Monday September 9 2013
Some vapers are using e-cigs to cut out tobacco
"E-cigarettes 'as effective' as nicotine patches," BBC News reports, while The Independent suggests that they are actually more effective.
The well-designed research behind the headlines looked at the number of people who achieved continuous abstinence from smoking for six months. This was achieved by a slightly greater proportion of the people using e-cigarettes than those using nicotine replacement therapy (NRT) patches or a placebo (dummy) e-cigarette containing no nicotine.
However, there was no significant difference between any of the groups, meaning that people using nicotine e-cigarettes were no more or less likely to quit smoking than people using patches or placebo e-cigarettes. Similarly, there was no significant difference in the proportion of people abstinent over a seven-day period.
The quit rates in all groups were much lower than the researchers anticipated, so the findings may not be as reliable as the researchers had hoped.
The research did not have the statistical power to reliably detect significant differences between the three treatments.
This means it is still possible that e-cigarettes could be more effective than NRT patches, but this study couldn't detect this.
As the researchers conclude, "Uncertainty exists about the place of e-cigarettes in tobacco control, and more research is urgently needed to clearly establish their overall benefits and harms at both individual and population levels".
Where did the story come from?
The study was carried out by researchers from the University of Auckland and the University of Otago, New Zealand, Health New Zealand, and Queen Mary, University of London. Funding was provided by the Health Research Council of New Zealand.
The study was published in the peer-reviewed medical journal, The Lancet.
Although The Independent's headline reflects the trial's aim of seeing whether e-cigarettes are more effective than NRT patches, the BBC headline actually falls closer to the mark in reflecting the main findings of this trial: there was no significant difference found between the two treatments.
What kind of research was this?
This was a randomised controlled trial designed to investigate whether e-cigarettes are more effective than nicotine patches for helping smokers to quit.
E-cigarettes were launched in 2004 and are a battery-operated devices that vaporise nicotine for inhalation. As of May 2013, around a quarter of people trying to quit smoking were using e-cigarettes. However, the place of vaping in helping to reduce smoking is controversial, with a lack of reliable research on the devices because of their recent emergence.
This research tested the theory that e-cigarettes would be more effective than both nicotine replacement therapy (NRT) patches and placebo e-cigarettes containing no nicotine. The trial was conducted in New Zealand, where nicotine-containing e-cigarettes cannot be purchased over the counter, but "elusion" (placebo) e-cigarettes are widely available for purchase. A randomised controlled trial such as this is the best way of testing this theory.
What did the research involve?
The trial was conducted in Auckland, New Zealand, with initial recruitment through newspaper advertisements in September 2011. A total of 657 people met the eligibility criteria of being aged 18 or over, having smoked at least 10 cigarettes daily for the past year, and wanting to stop smoking.
The researchers did not include people using other cessation treatments, people with cardiovascular disease or those with other poorly controlled medical conditions.
Participants were randomised in a 4:4:1 ratio to the following groups:
- e-cigarettes (containing 10-16mg nicotine per ml) – 289 people
- NRT patches (delivering 21mg nicotine over 24 hours) – 295 people
- placebo e-cigarettes (without nicotine) – 73 people
People given the e-cigarettes did not know whether they had a placebo or not, but participants obviously were aware whether they had been given e-cigarettes or patches.
People randomised to either the e-cigarettes or the patches were advised to use the products from one week before until 12 weeks after their chosen quit date. All participants were referred to Quitline, which called the participants to offer telephone-based behavioural support. Researchers also asked the participants about their smoking history and prior quit attempts.
The main outcome that the researchers were interested in was "continuous smoking abstinence" at six months after quit date. This was defined as self-reported abstinence over the whole follow-up period (allowing five or fewer cigarettes in total), which was verified at that time by measuring exhaled breath carbon monoxide levels.
The researchers also looked at secondary outcomes at one, three and six months after quit date, including:
- proportion of participants reporting no smoking of tobacco cigarettes at all in the past seven days
- number of tobacco cigarettes smoked per day
- proportion of participants reducing tobacco smoking
- time to relapse to tobacco smoking
- number of patches or cartridges used
- use of other cessation treatments
- withdrawal symptoms
- adverse events
All 657 randomised participants were analysed in the groups that they had been assigned to, regardless of whether they completed follow-up (known as "intention to treat analysis"). Those who did not complete follow-up were assumed to be still smoking.
