Epidemiology of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a leading cause of world-wi de mortality and disability. On average similar to5-15% of adults in indust rialized countries have COPD defined by spirometry. In 1990, COPD was consi dered to be at the twelfth position world-wide as a cause of combined morta lity and disability but is expected to become the fifth cause by the year 2 020. COPD has a chronic long-lasting course characterized by irreversible declin e of forced expiratory volume in one second (FEV1), increasing presence of dyspnoea and other respiratory symptoms, and progressive deterioration of h ealth status. After diagnosis the 10-yr survival rate is similar to 50% wit h more than one-third of patients dying due to respiratory insufficiency. Several environmental exposures such as air pollution increase the risk of death in COPD patients. The aetiology of COPD is overwhelmingly dominated b y smoking although many other factors could play a role. Particular genetic variants are likely to increase the susceptibility to environmental factor s although little is known about which are the relevant genes. There is cle ar evidence about the role of the alpha -1-antitrypsin but the fraction of COPD attributable to the relevant variants is only 1%. Phenotypic traits th at are considered to play a role in the development of COPD include sex, wi th females being at a higher risk, bronchial responsiveness and atopy. Ther e is strong causal evidence regarding the relationship between smoking and COPD with decline in FEV1 levelling off after smoking cessation. Passive sm oking has been found to be associated with a small though statistically sig nificant decline in FEV1. Other risk factors that are likely to be relevant in the development of COPD are occupation, low socioeconomic status, diet and possibly some environmental exposures in early life. Although there is accumulating evidence that oxygen therapy, pharmacologica l treatment and rehabilitation may improve the course of chronic obstructiv e pulmonary disease, preventing smoking continues to be the most relevant m easure, not only to prevent chronic obstructive pulmonary disease, but also to arrest its development.