LAUSR

Objective We sought to quantify the impact of vaping introduction on cigarette smoking across settings with varied regulatory approaches to vaping. Design Interrupted time series analysis, adjusted for cigarette tax levels. Setting Four Canadian provinces, UK and Australia. Participants Entire population of smokers in each country. Interventions The year that vaping was widely introduced in each country. Primary and secondary outcome measures The primary outcome is cigarette consumption per adult, and the secondary outcome is smoking prevalence among young adults. Results Based on allowable nicotine levels, restrictions on e-cigarette advertising, sales and access, and taxation, the least to most restrictive jurisdictions were, in order, Alberta, Ontario, Quebec and British Columbia (all in Canada), UK and Australia. In most, but not all, settings where higher nicotine content was permitted in vaping products (66 mg/mL), vaping introduction led to a reduction in cigarette consumption per capita (Ontario: p=0.037, Quebec: p=0.007) or in smoking prevalence among young adults (Alberta men, p=0.027; Quebec men, p=0.008; Quebec women, p=0.008). In the UK, where the maximum permitted nicotine content in vaping products was 20 mg/mL, vaping introduction slowed the declining trend in cigarette smoking among men aged 16–24 years (p=0.031) and 25–34 years (p=0.002) but not in cigarette consumption per adult. In Australia, where nicotine was not permitted in e-cigarettes, e-cigarette introduction slowed the declining trend in cigarette consumption per capita and in smoking prevalence among men aged 18–24 years (cigarette consumption: p=0.015, prevalence: p=0.044). Conclusion In environments that enable substitution of cigarettes with e-cigarettes, e-cigarette introduction reduces overall cigarette consumption. Thus, to reduce cigarette smoking, policies that encourage adults to substitute cigarette smoking with vaping should be considered.