A protocol for the economic evaluation of the Smoking Cessation in Pregnancy Incentives Trial (CPIT III)

Nicola McMeekin, Lesley Sinclair, Linda Bauld, David M Tappin, A Mitchell, Kathleen A. Boyd

Research output: Contribution to journalArticlepeer-review


Smoking results in an average 10-year loss of life, but smokers who permanently quit before age 40 can expect a near normal lifespan. Pregnancy poses a good opportunity to help women to stop; around 80% of women in the UK have a baby, most less than age 40. Smoking prevalence during pregnancy is high; 17-23% in the UK. Smoking during pregnancy causes low birth weight and increases the risk of premature birth. Post-birth, passive smoking is linked to sudden infant death syndrome, respiratory diseases and increased likelihood of taking up smoking. These risks impact the long-term health of the child with associated increase in health costs. Emerging evidence suggests that offering financial incentives to pregnant women to quit is highly cost-effective.
This protocol describes the economic evaluation of a multi-centre randomised controlled trial (CPIT III) designed to establish whether offering financial incentives, in addition to usual care, is effective and cost-effective in helping pregnant women to quit.

Methods and Analysis
The economic evaluation will identify, measure and value resource use and outcomes from CPIT III, comparing participants randomised to either usual care or usual care plus up to £400 financial incentives. Within-trial and long-term analyses will be conducted from a National Health Service and Personal Social Services perspective, the outcome for both analyses will be quality adjusted life-years measured using EQ-5D-5L. Patient level data collected during the trial will be used for the within-trial analysis, with an additional outcome of cotinine validated quit rates at 34-38 weeks gestation and six-months post-partum. The long-term model will be informed by data from the trial and published literature.

Ethics and Dissemination
Ethics approval received from NHS West of Scotland Research Ethics Committee-2, August 2017. Dissemination through peer-reviewed publications and presentations.

Registration details
Trial registration number: ISRCTN15236311, date registered 09/10/2017

Strengths and limitations of this study:
• Prospectively designed economic evaluation of a phase III randomised controlled trial with sites across the UK
• Preference-based (utility) outcome measures at late-stage pregnancy and 6-months post-partum to enable decision-making
• 6-months post-partum follow-up is the longest we are aware of, making this a novel study
• Lifetime extrapolation includes costs and outcomes for both mother and infant
• Challenges relate to different smoking cessation service delivery at each trial site
Original languageEnglish
JournalBMJ Open
Issue number10
Early online date27 Oct 2020
Publication statusE-pub ahead of print - 27 Oct 2020


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