Spirometric instability - another hurdle in achieving real-world COPD diagnostic criteria?

Globally, mortality, morbidity and the economic burden of chronic obstructive pulmonary disease (COPD) are on the rise. In addition, its diagnosis continues to pose challenges to the physicians, which is compounded further by its new feature "spirometric instability." Based on the findings from the two recent observational studies, the Global Initiative for Chronic Obstructive Lung Disease (GOLD) recommended repeat spirometry for the individuals with a fixed ratio between 0.6 and 0.8. In this perspective, we discuss the uncertainties and consequences of this critical update in the 2018 GOLD report.