An analysis of a national study by UC San Diego researchers published Monday found starting tobacco products, including e-cigarettes before the age of 18 is a major risk factor for people becoming daily cigarette smokers.
In the report, published in Monday's online edition of Pediatrics, Herbert Wertheim School of Public Health and Human Longevity Science researchers found in 2014 people ages 12 to 24 using e-cigarettes were three times as likely to become daily cigarette smokers in the future.
Among those who reported using a tobacco product, daily use increased with age through age 28. Daily cigarette smoking nearly doubled among 18 to 21-year-olds and 25 to 28-year-olds from 12% to 21%.
"This is the first paper that actually looks at progression to dependent cigarette smoking among young adults," said the study's first author, John Pierce, professor emeritus at the Herbert Wertheim school and UCSD Moores Cancer Center.
"In these data, e-cigarettes are a gateway for those who become daily cigarette smokers. The start product has changed from cigarettes to e-cigarettes, but the end product has stayed the same. When users become dependent on nicotine, they are converting to cigarette smoking," Pierce said.
Researchers used data from the Population Assessment of Tobacco and Health Study, a study of tobacco use and its effect on the health of people in the United States. The PATH Study enrolled a nationally representative sample of 12 to 24-year-olds between 2013 and 2014 and re-interviewed them annually for four years to explore progression to daily use among experimenters of 12 tobacco products.
In the first year, 45% of study participants reported using at least one tobacco product in their lifetime. By the fourth year, as participants aged, 62% reported some tobacco experimentation.
Among those who have experimented with tobacco, 73% had tried cigarettes and 72% had tried e-cigarettes. More than half tried hookahs and cigarillos. Traditional cigars, filtered cigars, smokeless products, pipes and snuffs were each tried by more than 10% of study participants.
The analyses revealed that, by year four, 12 % of participants were using tobacco products daily — half of whom became daily users after the first year. Of daily users, 70% smoked cigarettes and 63% used cigarettes exclusively. Of those who smoked cigarettes and used another tobacco product, half vaped e-cigarettes on a non-daily basis.
Among the 17% of daily users who were vaping every day, almost half were also non-daily cigarette smokers. Further follow-up will determine whether these young daily tobacco users continue to use both products or whether they settle on a single product, Pierce said.
"What we're seeing is that the proportion who are daily e-cigarette users did not increase with age. Whereas with cigarettes, the number of users jumps up rapidly with age," said Pierce. "This rapid increase with age only occurred with cigarettes, not with any other tobacco products."
Less than 1% of study participants who experimented with just one tobacco product progressed to daily cigarette smoking. People who had tried five or more products increased their risk of becoming daily cigarette smokers by 15 percentage points.
"Trying e-cigarettes and multiple other tobacco products before the age of 18 is also strongly associated with becoming daily cigarette smokers," said senior author Karen Messer, professor at the Herbert Wertheim School and director of biostatics at Moores Cancer Center.
"We know that e-cigarette use among high school seniors, most under the age of 18, increased from 38% in 2016 to 45% in 2019. These results suggest that recent rapid growth in adolescent e-cigarette use will lead to increased daily cigarette smoking among young adults in the United States, reversing decades of decline in cigarette smoking," she said.
