Reducing the Smoking-Related Health Burden in the US through Diversion to Electronic Cigarettes: A System Dynamics Simulation Study

Abstract

Background: Electronic cigarettes (“e-cigarettes”) have altered tobacco use trends, and their impacts are controversial. Given their lower risk relative to conventional cigarettes, e-cigarettes have potential for harm reduction. This study presents a simulation-based analysis of an e-cigarette harm reduction policy set in the US. Methods: A system dynamics simulation model was constructed, with separate aging chains representing different stages of use for both cigarette smokers and e-cigarette users. These structures interact with a policy module to close the gap between actual (simulated) and goal numbers of cigarette smokers, chosen to reduce the tobacco-attributable death rate to that due to all accidents in the general population. The policy is two-fold, removing existing flavor bans and providing an informational campaign promoting e-cigarettes as a lower-risk alternative. Realistic practical implementation challenges are modeled in the policy sector, including time delays, political resistance, and budgetary limitations. Effects of e-cigarettes on conventional smoking occurs through three mechanisms: 1) diversion from ever initiating conventional smoking; 2) reducing progression to established smoking; and 3) increasing smoking cessation. An important unintended effect was included, which increases the tobacco-related mortality accordingly with an increase in nicotine users due to e-cigarettes. Results: The base-case model replicated the historical exponential decline in smoking and the exponential increase in e-cigarette use since 2010. The ideal-case policy was able to reduce conventional smoking to the goal level approximately 40 years after implementation. Implementation obstacles (time delays, political resistance, and budgetary constraints) delayed and weakened the effect of the policy by up to 95% in the worst case, relative to the ideal-case scenario; however, these discrepancies substantially decreased over time in dampened oscillations as negative feedback loops stabilize the system after the one-time “shock” introduced by policy changes. Conclusions: Current findings demonstrate that the promotion of e-cigarettes as a harm-reduction policy is a viable strategy, given current knowledge of e-cigarettes’ effects on conventional smoking. Given the strong effects of implementation challenges on policy effectiveness in the short term, accurately modeling such obstacles is essential in policy design. Ongoing research is needed with forthcoming data on e-cigarette use prevalence and possible effects on cigarette smoking.