New review from Cochrane Tobacco and Addiction GroupKey messages
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 the authors are uncertain whether this is caused by people switching from cigarettes to heated tobacco.
The authors 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.
Because cigarette smoking is addictive, many people find it difficult to stop despite the harm it causes. The author team aimed to find out whether trying to switch to heated tobacco helps people stop smoking cigarettes, and whether it results in unwanted effects. They also wanted to find out whether rising heated tobacco use has affected smoking rates or cigarette sales.
They 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 they 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, they searched for studies looking at changes in smoking rates and cigarette sales following the launch of heated tobacco to market. They included studies published up to January 2021.
Their 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?
The authors do not know whether using heated tobacco helps people to stop smoking cigarettes (no studies measured this).
They 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.