Table 1.

Nosology Used in This Review

Term	Definition
Early COPD	Biological term that indicates that the disease is near its beginning (at any age); requires validated biomarkers to be identified/quantified in clinical practice
Mild COPD	Functional term that indicates that the disease is associated with mild airflow limitation (at any age)
COPD in Young Patients	Age-dependent term that identifies a subpopulation of patients with COPD (FEV1/FVC < 0.7) between 20 and 50 years of age (independent of the severity of airflow limitation present)
Pre-COPD	Individuals (of any age) who present chronic respiratory symptoms, with or without structural and/or functional abnormalities, in the absence of airflow limitation (FEV1/FVC > 0.7) who may (or may not) develop persistent airflow limitation (i.e., COPD) over time
Disease activity	Biological term that relates to the level of activation of the pathobiological processes (endotypes) that cause the disease; it can ideally be identified and quantified by validated biomarkers (currently lacking in COPD)
Disease progression	Clinical term that refers to a progressive deterioration in an objective marker of pathology or lung function
Primary prevention	Aimed at preventing the disease before it occurs by eliminating exposures to risk factors and/or increasing resistance to disease should exposure occur
Secondary prevention	Aimed at reducing the impact of a disease that has already occurred by diagnosing and treating it as soon as possible to halt or slow its progress
Tertiary prevention	Aimed at mitigating the impact of an ongoing illness

Definition of abbreviation: COPD = chronic obstructive pulmonary disease.

For further explanations, see the main text.