Fig. 1
From: Measuring disease activity in COPD: is clinically important deterioration the answer?
The relationships between the key components of COPD [4]. The relationships between components of COPD. Severity, (disease) activity, and impact are components of COPD; severity and activity determine the level of impact on a patient. Disease activity drives disease progression, which worsens severity. COPD, chronic obstructive pulmonary disease. Reprinted with permission of the American Thoracic Society. Copyright© 2019 American Thoracic Society. The American Journal of Respiratory and Critical Care Medicine is an official journal of the American Thoracic Society