PURPOSE: Defining airway obstruction is still in the area of controversies. In the most recent international guideline, the spirometric definition of postbronchodilator FEV1/FVC < 0.7 is recommened to diagnose chronic obstructive lung disease (COPD). But there are concerns about over-diagnosing airway obstruction especially in elderly people because FEV1/FVC tends to decline with age. So some of the guidelines advocate the use of lower limit of normal(LLN) FEV1/FVC instead of fixed ratio. On the other hand, a recent article reported that elderly subjects classified as normal using the lower limit of normal(LLN) FEV1/FVC, but abnormal using the fixed ratio, are more likely to die and have COPD-related hospitalization. We conducted this study to elucidate whether FEV1/FVC ratio differs according to smoking history in elderly people whose FEV1/FVC is over 0.7.
METHODS: This study was conducted as a part of the Korean Longitudinal Study on Health and Aging (KLOSHA) that is a population-based cohort study with people aged >65 years living in City of Seongnam. Spirometric test was performed as predefined manner and detailed smoking history was taken.
RESULTS: Among 1,000 randomly selected subjects, 593 were able to perform pulmonary function testing. Of those, 488 subjects were those whose FEV1/FVC≥ 0.7. We categorized people in three groups according to smoking history. Never smokers or smoking less than 5 pack-years as group 1 (n=320), more than 5 and less than 30 pack-years of smokers as group 2 (n=74), and smokers with more than 30 pack-year history as group 3 (n=84). The ratio of FEV1/FVC in each group was 0.7998±0.060 for group 1, 0.7864±0.059 for group 2, and 0.7838±0.063 for group 3. (p=0.04 by analysis of variance).
CONCLUSION: FEV1/FVC ratio differs according to smoking history even in elderly patients with FEV1/FVC ≥ 0.7.
CLINICAL IMPLICATIONS: Smoking induced airway damages are reflected in FEV1/FVC ratio even when it is over 0.7 in elderly people.
DISCLOSURE: Ho Il Yoon, No Financial Disclosure Information; No Product/Research Disclosure Information