The association between treatment adherence to nicotine patches and smoking cessation in pregnancy

Conference: 
SAPC ASM 2016 - Dublin
Talk Code: 
P1.41
Presenter: 
Luis Vaz
Co-authors: 
Paul Aveyard, Sue Cooper, Jo Leonardi-Bee, Tim Coleman, on behalf of the SNAP trial team
Author institutions: 
University of Nottingham, University of Oxford

Problem

In non-pregnant ‘quitters’, adherence to nicotine replacement therapy (NRT) increases the chances of smoking cessation. However, NRT is poorly adhered to by pregnant ‘quitters’ and this may explain the apparently lower efficacy of NRT in pregnancy. We investigated relationships between adherence to placebo or NRT patches and cessation in pregnancy, including an assessment of reverse causation.

Approach

Data from 1,050 pregnant women randomised to placebo or NRT patches were analysed using regression models to investigate associations between maternal characteristics and number of patches used (adherence), and adherence and odds of smoking cessation, investigating moderation of this latter relationship by treatment allocation. Sensitivity analyses were conducted using a subgroup of abstinent participants in whom reverse causation could not explain apparent associations.

Findings

Reported adherence during the first month of treatment was significantly higher in women with lower cotinine concentrations when smoking (adjusted beta -0.08, 95%CI -0.15 to -0.01) and in those randomised to NRT rather than placebo (adjusted beta 2.59, 95%CI 1.50 to 3.68). Reported adherence during the first and second months of treatment was lower in more dependent women (adjusted beta -0.27, 95%CI -0.50 to -0.05, p<0.001) and higher in women randomised to NRT (adjusted beta 0.51, 95%CI 0.29 to 0.72, p<0.001). Adherence with any trial patch was associated with increased odds of cessation at one month (for each extra day of patch use: adjusted OR 1.11, 95%CI 1.08 to 1.13) and at delivery (adjusted OR 1.06, 95%CI 1.03 to 1.09). In the full sample, greater adherence to nicotine, but not placebo, patches was associated with increased odds of cessation (OR 2.47, 95%CI 1.32 to 4.63); but this was not seen in the sensitivity analyses (OR 0.98, 95%CI: 0.44 to 2.18).

Consequences

Women who were more adherent to NRT were more likely to achieve abstinence; more nicotine dependent women probably showed lower adherence to NRT because they relapsed to smoking more quickly. However, adherence to nicotine patches was higher than placebo patches, suggesting that the association between adherence and cessation is not entirely explained by reverse causation.

Submitted by: 
Luis Vaz
Funding acknowledgement: 
This work was supported by a grant from the National Institute for Health Research (NIHR) Health Technology Assessment (HTA) Programme [HTA 06/07/01]. The views and opinions expressed in this article are those of the authors and do not necessarily reflect those of the NIHR HTA Programme, the NIHR, the NHS, or the Department of Health. LRV’s studentship, provided by the UK Centre for Tobacco and Alcohol Studies (UKCTAS), was funded by the UK Clinical Research Collaboration (UKCRC). LRV, TC, SC and PA are members of the NIHR School for Primary Care Research. LRV, TC, SC, PA and JLB are members of the UK Centre for Tobacco and Alcohol Studies (http://www.ukctas.ac.uk). Funding from the British Heart Foundation, Cancer Research UK, the Economic and Social Research Council, the Medical Research Council and the National Institute of Health Research, under the auspices of the UK Clinical Research Collaboration, is gratefully acknowledged. The research was supported by the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care East Midlands at NHS Nottingham City CCG.