title: Is smoking a risk factor for proliferative diabetic retinopathy in type 1 diabetes?
abstract: OBJECTIVE
  The aim was to evaluate if smoking was a risk factor for proliferative retinopathy (PDR) in a 25-year follow-up study.
  
  
  METHODS
  201 persons from a population-based cohort of Danish type 1 diabetic patients were examined at baseline and again 25 years later. At both examinations the patients were asked about their smoking habits. The level of retinopathy was evaluated by ophthalmoscopy at baseline and by nine 45-degree colour field fundus photos at the follow-up.
  
  
  RESULTS
  In multivariate analyses there was a trend that current smokers at baseline were more likely to develop PDR at the follow-up (odds ratio 1.90, 95% confidence interval 0.88-4.11, p = 0.10). Neither smoking status at the follow-up nor pack-years of smoking were associated with PDR.
  
  
  CONCLUSIONS
  We found neither a beneficial nor a harmful effect of smoking on long-term incidence. Selective mortality among smokers and patients with PDR at baseline might provide at least part of the explanation for this.
authors.affiliation: Department of Ophthalmology, Odense University Hospital, DK-5000 Odense C, Denmark. mgthorlund@gmail.com
authors.forename: Mie
authors.initials: M
authors.lastname: Gaedt Thorlund
authors.forename: Mette
authors.initials: M
authors.lastname: Borg Madsen
authors.forename: Anders
authors.initials: A
authors.lastname: Green
authors.forename: Anne Katrin
authors.initials: AK
authors.lastname: Sjølie
authors.forename: Jakob
authors.initials: J
authors.lastname: Grauslund
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D003718:Denmark / Q000453:epidemiology; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology*; D003930:Diabetic Retinopathy / Q000453:epidemiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology*; D055815:Young Adult