Short-term effect of changes in smoking behaviour on emphysema quantification by CT.
BACKGROUND
The effect of smoking cessation and smoking relapse on lung density was studied using low-dose CT.


METHODS
Spiral, multidetector, low-dose CT was performed on 726 current and former smokers (>20 pack-years) recruited from a cancer screening trial. Lung density was quantified by calculating the 15th percentile density (PD15), which was adjusted to predicted total lung capacity. Data were analysed by linear regression models.


RESULTS
At baseline mean PD15 was 45 g/l in former smokers (n=178) and 55 g/l in current smokers (n=548), representing a difference of 10 g/l (p<0.001). After smoking cessation (n=77) PD15 decreased by 6.2 g/l (p<0.001) in the first year, and by a further 3.6 g/l (p<0.001) in the second year, after which no further change could be detected. Moreover, the first year after relapse to smoking (n=18) PD15 increased by 3.7 g/l (p=0.02).


CONCLUSIONS
Current smoking status has a major influence on lung density assessed by CT, and the difference in lung density between current and former smokers observed in cross-sectional studies corresponds closely to the change in lung density seen in the years after smoking cessation. Current smoking status, and time since cessation or relapse, should be taken into account when assessing the severity of diseases such as emphysema by CT lung density.
Ashraf
Haseem
H
Department of Respiratory Medicine, Gentofte University Hospital, Hellerup, Denmark. haseem.ashraf@gmail.com
Lo
Pechin
P
Shaker
Saher Burhan
SB
de Bruijne
Marleen
M
Dirksen
Asger
A
Tønnesen
Philip
P
Dahlbäck
Magnus
M
Pedersen
Jesper Holst
JH
D000368:Aged; D004812:Epidemiologic Methods; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging* / Q000209:etiology* / Q000503:physiopathology; D012907:Smoking / Q000009:adverse effects*; D016540:Smoking Cessation; D036542:Tomography, Spiral Computed