The desire to reach “hard core” smokers, typically characterized as smokers who “cannot or will not quit,” is one of the core justifications for e-cigarettes and other new alternative tobacco products are part of the industry’s “harm reduction” agenda. Now Miranda Harris and her Australian colleagues have produced a systematic review debunking the hardening hypothesis and showing that under most definitions smoking populations are “softening” over time. Their paper, “Smokers increasingly motivated and able to quit as smoking prevalence falls: umbrella and systematic review of evidence relevant to the ‘hardening hypothesis’, considering transcendence of manufactured doubt,” identifies 3 earlier reviews and ten repeat cross-sectional studies from around the world. They find that established tobacco control policies, including smokefree laws, taxes, graphic warnings, plain packaging and other established interventions that reduce smoking prevalence “fosters a smoking population more amenable to evidence-based [cessation] interventions” and conclude that “the time has come to take active steps to combat the myth of hardening and to replace it with the reality of ‘softening’.”
They note that there is not a single precise definition of “hardening” and carefully walk through the different definitions based on smoker motivations or level of dependence and show that now matter which one you use, the smoking population softens as prevalence drops.
With regard to motivation, they found
International evidence from five studies on quit intentions and attempts indicates that as smoking prevalence declines, the smoking population is either becoming more motivated to quit, or remaining stable in its motivation.
With regard to dependence they found:
The available evidence indicates that dependence is on average declining or not changing in smokers, demonstrated by a decrease or no change in the proportion of smokers who were daily or heavy smokers, a decrease or no change in the proportion of smokers who were smoking soon after waking, no change in the proportion of smokers with four or more quit attempts of more than 24 hours in the past year5 and a decrease in dependence scores on the Nicotine Dependence Severity Scale. Of the smokers that continued to smoke, consumption, measured by average number of cigarettes per day, declined over time. [citations deleted]
They sum up the evidence as follows:
Despite repeated concerns expressed regarding hardening, there is no evidence it is happening in smoking populations in the countries examined, with virtually all indicators consistent with softening or showing no significant change. The available evidence from studies from Australia, Canada, England, Europe, New Zealand, Norway and the US does not indicate hardening of the population of smokers between 1992 and 2016, and in many cases shows softening – that is, becoming on average more motivated to quit and less dependent on smoking. The findings are consistent with the reviews by Warner and Burns, Hughes (2011) and Hughes (2019), which did not find evidence of hardening. They are also consistent with a recent review regarding the prevalence of hardcore smoking, published outside the timeframes of this review, incorporating publications to mid-2018. Based on the evidence to date, the lack of hardening within the population of smokers is almost completely consistent across the range of hardening indicators employed, their definitions, countries (and tobacco control environments) and time periods examined. [citations deleted; emphasis added]
Harris and her colleagues also squarely position the hardening hypothesis in the tobacco companies’ playbook for protecting their markets and using e-cigarettes and other new products to protect industry interests:
Portraying heavy addiction among smokers as an immutable property of the smoker themselves denies the active role the tobacco industry plays in creating and prolonging addiction and supports its calculated shift from perpetrator to “saviour” — through investment in and promotion of products such as e-cigarettes and heated tobacco products — while continuing to profit from tobacco and nicotine products.
