Global Initiative for Chronic Obstructive Lung Disease - GOLD

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SCOPE OF THE REPORT
The focus of this Report is primarily on COPD caused by
inhaled particles and gases, the most common of which
worldwide is tobacco smoke. Poorly reversible airflow
limitation associated with bronchiectasis, cystic fibrosis,
tuberculosis, or asthma is not included except insofar as
these conditions overlap with COPD.
Asthma and COPD
COPD can coexist with asthma, the other major chronic
obstructive airway disease characterized by an underlying
airway inflammation. Asthma and COPD have their major
symptoms in common, but these are generally more
variable in asthma than in COPD. The underlying chronic
airway inflammation is also very different (Figure 1-4):
that in asthma is mainly eosinophilic and driven by CD4 +
T lymphocytes, while that in COPD is neutrophilic and
characterized by the presence of increased numbers of
macrophages and CD8 + T lymphocytes. In addition,
airflow limitation in asthma is often completely reversible,
either spontaneously or with treatment, while in COPD it is
never fully reversible and is usually progressive if exposure
to noxious agents continues. Finally, the responses to
treatment of asthma and COPD are dramatically different,
in terms of both the overall magnitude of the achievable
response and the qualitative effects of specific treatments
such as anticholinergics and glucocorticosteroids.
However, there is undoubtedly an overlap between
asthma and COPD. Individuals with asthma who are
exposed to noxious agents that cause COPD may develop
a mixture of "asthma-like" inflammation and "COPD-like"
inflammation. There is also evidence that longstanding
asthma on its own can lead to airway remodeling and
partly irreversible airflow limitation. Asthma can usually
be distinguished from COPD, but until the causal mechanisms
and pathognomonic markers of these diseases are
Figure 1-4. Asthma and COPD
Asthma
Sensitizing agent
Asthmatic airway inflammation
CD4 + T lymphocytes
Eosinophis
Completely
reversible
Airflow Limitation
COPD
Noxious agent
COPD airway inflammation
CD8 + T lymphocytes
Macrophages Neutrophils
Completely
irreversible
better understood it will remain difficult to differentiate the
two diseases in some individual patients. Given the current
state of medical and scientific knowledge, an attempt to
determine an absolutely rigid definition of COPD or asthma
is bound to end up in semantics.
Pulmonary Tuberculosis and COPD
In many developing countries both pulmonary tuberculosis
and COPD are common. In countries where tuberculosis
is very common, respiratory abnormalities may be too
readily attributed to this disease. Conversely, where the
rate of tuberculosis is greatly diminished, the possible
diagnosis of this disease is sometimes overlooked.
Chronic bronchitis/bronchiolitis and emphysema often
occur as complications of pulmonary tuberculosis and
are important contributors to the mixed lung function
changes characteristic of tuberculosis 4 . The degree of
obstructive airway changes 5 in treated patients with
pulmonary tuberculosis increases with age, the amount
of cigarettes smoked, and the extent of the initial
tuberculous disease 6 . In patients with both diseases,
COPD adds to the disability of pulmonary tuberculosis,
and vice versa.
Therefore, in all subjects with symptoms of COPD, a
possible diagnosis of tuberculosis should be considered,
especially in areas where this disease is known to be
prevalent. Investigations to exclude tuberculosis should
be a routine part of COPD diagnosis, the intensity of the
diagnostic procedures depending on the degree of
suspicion. Chest radiograph and sputum culture are
helpful in making the differential diagnosis.
REFERENCES
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of chronic obstructive pulmonary disease. New
York: Marcel Dekker; 1989. p. 1-22.
2. Vermeire PA, Pride NB. A "splitting" look at chronic nonspecific
lung disease (CNSLD): common features but
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3. Fletcher C, Peto R. The natural history of chronic airflow
obstruction. BMJ 1977; 1:1645-8.
4. Leitch AG. Pulmonary tuberculosis: clinical features. In:
Crofton J, Douglas A, eds. Respiratory diseases. Oxford:
Blackwell Science; 2000. p. 507-27.
5. Birath G, Caro J, Malmberg R, Simonsson BG. Airway
obstruction in pulmonary tuberculosis. Scand J Resp Dis
1966; 47:27-36.
6. Snider GL, Doctor L, Demas TA, Shaw AR. Obstructive airway
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Am Rev Respir Dis 1971; 103:625-40.
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