title: Rate of progression of CT-quantified emphysema in male current and ex-smokers: a follow-up study.
abstract: BACKGROUND
  Little is known about the factors associated with CT-quantified emphysema progression in heavy smokers. The objective of this study was to investigate the effect of length of smoking cessation and clinical / demographical factors on the rate of emphysema progression and FEV1-decline in male heavy smokers.
  
  
  METHODS
  3,670 male smokers with mean (SD) 40.8 (17.9) packyears underwent chest CT scans and pulmonary function tests at baseline and after 1 and 3 years follow-up. Smoking status (quitted ≥5, ≥1-<5, <1 years or current smoker) was noted. Rate of progression of emphysema and FEV1-decline after follow-up were assessed by analysis of variance adjusting for age, height, baseline pulmonary function and emphysema severity, packyears, years in study and respiratory symptoms. The quitted ≥5 group was used as reference.
  
  
  RESULTS
  Median (Q1-Q3) emphysema severity,<-950 HU, was 8.8 (5.1 - 14.1) and mean (SD) FEV1 was 3.4 (0.73) L or 98.5 (18.5) % of predicted. The group quitted '>5 years' showed significantly lower rates of progression of emphysema compared to current smokers, 1.07% and 1.12% per year, respectively (p<0.001). Current smokers had a yearly FEV1-decline of 69 ml, while subjects quit smoking >5 years had a yearly decline of 57.5 ml (p<0.001).
  
  
  CONCLUSIONS
  Quit smoking >5 years significantly slows the rate of emphysema progression and lung function decline.
  
  
  BACKGROUND
  Registered at http://www.trialregister.nl with trial number ISRCTN63545820.
authors.affiliation: Department of Respiratory Medicine, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, the Netherlands. fmohamedhoesein@gmail.com
authors.forename: Firdaus A A
authors.initials: FA
authors.lastname: Mohamed Hoesein
authors.forename: Pieter
authors.initials: P
authors.lastname: Zanen
authors.forename: Pim A
authors.initials: PA
authors.lastname: de Jong
authors.forename: Bram
authors.initials: B
authors.lastname: van Ginneken
authors.forename: H Marike
authors.initials: HM
authors.lastname: Boezen
authors.forename: Harry J M
authors.initials: HJ
authors.lastname: Groen
authors.forename: Mathijs
authors.initials: M
authors.lastname: Oudkerk
authors.forename: Harry J
authors.initials: HJ
authors.lastname: de Koning
authors.forename: Dirkje S
authors.initials: DS
authors.lastname: Postma
authors.forename: Jan-Willem J
authors.initials: JW
authors.lastname: Lammers
mesh_terms: D015897:Comorbidity; D018450:Disease Progression; D004646:Emphysema / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D012307:Risk Factors; D012720:Severity of Illness Index; D012907:Smoking / Q000453:epidemiology*; D016540:Smoking Cessation / Q000706:statistics & numerical data*; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*