Combined effects of smoking and systolic blood pressure on risk of coronary heart disease: a cohort study in Chinese women

The Canadian Women’s Heart Health Alliance Atlas on the Epidemiology, Diagnosis, and Management of Cardiovascular Disease in Women — Chapter 4: Sex- and Gender-Unique Disparities: CVD Across the Lifespan of a Woman

Women have unique sex- and gender-related risk factors for cardiovascular disease (CVD) that can present or evolve over their lifespan. Pregnancy-associated conditions, polycystic ovarian syndrome, and menopause can increase a woman’s risk of CVD. Women are at greater risk for autoimmune rheumatic disorders, which play a role in the predisposition and pathogenesis of CVD. The influence of traditional CVD risk factors (eg, smoking, hypertension, diabetes, obesity, physical inactivity, depression, anxiety, and family history) is greater in women than men. Finally, there are sex differences in the response to treatments for CVD risk and comorbid disease processes. In this Atlas chapter we review sex- and gender-unique CVD risk factors that can occur across a woman’s lifespan, with the aim to reduce knowledge gaps and guide the development of optimal strategies for awareness and treatment.

Central rather than brachial pressures are stronger predictors of cardiovascular outcomes: A longitudinal prospective study in a Chinese population

The purpose of this study was to assess the association of blood pressure (BP) measurements with the risk of cardiovascular disease (CVD) and examine whether central systolic BP (CSBP) predicts CVD better than brachial BP measurements (SBP and pulse pressure [PP]). Based on a cross-sectional study conducted in 2009-2010 with follow-up in 2016-2017 among 35- to 64-year-old subjects in China, we evaluated the performance of non-invasively predicted CSBP over brachial BP measurements on the first CVD events. Each BP measurement, individually and jointly with another BP measurement, was entered into the multivariate Cox proportional-hazards models, to examine the predictability of central and brachial BP measurements. Mean age of participants (n = 8710) was 50.1 years at baseline. After a median follow-up of 6.36 years, 187 CVD events occurred. CSBP was a stronger predictor for CVD than brachial BP measurements (CSBP, 1-standard deviation increment HR = 1.49, 95%CI: 1.31-1.70). With CSBP and SBP entering into models jointly, the HR for CSBP and SBP was 1.28 (1.04-1.58) and 1.22 (0.98-1.50), respectively. With CSBP and PP entering into models jointly, the HR for CSBP and PP was 1.51 (1.28-1.78) and 0.98 (0.83-1.15), respectively. For subgroup analysis, the association of CSBP with CVD was stronger than brachial BP measurements in women, those with hypertension and obesity. In the middle-aged Chinese population, noninvasively estimated CSBP may offer advantages over brachial BP measurements to predict CVD events, especially for participants with higher risk. These findings suggest prospective assessment of CSBP as a prevention and treatment target in further trials.

Smoking, Blood Pressure, and Cardiovascular Disease Mortality in a Large Cohort of Chinese Men with 15 Years Follow-up

BACKGROUND

To examine the joint effects of smoking and blood pressure on the risk of mortality from cardiovascular disease (CVD) in a cohort of Chinese men.

METHODS

This study followed a cohort of 213,221 men over 40 years of age who were recruited from 45 district/counties across China between 1990⁻1991, and whose cause-specific mortality was examined for 15 years, up to 31 December 2005. We calculated hazard ratios for all-cause mortality and CVD, ischemic heart disease (IHD), and stroke mortality for the combined sets of smoking status and blood pressure levels using the Cox proportional hazard model, adjusting for potential individual-level and contextual-level risk factors.

RESULTS

During the 15 years of follow-up, 52,795 deaths occurred, including 18,833 deaths from CVD, 3744 deaths from IHD, and 11,288 deaths from stroke. The risk of mortality from CVD, IHD, and stroke increased significantly, with increased systolic blood pressure (SBP), diastolic blood pressure (DBP), and with more pack years of smoking. Compared with never-smokers with normal blood pressure, the hazard ratios and 95% CI of CVD, IHD, and stroke mortality for those who smoked over 20 pack years with hypertension were remarkably increased to 2.30 (95% CI: 2.12⁻2.50), 1.78 (95% CI: 1.48⁻2.14), and 2.74 (95% CI: 2.45⁻3.07), respectively.

CONCLUSION

There was a combined effect on the risk of CVD, IHD, and stroke mortality between smoking and hypertension. The joint efforts on smoking cessation and lowered blood pressure should be made to prevent cardiovascular disease mortality in Chinese men.

