Objectively Measured Secondhand Smoke Exposure and Risk of Cardiovascular Disease

Objectives To examine the association between objectively measured second–hand-smoke (SHS) exposure and incident CVD death, and assess the extent to which this association can be explained through novel circulating markers of inflammation and haemostasis. Background Existing evidence suggests there is an association between SHS and cardiovascular disease (CVD) risk, although the mechanisms remain poorly understood. Methods In a prospective study of 13,443 participants living in England and Scotland [aged 53.5, (SD 12.6 yrs), 52.3% women] we measured salivary cotinine (an objective marker of SHS exposure) and novel CVD biomarkers (C-reactive protein, fibrinogen) at baseline. Results 20.8% of the sample had high SHS exposure based on elevated levels of salivary cotinine (0.71 – 14.99 ng/mL). During a mean follow-up of 8 years, there were 1221 all-cause deaths and 364 CVD deaths. High SHS was associated with all-cause (age adjusted HR= 1.25, 95% CI, 1.02 – 1.53) and CVD death (age adjusted HR= 1.21, 95% CI, 0.85 – 1.73). High SHS was also associated with elevated CRP, which explained 48% of the association between SHS and CVD death. The excess risk of CVD associated with active smoking was exaggerated in relation to self report (age adjusted HR= 3.27, 95% CI, 2.48 – 4.31) compared with objective assessment (age adjusted HR= 2.44, 95% CI, 1.75 – 3.40). Conclusion Among a large representative sample of British adults we observed elevated levels of low grade inflammation in otherwise healthy participants exposed to high SHS, and this partly explained their elevated risk of CVD death.