Wednesday January 28 2015
Smoking exposes an unborn baby to around 4,000 chemicals
"Offering shopping vouchers worth a total of £400 to pregnant smokers makes them more likely to quit the habit, say researchers," BBC News reports.
The study, conducted in Glasgow, involved 612 pregnant women referred to pregnancy stop smoking services. The women were randomised to receive standard stop smoking care alone (control), or standard care in addition to up to £400 in vouchers if they successfully quit the habit.
The study found significantly more women in the voucher group (22.5%) stopped smoking by late pregnancy (34 to 38 weeks) compared with the control group (8.6%).
An obvious response to this – found in many news websites, as well as comments on message boards – is why should we bribe women to do what is best for their unborn baby?
A pragmatic answer to that question is it could save children's lives. Smoking during pregnancy is a major health problem estimated to cause the deaths of 5,000 unborn foetuses and babies each year in the UK, and costs the health system millions of pounds.
And the results of this study were within the range considered to be a cost effective use of healthcare resources.
A caveat of the research, though, is those who took part in the study represented only one-fifth of all pregnant smokers.
The way to reduce smoking among the apparent majority who do not wish to engage with stop smoking services, and may be less motivated to quit, is another problem.
Further studies in other parts of the UK are now needed to see if a national programme would be cost effective.
Where did the story come from?
The study was carried out by researchers from the University of Stirling, Glasgow University, and the University of Nottingham.
Funding was provided primarily by the Chief Scientist Office and the Scottish government, with additional funding from the Glasgow Centre for Population Health, the Education and Research Endowment Fund of the Director of Public Health Greater Glasgow and Clyde Health Board, the Yorkhill Children's Charity, and the Royal Samaritan Endowment Fund.
The study was published in the peer-reviewed British Medical Journal, and the article is open access, so it can be read for free online or downloaded as a PDF.
The media is generally representative of this research, and most coverage contains various discussions around the ethical aspects of financial incentives.
Interestingly, a comparable media response was seen after a similar – and apparently successful – voucher scheme hit the headlines, which we discussed in November 2014, where mothers were given vouchers if they committed to breastfeeding their baby.
What kind of research was this?
This was a phase II randomised controlled trial (RCT) that aimed to assess the effectiveness of adding a financial incentive to routine specialist stop smoking services for pregnant women to help them quit.
There are various stages of clinical trial that go towards demonstrating whether or not a particular treatment is safe and effective, and could possibly be appropriate for wider use.
Phase II trials follow on from phase I trials and include more people. They gather more evidence about whether the particular treatment is safe and if there are any side effects, who it is most effective for, and what's the best way to give treatment.
If phase II trials are successful, they lead on to larger phase III trials, which aim to demonstrate whether or not the treatment is effective compared with a control or another active treatment.
Smoking in pregnancy is associated with various adverse effects during pregnancy, including an increased risk of miscarriage, premature birth, low birthweight, and stillbirth, in addition to various maternal health effects.
The National Institute for Health and Care Excellence (NICE) has highlighted the need for evidence on the effectiveness of financial incentives. Recent studies have suggested financial incentives may help pregnant smokers stop, but more evidence is needed.
The researchers involved in this study carried out the RCT in a single centre in Glasgow to look at the acceptability and effectiveness of giving up to £400 of shopping vouchers, in addition to routine specialist pregnancy NHS stop smoking services, to help these women quit.
What did the research involve?
Pregnant women over the age of 16 were recruited from maternity booking clinics in Glasgow between December 2011 and February 2013. They were eligible if they reported they were smokers and special breath tests (carbon monoxide test) also indicated they were smokers.
All pregnant smokers were referred to specialist pregnancy stop smoking services. Women who agreed to take part in the trial were then randomly allocated to either receive up to £400 of shopping vouchers (staggered over time) if they engaged with services and subsequently quit smoking, in addition to routine stop smoking services or routine stop smoking services alone.
Stop smoking services offer an initial one-hour appointment to discuss smoking and set a quit date, followed by four further support calls and free nicotine replacement treatment for 10 weeks. Smoking status was assessed four weeks, 12 weeks, and one year after the set quit date.
In the incentives group, people received £50 if they attended their initial appointment and set a quit date.
Those who reported not smoking at all for the past two weeks (abstinence) at the four-week point after their quit date were visited at home and took a breath test to confirm this.
Confirmed quitters received another £50 voucher. If 12 weeks later they had still quit, they received £100.
