title: Modeling smoking history: a comparison of different approaches in the MARS study on age-related maculopathy.
abstract: OBJECTIVE
  Smoking is an established risk factor for the development of age-related maculopathy (ARM), and its end stage, age-related macular degeneration (AMD). We evaluated the benefit of various smoking-related variables in modeling the association of smoking with ARM and AMD in a mixed sample of current, former, and never smokers.
  
  
  METHODS
  This was a cross-sectional study in participants of the Muensteraner Altern- und Retina-Studie (MARS). Participants were classified according to the Rotterdam classification system as healthy, or having ARM or AMD. Using multinomial logistic regression techniques, the association with number of cigarettes, years of smoking, pack-years and time since cessation in former smokers were evaluated.
  
  
  RESULTS
  Mean age of the 982 participants (58.6% females) was 70.9 +/- 5.5 years. ARM was present in 483 (49.2%) and AMD in 285 (29.0%) individuals. The adjusted prevalence odds ratio (OR) in current smokers versus never smokers was 2.61 (95% confidence interval [CI] 1.34-5.09) for ARM and 3.94 (95% CI 1.91-8.14) for AMD. This effect decreased in former smokers with an OR = 0.55 (95% CI 0.33-0.99) per log-transformed time since smoking cessation for ARM and an OR = 0.52 (95% CI 0.30-0.90) for AMD.
  
  
  CONCLUSIONS
  By including a variable for time since smoking cessation, we were able to handle current, former, and never smokers in one model that estimates the association of smoking with ARM or AMD. Logarithmical transformation of the time since smoking cessation seemed to increase the model fit and to reflect a non-linear protective effect of smoking cessation on the onset of ARM and AMD in former smokers.
authors.affiliation: Institute of Epidemiology and Social Medicine, University of Muenster, Muenster, Germany. neuner@uni-muenster.de
authors.forename: Bruno
authors.initials: B
authors.lastname: Neuner
authors.forename: Juergen
authors.initials: J
authors.lastname: Wellmann
authors.forename: Burkhard
authors.initials: B
authors.lastname: Dasch
authors.forename: Thomas
authors.initials: T
authors.lastname: Behrens
authors.forename: Birte
authors.initials: B
authors.lastname: Claes
authors.forename: Martha
authors.initials: M
authors.lastname: Dietzel
authors.forename: Daniel
authors.initials: D
authors.lastname: Pauleikhoff
authors.forename: Hans-Werner
authors.initials: HW
authors.lastname: Hense
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D016015:Logistic Models; D008268:Macular Degeneration / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D016017:Odds Ratio; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology; D016540:Smoking Cessation / Q000706:statistics & numerical data*; D013997:Time Factors