More importantly, these data demonstrate a clear need to actively challenge and replace the hardening discourse with an evidence-based discourse about what truly happens as smoking prevalence falls. To the extent that the scientific and public discourse centres around hardening, the more people may believe the hardening hypothesis. Even more worrying would be in the context of policy development, in which decisions around smoking interventions could be influenced by messages that felt intuitively appealing, rather than those with a foundation of robust empirical evidence. … The studies we have reviewed here suggest that such interventions may be warranted in the future if a hardening rhetoric continues, given that the large volume of evidence indicates shifting to softening is empirically valid and will lead to more evidence-based policy, practice and public awareness. [citations deleted; emphasis added]
They go on to explain how established tobacco control policies act through softening:
Comprehensive and multifaceted tobacco control measures have proved effective in
reducing the prevalence of smoking in many countries. These measures include smoke-free policies, mass media campaigns, plain packaging, graphic health warnings on packaging, price increases, and prohibitions on tobacco advertising, promotion and sponsorship. Such measures actually act through softening: they make it more challenging for smokers to continue smoking large numbers of cigarettes by reducing opportunities to smoke, making it very expensive to do so, and reducing its social acceptability. These measures also increase smokers’ motivation to quit, including through awareness of harms. [citations deleted; emphasis added]
Here is the abstract:
Introduction: The “hardening hypothesis” proposes that as the prevalence of smoking in a population declines, there will be a “hardening” of the remaining smoker population. This review examines the evidence regarding smokers’ motivation, dependence and quitting behaviour as smoking prevalence declines, to assess whether population “hardening” (decreasing propensity to quit) or “softening” (the converse) is occurring.
Methods: MEDLINE, PsychINFO, Scopus, Web of Science and Cochrane Library were searched to July 2019, using terms related to smoking and hardening, for reviews and large, population-based repeat cross-sectional studies. There were additional searches of reference lists and citations of key research articles. Two reviewers screened half the titles and abstracts each, and two reviewers screened full texts independently using tested criteria. Four reviewers independently and systematically extracted data from eligible publications, with one reviewer per study, checked by another reviewer.
Results: Of 265 titles identified, three reviews and ten repeat cross-sectional studies were included. Reviews concluded that hardening has not occurred among the general smoking population over time. Among repeated cross-sectional studies, five examined motivation, nine examined dependence, five examined hardcore smoking, and two examined quit outcomes. All but one study found a lack of hardening. Most found softening within the smoking population, consistent across hardening indicators, definitions, countries (and tobacco control environments) and time periods examined.
Conclusions: Tobacco control reduces smoking prevalence and fosters a smoking population more amenable to evidence-based interventions. Based on the weight of the available evidence, the “hardening hypothesis” should be rejected and the reality of softening accepted.
Implications: This umbrella review and systematic review provides a critical consideration of evidence from psychology and other fields regarding the “hardening hypothesis” – a persistent myth undermining tobacco control. It reaches the conclusion that the sum-total of the world-wide evidence indicates either “softening” of the smoking population, or a lack of hardening. Hence, tobacco control reduces smoking prevalence and fosters a smoking population more amenable to evidence-based interventions. The review indicates that the time has come to take active steps to combat the myth of hardening and to replace it with the reality of “softening”.
The full citation is: Harris M, Martin M, Yazidjoglou A, Ford L, Lucas RM, Newman E, Banks E. Smokers increasingly motivated and able to quit as smoking prevalence falls: umbrella and systematic review of evidence relevant to the ‘hardening hypothesis’, considering transcendence of manufactured doubt. Nicotine Tob Res. 2022 Mar 3:ntac055. doi: 10.1093/ntr/ntac055. Epub ahead of print. PMID: 35239960. It is available here.
In addition to one of our papers Harris et al included in their analysis, we published two other papers dealing with subpopulations (that were not included because the paper only deals with full populations) that are, nevertheless, consistent with their findings:
- Kulik MC, Glantz SA. Softening Among U.S. Smokers With Psychological Distress: More Quit Attempts and Lower Consumption as Smoking Drops. Am J Prev Med. 2017 Dec;53(6):810-817. doi: 10.1016/j.amepre.2017.08.004. Epub 2017 Oct 10. PMID: 29029966; PMCID: PMC5696017.
- Kulik MC, Glantz SA. Similar softening across different racial and ethnic groups of smokers in California as smoking prevalence declined. Prev Med. 2019 Mar;120:144-149. doi: 10.1016/j.ypmed.2019.01.020. Epub 2019 Jan 29. Erratum in: Prev Med. 2019 Feb 15;: PMID: 30703378; PMCID: PMC6400071.
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