title: Educational attainment and cigarette smoking: a causal association?
abstract: BACKGROUND
  Despite abundant evidence that lower education is associated with a higher risk of smoking, whether the association is causal has not been convincingly established.
  
  
  METHODS
  We investigated the association between education and lifetime smoking patterns in a birth cohort established in 1959 and followed through adulthood (n = 1311). We controlled for a wide range of potential confounders that were measured prior to school entry, and also estimated sibling fixed effects models to control for unmeasured familial vulnerability to smoking.
  
  
  RESULTS
  In the full sample of participants, regression analyses adjusting for multiple childhood factors (including socioeconomic status, IQ, behavioural problems, and medical conditions) indicated that the number of pack-years smoked was higher among individuals with less than high school education [rate ratio (RR) = 1.58, confidence interval (CI) = 1.31, 1.91]. However, in the sibling fixed effects analysis the RR was 1.23 (CI = 0.80, 1.93). Similarly, adjusted models estimated in the full sample showed that individuals with less than high school education had fewer short-term (RR = 0.40; CI = 0.23, 0.69) and long-term (RR = 0.59; CI = 0.42, 0.83) quit attempts, and were less likely to quit smoking (odds ratio = 0.34; CI = 0.19, 0.62). The effects of education on quitting smoking were attenuated in the sibling fixed effects models that controlled for familial vulnerability to smoking.
  
  
  CONCLUSIONS
  A substantial portion of the education differential in smoking that has been repeatedly observed is attributable to factors shared by siblings that contribute to shortened educational careers and to lifetime smoking trajectories. Reducing disparities in cigarette smoking, including educational disparities, may therefore require approaches that focus on factors early in life that influence smoking risk over the adult life span.
authors.affiliation: Department of Society, Human Development, and Health, Harvard School of Public Health, Boston, MA, USA. sgilman@hsph.harvard.edu
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Gilman
authors.forename: Laurie T
authors.initials: LT
authors.lastname: Martin
authors.forename: David B
authors.initials: DB
authors.lastname: Abrams
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kawachi
authors.forename: Laura
authors.initials: L
authors.lastname: Kubzansky
authors.forename: Eric B
authors.initials: EB
authors.lastname: Loucks
authors.forename: Richard
authors.initials: R
authors.lastname: Rende
authors.forename: Rima
authors.initials: R
authors.lastname: Rudd
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Buka
mesh_terms: D000328:Adult; D001290:Attitude; D015986:Confounding Factors, Epidemiologic; D004522:Educational Status; D006801:Humans; D007360:Intelligence; D011446:Prospective Studies; D012044:Regression Analysis; D012907:Smoking / Q000523:psychology*; D012959:Socioeconomic Factors