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The association between smoking quantity and hypertension mediated by inflammation in Chinese current smokers

Feng, Dana,*; Liu, Taob,*; Su, Dong-Fanga; Wang, Huib; Ding, Pengb; He, Yan-Huib; Deng, Xue-Qingc; Hou, Meng-Junc; Ling, Wen-Huaa; Chen, Wei-Qingb

doi: 10.1097/HJH.0b013e328362c21a
ORIGINAL PAPERS: Epidemiology

Objectives: Previous studies indicated that cigarette smokers were more likely to develop hypertension, and both smoking and hypertension were associated with inflammation. Whether inflammation mediates the relationship of them is unclear. This study aims to examine whether inflammation mediates the association between smoking and hypertension.

Methods: Nine hundred and eighty-four Chinese current smokers from a community-based chronic diseases survey in Guangzhou and Zhuhai were interviewed about sociodemographics, smoking, chronic conditions, and other health-related variables. Hypertension was defined according to 2007 European Society of Hypertension and European Society of Cardiology (ESH-ESC) Practice Guidelines. Inflammatory markers including C-reactive protein (CRP), interleukin (IL)-6, IL-1β, monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-α (TNF-α), and vascular cell adhesion molecule-1 (VCAM-1) were measured by flow cytometry. Logistic regressions were performed to assess the mediation of inflammation on the relationship between smoking quantity and hypertension.

Results: We observed a positive association between smoking quantity and hypertension (P < 0.05). After controlling for potential confounders, daily cigarette consumption was significantly associated with higher level of CRP and VCAM-1 and lower level of TNF-α among six measured inflammatory markers, and the current smokers with hypertension had significantly higher level of MCP-1 and CRP than those smokers who were normotensive. Furthermore, the association between smoking quantity and hypertension was mediated by CRP, which accounted for 58.59% of the estimated causal effect of smoking on hypertension.

Conclusion: We have confirmed previous observations that smoking quantity was positively associated with hypertension, and the results of our study suggested that the association between smoking and hypertension was probably mediated by CRP.

aDepartment of Preventive Medicine

bDepartment of Biostatistics and Epidemiology

cExperimental Centre, School of Public Health, Sun Yat-Sen University, Guangzhou, China

*Dan Feng and Tao Liu contributed equally to the writing of the article.

Correspondence to Wei-Qing Chen, School of Public Health, Sun Yat-Sen University (Northern Campus), 74 Zhongshan Road 2, Guangzhou 510080, China. Tel: +86 20 8733 2199; fax: +86 20 8733 0446; e-mail: chenwq@mail.sysu.edu.cn

Abbreviations: CRP, C-reactive protein; IL-1β, interleukin-1β; IL-6, interleukin-6; MCP-1, monocyte chemoattractant protein-1; TNF-α, tumor necrosis factor-α; VCAM-1, vascular cell adhesion molecule-1

Received 16 November, 2012

Revised 6 April, 2013

Accepted 30 April, 2013

© 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins