title: Longitudinal study of long-term smoking behaviour by biomarker-supported determination of exposure to smoke.
abstract: BACKGROUND
  Long-term studies of smokers who switch to lower nicotine yield cigarettes have been identified by the World Health Organization Study Group TobReg and the US Food and Drug Administration as one key area where new knowledge is required to guide science based regulation. The limited number of long-term switching studies have concluded that smokers who switch to lower nicotine yield cigarettes show evidence of partial compensation. Since the European Union tobacco product directive of 2001 introduced tar and nicotine yield ceilings, there has been no long-term observational switching study. To address the limitations of previous studies where smokers were forced switched for relatively short durations, we plan to undertake a long-term study of spontaneous switching which is appropriately powered and includes non-switchers as a control group.
  
  
  METHODS
  Healthy adult smokers aged 21-64 years will be enrolled into this 5-year non-residential, multicentre study across 10 cities in Germany. They will be assessed at 10 timepoints with 6 month intervals during which inclusion criteria will be reassessed and spent cigarette filter tips, saliva and 24 h urine samples will be collected. These samples will be used to determine average daily cigarette consumption, estimate mouth-level exposure to tar and nicotine and measure selected biomarkers of exposure, respectively. Spontaneous changes in subjects' preferred cigarette products and any consequent change in tar or nicotine yield will be monitored. Subjects will be required to complete questionnaires on quality of life, smoking behaviours, smoking-related sensory attributes and recent life changes.
  
  
  CONCLUSIONS
  The planned study is anticipated to contribute to understanding smokers' behaviours and their consequent exposure to smoke constituents. It will also allow assessment of compensatory changes in their behaviour following spontaneous switching of cigarette product smoked. Data from this study are expected to provide insights into study design and conduct for non-clinical assessment of smokers' exposure as part of post marketing surveillance programmes.
  
  
  BACKGROUND
  Current Controlled Trials Database reference ISRCTN95019245.
authors.affiliation: Group Research and Development, British American Tobacco (Investments) Ltd, Regents Park Road, Southampton SO15 8TL, UK. Anthony_Cunningham@bat.com.
authors.forename: Anthony
authors.initials: A
authors.lastname: Cunningham
authors.forename: Johan
authors.initials: J
authors.lastname: Sommarström
authors.forename: Ajit S
authors.initials: AS
authors.lastname: Sisodiya
authors.forename: Graham
authors.initials: G
authors.lastname: Errington
authors.forename: Krishna
authors.initials: K
authors.lastname: Prasad
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000032:analysis / Q000652:urine; D005260:Female; D005858:Germany; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009538:Nicotine / Q000032:analysis; D011788:Quality of Life; D012463:Saliva / Q000737:chemistry; D012907:Smoking / Q000453:epidemiology / Q000652:urine; D062789:Tobacco Products / Q000032:analysis; D014481:United States; D055815:Young Adult
chemical_list: D015415:Biomarkers; D009538:Nicotine
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