乌鸦传媒

The harms that electronic cigarettes currently pose to non-smoking teens and young adults far outweigh the potential benefits to adult smokers who want to give up conventional cigarettes, according to findings from a newly published risk analysis.

The risk model by Samir Soneji, PhD, of Dartmouth-Hitchcock Norris Cotton Cancer Center, Lebanon, N.H., and colleagues found that in a single year, 2,070 adult smokers would successfully kick the habit using e-cigarettes (albeit with a wide 95% confidence interval).

But the model also estimated that e-cigarette use among non-smoking teens and young adults would lead to 168,000 new smokers.

The study, published in , concluded that e-cigarette use currently represents more harm than benefit at the population level.

"The model suggests that the harms to kids are substantial in magnitude, while the promised benefits for smokers wanting to quit are not very robust," Soneji told 乌鸦传媒.

He said the study is among the first to attempt to quantify the balance of harms and benefits associated with e-cigarette use.

The researchers used census counts, national health and tobacco use surveys, and recent e-cigarette studies to calculate the expected years of life gained or lost from e-cigarette use on smoking cessation among current smokers and transition to long-term cigarette use among never smokers in a 2014 population cohort.

Using these data, the team performed stochastic simulation using the Monte Carlo model.

The investigators assessed three outcomes:

• Additional number of current cigarette smokers who will quit smoking through the current use of e-cigarettes and abstain from smoking for ≥7 years, compared with those who do not currently use e-cigarettes
• Additional number of adolescents and young adults who will initiative cigarette smoking through the ever use of e-cigarettes and eventually become daily cigarette smokers at age 35-39, compared with those who never used e-cigarettes
• Total number of expected years of life gained or lost across all these population subgroups

The estimates based on the modeling were as follows:

• A total of 2,070 additional current cigarette smoking adults ages 25-69 (95% CI -42,900 to 46,200) would quit smoking in 2015 and remain continually abstinent from smoking for ≥7 years through the use of e-cigarettes in 2014
• A total of 168,000 additional never-cigarette smoking adolescents ages 12-17 and young adults ages 18-29 (95% CI 114,000-229,000) would initiate cigarette smoking in 2015 and eventually become daily cigarette smokers at age 35-39 through the use of e-cigarettes in 2014
• E-cigarette use in 2014 would lead to 1,510,000 years of life lost (95% CI 920,000-2,160,000), assuming an optimistic 95% relative harm reduction of e-cigarette use compared with cigarette smoking
• Assuming an approximately 75% relative harm reduction, the model estimated -1,550,000 years of life lost (95% CI -2,200,000 to -980,000); assuming an approximately 50% harm reduction, the model estimated -1,600,000 years of life lost (95% CI -2,290,000 to -1,030,000)

Although electronic cigarette use is widely accepted as being safer than smoking combustible cigarettes, there is now strong evidence that their use by teens and young adults increases smoking risk, Soneji noted.

"There have now been about a dozen studies from different countries consistently showing about a threefold increased risk of smoking initiation among kids who vape. What is even more concerning is that the risk appears to be greatest among kids who are otherwise at low- or moderate-risk of starting smoking."

He said the current, population-level risk balance could shift if e-cigarettes are adequately regulated to make them unattractive and unavailable to teens, while optimizing their effectiveness as reduced-harm products for smoking cessation.

"Ten million smokers tried to quit last year. Half tried to quit cold turkey, which is a very ineffective way to quit. E-cigarettes may have some advantages over currently available nicotine-replacement therapies, in that, like cigarettes, they deliver nicotine through inhalation."

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