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PAD, atherosclerosis may be linked to secondhand smoke exposure
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Exposure to secondhand smoke is associated with inflammation and peripheral artery disease, according to new data.
“The enactment of indoor smokefree policies have been followed by important reductions in [CHD] hospitalizations, providing additional support for the potential [CV] benefits of reducing [secondhand smoke] exposure,” Miranda R. Jones, PhD, assistant professor of epidemiology at Johns Hopkins Bloomberg School of Public Health, and colleagues wrote in the study background. “The 2014 Surgeon General Report, however, estimated that around 33,000 nonsmokers continue to die every year from [secondhand smoke]related [CHD] in the United States.”
Jones and colleagues used data from the Multi-Ethnic Study of Atherosclerosis, which recorded data on subclinical CVD and its risk factors in six urban communities in the United States.
Participants (n = 5,032) were nonsmokers aged 45 to 84 years and free of clinically apparent CVD at baseline.
Secondhand smoke exposure was assessed by self-report and categorized by number of hours per week of exposure. Urinary cotinine was assessed in a random subset (n = 2,893). The researchers assessed carotid intima-media thickness by ultrasound and coronary artery calcium by CT.
Exposure and CHD
The researchers found that 60% of participants (n = 3,035) were unexposed to secondhand smoke in the past year. Of those reporting secondhand smoke exposure, the median was 3 hours of secondhand smoke exposure per week and 8.1% of participants reported at least 12 hours of exposure per week.
Participants with higher exposure were more likely to have lower income and education, be former smokers and have higher BMI (P < .001 for all), according to the researchers.
Jones and colleagues compared the 407 participants with secondhand smoke exposure of at least 12 hours per week vs. the 3,035 unexposed participants and found that, after adjustment for potential compounding factors excluding BMI, they had a 24% increase in highsensitivity Creactive protein and a 10% increase in interleukin6 levels.
After adjustment for BMI, only the association with highsensitivity CRP remained significant (geometric mean ratio = 1.13; 95% CI, 1.02-1.26; OR for highsensitivity CRP 2 mg/L = 1.32; 95% CI, 1.04-1.67).
Participants with more than 12 hours of secondhand smoke exposure per week had an increase in carotid intimamedia thickness (geometric mean ratio = 1.02; 95% CI, 0.97-1.07), but this association was not significant when adjusted for BMI.
Fibrinogen and coronary artery calcification were not associated with secondhand smoke, the researchers found.
Implications for PAD
Urinary cotinine was associated with prevalence of PAD as defined by an anklebrachial index 0.9 or 1.4 (OR = 2.1; 95% CI, 1.09-4.04).
PAD was not associated with self-reported secondhand smoke exposure, and urinary cotinine was not associated with inflammation or carotid intimamedia thickness.
“This study suggests that [secondhand smoke] exposure may increase the risk of CVD by influencing inflammation and atherosclerosis pathways,” the researchers wrote. “The association was stronger for [high-sensitivity] CRP than for subclinical measures of atherosclerosis, potentially providing a possible mechanism for the observed shortterm reductions in [CHD] admissions following the enactment of smokefree laws in many populations around the world.” – by Cassie Homer
Disclosures: The researchers report no relevant financial disclosures.
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