In the UK, smoking during pregnancy kills 4000 babies annually and costs an extra £20–90 million for pregnancy and infant care. Only 5–10% of pregnant smokers quit when offered current interventions. We aimed to assess efficacy, cost-effectiveness, and acceptability of adding £400 of shopping vouchers to routine pregnancy smoking cessation services.
This study was a phase 2, single-centre, single-blinded, parallel-group individually randomised controlled superiority trial with qualitative and health economic components. Participants were self-reported pregnant smokers referred to Stop Smoking Services between Dec 15, 2011, and Feb 28, 2013, in Greater Glasgow and Clyde, Scotland. Randomisation, with allocation concealed from staff and participants, was by computer generated permuted blocks of four. 306 participants were randomised to routine care and 306 to the intervention (routine care plus incentives), giving 90% power to detect an increase in smoking cessation from 4·0% in women in the control group to 11·4% in women given incentives. Assessors of the primary outcome were masked to allocation. Women in both groups were offered routine care—namely, the offer of face-to-face contact to set a quit date, 10 weeks' free nicotine replacement therapy, and support calls weekly for 4 weeks. In addition, women in the intervention group were offered £50 in vouchers for setting a quit date, £50 if carbon monoxide confirmed smoking cessation after 4 weeks, £100 after 12 weeks, and £200 in late pregnancy (34–38 weeks' gestation). The primary outcome, analysed by intention to treat, was self-report of quitting in late pregnancy corroborated by cotinine in saliva (<14·2 ng/mL) or urine (<44·7 ng/mL). Cost-benefit analysis used routine and trial derived data. Ethics approval supported telephone consent. This trial is registered with Current Controlled Trials, ISRCTN87508788.
Significantly more smokers who were offered incentives quit than did controls (69/306 [23%] vs 26/303 [9%], 95% CI 8·3–19·5). Three control participants opted out. The relative risk of smoking in late pregnancy was 0·85 (95% CI 0·79–0·91). No harms were reported, and incentives were acceptable to clients and health workers. Short-term incremental cost per quitter was £1127 and longer-term cost per quality-adjusted life year gained was £482.
This trial provides evidence for the efficacy and cost-effectiveness of financial incentives, which must now be tested in other centres and with varied cessation services.