Predictors of oxidative stress and vascular function in an experimental study of tobacco versus electronic cigarettes. A post hoc analysis of the SUR-VAPES 1 study

INTRODUCTION Use of a conventional cigarette (CC) or electronic cigarette (EC) leads to oxidative stress and endothelial dysfunction, but the impact of other features and their interplay with CCs and ECs have been incompletely appraised. We explored moderators of CC and EC effects on oxidative stress and endothelial dysfunction. METHODS We have conducted an experimental study on CCs and ECs in which repeated indicators of oxidative stress (serum levels of soluble NOX2-derived peptide, nitric oxide bioavailability, 8-iso-prostaglandin F2α-III, and vitamin E) and endothelial dysfunction (flow-mediated dilation) were collected in 40 subjects (20 smokers, 20 non-smokers). Several moderating features were appraised, adjusting for smoking status and cigarette type. RESULTS Absolute changes in oxidative stress and vascular features after smoking a CC or vaping an EC were significantly correlated (all p<0.05), with the notable exception of 8-iso-prostaglandin F2α-III levels (p=0.030). Inferential analysis based on generalized estimating equations highlighted that the only variable significantly associated with oxidative stress and vascular features was smoking status (all p<0.05). Specifically, we found that smokers had a less pronounced untoward oxidative and vascular response after vaping an EC in comparison to non-smokers, who had oxidative and vascular reactions to an EC that resembled more those seen after smoking a CC. Intriguingly, women taking oral contraceptives appeared to have more unfavorable changes in vitamin E (p=0.002) and FMD (p=0.008). CONCLUSIONS This study suggests that the comparative oxidative and vascular effects of an EC versus a CC may be influenced by smoking status, with a potential interaction in women taking oral contraceptives. These findings need further confirmation but could have important clinical and policy implications