Urinary tobacco and nicotine exposure biomarkers as predictors of transitions between cigarette and e-cigarette use in the Exhale longitudinal cohort study.

Abstract

Introduction: Urinary tobacco and nicotine exposure biomarkers may be predictive of subsequent transitions in product use.

Methods: We used data from an observational study of 371 adults who smoked cigarettes daily, some of whom also used e-cigarettes, and who were followed every two months for up to two years (Wisconsin, US, 2015-19). Using a multistate transition model, we assessed continuous associations between transition propensities and urinary tobacco biomarker concentrations, namely 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol) (NNAL) and NE-2 (cotinine + trans-3'-hydroxycotinine), the nicotine metabolite ratio (NMR; trans-3'-hydroxycotinine:cotinine), and NNAL:NE-2, measured every 4 months.

Results: The biomarkers were generally more predictive of transitions from dual use, but not from cigarette-only use, than self-reported product use was. Propensity to stop smoking cigarettes decreased with increasing concentrations of NNAL and NE-2, for both participants who smoked only cigarettes and those who used both cigarettes and e-cigarettes. For example, we estimated that, at 20 pg NNAL per mg creatinine, 30.2% (95%CI, 14.6%, 47.0%) of those who only smoke cigarettes and 26.6% (95% CI, 11.3%, 42.5%) who dual use would transition to non-current cigarette use and e-cigarette use in one year, while at the 200 pg/ng, we estimate these probabilities to be 3.2% (95%CI, 1.7%, 5.8%) and 3.9% (95% CI, 1.9%, 8.5%), respectively. The ratio NNAL:NE-2 was predictive of transitions from dual use to cigarette-only (higher ratio) or e-cigarette-only (lower ratio) use.

Conclusions: Urinary tobacco biomarkers were non-linearly associated with transitions in tobacco product use and may guide the development of clinical interventions to promote harm-reducing product use transitions.