Smoking prevalence following tobacco tax increases in Australia between 2001 and 2017: an interrupted time-series analysis

Evidence before this study

We searched PubMed with the search terms: “smok*” (ie, smoking; smoker or smokers; smoked; smoke or smokes; smoke-free); “cigar*” (cigar or cigars; cigarillo or cigarillos; and cigarette or cigarettes); and “tobacco”. We reviewed titles and abstracts, and we excluded articles not in English, that did not use a human sample, or that were not relevant to tobacco use or policy. Given the extensive literature on tobacco control and tobacco taxation specifically, we included seminal reports and studies and any studies that were specific to large tax increases or to Australasia. Previous work consistently showed that tobacco tax increases are an effective intervention to reduce tobacco use in low-income, middle-income, and high-income countries. Regarding the effects of very large tax increases, one study in a single Australian jurisdiction found an increase in quit attempts after the 25% increase in tobacco tax in Australia, but the study only evaluated the effects for 3 months of follow-up. Two studies assessed the effects of 10% annual tax increases that were implemented in New Zealand in January, 2010; however, these studies were before-and-after comparisons among a small sample of smokers, using no more than 6 months of follow-up. Price monitoring in the UK has documented tobacco companies increasing prices gradually ahead of and after tax increases announced each year in the UK Budget, thereby cushioning the effects on consumers. Researchers have called for tax increases to be introduced without forewarning, to circumvent industry mitigation. We found no studies that examined the effects of a series of pre-announced increases in tobacco taxes on smoking prevalence at a national level that used extended population-level outcome data.

Added value of this study

To our knowledge, this is the first study internationally to examine the short-term and long-term effects of two different approaches to implementing large increases in tobacco tax on population smoking prevalence, both overall and in population groups. Our study used a robust analysis approach, with estimates adjusted for other tobacco control policies. Our findings provide evidence that both major tax policy initiatives were effective in the short term and the longer term. Our results also provide insights into the potential for the tobacco industry to mitigate the effect of increases if taxes are not congruent across different forms of tobacco products.

Implications of all the available evidence

Large tobacco tax increases should be considered by all countries as a priority, and they are important for reducing tobacco-related disparities. Both unannounced large tax increases and pre-announced, staged substantive increases in taxes can be immediately effective in reducing the prevalence of smoking. Pre-announced, staged substantive increases might be more effective over time in reducing smoking prevalence than one-off unannounced large tax increases. To maximise the effectiveness of increases in tobacco taxes and to reduce product substitution, nations should structure taxes so that roll-your-own (loose) tobacco product prices increase in line with price increases in factory-made cigarettes. Standardisation of pack and pouch size and use of minimum prices would reduce the ability of tobacco companies to market products that are cheaper upfront, or which otherwise lessen the impact of or confuse price signals after tax increases.