Post-bronchodilator spirometric measurement is thought to be the best way to classify chronic obstructive pulmonary disease (COPD). There are limited studies on the relationship between reversibility, as defined by at least a 12% increase in FEV1 and/or FVC after administration of a bronchodilator, and the presence of a person switching from obstructed to unobstructed in FEV1/FVC ratio or vice versa.
The Burden of Lung Disease Initiative (BOLD) is a community-based study to measure country specific prevalence of COPD. Pre- and post-bronchodilator spirometry was collected for 575 non-institutionalized adults aged 40 years or older at a 26 county site in Southeastern Kentucky. These data were analyzed for presence of at least a 12% increase in FEV1 and/or FVC after bronchodilator administration, COPD Stage (based on post-bronchodilator measurement), and movement either to or from an “obstructed” FEV1/FVC (<0.70).
The final study population with acceptable pre- and post-bronchodilator spirometry included 440 participants. A 12% increase in the FEV1 and/or FVC was seen in 65/440 (14.7%), a change from “obstructed” to “unobstructed” was seen in 32/440 (7.3%), and a change from “unobstructed” to “obstructed” was seen in 19/440 (4.3%). Of people who demonstrated a significant increase in the FEV1 or FVC, only 19/65 (29.2%) changed categories, and of people who changed categories, 19/51 (37.3%) demonstrated a 12% increase. Among subjects with Stage 3 or 4 COPD, 70.6% demonstrated a 12% increase in FEV1 and/or FVC, with 43.8% demonstrating this in Stage 2 COPD.
The analysis indicates little overlap between reversibility by at least a 12% increase in FEV1 and/or FVC and switching to unobstructed after bronchodilator administration.
These findings highlight the difference between “reversibility” and the means in which we classify obstruction among people both clinically and in epidemiologic studies. It also suggests there may be an important overlap of “asthma like” reversibility in patients with moderate and severe COPD.
Heather Prentice, No Financial Disclosure Information; No Product/Research Disclosure Information