The material covered in this review is based on an extensive literature search and participation in expert meetings during the writing and updating of the GOLD guidelines, and on many years of research in the subject. We did a systematic MEDLINE search for articles in English or with English abstracts with keywords COPD, prevalence, morbidity, burden, cost, pollution, occupation, genetic, and severity, up to June, 2004.
SeminarBurden and clinical features of chronic obstructive pulmonary disease (COPD)
Section snippets
Definition
For years, clinicians, physiologists, pathologists, and epidemiologists have struggled with the definitions of disorders associated with chronic airflow limitation. The definition of COPD as given by GOLD is now rapidly gaining general acceptance: “COPD is a disease state characterized by airflow limitation that is not fully reversible. The airflow limitation is usually both progressive and associated with an abnormal inflammatory response of the lungs to noxious particles or gases.” 3
Chronic
Prevalence
COPD prevalence and morbidity data probably greatly underestimate the true burden of the disease, because it is not usually recognised until it is clinically apparent and moderately advanced. Studies of COPD prevalence have used self-reported respiratory symptoms, physician diagnosis of COPD, or the presence of airflow limitation as criteria. Use of self-reported symptoms will include people with chronic bronchitis but without airflow limitation.
More recent epidemiological surveys have used
Economic burden
Because of the high prevalence of the disease and the potential for severe disability, COPD represents a substantial economic and social burden. It is, therefore, surprising how little information is available on the direct and indirect costs resulting from morbidity and premature death from COPD.
Some countries have attempted to assess the economic burden of COPD, separating costs directly and indirectly attributable to the disease. Data from developing countries are not yet available, but data
Risk factors
Most evidence about exogenous risk factors for COPD comes from cross-sectional epidemiological studies that identify associations rather than links between cause and effect3 (figure 4).
Clinical features
COPD should be considered in any patient presenting with cough, sputum production, or dyspnoea, especially if the patient has been exposed to risk factors for the disease. Clinical diagnosis is confirmed by standardised spirometric tests that show the presence of airflow limitation (ie, postbronchodilator FEV1<80% of the predicted value in combination with an FEV1/FVC <0·7). Clinical symptoms and signs, such as abnormal shortness of breath and increased forced expiratory time, can be used to
Cough and sputum
Cough may initially occur intermittently but it is usually the first symptom of COPD to develop.37 It may be unproductive38 and is frequently neglected as a clinical sign by patients. Regular production of sputum for 3 months or more in 2 consecutive years has been the epidemiological definition of chronic bronchitis39 for many years but this pattern of sputum production is not really the same as that seen in COPD patients, which is generally very variable and sometimes difficult to assess.4
Dyspnoea
Natural history
Studies on the natural history of COPD show that it is usually a progressive disease, although differences exist between individuals. Continued exposure to noxious agents promotes a more rapid decline in lung function and increases the risk for repeated exacerbations (figure 5). If exposure to noxious agents is stopped, the disease may still progress because of the age-related decline in lung function, and the persistence of aspects of the inflammatory response.58 Nevertheless, efforts need to
Search strategy
Conflict of interest statement
None declared.
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