Chronic obstructive pulmonary disease in the older adult: what defines abnormal lung function?
- 1Division of Pulmonary, Critical Care and Sleep Medicine, University of Kentucky Medical Center, Lexington, Kentucky, USA
- 2Department of Medicine, Oregon Health and Science University, Portland, Oregon, USA
- 3Kaiser Permanente Center for Health Research, Portland, Oregon, USA
- Correspondence to:
Dr D M Mannino
Division of Pulmonary and Critical Care Medicine, University of Kentucky Medical Center, 740 S Limestone, K-528, Lexington, KY 40536, USA;
- Received 10 July 2006
- Accepted 1 September 2006
- Published Online First 7 November 2006
Background: The Global Initiative on Obstructive Lung Disease stages for chronic obstructive pulmonary disease (COPD) uses a fixed ratio of the post-bronchodilator forced expiratory volume in 1 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 more than the lower limit of normal (LLN).
Methods: The severity of COPD was classified in 4965 participants aged ⩾65 years in the Cardiovascular Health Study using these two methods and the age-adjusted proportion of the population who had died or had a COPD-related hospitalisation in up to 11 years of follow-up was determined.
Results: 1621 (32.6%) subjects died and 935 (18.8%) had at least one COPD-related hospitalisation during the follow-up period. Subjects (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% CI 1.1 to 1.5) and COPD-related hospitalisation (HR 2.6, 95% CI 2.0 to 3.3) during follow-up compared with 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 hospitalisation during follow-up. This suggests that a fixed FEV1/FVC ratio of <0.70 may identify at-risk patients, even among older adults.
- BMI, body mass index
- CHS, Cardiovascular Health Study
- COPD, chronic obstructive pulmonary disease
- FEV1, forced expiratory volume in 1 second
- FVC, forced vital capacity
- GOLD, Global Initiative on Obstructive Lung Disease
- LLN, lower limit of normal
Published Online First 7 November 2006
Competing interests: None declared.