What were the basic results?
Although all participants were analysed, actual follow-up at six months was 83% of the e-cigarette group, 73% of the NRT patches group and 78% of the placebo e-cigarette group.
The main outcome of six months of continuous smoking abstinence was achieved by 7.3% of the nicotine e-cigarette group, 5.8% of the NRT patches group and 4.1% of the placebo e-cigarette group.
Despite the higher quit rates in the nicotine e-cigarette group, the differences seen in the patches and placebo group were not significant. This means that people using nicotine e-cigarettes were no more likely to quit smoking than those using patches or a placebo.
Of the other outcomes, the rates of participants who achieved abstinence for seven days were higher than continuous smoking abstinence in all groups:
- 23% at one month to 21% at six months for the nicotine e-cigarette group
- 17% at one month to 16% at six months for the NRT patches group
- 16% at one month to 22% at six months for the placebo e-cigarette group
However, despite the higher apparent rates in the nicotine e-cigarette group, again they were not significantly more likely to achieve this outcome at one, three or six months than those using NRT patches or placebo.
People using the nicotine e-cigarettes were, however, smoking around two fewer cigarettes per day (average nine per day) during follow-up than those using the NRT patches (average 11 per day), which was a significant difference.
When looking at time to relapse, average time to relapse was also significantly longer in the nicotine e-cigarettes group (35 days) than the patches group (14 days) or placebo e-cigarettes group (12 days).
There was no difference in the rate of any adverse events between nicotine e-cigarette and patches groups, which happened at a rate of around 0.8 events per person with nicotine e-cigarettes versus 0.9 with patches.
Serious adverse events (including deaths, hospital admissions or significant medical problems) accounted for 6% of all adverse events in the nicotine e-cigarettes group, 4% in the patches group and 3% in the placebo group. However, none of these serious events were considered to be related to study treatment.
How did the researchers interpret the results?
The researchers conclude that: "E-cigarettes, with or without nicotine, were modestly effective at helping smokers to quit, with similar achievement of abstinence as with nicotine patches, and few adverse events. Uncertainty exists about the place of e-cigarettes in tobacco control, and more research is urgently needed to clearly establish their overall benefits and harms at both individual and population levels."
This was a well-designed trial that set out to see whether nicotine-containing e-cigarettes are more effective than nicotine replacement patches at helping people to quit smoking.
This is an important research question because of the health benefits associated with quitting smoking and the rising popularity of e-cigarettes over the past decade or so.
Vapour analyses conducted in this trial showed that 300 puffs from one nicotine e-cigarette cartridge delivers 3-6mg of nicotine, the equivalent of smoking between one and five tobacco cigarettes.
The main outcome the researchers wanted to investigate was the continuous abstinence rate six months after the planned quit date. Despite the higher apparent rates of people achieving this outcome in the nicotine e-cigarette group, the difference in rates from the patches and placebo group were not significant. This meant people using e-cigarettes were no more likely to quit smoking than people using patches or a placebo.
In this sense, the researchers did not achieve the main objective of their trial, which was to demonstrate that e-cigarettes are more effective than NRT patches, as this was not demonstrated. E-cigarettes were found to in fact be no more or less effective than patches (or dummy e-cigarettes) for the main outcome of the trial.
As the researchers say, though, the proportion of people who achieved continuous abstinence at six months was low in all groups, and lower than they had expected. Therefore, the results for this primary outcome may be less reliable – that is, they are less able to reliably detect statistically significant differences between the groups when their analyses include such small numbers of people.
Seven-day abstinence rates were higher in all groups, although again there was no significant difference between nicotine e-cigarette, patches and placebo groups.
Some beneficial effects of nicotine e-cigarettes were noted, however: people using them smoked fewer cigarettes than those in the patches group (two fewer per day) and the time to relapse was longer. However, these were not the main outcomes the trial set out to investigate. Rates of adverse effects did not differ between groups.
Overall, the results of this trial suggest that patches, nicotine-containing e-cigarettes and dummy e-cigarettes were equally effective (or ineffective, depending on your view) at helping people quit smoking. But, as the researchers say, more research is needed to clearly establish the overall benefits and harms of e-cigarettes at both individual and population levels.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.