关键信息
加热烟草可能使人们接触到的毒素比香烟少，但可能比不使用任何烟草多。在日本推出加热烟草后，香烟销量的下降似乎加快了，但我们不确定这是否因为人们从香烟转向加热烟草所致。
我们需要更多独立资助的研究来探索是否加热烟草可以帮助人们戒烟，是否它会导致不良影响，以及加热烟草使用增加对吸烟率的影响。
（图片来自The BMJ）
什么是加热烟草制品？
加热烟草制品旨在将其加热到足够高的温度以释放蒸汽，而不会使其燃烧或产生烟雾。它们不同于电子烟，因为它们加热的是烟草叶或薄片，而非液体。香烟烟雾中的许多有害化学物质是由烟草燃烧产生的。因此，加热而非燃烧烟草可以减少使用者摄入其化学物质的量。有些人说可以通过转用加热烟草来完全戒烟。
我们为什么做本Cochrane综述
因为吸烟会使人上瘾，尽管它会造成伤害，很多人还是难以戒掉。我们的目的是了解尝试改用加热烟草是否可以帮助人们戒烟，以及是否它会导致不良影响。我们还想知道加热烟草使用的增加是否会影响吸烟率或香烟销量。
我们做了哪些工作？
我们检索那些报告了使用加热烟草来戒烟的研究，这些研究还报告了加热烟草使用者的不良反应和毒物暴露情况。在这里，我们仅纳入那些随机给予人们治疗的随机对照试验。这种类型的研究被认为是确定治疗是否有效的最可靠方法。最后，我们检索有关加热烟草上市后吸烟率和香烟销量变化的研究。我们纳入了截止2021年1月所发表的研究。
我们发现了什么
我们检索到13篇相关研究。没有研究报告加热烟草是否可以帮助人们戒烟。11项试验均由烟草公司资助，涉及2666名成年吸烟者，比较了被随机分到使用加热烟草组、继续吸香烟组或戒烟组的人群其不良反应和毒物暴露水平。
2项研究关注日本加热烟草推出后香烟销量的趋势如何变化。
我们的综述结果如何？
我们不知道使用加热烟草是否会帮助人们戒烟（没有研究对此进行测量）。
我们不确定被分到使用加热烟草而出现不良症状的几率是否与使用香烟（6项研究，1713名受试者）或戒烟（2项研究，237名受试者）不同。在所研究的短时间内（平均13周），严重不良症状在所有的分组中都很少见，这意味着我们不确定是否有差异。使用加热烟草的人其毒物水平很可能低于吸香烟者（10项研究，1959名受试者），但可能高于不适用任何烟草制品的人（5项研究，382名受试者）。
日本推出加热烟草可能导致香烟销量随着时间的推移而加速下降（2项研究），但尚不清楚吸烟者的比例是否也加速下降，因为没有研究关注这一点。
这些结果可信度如何？
结果基于少数研究的资料，这些研究中大多数都是由烟草公司资助的。
当有更多证据可用时，不良反应的结果可能会改变。然而，我们认为使用加热药草的人比吸香烟的人所测毒物的水平更低有中等程度的可信度，但其毒物水平比不吸烟的人更高有较低的可信度。我们认为加热药草推出导致香烟销量加速下降有较低的可信度，因为这一结果来自单一国家。
作者结论:
没有研究报告了戒烟情况，因此加热烟草用于戒烟的有效性仍不确定。没有足够的证据表明短期内被随机分到改为加热烟草组、吸香烟组或尝试戒烟组在不良或严重不良事件风险上存在差异。中等质量证据显示加热烟草组暴露于毒物或致癌物的风险相较于吸香烟组更低，而极低质量至中等质量证据显示，与那些尝试解除所有烟草的人相比，加热烟草组暴露风险更高。需要对HTPs有效性和安全性进行独立资助的研究。
在日本市场引入加热烟草后，香烟销量的下降速度更快了，但由于资料是的观察性的，有可能存在其他因素引起这些变化。此外，香烟销量的下降可能无法转化为吸烟率的下降，日本的变化可能无法推广到其他地方。为了阐明加热烟草的使用增加对吸烟率的影响，有必要进行时间序列研究来检验这一关联。
作者：Tattan-Birch H, Hartmann-Boyce J, Kock L, Simonavicius E, Brose L, Jackson S, Shahab L, Brown J；译者：孙雅佳，兰州大学循证医学中心；审校：郑偌祥，北京中医药大学循证医学中心；编辑排版：蒋子昀，北京中医药大学循证医学中心
相关文章链接
【Cochrane Plain Language Summary】
Do heated tobacco products help people to quit smoking, are they safe for this purpose, and have they led to falls in smoking rates?
