The impact of tobacco tax increases on cost-minimising behaviours and subsequent smoking cessation in Australia: an analysis of the International Tobacco Control Policy Evaluation Project

Objective We examined the relationship in Australia from 2007 to 2020 between tobacco tax increases and use of cost-minimising behaviours (CMBs) when purchasing tobacco and: (1) tobacco expenditure and (2) smoking cessation attempts and quit success.Methods We used data collected from adults who smoked factory-made and/or roll-your-own (RYO) cigarettes in nine waves (2007-2020) of the International Tobacco Control Policy Evaluation Project Australia Survey (Nsample=4975, Nobservations=10 474). CMBs included buying RYO tobacco, cartons, large-sized packs, economy packs, or tax avoidance/evasion, smoking reduction and e-cigarette use. Logistic regression, fit using generalised estimating equations, estimated the CMB-outcome association for quit attempts and quit success at the next wave follow-up (Nsubsample=2984, Nobservations=6843).Results Over half of respondents used a CMB for tobacco purchase (P-CMB) at baseline (57.1% in 2007-2008), increasing to 76.8% (2018) post-tax increases. Participating in any P-CMB was associated with having higher weekly tobacco expenditure. Engaging in any P-CMB was negatively associated with attempting to quit (aOR=0.82, 95% CI 0.69-0.98). Purchasing RYO tobacco or cartons was associated with making no quit attempts (aOR=0.66, 95% CI 0.52-0.83; aOR=0.72, 95% CI 0.59-0.89, respectively). Among respondents smoking cigarettes who made quit attempts, there were no significant associations between all P-CMBs and quit success. Neither smoking reduction nor vaping were significantly associated with quit attempts.Conclusion P-CMBs are associated with reduced smoking cessation. Reducing opportunities for industry to promote purchasing-related CMB options, such as by standardising pack sizes and reducing the price differential between RYO and manufactured cigarettes could increase the effectiveness of tax increases.