Less Support for Gateway Effect: Study

Are young adults who vape but don’t smoke more likely to smoke in the future? Two recent research studies suggest that there is less support for the “gateway effect” than previously thought. The gateway effect is the idea that vaping e-cigarettes causes young people to smoke.

The Gateway Effect

Existing research indicates that vaping e-cigarettes is safer than smoking. Many people vape as a smoking cessation tool. However, concerns remain that vaping e-cigarettes may lead to smoking traditional cigarettes, particularly among the young. If it is true that this kind of a gateway effect exists, the presence of vaping products and e-cigarettes on the market might ultimately lead to more smokers, not fewer, over time.

The researchers in the first study conducted a meta-analysis, combining the results from 17 studies. Their aim was to investigate whether e-cigarette use in young non-smokers is associated with smoking cigarettes later. The team was able to calculate an odds ratio for each of the 17 studies examined here, which all investigated e-cigarette use and subsequent smoking.

Although the researchers found that young never smokers who had used e-cigarettes were four-and-a half times more likely to smoke later, they also identified a number of issues with the studies that were part of the analysis. This made them reluctant to make the connection that vaping leads to smoking.

National Youth Tobacco Survey

The second study examined data from the US National Youth Tobacco Survey between 2014 and 2017. That data included responses from approximately 40,000 US teens.

Researchers asked the teens were asked if they had ever tried a cigarette, even just a puff, and yes responses were “ever smokers.” Those who had smoked one or more cigarettes in the past 30 dats were also in their own category, with “established smokers” in a third category of teens who had smoked over 100 cigarettes to date.

In every group, the researchers compared teens who had tried e-cigarettes first to those who tried any other combustible tobacco product first, including cigars, pipes, cigarillos, or hookahs, and teens who first used non-combustible tobacco products, such chewing tobacco. They then adjusted the teens in these three groups for behavioral, demographic, and social characteristics.

Traditional cigarettes remained the most common ‘starter’ product, followed by other combustibles, and then e-cigarettes, and finally non-combustible tobacco products. This remained true even though e-cigarettes were used more frequently than all other products starting in 2015.

The researchers also found that girls were less likely to have tried any products, and the likelihood of experimentation increased with age.

Takeaways on Youth Vaping Research

“Policymakers have used the findings of studies, including the studies we reviewed in this research, to support the heavy regulation of e-cigarettes, including restrictions on flavors and even total bans, but the evidence that e-cigarette use might cause young people to take up smoking is not as strong as it might appear,” said researcher Jasmine Khouja in press materials from the first study.

For example, the evidence the team considered was limited in that it lacked biochemical verification, and relied instead on self-reporting. There were no negative controls in any of the studies, leaving the question of causality more open. Many studies also failed to assess nicotine content, so it is impossible to assess how nicotine drives these behaviors and associations.

The team recommends that future research take on the issues they have identified. For example, teams should address the nicotine content issue, confirm self-reporting results with biochemical analysis, and implement different statistical analyses, depending on the facts.

Notably, according to the press materials, a 2016 meta-analysis study covering nine studies found that young vapers were almost four times more likely to smoke later. This suggests that while the researchers are correct to suggest caution, more research, and better techniques, the association may yet be present.

From the second study, most importantly: those who vaped e-cigarettes first were less likely to ever smoke compared with those who first used tobacco alternatives to cigarettes. Furthermore, less than 1 percent of teenage  e-cigarette “triers” became established smokers–less than from any other category. In fact, only 2.7 percent of teens who vaped first became established smokers, compared to 9 percent of teens who first used combustible tobacco products and 16 percent of teen users of non-combustible products.

“This underlines the fact that cigarettes act as a much more important gateway for any product use,” state the researchers in the press materials. “This suggests that, over the time period considered, e-cigarettes were unlikely to have acted as an important gateway towards cigarette smoking, and may, in fact, have acted as a gateway away from smoking for vulnerable adolescents….The postulated gateway effect is likely to be small.”

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