Scholars have additional evidence that among U.S. adults some recent cigarette quitters may have done so with the assistance of electronic cigarettes.

The research informs the ongoing debate as to whether e-cigarettes are effective aids for smoking cessation or instead promote uptake by non-tobacco users.

Scholars analyzed data from the 2014 National Health Interview Survey (NHIS) of 36,697 U.S. adults age 18 and over to assess daily e-cigarette use and its association with demographic characteristics and cigarette smoking status. The researchers analyzed e-cigarette use among adults who are current daily cigarette smokers, current some day cigarette smokers, recent quitters - those who quit within the last year, former smokers who quit two to three years ago, former smokers who quit four or more years ago and never smokers.

Consistent with a report recently released by the U.S. Centers for Disease Control and Prevention (CDC), the authors found that, overall, 12.6 percent of all adults report having ever tried e-cigarettes. The Rutgers/Truth Initiative study goes further by examining daily use of e-cigarettes and found that nearly half (49 percent) of daily cigarette smokers have ever tried e-cigarettes. "The highest prevalence of daily e-cigarette use we observed was among current smokers and former smokers who quit within the past year.

The recent quitters are four times more likely to be daily users of e-cigarettes than current cigarette smokers (13 percent vs. 3.5 percent)," said Cristine Delnevo, the study's lead author. "This study is in line with other recent evidence that regular, daily e-cigarette use may help some smokers quit cigarettes."

The researchers also found that while any e-cigarette use was higher among young adults, daily e-cigarette use was more common among adults over age 25 than among young adults aged 18-24. They noted that e-cigarette experimentation was extremely low for adults who never smoked cigarettes or who quit more than four years ago.

Among their key takeaways: e-cigarettes do not appear to attract young adults, non-smokers or promote relapse among longer-term former smokers.

"The finding that daily e-cigarette use is less common among 18-24 year olds and never smokers is good news," according to David Abrams, executive director of the Schroeder Institute. "It suggests that e-cigarettes could be used to displace use of much more deadly cigarettes among smokers and could generate an impressive public health benefit in terms of lives saved. It is important to be clear, however, that e-cigarettes deliver nicotine, an addictive stimulant. They are not appropriate products for children and youth."

Longitudinal cohort studies will be needed to better understand issues such as dual use, exclusive e-cigarette use and e-cigarette use as a potential cessation aid.

"Patterns Of Electronic Cigarette Use Among Adults in the United States" was published in Nicotine&Tobacco Research.