title: Changes Over Time in Absolute and Relative Socioeconomic Differences in Smoking: A Comparison of Cohort Studies From Britain, Finland, and Japan.
abstract: Socioeconomic differences in smoking over time and across national contexts are poorly understood. We assessed the magnitude of relative and absolute social class differences in smoking in cohorts from Britain, Finland, and Japan over 5-7 years.
  
  
  
  The British Whitehall II study (n = 4350), Finnish Helsinki Health Study (n = 6328), and Japanese Civil Servants Study (n = 1993) all included employed men and women aged 35-68 at baseline in 1997-2002. Follow-up was in 2003-2007 (mean follow-up 5.1, 6.5, and 3.6 years, respectively). Occupational social class (managers, professionals and clerical employees) was measured at baseline. Current smoking and covariates (age, marital status, body mass index, and self-rated health) were measured at baseline and follow-up. We assessed relative social class differences using the Relative Index of Inequality and absolute differences using the Slope Index of Inequality.
  
  
  
  Social class differences in smoking were found in Britain and Finland, but not in Japan. Age-adjusted relative differences at baseline ranged from Relative Index of Inequality 3.08 (95% confidence interval 1.99-4.78) among Finnish men to 2.32 (1.24-4.32) among British women, with differences at follow-up greater by 8%-58%. Absolute differences remained stable and varied from Slope Index of Inequality 0.27 (0.15-0.40) among Finnish men to 0.10 (0.03-0.16) among British women. Further adjustment for covariates had modest effects on inequality indices.
  
  
  
  Large social class differences in smoking persisted among British and Finnish men and women, with widening tendencies in relative differences over time. No differences could be confirmed among Japanese men or women.
  
  
  
  Changes over time in social class differences in smoking are poorly understood across countries. Our study focused on employees from Britain, Finland and Japan, and found relative and absolute and class differences among British and Finnish men and women. Key covariates had modest effects on the differences. Relative differences tended to widen over the 4- to 7-year follow-up, whereas absolute differences remained stable. In contrast, class differences in smoking among Japanese men or women were not found. Britain and Finland are at the late stage of the smoking epidemic model, whereas Japan may not follow the same model.
authors.affiliation: Department of Public Health, University of Helsinki, Helsinki, Finland; eero.lahelma@helsinki.fi.
authors.forename: Eero
authors.initials: E
authors.lastname: Lahelma
authors.affiliation: Department of Public Health, University of Helsinki, Helsinki, Finland;
authors.forename: Olli
authors.initials: O
authors.lastname: Pietiläinen
authors.affiliation: Department of Epidemiology and Public Health, University College London, London, UK; School of Community and Social Medicine, University of Bristol, Bristol, UK;
authors.forename: Jane
authors.initials: J
authors.lastname: Ferrie
authors.affiliation: Department of Public Health, University of Helsinki, Helsinki, Finland; Department of Epidemiology and Public Health, University College London, London, UK; Centre of Expertise for Development of Work and Organizations, Finnish Institute of Occupational Health, Helsinki, Finland;
authors.forename: Mika
authors.initials: M
authors.lastname: Kivimäki
authors.affiliation: Department of Public Health, University of Helsinki, Helsinki, Finland;
authors.forename: Jouni
authors.initials: J
authors.lastname: Lahti
authors.affiliation: Department of Epidemiology and Public Health, University College London, London, UK;
authors.forename: Michael
authors.initials: M
authors.lastname: Marmot
authors.affiliation: Department of Public Health, University of Helsinki, Helsinki, Finland;
authors.forename: Ossi
authors.initials: O
authors.lastname: Rahkonen
authors.affiliation: Department of Epidemiology and Health Policy, University of Toyama, Toyama, Japan.
authors.forename: Michikazu
authors.initials: M
authors.lastname: Sekine
authors.affiliation: Department of Epidemiology and Public Health, University College London, London, UK;
authors.forename: Martin
authors.initials: M
authors.lastname: Shipley
authors.affiliation: Department of Epidemiology and Health Policy, University of Toyama, Toyama, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Tatsuse
authors.affiliation: Department of Public Health, University of Helsinki, Helsinki, Finland; Centre of Expertise for Development of Work and Organizations, Finnish Institute of Occupational Health, Helsinki, Finland;
authors.forename: Tea
authors.initials: T
authors.lastname: Lallukka
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012907:Smoking / Q000453:epidemiology* / Q000639:trends; D000074606:Smoking Prevention; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D006113:United Kingdom / Q000453:epidemiology