Institute of Epidemiology & Health Care


Long Term Nicotine Replacement Therapy

Impact of long-term nicotine replacement therapy use and impact of nicotine metabolite ratio on pharmacotherapy effectiveness

As part of the Evaluating Long-term Outcomes of NHS Stop Smoking Services (ELONS) study, we collected saliva samples from nearly 2,000 smokers who attended Stop Smoking Services and who were followed up for a year. Part of the results have already been published (PMID: 27664995), showing that clients rarely use products for up to a year and that nicotine replacement therapy (NRT) use does not affect users' stress response. Ex-smokers using NRT long-term can completely replace nicotine from cigarettes with nicotine from NRT; long-term NRT use by continuing smokers does not increase nicotine intake. Long-term NRT appears to be a safe and effective way to reduce exposure to combustible nicotine. As a second part of this project, we will evaluate whether the nicotine metabolite ratio (trans-3'-hydroxycotinine/cotinine; a biomarker of total nicotine clearance) impacts treatment effectiveness and whether this biomarker is a useful tool for personalising smoking cessation pharmacotherapy allocation.

Investigators: Lion Shahab

Contact: Lion Shahab (lion.shahab[at]ucl.ac.uk)


  • National Institute of Health Research (NIHR) Health Technology Assessment (HTA)
  • Global Research Awards for Nicotine Dependence (GRAND)
  • UK Centre for Tobacco and Alcohol Studies (UKCTAS) (formerly UK Centre for Tobacco Control Studies, UKCTCS)  

External collaborators

  • Kings College London
  • University of Stirling
  • University of Toronto
  • Global Research Award for Nicotine Dependancy