Comparing Adult Smokers who Switched to JUUL vs Continuing Smokers: Biomarkers of Exposure and of Potential Harm and Respiratory Symptoms

Abstract Introduction: More real-world evidence on exposure to harmful and potentially harmful constituents (HPHCs) and on biological effects when cigarette smokers switch to e-cigarettes would be useful. Methods: This cross-sectional, observational study assessed adults who had smoked ≥ 10 cigarettes/day for ≥ 10 years, comparing 124 continuing cigarette smokers (Smokers) to 140 former smokers who switched to JUUL-brand e-cigarettes exclusively for ≥ 6 months (Switchers). Assessments included biomarkers of exposure (BOEs) to select HPHCs, biomarkers of potential harm (BOPHs) related to smoking-related diseases, and psychometric assessments of tobacco dependence and respiratory symptoms. Planned analyses compared geometric means, adjusted for covariates; exploratory analyses adjusted for additional covariates. Results: Nicotine was higher in Switchers, who were heavy users of JUUL. All other BOEs, including NNAL and HPMA3 (primary endpoints), were significantly lower in Switchers than Smokers. Most BOPHs (sICAM-1 [primary], and e.g., white blood cell count, MCP1, HbA1c) were significantly lower in Switchers than Smokers; HDL was significantly higher. Switchers reported significantly lower tobacco dependence and respiratory symptoms than Smokers. Conclusions: Compared to continuing smokers, smokers who switched to JUUL had substantially lower exposures to multiple HPHCs, favorable differences in markers of inflammation, endothelial function, oxidative stress, and cardiovascular risk, and less respiratory symptoms.