National Centre for Epidemiology and Population Health, The Australian National University, Canberra, Australia.
Research School of Psychology, College of Health and Medicine, The Australian National University, Canberra, Australia.
Nicotine Tob Res. 2022 Jul 13;24(8):1321-1328. doi: 10.1093/ntr/ntac055.
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 behavior as smoking prevalence declines, to assess whether population "hardening" (decreasing propensity to quit) or "softening" (the converse) is occurring.
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.
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.
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.
This umbrella review and systematic review provides a critical consideration of evidence from epidemiology and psychology and other fields regarding the "hardening hypothesis"-a persistent myth undermining tobacco control. It reaches the conclusion that the sum-total of the worldwide 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."
“硬化假说”提出，随着人群中吸烟的流行率下降，剩余吸烟者的人群会“硬化”。本综述考察了吸烟流行率下降时吸烟者的动机、依赖和戒烟行为的证据，以评估人群是在“硬化”（戒烟倾向下降）还是“软化”（相反）。
使用与吸烟和硬化相关的术语，对 MEDLINE、PsychINFO、Scopus、Web of Science 和 Cochrane Library 进行了检索，检索时间截至 2019 年 7 月，检索内容为综述和基于人群的大型重复横断面研究。还对关键研究文章的参考文献列表和引文进行了额外搜索。两位审查员每人筛选了一半的标题和摘要，两位审查员使用经过测试的标准独立筛选全文。四位审查员独立且系统地从合格出版物中提取数据，每项研究由一位审查员负责，由另一位审查员检查。
在 265 个标题中，有三篇综述和十项重复的横断面研究被纳入。综述的结论是，随着时间的推移，一般吸烟人群中并没有出现硬化现象。在重复的横断面研究中，有五项研究检查了动机，九项研究检查了依赖性，五项研究检查了硬核心吸烟，两项研究检查了戒烟结果。除一项研究外，其余研究均未发现硬化现象。大多数研究发现吸烟人群中存在软化现象，这在硬化指标、定义、国家（和烟草控制环境）以及研究期间都一致。
烟草控制降低了吸烟流行率，并促进了更能接受基于证据的干预措施的吸烟人群。基于现有证据的权重，应该拒绝“硬化假说”，并接受软化的现实。
本综述和系统综述对来自流行病学、心理学和其他领域的关于“硬化假说”的证据进行了批判性考虑，该假说一直是烟草控制的一个持久神话。结论是，全世界的证据总和表明，吸烟人群要么是“软化”，要么是缺乏硬化。因此，烟草控制降低了吸烟流行率，并促进了更能接受基于证据的干预措施的吸烟人群。该综述表明，现在是时候采取积极措施打击硬化神话，并用软化的现实取而代之了。