Review question
Heated tobacco probably exposes people to fewer toxins than cigarettes, but possibly more than not using any tobacco. Falls in cigarette sales appeared to speed up following the launch of heated tobacco in Japan, but we are uncertain whether this is caused by people switching from cigarettes to heated tobacco.
We need more independently funded research into whether heated tobacco helps people stop smoking, whether it results in unwanted effects, and the impact of rising heated tobacco use on smoking rates.
What are heated tobacco products?
Heated tobacco products are designed to heat tobacco to a high enough temperature to release vapour, without burning it or producing smoke. They differ from e-cigarettes because they heat tobacco leaf/sheet rather than a liquid. Many of the harmful chemicals in cigarette smoke are created by burning tobacco. So heating not burning tobacco could reduce the amount of chemicals a user ingests. Some people report stopping smoking cigarettes entirely by switching to using heated tobacco.
Why we did this Cochrane Review
Because cigarette smoking is addictive, many people find it difficult to stop despite the harm it causes. We aimed to find out whether trying to switch to heated tobacco helps people stop smoking cigarettes, and whether it results in unwanted effects. We also wanted to find out whether rising heated tobacco use has affected smoking rates or cigarette sales.
What did we do?
We looked for studies that reported on the use of heated tobacco for stopping smoking, and on unwanted effects and toxin exposure in people asked to use heated tobacco. Here we only included randomised controlled trials, where treatments were given to people at random. This type of study is considered the most reliable way of determining if a treatment works. Finally, we searched for studies looking at changes in smoking rates and cigarette sales following the launch of heated tobacco to market. We included studies published up to January 2021.
What we found
Our search found 13 relevant studies. No studies reported whether heated tobacco helps people stop smoking cigarettes. Eleven trials, all funded by tobacco companies and with 2666 adult smokers, compared unwanted effects and toxin levels in people randomly assigned to use heated tobacco or to continue smoking cigarettes or abstain from tobacco use.
Two studies looked at how trends in cigarette sales changed following the launch of heated tobacco in Japan.
What are the results of our review?
We do not know whether using heated tobacco helps people to stop smoking cigarettes (no studies measured this).
We are uncertain whether the chances of getting unwanted symptoms from being asked to use heated tobacco are different compared with cigarettes (6 studies, 1713 participants) or no tobacco (2 studies, 237 participants). Serious unwanted symptoms in the short time period studied (average 13 weeks) were rare in all groups, which means we are uncertain about any differences. Toxin levels were probably lower in people using heated tobacco than those smoking cigarettes (10 studies, 1959 participants), but may be higher than in people not using any tobacco products (5 studies, 382 participants).
The launch of heated tobacco products in Japan may have caused the decline in cigarette sales to speed up over time (two studies), but it is unclear whether the fall in the percentage of people who smoke also sped up because no studies looked at this.
How reliable are these results?
Results are based on data from a small number of studies, most of which were funded by tobacco companies.
Results on unwanted effects are likely to change as more evidence becomes available. However, we are moderately confident that levels of measured toxins are lower in people using heated tobacco than smoking cigarettes, but less confident that levels were higher than in people not using any tobacco. We are also less confident that the launch of heated tobacco caused the fall in cigarette sales to speed up, as results came from a single country.
Authors' conclusions:
No studies reported on cigarette smoking cessation, so the effectiveness of heated tobacco for this purpose remains uncertain. There was insufficient evidence for differences in risk of adverse or serious adverse events between people randomised to switch to heated tobacco, smoke cigarettes, or attempt tobacco abstinence in the short-term. There was moderate-certainty evidence that heated tobacco users have lower exposure to toxicants/carcinogens than cigarette smokers and very low- to moderate-certainty evidence of higher exposure than those attempting abstinence from all tobacco. Independently funded research on the effectiveness and safety of HTPs is needed.
The rate of decline in cigarette sales accelerated after the introduction of heated tobacco to market in Japan but, as data were observational, it is possible other factors caused these changes. Moreover, falls in cigarette sales may not translate to declining smoking prevalence, and changes in Japan may not generalise elsewhere. To clarify the impact of rising heated tobacco use on smoking prevalence, there is a need for time-series studies that examine this association.
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