Spirometric variability in smokers: transitions in COPD diagnosis in a five-year longitudinal study

Area of Science:

• Pulmonary Medicine
• Respiratory Health
• Epidemiology

Background:

• Chronic obstructive pulmonary disease (COPD) is typically viewed as a progressive condition.
• The natural history and potential for improvement in spirometrically-defined COPD states are not well-understood.

Purpose of the Study:

• To investigate the possibility of beneficial transitions in spirometrically-defined COPD states.
• To determine if COPD diagnoses are stable or can undergo improvement over time.

Main Methods:

• Longitudinal study of 1553 smokers over 5 years (Lovelace Smokers' Cohort).
• Categorization of spirometric states including normal, COPD Stage I, Unclassified, and COPD Stage II+ (GOLD guidelines).
• Analysis using a Markov-like model to calculate transition probabilities for beneficial changes.

Main Results:

• Beneficial transitions (improvement or resolution) occurred in 16% of COPD Stage I, 39% of Unclassified, and 22% of COPD Stage II+ states.
• Resolution of spirometric abnormalities was observed in 16%, 35%, and 4% of these states, respectively.
• Beneficial transitions were more frequent in new-onset disease and associated with Hispanic ethnicity and excess weight.

Conclusions:

• Spirometrically-defined COPD states are not uniformly progressive and can improve or resolve.
• The spirometric diagnosis of COPD may be unstable, indicating potential for reversibility.
• A pre-disease state for COPD may exist where interventions could alter its natural course.