Abstract
BackgroundA low FEV1/FVC from post-bronchodilator spirometry is required to diagnose COPD. Both the FEV1 and the FVC can vary over time; therefore, individuals can be given a diagnosis of mild COPD at one visit, but have normal spirometry during the next appointment, even without an intervention.MethodsWe analyzed two population-based surveys of adults with spirometry carried out for the same individuals 5-9 years after their baseline examination. We determined the factors associated with a change in the spirometry interpretation from one exam to the next utilizing different criteria commonly used to diagnose COPD.ResultsThe rate of an inconsistent diagnosis of mild COPD was 11.7% using FEV1/FVC <0.70, 5.9% using FEV1/FEV6 <the lower limit of the normal range, LLN and 4.1% using the GOLD stage 2-4 criterion. The most important factor associated with diagnostic inconsistency was the closeness of the ratio to the LLN during the first examination. Inconsistency decreased with a lower FEV1.ConclusionsUsing FEV1/FEV6 <LLN or GOLD stage 2-4 as the criterion for airflow obstruction reduces inconsistencies in the diagnosis of mild COPD. Further improvement could be obtained by defining a borderline zone around the LLN (e.g. plus or minus 0.6 SD), or repeating the test in patients with borderline results.
Highlights
Population-based prevalence of poorly reversible airflow obstruction (COPD) has been recently estimated for a variety of countries in Latin America [1] and other continents [2] with standardized methods including post-bronchodilator spirometry. In those and other surveys, it has been clear that the several criteria to define airflow obstruction would produce important differences in COPD prevalence, which would be lower with criteria based on FEV1/FVC or FEV1/FEV6 below the 5th percentile, than with the traditional Global Initiative for Obstructive Lung Disease (GOLD) definition (FEV1/FVC
In a population-based survey, COPD prevalence based on FEV1/FEV6
Other variables analyzed were age, continuous smoking, Body mass index (BMI), gender, clinical diagnosis of COPD, use of respiratory medications and the duration of the expiratory maneuvers, but all together they explained about 7–17% of the variability of inconsistent diagnosis, and the statistical significance disappeared once we included in the models the proximity of the spirometry measurements to the threshold for airflow obstruction and FEV1
Summary
A low FEV1/FVC from post-bronchodilator spirometry is required to diagnose COPD. Both the FEV1 and the FVC can vary over time; individuals can be given a diagnosis of mild COPD at one visit, but have normal spirometry during the appointment, even without an intervention.
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call