title: A systematic review of studies assessing the association between adherence to smoking cessation medication and treatment success.
abstract: OBJECTIVE
  Lack of adherence to smoking cessation medication regimens is assumed to play a significant role in limiting their effectiveness. This study aimed to assess evidence for this assumption.
  
  
  METHODS
  A systematic search was conducted, supplemented by expert consultation, of papers reporting on randomized trials and observational studies examining the association between adherence to cessation medication and the success of quit attempts. To rule out reverse causality, only studies where adherence was assessed prior to relapse were included. Five studies met the inclusion criteria and results were extracted independently by two researchers. Heterogeneity between studies precluded a pooled analysis of the data.
  
  
  RESULTS
  Studies varied widely with regard to both the definition of adherence and outcome measures. The included studies only addressed adherence to nicotine replacement therapy. One study of lozenge use found that the amount of medication used between 1 and 2 weeks after the quit date predicted abstinence at 6 weeks [adjusted odds ratio (OR) for 'high' versus 'low' lozenge use 1.25; 95% confidence interval (CI) = 1.05-1.50; P < 0.02]. Similarly, one study found a significant impact of oral nicotine consumption during the first week on abstinence at 4 weeks (adjusted OR per additional mg/day = 1.05; CI = 1.01-1.10). Another study found that participants using nicotine replacement therapy for at least 5 weeks were significantly more likely to self-report continuous abstinence at 6 months. The remaining two studies failed to find a significant effect of treatment duration on outcome at 1 and 2 years but had very low power to detect such an effect.
  
  
  CONCLUSIONS
  There is modest evidence to support the assumption that lack of adherence to nicotine replacement therapy regimens undermines effectiveness in clinical studies.
authors.affiliation: Department of Cardiology and Pneumology, University Hospital Göttingen, Göttingen, Germany; Cancer Research UK Health Behaviour Research Centre, University College London, London, UK.
authors.forename: Tobias
authors.initials: T
authors.lastname: Raupach
authors.forename: Jamie
authors.initials: J
authors.lastname: Brown
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Herbec
authors.forename: Leonie
authors.initials: L
authors.lastname: Brose
authors.forename: Robert
authors.initials: R
authors.lastname: West
mesh_terms: D001552:Benzazepines / Q000627:therapeutic use*; D016642:Bupropion / Q000627:therapeutic use*; D018765:Dopamine Uptake Inhibitors / Q000627:therapeutic use*; D006801:Humans; D055118:Medication Adherence; D018722:Nicotinic Agonists / Q000627:therapeutic use*; D011810:Quinoxalines / Q000627:therapeutic use*; D012907:Smoking / Q000188:drug therapy*; D016540:Smoking Cessation / Q000379:methods*; D016896:Treatment Outcome; D000068580:Varenicline
chemical_list: D001552:Benzazepines; D018765:Dopamine Uptake Inhibitors; D018722:Nicotinic Agonists; D011810:Quinoxalines; D016642:Bupropion; D000068580:Varenicline
keywords: Adherence; bupropion; cessation; compliance; medication; nicotine replacement therapy; quitting; smoking; success; varenicline