Secondhand smoke exposure is associated with increased carotid artery intima-media thickness: the Bogalusa Heart Study.

Background: Secondhand smoke (SHS) exposure increases cardiovascular disease risk. The objective of this study was to examine the association of SHS exposure in childhood and adulthood with adult arterial thickness.
Methods: The study cohort consisted of 415 nonsmoking adults (301 whites and 114 blacks; ages 26.2-48.0 years) enrolled in 2004-2010. The arterial wall thickness was measured as common, bulb and internal carotid artery intima-media thickness (IMT). SHS exposure data in childhood and adulthood were obtained by a questionnaire survey.
Results: Increased adult composite carotid IMT was significantly associated with SHS exposure (regression coefficient, β = 53.1 μm, p < 0.001) after adjusting for race, age, gender, education, income, body mass index, systolic blood pressure, LDL cholesterol and triglycerides/HDL cholesterol ratio, with blacks (β = 81.2 μm, p = 0.005) and whites (β = 38.9 μm, p = 0.017) showing the same direction of the association. Furthermore, the SHS exposure in childhood showed a relatively stronger association with increased carotid IMT than the exposure in adulthood based on standardized βs (0.180 vs. 0.106); the same trend in the difference between childhood and adulthood exposure was noted for duration of SHS exposure (0.186 vs. 0.145). The covariates-adjusted composite carotid IMT showed a significant increasing trend by the order of exposure status of none, adulthood only, childhood only and both (p for trend<0.001).
Conclusions: If the relationship is causal, the associations observed in this study suggest that more awareness should be raised on the dangers of SHS exposure during childhood so that its effect may be mitigated and controlled early in the cardiovascular disease process.
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