By switching to e-cigarettes, the researchers say tobacco users may reduce their exposure to certain carcinogens, or cancer causing substances.
For six months, the research team followed 520 smokers looking to reduce their cigarette consumption by at least 50% but had no plans to quit. They observed whether the use of various electronic nicotine delivery systems (ENDS)—used by around 10 million US adults—led to reduced cigarette consumption.
Study participants randomly received an ENDS containing 0 mg/mL (placebo), 8 mg/mL, or 36 mg/mL nicotine, or a cigarette substitute with no nicotine, electronics, or aerosols.
Throughout the study, researchers encouraged participants to reduce their cigarette consumption. At the end of six months, significantly more participants who had received the 36 mg/mL nicotine ENDS, which has similar nicotine delivery to a cigarette, reported remaining abstinent from cigarettes compared to the other study groups.
“Across the board, quit rates were low as none of the participants entering the trial had plans to quit, nor did they receive advice to quit during those six months,” says Jonathan Foulds, professor of public health sciences at the College of Medicine at Penn State and lead author of the study in Nicotine and Tobacco Research.
“However, over time, we noticed that the number of those receiving the high nicotine-delivery ENDS who abstained from cigarettes gradually increased. That trend was not observed in those receiving the placebo ENDS or the non-ENDS cigarette substitute.
“This is the first randomized clinical trial of electronic cigarettes to find that a nicotine e-cig produced a significant increase in smoking cessation at six months follow-up, compared with a placebo e-cig as well as compared to a non-ENDS cigarette substitute.”
NICOTINE DELIVERY MATTERS
Previous trials have examined the effects of ENDS on cigarette cessation, but the researchers note many of those studies used devices and liquids with unknown or unconfirmed nicotine delivery profiles.
“One of the strengths of our study was that the nicotine delivery of the specific ENDS device paired with the different liquids used in this study were confirmed before the trial,” says coauthor Thomas Eissenberg, professor at Virginia Commonwealth University. “It is evident based on our findings that ENDS with ineffective or less potent nicotine delivery likely won’t help participants to quit cigarette smoking.”
The researchers encouraged participants to reduce their cigarette consumption by 50% and then 75% for a six-month period. They measured cigarette consumption and various biomarkers, such as exhaled carbon monoxide levels, during eight follow-up visits. They determined the proportion of participants in each group who reported that they had smoked no cigarettes in the prior week.
At the six-month mark, significantly more participants in the 36 mg/mL nicotine group (about 11%) reported cigarette abstinence than in the 0 mg/mL (1%) and cigarette substitute (3%) groups. Approximately 5% of participants in the 8 mg/mL group reported cigarette abstinence at the six-month mark.
“We were surprised to see that the 8 mg/mL group didn’t have a significantly higher quit rate than the placebo group,” says Jessica Yingst, Penn State Cancer Institute researcher and assistant professor of public health sciences at Penn State College of Medicine. “These results indicate that if an ENDS doesn’t deliver as much nicotine as a cigarette, then it’s less likely that smokers using those devices will abstain from using cigarettes.”
The main conclusion of the study, the researchers say, is that when people seeking to reduce smoking try ENDS, few quit cigarettes in the short term. However, smokers that continued to use an ENDS with cigarette-like nicotine delivery (the 36 mg/mL group), were more likely to stop smoking in the short term and completely switch to ENDS, compared to those who used a placebo ENDS.
Devices with nicotine delivery similar to a cigarette may be more effective in enabling ambivalent smokers to quit cigarettes.
“In addition to having a higher quit rate at the end of the trial, the 36 mg/mL group also reported more days without smoking cigarettes throughout the trial than the other three groups,” notes Caroline Cobb, coauthor and associate professor at Virginia Commonwealth University.
NOT A MAGIC BULLET
The study team says that more research is needed to confirm and expand upon their findings, but they are encouraged that participants using ENDS products while still smoking cigarettes did not have a higher frequency of serious adverse events. They note that the medical monitors did not attribute any serious adverse events observed during the study to the use of the ENDS devices.
“The results of our study reflect many patterns of ENDS use that have been found in other studies and in society in general,” says Foulds, a Penn State Cancer Institute researcher. “Many people use ENDS and continue smoking cigarettes for a period of time before quitting smoking. ENDS are not a magic bullet, but our results support the idea that ENDS with cigarette-like nicotine delivery may be critical to someone’s ability to abstain from cigarettes.”
Additional coauthors are from Virginia Commonwealth University, the University of Wisconsin-Milwaukee, the University of Auckland, and Penn State College of Medicine.
Jonathan Foulds has done paid consulting for pharmaceutical companies involved in manufacturing smoking-cessation medications (e.g., Pfizer, GlaxoSmithKline, Johnson & Johnson); and has acted as a deposed and compensated expert witness on behalf of plaintiffs suing cigarette manufacturers. Other author disclosures can be read in the published manuscript.
The National Institute on Drug Abuse of the National Institutes of Health and the Center for Tobacco Products of the US Food and Drug Administration funded the work. The National Center for Advancing Translational Sciences supported data collection. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or the Food and Drug Administration.