title: Rapid fall in lung density following smoking cessation in COPD.
abstract: BACKGROUND
  Whether smoking-induced lung inflammation subsides after smoking cessation is currently a matter of debate. We used computed tomography (CT) to evaluate the effect of smoking cessation on lung density in patients with COPD.
  
  
  METHODS
  Thirty-six patients quit smoking out of 254 current smokers with COPD who were followed with annual CT and lung function tests (LFT) for 2?4 years as part of a randomised placebo-controlled trial of the effect of inhaled budesonide on CT-lung density. Lung density was expressed as the 15th percentile density (PD15) and relative area of emphysema below -910 HU (RA-910). From the time-trends in the budesonide and placebo groups the expected CT-lung densities at the first visit after smoking cessation were calculated by linear regression and compared to the observed densities.
  
  
  RESULTS
  Following smoking cessation RA-910 increased by 2.6% (p = 0.003) and PD15 decreased by -4.9 HU (p = 0.0002). Furthermore, changes were larger in the budesonide group than the placebo group (PD15: -7.1 vs -2.8 HU. RA-910 3.7% vs 1.7%). These differences were, however, not statistically significant. The LFT parameters (FEV(1) and diffusion capacity) were not significantly influenced by smoking cessation.
  
  
  CONCLUSIONS
  Inflammation partly masks the presence of emphysema on CT and smoking cessation results in a paradoxical fall in lung density, which resembles rapid progression of emphysema. This fall in density is probably due to an anti-inflammatory effect of smoking cessation.
authors.affiliation: Gentofte University Hospital, Dept. of Respiratory Medicine, Hellerup, Denmark. saher@dadlnet.dk
authors.forename: Saher B
authors.initials: SB
authors.lastname: Shaker
authors.forename: Trine
authors.initials: T
authors.lastname: Stavngaard
authors.forename: Lars Christian
authors.initials: LC
authors.lastname: Laursen
authors.forename: Berend C
authors.initials: BC
authors.lastname: Stoel
authors.forename: Asger
authors.initials: A
authors.lastname: Dirksen
mesh_terms: D000368:Aged; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use; D019819:Budesonide / Q000627:therapeutic use; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011653:Pulmonary Diffusing Capacity; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000503:physiopathology*; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging; D016540:Smoking Cessation; D036542:Tomography, Spiral Computed; D014057:Tomography, X-Ray Computed
chemical_list: D000893:Anti-Inflammatory Agents; D019819:Budesonide