Synergistic and Non-synergistic Associations for Cigarette Smoking and Non-tobacco Risk Factors for Cardiovascular Disease Incidence in the Atherosclerosis Risk In Communities (ARIC) Study

INTRODUCTION

Cigarette smoking, various metabolic and lipid-related factors and hypertension are well-recognized cardiovascular disease (CVD) risk factors. Since smoking affects many of these factors, use of a single imprecise smoking metric, for example, ever or never smoked, may allow residual confounding and explain inconsistencies in current assessments of interactions.

METHODS

Using a comprehensive model in pack-years and cigarettes/day for the complex smoking-related relative risk (RR) of CVD to reduce residual confounding, we evaluated interactions with non-tobacco risk factors, including additive (non-synergistic) and multiplicative (synergistic) forms. Data were from the prospective Atherosclerosis Risk in Communities (ARIC) Study from four areas of the United States recruited in 1987-1989 with follow-up through 2008. Analyses included 14 127 participants, 207 693 person-years and 2857 CVD events.

RESULTS

Analyses revealed distinct interactions with smoking: including statistical consistency with additive (body mass index [BMI], waist to hip ratio [WHR], diabetes mellitus [DM], glucose, insulin, high density lipoproteins [HDL] and HDL(2)); and multiplicative (hypertension, total cholesterol [TC], low density lipoproteins [LDLs], apolipoprotein B [apoB], TC to HDL ratio and HDL(3)) associations, as well as indeterminate (apolipoprotein A-I [apoA-I] and triglycerides) associations.

CONCLUSIONS

The forms of the interactions were revealing but require confirmation. Improved understanding of joint associations may help clarify the public health burden of smoking for CVD, links between etiologic factors and biological mechanisms, and the consequences of joint exposures, whereby synergistic associations highlight joint effects and non-synergistic associations suggest distinct contributions.

IMPLICATIONS

Joint associations for cigarette smoking and non-tobacco risk factors were distinct, revealing synergistic/multiplicative (hypertension, TC, LDL, apoB, TC/HDL, HDL(3)), non-synergistic/additive (BMI, WHR, DM, glucose, insulin, HDL, HDL(2)) and indeterminate (apoA-I and TRIG) associations. If confirmed, these results may help better define the public health burden of smoking on CVD risk and identify links between etiologic factors and biologic mechanisms, where synergistic associations highlight joint impacts and non-synergistic associations suggest distinct contributions from each factor.

Does cigarette smoking exacerbate the effect of blood pressure on the risk of cardiovascular and all-cause mortality among hypertensive patients?

OBJECTIVE

To examine the risk of cigarette smoking on cardiovascular disease (CVD) and all-cause mortality among hypertensive patients.

METHODS

We conducted a prospective cohort study among 36,943 hypertensive patients aged at least 40 years. Data on smoking and other variables were obtained in 1991 and follow-up evaluation was conducted in 1999-2000.

RESULTS

During a median follow-up of 8.2 years, we documented 7194 deaths among 36 943 hypertensive patients. Compared with never-smokers, the multivariate-adjusted relative risks (MRRs) [95% confidence intervals (CIs)] for CVD mortality were 1.19 (1.07, 1.31) and 1.33 (1.23, 1.45) for those who smoked 0.1-19 pack-years and at least 20 pack-years (P for linear trends <0.001 for all). A similar pattern was observed for all-cause mortality. A dose-response association between pack-years smoked and risk of CVD and all-cause mortality (all P ≤ 0.01) was found among the SBP groups (140-159, 160-179, and ≥ 180 mmHg), DBP groups (<90, 90-94, and 100-109 mmHg), and pulse pressure groups (50-59, 60-69, and ≥ 70 mmHg). In addition, compared to never-smokers with stage 1 hypertension, MRRs of CVD and all-cause mortality for those who smoked at least 20 pack-years with stage 3 hypertension were remarkably increased to 3.06 (2.64, 3.54) and 2.51 (2.24, 2.80), respectively.

CONCLUSIONS

Smoking not only significantly increased the risk of CVD and all-cause mortality among hypertensive groups, but the synergistic effect on the risk of CVD and all-cause mortality existed between cigarette smoking and blood pressure category. Therefore, apart from hypertension management, smoking cessation should be an essential component for preventing deaths related to smoking.