title: Prevalence of NRT use and associated nicotine intake in smokers, recent ex-smokers and longer-term ex-smokers.
abstract: BACKGROUND
  Nicotine replacement therapy (NRT) is used by smokers wanting to reduce their smoking and to quit. However, there are very little data on nicotine intake associated with NRT use in representative population samples. This study aimed to provide estimates for NRT use and associated nicotine exposure among smokers, recent and longer-term ex-smokers in England, a country with a permissive regulatory regime for nicotine substitution.
  
  
  METHODS
  In the Smoking Toolkit Study, a monthly series of representative household surveys of adults aged 16+ in England, current and recent ex-smokers who agreed to be re-contacted were followed up 6 months later and standard socio-demographic and smoking characteristics assessed (N = 5,467, response rate 25.1%). A random sub-sample (N = 1,614; 29.5%) also provided saliva, analysed for cotinine.
  
  
  RESULTS
  The sample followed up was broadly representative of the original sample. At follow-up, 11.8% (95%CI 10.9-12.8, N = 565) of current smokers, 34.8% (95%CI 28.9-41.3, N = 77) of recent (≤ 3 months) ex-smokers, and 7.8% (95%CI 5.6-10.6, N = 36) of longer-term (> 3 months) ex-smokers reported using NRT. Smokers who used NRT had similar saliva cotinine concentrations to smokers who did not use NRT (mean ± sd  = 356.0 ± 198.6 ng/ml vs. 313.1 ± 178.4 ng/ml). Recent ex-smokers who used NRT had levels that were somewhat lower, but not significantly so, than current smokers (216.7 ± 179.3 ng/ml). Longer-term ex-smokers using NRT had still lower levels (157.3 ± 227.1 ng/ml), which differed significantly from smokers using NRT (p = 0.024).
  
  
  CONCLUSIONS
  Concurrent use of nicotine replacement therapy while smoking is relatively uncommon and is not associated with higher levels of nicotine intake. Among ex-smokers, NRT use is common in the short but not longer-term and among longer-term users is associated with lower nicotine intake than in smokers.
authors.affiliation: Department of Epidemiology and Public Health, University College London, London, United Kingdom.
authors.forename: Lion
authors.initials: L
authors.lastname: Shahab
authors.affiliation: Department of Epidemiology and Public Health, University College London, London, United Kingdom.
authors.forename: Emma
authors.initials: E
authors.lastname: Beard
authors.affiliation: Department of Epidemiology and Public Health, University College London, London, United Kingdom; Department of Clinical, Educational and Health Psychology, University College London, London, United Kingdom.
authors.forename: Jamie
authors.initials: J
authors.lastname: Brown
authors.affiliation: Department of Epidemiology and Public Health, University College London, London, United Kingdom.
authors.forename: Robert
authors.initials: R
authors.lastname: West
mesh_terms: D003710:Demography; D004739:England / Q000453:epidemiology; D006801:Humans; D016014:Linear Models; D009538:Nicotine / Q000008:administration & dosage*; D015995:Prevalence; D012907:Smoking / Q000453:epidemiology*; D016540:Smoking Cessation / Q000379:methods* / Q000706:statistics & numerical data; D000074606:Smoking Prevention; D012959:Socioeconomic Factors; D061485:Tobacco Use Cessation Devices / Q000706:statistics & numerical data*
chemical_list: D009538:Nicotine