Structural Predictors of Lung Function Decline in Young Smokers with Normal Spirometry.

RATIONALE: Chronic obstructive pulmonary disease (COPD) due to tobacco smoking commonly presents when extensive lung damage has occurred.

OBJECTIVES: We hypothesised that structural change would be detected early in the natural history of COPD and would relate to loss of lung function with time.

METHODS: We recruited 431 current smokers (median age 39 years, 16 pack-years smoked) and recorded symptoms by the COPD Assessment Test (CAT), spirometry and quantitative thoracic CT (QCT) scans at study entry. These scans results were compared to 67 never smoking controls. 368 participants were followed every six months with measurement of post-bronchodilator spirometry for a median of 32 months. The rate of FEV1 decline, adjusted for current smoking status, age and sex was related to the initial QCT appearances and symptoms, measured with the CAT.

MEASUREMENTS AND MAIN RESULTS: There were no material differences in demography or subjective CT appearances between the young smokers and controls, but 55.7% of the former had a CAT score above 10 and 24.2% reported chronic bronchitis. QCT assessments of Disease Probability-defined functional small airways disease, ground glass opacification, bronchovascular prominence and small blood vessel to total pulmonary vessel volume ratio were increased compared to controls and were all associated with a faster FEV1 decline as was a higher CAT score.

CONCLUSIONS: Radiologic abnormalities on CT are already established in young smokers with normal lung function and is associated with FEV1 loss independently of the impact of symptoms. Structural abnormalities are present early in the natural history of COPD and are markers of disease progression. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (https://creativecommons.org/licenses/by-nc-nd/4.0/).