Women's smoking status was assessed again between 34 and 38 weeks of pregnancy, and £200 was given if they were confirmed to be abstinent.
Being abstinent at this stage was defined as the woman reporting not smoking, or smoking fewer than five cigarettes in the past eight weeks.
This was verified by testing the women's urine or saliva for the levels of a chemical called cotinine, which is increased in smokers.
The main outcome the researchers were interested in was quitting smoking in late pregnancy, at between 34 and 38 weeks.
Other outcomes included attendance for the initial appointment, not smoking four weeks after the quit date, quitting six months after birth (postnatally), and pregnancy outcomes (miscarriage, pre-term birth, low birthweight and stillbirth).
What were the basic results?
A total of 612 women agreed to participate in the trial – 306 were allocated to the financial incentive group and 306 to the control group.
This represented only 20% of all self-reported smokers who attended for a maternity booking during the study period (3,052 women), and 53% of those who got as far as being contacted by stop smoking services (1,150 women).
Significantly more women stopped smoking between 34 and 38 weeks in the incentive group (22.5%) than the control group (8.6%).
This was calculated as a more than doubled likelihood of stopping smoking by the end of the pregnancy with the financial incentive (relative risk [RR] 2.63, 95% confidence interval [CI] 1.73 to 4.01).
The researchers calculated this meant around 7 to 8 women would need to receive a financial incentive for one additional woman to stop smoking. Or, in more precise terms, the intervention had a number needed to treat (NNT) of 7.2.
Looking at other outcomes, incentives increased self-reported abstinence four weeks after the women's agreed quit dates, but had no effect on the percentage of women attending the initial engagement with stop smoking services or any of the birth outcomes.
How did the researchers interpret the results?
The researchers concluded that: "This phase II randomised controlled trial provides substantial evidence for the efficacy of incentives for smoking cessation in pregnancy."
They say that as it was only a single-centre trial, financial incentives should now be tested in different types of pregnancy cessation services in different parts of the UK.
This randomised controlled trial demonstrates that adding financial incentives to standard stop smoking services increases the proportion of women who stop smoking in late pregnancy.
The trial was well conducted, including regular contact with participants up to six months postnatally, and all self-reported smoking measures were checked with chemical tests.
The proportion of women who could not be followed up was also fairly low, and was the same in both groups (about 15%). The researchers assumed those who could not be followed up were still smokers in their analyses, which is appropriately cautious.
The study does demonstrate such schemes may be successful. As the researchers say, their study has only looked at services in Glasgow, and other studies would now be needed in other parts of the UK to see if the scheme works as well.
The study does raise some questions, though. Financial incentives were demonstrated to have more than doubled cessation rates by the end of pregnancy, but only among pregnant smokers who agreed to be referred to stop smoking services.
These were women who the services were able to contact through repeated calls and who then agreed to take part. In the end, this was only 20% of self-reported smokers who attended maternity bookings during this period.
The results therefore may not be representative of what could be achieved in the other 80% of pregnant smokers, who may be less motivated to quit.
Further study may benefit from exploring the reasons why some women may not engage with specialist pregnancy smoking services, and ways to reach greater numbers of women.
Another issue the researchers raise about these types of schemes is the potential for women to be untruthful if the outcomes are reliant on self-reported smoking status alone, without being verified through breath, blood and urine tests, as used in this trial context.
As they also say, it is possible the women in this study only stopped smoking temporarily around the time the measures were taken. Further study therefore may be needed looking at the issue of unreliable reporting around real smoking status in pregnancy.
Some may also be concerned about the potential extra financial strain these schemes could put on the NHS. The researchers report the extra cost for each extra quitter who had stopped smoking by late pregnancy was £1,127 – as well as the actual vouchers, there are administrative and staffing costs to take into account.
Additional calculations suggest the scheme would represent good value for money for the NHS, based on the thresholds usually used.
Financial incentives for health behaviour change are always going to be controversial: "Public perceptions of 'paying' individuals to change behaviour can be negative," the researchers acknowledged. But they report a public opinion survey conducted as part of a related study deemed such schemes acceptable.
Whatever opinions and ethical considerations there may be around financial incentives, smoking during pregnancy remains a major health problem – estimated to cause the deaths of 5,000 unborn foetuses and babies each year in the UK – and is currently responsible for millions of pounds of healthcare spending. These factors need to be balanced, and it clearly remains an important and sensitive area to be addressed.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.