A comprehensive review of global research on smoking cessation suggests that nicotine-containing e-cigarettes may help more people quit smoking than other commonly used methods. These include nicotine replacement therapies (such as nicotine patches, gum, and lozenges), as well as nicotine-free e-cigarettes and behavioral support programs.
This analysis brings together findings from multiple systematic reviews to get a clearer picture of what is most effective for smoking cessation. In total, the researchers synthesized the results of 14 systematic reviews conducted between 2014 and 2023 to facilitate interpretation and comparison of the evidence.
The strongest evidence supporting nicotine e-cigarettes
When focusing on the highest quality studies, results consistently show that nicotine e-cigarettes lead to higher quit rates than other approaches. In contrast, lower quality studies produced less consistent and more uncertain results. Overall, the most reliable evidence shows that nicotine e-cigarettes are superior to nicotine replacement therapy, non-nicotine e-cigarettes, and other alternatives.
As part of the project, researchers developed an ‘Evidence and Gap Map’ (EGM) highlighting areas where further research is needed. Currently, there are no high-quality systematic reviews directly comparing nicotine-containing e-cigarettes and treatments such as cytisine, bupropion, or nicotine pouches. The evidence comparing e-cigarettes and varenicline is also very limited, based on just one small study with a high risk of bias.
The EGM also shows that the evidence regarding serious adverse events associated with e-cigarettes remains uncertain. Furthermore, most of the available data comes from high-income countries. The researchers highlight the need for future studies to better track potential risks and include populations in low- and middle-income countries.
Researchers say the evidence is clear
Dr Angela Diffen Wu, Principal Researcher and Lecturer at the University of Oxford’s Nuffield School of Primary Care and Health Sciences, said: “We hope that this overview, evidence and gap map can allay some claims that the evidence is ‘mixed’ regarding the impact of nicotine e-cigarettes on smoking cessation. In fact, the evidence is clear and consistent across all the meta-analyses we have consulted. E-cigarettes are effective in helping people quit smoking.”
This research work was funded by Cancer Research UK (grant number PRCPJT-Nov22/100012).
