2020 Volume 35 Issue 2 Pages 155-163
Objective: To examine temporal changes in spirometry and chronic obstructive pulmonary disease (COPD)-related subjective symptoms among males with respect to a smoking index with a 6-year follow-up historical cohort study.
Methods: Overall, 2,454 men who underwent annual human dock were recruited in 2010. Of those participants, men with missing values related to smoking, respiratory, and heart diseases or arrhythmia; ex-smokers; and men repeatedly considered as smokers or non-smokers were excluded. Finally, 1,066 participants who were classified based on pack-years (Py) <20, ≥20 and <40, ≥40, and non-smokers (Py=0) completed the spirometry test and self-reported symptoms for 6 years follow-up. Changes in spirometry were analyzed using a repeated analysis with analysis of variance. The symptoms (cough or sputum, breathlessness) were analyzed using the Cochran Q test and multiple logistic regression model.
Results: Compared with baseline, FEV1% of Py≥40 (2.6%), Py20-40 (2.3%), Py<20 (2.3%), and Py=0 (1.4%) significantly decreased after 6 years of follow-up (p <0.001). %FEV1 of Py20-40 and ≥40 significantly decreased and were lower than Py=0 and Py<20 at each year. There was no significant change in symptoms over the years; however, the rate of cough or sputum symptoms in the Py≥40 group had the highest odds ratio among the four groups.
Conclusion: The higher Py, FEV1％, and %FEV1 declined early and largely. However, subjective symptoms in smokers, excluding Py≥40, appear few. These findings suggest that early detection of COPD without spirometry is more likely to be difficult. To prevent COPD and its progression, respiratory function tests are necessary for all smokers.
