Estimating the impact of a denicotinisation policy on smoking behaviours in Australia - an expert knowledge elicitation study

Background Mandatory reductions in tobacco product nicotine content to non-addictive levels may help achieve a tobacco endgame. Evidence exists for potential positive impacts of 'very low nicotine content' (VLNC) cigarettes in promoting smoking cessation in trial settings, but the population-level policy impact is unknown. Methods An online expert knowledge elicitation survey was undertaken to generate estimates for the impact of a VLNC mandate in Australia. Global experts in tobacco control were recruited to individually estimate impacts on smoking initiation, cessation, and switching to e-cigarettes or illicit market cigarettes. Linear pooling was used to estimate a combined (non-parametric) distribution per question, incorporating minimum, maximum, and best guess values from each respondent. Results The survey was completed by 15 experts. Interquartile ranges from pooled responses indicated that in the first year of a VLNC policy, smoking cessation could increase by 1.2-7.1 times the rate without the policy and switching to vaping by 1.3-8 times. Switching to illicitly supplied 'normal' nicotine cigarettes was estimated between 15-50% of those who smoke. Smoking initiation estimates varied greatly. Experts from Australia (n=8) consistently reported lower estimates for positive outcomes, and higher illicit market switching estimates, than experts from other countries. Conclusions Given the absence of implementation evidence, this study provides Australia-specific estimates of the potential behavioural effects of a VLNC policy. The findings suggest that denicotinisation would accelerate declines in smoking, but that it may be undermined by illicit cigarette access in Australia. Estimates should be updated with real-world evidence as it becomes available.