Chronic Obstructive Pulmonary Disease in the Older Adult: What Defines Abnormal Lung Function?

Abstract

Background: The Global Initiative on Obstructive Lung Disease (GOLD) stages for chronic obstructive pulmonary disease (COPD) uses a fixed ratio of the post- bronchodilator forced expiratory volume in one second ( FEV1 )/ forced vital capacity (FVC) of 0.70 as a threshold. Since the FEV1/FVC ratio declines with age, using the fixed ratio to define COPD may "overdiagnose" COPD in older populations

Objective: To determine morbidity and mortality among older adults whose FEV1/FVC is less than 0.70 but greater than the lower limit of normal (LLN).

Methods: We classified the severity of COPD in 4,965 participants age 65 years and older in the Cardiovascular Health Study using these two methods and determined the age-adjusted proportion of the population that died or had a COPD-related hospitalization in up to 11 years of follow-up.

Results: 1621(32.6%) subjects died and 935 (18.8%) had at least one COPD-related hospitalization during the follow-up period. People (n=1134) whose FEV1/FVC fell between the LLN and the fixed ratio had an increased adjusted risk of death (hazard ratio [HR] 1.3, 95% confidence interval [CI] 1.1, 1.5) and COPD-related hospitalization (HR 2.6, 95% CI 2.0, 3.3) during follow- up compared to asymptomatic individuals with normal lung function.

Conclusion: In this cohort, subjects classified as "normal" using the LLN but abnormal using the fixed ratio were more likely to die and to have a COPD-related hospitalization during follow-up. This suggests that a fixed FEV1/FVC < 0.70 may identify at-risk patients, even among older adults.