Objectives To evaluate the effectiveness of a complex intervention to improve referral and treatment of pregnant smokers in routine practice, and to assess the incremental costs to the National Health Service (NHS) per additional woman quitting smoking.
Design Interrupted time series analysis of routine data before and after introducing the intervention, within-study economic evaluation.
Setting Eight acute NHS hospital trusts and 12 local authority areas in North East England.
Participants 37 726 records of singleton delivery including 10 594 to mothers classified as smoking during pregnancy.
Interventions A package of measures implemented in trusts and smoking cessation services, aimed at increasing the proportion of pregnant smokers quitting during pregnancy, comprising skills training for healthcare and smoking cessation staff; universal carbon monoxide monitoring with routine opt-out referral for smoking cessation support; provision of carbon monoxide monitors and supporting materials; and an explicit referral pathway and follow-up protocol.
Main outcome measures Referrals to smoking cessation services; probability of quitting smoking during pregnancy; additional costs to health services; incremental cost per additional woman quitting.
Results After introduction of the intervention, the referral rate increased more than twofold (incidence rate ratio=2.47, 95% CI 2.16 to 2.81) and the probability of quitting by delivery increased (adjusted OR=1.81, 95% CI 1.54 to 2.12). The additional cost per delivery was £31 and the incremental cost per additional quit was £952; 31 pregnant women needed to be treated for each additional quitter.
Conclusions The implementation of a system-wide complex healthcare intervention was associated with significant increase in rates of quitting by delivery.
- smoking cessation
- natural experimental evaluation
- economic evaluation
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Contributors MWh and EMGM had the idea for the study. RB, MWh, SVG, SR, AC, JS, SH, LV and VAS obtained funding for the study. All authors contributed to the study design and development of the methods and interpretation of the data. SVG, EM, MWi and SJ collected data. SVG, ZVDW, EM, AC, RB, SJ, LV and SR contributed to the analyses. RB and SR wrote the manuscript with contributions from AC, ZVDW, EM, LV, SVG and VAS, and all authors commented on drafts. All authors approved the final version for publication. RB, LV and SR are the guarantors for the study.
Funding This article presents independent research funded by the NIHR School for Public Health Research (SPHR). NIHR SPHR is a partnership between the Universities of Sheffield, Bristol, Cambridge, Exeter, University College London; The London School for Hygiene and Tropical Medicine; the LiLaC collaboration between the Universities of Liverpool and Lancaster; and Fuse, the Centre for Translational Research in Public Health, a collaboration between Newcastle, Durham, Northumbria, Sunderland and Teesside Universities. Fuse is a UK Clinical Research Collaboration (UKCRC) Public Health Research Centres of Excellence, which receives funding from the British Heart Foundation, Cancer Research UK, Economic and Social Research Council, Medical Research Council, and the National Institute for Health Research.
Competing interests All authors have completed the unified disclosure form at www.icmje.org/coi_disclosure.pdf and declare no support from any organisation for the submitted work and no financial relationships with any organisations that might have an interest in the submitted work in the previous three years. We declare the following relationships and activities: MWh was on the commissioning panel for the intervention which appointed TCCC to deliver babyClear©. He is currently Director of the National Institute for Health Research’s Public Health Research programme. EMGM was Deputy Regional Director of Public Health for the North East Strategic Health Authority to March 2013, during which time he proposed and advocated the use of NHS funding for the initial commissioning of the intervention. MWi is employed by Fresh North East, which secured funding from the North East Strategic Health Authority to commission an intervention to improve the delivery of smoking cessation support to pregnant women. He was on the commissioning panel for the intervention.
Ethics approval The study was approved as a service evaluation by all eight participating hospitals. Caldicott approval for the release of data was obtained from trust, smoking cessation services or local authorities as appropriate.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data available.
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