[A prospective cohort study on the association between smoking and blood pressure among middle-aged and elderly...

Objective: Smoking is an important risk factor for cardiovascular events. However, data from some studies have shown that smoking is not associated with hypertension, and smokers may even have lower blood pressure than the non-smokers. Therefore, the association between smoking and blood pressure is yet to be further explored through longitudinal studies. This study explores the effect of smoking on blood pressure among people aged between forty five to eighty years old whose records are gathered from the China Health and Retirement Longitudinal Survey (CHARLS). Methods: Participants of CHARLS who completed all three surveys from both the national baseline investigation in 2011 and the follow-up surveys in 2013 and 2015, were enrolled. Multi-level linear regression was used to analyze the association between smoking and blood pressure, and Cox regression with time-varying variables was used to analyze the association between smoking and hypertension, after the adjustment for gender, age, education level, marital status, BMI, and alcohol consumption. Results: Subjects included in this study were with an average age of 58.8 years and 46.3% of them being male. After the adjustments of all the covariates, systolic and diastolic blood pressure of smokers appeared as 1.81 mmHg (95%CI: 0.55-3.07 mmHg, P<0.05) and 0.85 mmHg (95%CI: 0.10-1.60 mmHg, P<0.05), both higher than those of non-smokers, respectively. From the Cox regression analysis, data showed that smoking was not highly associated with the risk of hypertension development (HR=1.11, 95%CI: 0.89-1.38, P>0.05), statistically. Conclusions: Smoking seemed to be positively correlated with the elevation of blood pressure, among individuals aged between 45 and 80 years old. However, more evidence on the association between smoking and the risk of hypertension development needs to be further explored.