Quantitative assessment of lung structure changes in low-intensity smokers: a retrospective study in a Chinese male cohort

Background: With an increasing number of smokers who consume fewer cigarettes, it is crucial to understand the lung structure changes of low-intensity smoking. This study aimed to investigate the lung structure changes in low-intensity smokers in a Chinese male cohort.

Methods: Chest computed tomography (CT) examinations of 465 asymptomatic healthy male participants were divided into non-smoking (n=256), light-smoking (n=84), intermediate-smoking (n=85), and heavy-smoking (n=40) groups. Low-intensity smokers (fewer than 10 cigarettes per day) were included (n=32), and a new group of non-smokers was generated using propensity score matching according to age. Quantitative CT parameters, including the volume of the intrapulmonary vessel (IPVV), the volume of the lung, mean lung density (MLD), the low-attenuation areas below -910 Hounsfield units (LAA-910), and the volume ratio of intrapulmonary vessel to the lung for the total lung and each lobe were measured. Quantitative CT parameters were compared among the four smoking groups and also between the low-intensity smokers and non-smokers. Binary logistic regression was used to determine the independent quantitative CT measurements of smoking intensity.

Results: Compared with that in non-smokers, the IPVV and the MLD of the total lung and five lobes was significantly higher in light smokers (P<0.05); meanwhile, the LAA-910 of the total lung and five lobes of the light and intermediate smokers were significantly lower (P<0.05). The IPVV of the total lung and five lobes was significantly higher in the low-intensity smoking group (P<0.05). The IPVV of the total lung was the independent factor for discriminating between the non-smokers and light smokers (odds ratio =1.040; 95% confidence interval: 1.027-1.053) and between the non-smokers and low-intensity smokers (odds ratio =1.034; 95% confidence interval: 1.013-1.055).

Conclusions: CT-quantified measurements of the IPVVs and MLD increased in light and intermediate smokers. The IPVV of the total lung was selected as the independent factor between non-smokers and light smokers and between non-smokers and low-intensity smokers.