin D insufficiency, inflammatory markers have a slightly different association on BP. TNF-α significantly and inversely associated with SBP in the presence of vitamin D insufficiency, fully adjusted model β = -13.61 (95% CI -24.42 to -2.80); however, TNF-α was not associated with SBP in the absence of vitamin D insufficiency. CRP, IL-6 were also not significantly associated with BP measures, although the magnitude of association was greater for those with elevated inflammation and VD insufficiency.
This novel analysis shows in the presence of VD insufficiency, inflammation (particularly TNF-α) may affect SBP. Additional research is needed to elucidate these findings, and the temporal relationship between these variables.
高血压（BP）是心血管疾病的一个危险因素。研究炎症介质对 BP 的作用很重要，因为维生素 D（VD）是一种可调节的危险因素，它可能调节炎症细胞因子。本研究模拟了已知的炎症标志物 C 反应蛋白（CRP）、肿瘤坏死因子-α（TNF-α）和白细胞介素-6（IL-6）对连续 BP 测量的“平均控制直接效应（CDE）”，同时将 VD 固定为特定水平的中间变量。
横断面研究。
我们分析了 2005-2009 年在加拿大魁北克省进行的多社区环境与健康研究的数据。
这项研究招募了来自七个克里社区的 1425 名土著克里参与者。只有血清 VD 水平、炎症标志物和 BP 测量值均有数据的成年人被纳入本数据分析。
炎症标志物检测暴露的前 25%百分位数。VD“不足”（即 25-羟维生素 D 水平<50 nmol/L）由医学研究所定义。在存在和不存在人群 VD 不足的情况下，每种炎症标志物的 CDE 模拟了收缩压和舒张压（SBP 和 DBP）测量值的平均直接效应变化。所有模型均调整了暴露-中介结局关系。
在 161 名参与者中，有 97 名（60%）为女性。VD 不足的患病率为 32%。CDE 估计显示，在存在和不存在人群维生素 D 不足的情况下，炎症标志物对 BP 的关联略有不同。在维生素 D 不足的情况下，TNF-α与 SBP 呈显著负相关，全调整模型β=-13.61（95%CI-24.42 至-2.80）；然而，在不存在维生素 D 不足的情况下，TNF-α与 SBP 无关。CRP 和 IL-6 与 BP 测量值也没有显著相关，尽管炎症和 VD 不足程度较高时，关联幅度更大。
本研究的新颖分析表明，在 VD 不足的情况下，炎症（尤其是 TNF-α）可能会影响 SBP。需要进一步研究阐明这些发现以及这些变量之间的时间关系。
