Global Initiative for Chronic Obstructive Lung Disease - GOLD

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surfaces of the lung (alveoli), is a pathological term that
is often (but incorrectly) used clinically and describes
only one of several structural abnormalities present in
patients with COPD. Chronic bronchitis, or the presence
of cough and sputum production for at least 3 months in
each of two consecutive years, remains a clinically and
epidemiologically useful term. However, it does not
reflect the major impact of airflow limitation on morbidity
and mortality in COPD patients. It is also important to
recognize that cough and sputum production may precede
the development of airflow limitation; conversely, some
patients develop significant airflow limitation without
chronic cough and sputum production.
NATURAL HISTORY
COPD has a variable natural history and not all individuals
follow the same course. However, COPD is generally a
progressive disease, especially if a patient's exposure
to noxious agents continues. If exposure is stopped, the
disease may still progress due to the decline in lung
function that normally occurs with aging. Nevertheless,
stopping exposure to noxious agents, even after
significant airflow limitation is present, can result in
some improvement in function and will certainly slow or
even halt the progression of the disease.
Classification of Severity: Stages of COPD
For educational reasons, a simple classification of disease
severity into four stages is recommended (Figure 1-2).
The staging is based on airflow limitation as measured by
spirometry, which is essential for diagnosis and provides
a useful description of the severity of pathological
changes in COPD. Specific FEV 1 cut-points (e.g.,
< 80% predicted) are used for purposes of simplicity:
these cut-points have not been clinically validated.
The impact of COPD on an individual patient depends
not just on the degree of airflow limitation, but also on
the severity of symptoms (especially breathlessness and
decreased exercise capacity) and complications of the
disease. The management of COPD is largely symptom
driven, and there is only an imperfect relationship between
the degree of airflow limitation and the presence of
symptoms. The staging, therefore, is a pragmatic
approach aimed at practical implementation and should
only be regarded as an educational tool, and a very
Figure 1-2. Classification of Severity of COPD
Stage
Characteristics
0: At Risk • normal spirometry
• chronic symptoms (cough, sputum production)
I: Mild COPD • FEV 1 /FVC < 70%
• FEV 1 ≥ 80% predicted
• with or without chronic symptoms (cough, sputum production)
II: Moderate COPD • FEV 1 /FVC < 70%
• 50% ≤ FEV 1 < 80% predicted
• with or without chronic symptoms (cough, sputum production)
III: Severe COPD • FEV 1 /FVC < 70%
• 30% ≤ FEV 1 < 50% predicted
• with or without chronic symptoms (cough, sputum production)
IV: Very Severe COPD • FEV 1 /FVC < 70%
• FEV 1 < 30% predicted or FEV 1 < 50% predicted plus chronic respiratory
failure
Classification based on postbronchodilator FEV 1
FEV 1 : forced expiratory volume in one second; FVC: forced vital capacity; respiratory failure: arterial partial pressure of oxygen (PaO 2 ) less than
8.0 kPa (60 mm Hg) with or without arterial partial pressure of CO 2 (PaCO 2 ) greater than 6.7 kPa (50 mm Hg) while breathing air at sea level.
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