title: How effective is nicotine replacement therapy in helping people to stop smoking?
abstract: OBJECTIVE
  To assess the efficacy of nicotine replacement therapy in helping people to stop smoking.
  
  
  METHODS
  Analysis of the results of 28 randomised trials of nicotine 2 mg chewing gum, six trials of nicotine 4 mg chewing gum, and six trials of nicotine transdermal patch.
  
  
  METHODS
  Subjects were self referred (responding to advertisements or attending anti-smoking clinics) in 20 trials and invited (general practice or hospital patients) in 20. Therapists in self referred trials were generally experienced in helping people stop smoking but not in invited trials.
  
  
  METHODS
  Efficacy was defined as difference in percentages of treated and control subjects who had stopped smoking at one year.
  
  
  RESULTS
  Efficacy was highly significant (P < 0.001) for both gum and patch. Nicotine 2 mg chewing gum had an overall efficacy of 6% (95% confidence interval 4% to 8%), greater in self referred subjects than in invited subjects (11% v 3%). Efficacy depended on the extent of dependence on nicotine as assessed by a simple questionnaire; it was 16% (7% to 25%) in "high dependence" smokers, but in "low dependence" smokers there was no significant effect. The 4 mg gum was effective in about one third of "high dependence" smokers. The efficacy of the nicotine patch (9% (6% to 13%) overall) was less strongly related to nicotine dependence, perhaps because the patch cannot deliver a bolus of nicotine to satisfy craving.
  
  
  CONCLUSIONS
  Both gum and patch are effective aids to help nicotine dependent smokers who seek help in stopping. Among the most highly nicotine dependent smokers (those craving a cigarette on waking) the 4 mg gum is the most effective form of replacement therapy; it could enable one third to stop. In less highly dependent smokers the different preparations are comparable in their efficacy but the patch offers greater convenience and minimal need for instruction in its use. Overall, nicotine replacement therapy could enable about 15% of smokers who seek help in stopping smoking to give up the habit.
authors.affiliation: Department of Environmental and Preventive Medicine, Wolfson Institute of Preventive Medicine, St Bartholomew's Hospital Medical College, London.
authors.forename: J L
authors.initials: JL
authors.lastname: Tang
authors.forename: M
authors.initials: M
authors.lastname: Law
authors.forename: N
authors.initials: N
authors.lastname: Wald
mesh_terms: D000279:Administration, Cutaneous; D002638:Chewing Gum; D004334:Drug Administration Schedule; D006801:Humans; D009538:Nicotine / Q000008:administration & dosage* / Q000097:blood; D016032:Randomized Controlled Trials as Topic; D012907:Smoking / Q000097:blood; D016540:Smoking Cessation / Q000379:methods*; D019966:Substance-Related Disorders / Q000188:drug therapy
chemical_list: D002638:Chewing Gum; D009538:Nicotine