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Financial incentives for smoking cessation in pregnancy: randomised controlled trial

BMJ 2015; 350 doi: https://doi.org/10.1136/bmj.h134 (Published 27 January 2015) Cite this as: BMJ 2015;350:h134
  1. David Tappin, professor1,
  2. Linda Bauld, professor2,
  3. David Purves, research fellow3,
  4. Kathleen Boyd, lecturer4,
  5. Lesley Sinclair, trial manager2,
  6. Susan MacAskill, research fellow2,
  7. Jennifer McKell, research fellow2,
  8. Brenda Friel, health improvement senior5,
  9. Alex McConnachie, senior lecturer6,
  10. Linda de Caestecker, director of public health5,
  11. Carol Tannahill, director7,
  12. Andrew Radley, consultant in public health 8,
  13. Tim Coleman, professor9
  14. for the Cessation in Pregnancy Incentives Trial (CPIT) Team
  1. 1PEACH Unit, Child Health, Glasgow University, Yorkhill, Glasgow G3 8SJ, UK
  2. 2Institute for Social Marketing and UK Centre for Tobacco and Alcohol Studies, University of Stirling, Stirling, UK
  3. 3Strathclyde University, Glasgow, UK
  4. 4Health Economics and Health Technology Assessment Unit, Institute of Health and Wellbeing, Glasgow University, Glasgow, UK
  5. 5Public Health, NHS Greater Glasgow and Clyde, Glasgow, UK
  6. 6Robertson Centre for Biostatistics and Glasgow Clinical Trials Unit, Glasgow University, Glasgow, UK
  7. 7Glasgow Centre for Population Health, Glasgow, UK
  8. 8Directorate of Public Health, NHS Tayside, Dundee, UK
  9. 9Division of Primary Care and, UK Centre for Tobacco and Alcohol Studies, University of Nottingham, Nottingham, UK
  1. Correspondence to: D Tappin david.tappin{at}glasgow.ac.uk
  • Accepted 9 December 2014

Abstract

Objective To assess the efficacy of a financial incentive added to routine specialist pregnancy stop smoking services versus routine care to help pregnant smokers quit.

Design Phase II therapeutic exploratory single centre, individually randomised controlled parallel group superiority trial.

Setting One large health board area with a materially deprived, inner city population in the west of Scotland, United Kingdom.

Participants 612 self reported pregnant smokers in NHS Greater Glasgow and Clyde who were English speaking, at least 16 years of age, less than 24 weeks pregnant, and had an exhaled carbon monoxide breath test result of 7 ppm or more. 306 women were randomised to incentives and 306 to control.

Interventions The control group received routine care, which was the offer of a face to face appointment to discuss smoking and cessation and, for those who attended and set a quit date, the offer of free nicotine replacement therapy for 10 weeks provided by pharmacy services, and four, weekly support phone calls. The intervention group received routine care plus the offer of up to £400 of shopping vouchers: £50 for attending a face to face appointment and setting a quit date; then another £50 if at four weeks’ post-quit date exhaled carbon monoxide confirmed quitting; a further £100 was provided for continued validated abstinence of exhaled carbon monoxide after 12 weeks; a final £200 voucher was provided for validated abstinence of exhaled carbon monoxide at 34-38 weeks’ gestation.

Main outcome measure The primary outcome was cotinine verified cessation at 34-38 weeks’ gestation through saliva (<14.2 ng/mL) or urine (<44.7 ng/mL). Secondary outcomes included birth weight, engagement, and self reported quit at four weeks.

Results Recruitment was extended from 12 to 15 months to achieve the target sample size. Follow-up continued until September 2013. Of the 306 women randomised, three controls opted out soon after enrolment; these women did not want their data to be used, leaving 306 intervention and 303 control group participants in the intention to treat analysis. No harms of financial incentives were documented. Significantly more smokers in the incentives group than control group stopped smoking: 69 (22.5%) versus 26 (8.6%). The relative risk of not smoking at the end of pregnancy was 2.63 (95% confidence interval 1.73 to 4.01) P<0.001. The absolute risk difference was 14.0% (95% confidence interval 8.2% to 19.7%). The number needed to treat (where financial incentives need to be offered to achieve one extra quitter in late pregnancy) was 7.2 (95% confidence interval 5.1 to 12.2). The mean birth weight was 3140 g (SD 600 g) in the incentives group and 3120 (SD 590) g in the control group (P=0.67).

Conclusion This phase II randomised controlled trial provides substantial evidence for the efficacy of incentives for smoking cessation in pregnancy; as this was only a single centre trial, incentives should now be tested in different types of pregnancy cessation services and in different parts of the United Kingdom.

Trial registration Current Controlled Trials ISRCTN87508788.

Footnotes

  • Other members of the Cessation in Pregnancy Incentives Trial (CPIT) Team are: Andrew Briggs, chair in health economics, Health Economics and Health Technology Assessment Unit, University of Glasgow; Alan Cameron, honorary professor, obstetrics and gynaecology, School of Medicine, University of Glasgow; Liz Grant, lead public health pharmacist (health improvement); Margaret McFadden, research nurse; Anne Benson, project assistant, NHS Greater Glasgow and Clyde; Sue Stevenson, research nurse, University of Glasgow; Carol Anne Greenan, research administrator, University of Stirling; Caroline Haig, trainee biostatistician; John McHugh, clinical database manager, Robertson Centre for Biostatistics and Glasgow Clinical Trials Unit; and Janet Ferguson, trial manager (when the study was set up), University of Stirling.

  • Contributors: DT, LB, LdeC, CT, AM, KB, SM, and JM conceived and designed the work. LS managed the trial and, along with BF, SM, and JM collected the data. KB, DP, SM, JM, and AM analysed the data. AR, TC, DT, LB, and AM interpreted the data. All authors drafted the work or revised it critically for important intellectual content, gave final approval of the version to be published, and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. DT and LB are the guarantors.

  • Funding: The primary funder was the Chief Scientist Office, Scottish Government. Two additional main funders were the Glasgow Centre for Population Health and the Education and Research Endowment Fund of the Director of Public Health Greater Glasgow and Clyde health board. Additional funders were the Yorkhill Children’s Charity and the Royal Samaritan Endowment Fund. The funders had no role in writing the manuscript or the decision to submit it for publication. No payment from a pharmaceutical or any other company has been paid to write this article. The corresponding author had full access to all the study data and had the final responsibility for the decision to submit for publication. TC acknowledges the support of East Midlands Collaboration for Leadership in Applied Health Research and Care for his work in general, but no payment was received by him specifically for this study.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: This study was approved by West of Scotland research ethics committee 2.

  • Data sharing: Glasgow University in conjunction with the UK Centre for Tobacco and Alcohol Studies (Stirling University) and ECHO Managed Services, owners of the database are willing to examine all requests for the dataset on an individual basis after a period of three years from the date of this publication. Access to data will be formalised on a contractual basis with the UK Centre for Tobacco and Alcohol Studies in conjunction with Glasgow and Stirling Universities and ECHO Managed Services. The research protocol is available on request from the first author (david.tappin{at}glasgow.ac.uk). The protocol has been published: Tappin DM, Bauld L, Tannahill C, de Caestecker L, Radley A, McConnachie A, et al. The Cessation in Pregnancy Incentives Trial (CPIT): study protocol for a randomised controlled trial. Trials 2012;13:113.

  • Transparency: The lead author (DT) affirms that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

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