Chronic Obstructive Pulmonary Disease (COPD) Overview

Chronic obstructive pulmonary disease (COPD) is the name for a group of progressive respiratory disorders that are characterized by a persistent cough, shortness of breath, and fatigue.¹ The most common types of COPD are chronic bronchitis and emphysema, and these two conditions often occur in the same person.² Chronic bronchitis is a result of prolonged inflammation of the bronchi, which leads to persistent coughing and an increase in sputum production.³ In people with emphysema, the alveolar walls have been damaged to the extent that they that can no longer efficiently facilitate the exchange of oxygen and carbon dioxide in the blood.²

In the United States, smoking has typically been the main risk factor for COPD, although long-term exposure to environmental pollutants and other factors (e.g., altered lung development) can also increase the risk of developing this condition.⁴ Certain infections and genetic factors may also play a role in the development of COPD.

Women were previously thought to have a lower risk of COPD than men, resulting in a diagnostic bias that has caused this condition to be underdiagnosed in women.⁵ More recent data suggest that women are more likely than men to receive a diagnosis of early onset COPD, be hospitalized for COPD, and have flare-ups called exacerbations.⁶ In addition, studies have suggested that inhaling cigarette smoke or environmental pollutants causes more severe damage to the lungs at lower doses in women than in men, although the reasons for this discrepancy are not entirely clear.^{2 , 6} The risk of lung function decline increases around the menopausal transition for women with chronic pulmonary diseases, and early menopause is known to be a significant risk factor for COPD.^{7 , 8}

Women with COPD have a higher risk of developing lung cancer than women without COPD, even after adjusting for factors such as smoking status, body mass index, and income.⁹ In studies of the other comorbidities that are associated with COPD, women have been shown to have higher rates of depression, anxiety, osteoporosis, arthritis, and asthma than men but lower rates of cardiovascular diseases.^{10 , 11}

Anti-inflammatory drugs and bronchodilators can help reduce inflammation in people with COPD and allow them to breathe more easily. In more severe cases, people with COPD may require oxygen therapy or surgery (e.g., bullectomy, lung volume reduction surgery, lung transplant).¹²

Researchers are still working to determine the specific roles genetic factors and hormones play in the development of COPD. Other areas of active research include how comorbid conditions (e.g., anxiety, depression, lung cancer) and sex differences affect treatment response. Finally, cases of COPD that occur in people with no history of smoking are a pressing global issue, and this type of COPD is more likely to affect women than men.⁸ This creates the need for research into the environmental and social influences on this condition.

Researchers in the Division of Lung Diseases and the Obstructive Lung Diseases Branch at the National Heart, Lung, and Blood Institute (NHLBI) are investigating a wide range of COPD-related topics, including early detection methods, potential genetic therapies, and the impact of COPD on specific populations. The Genetic Epidemiology of COPD (COPDGene) Study and the Subpopulations and Intermediate Outcome Measures in COPD Study (SPIROMICS II) are longitudinal studies of people who are at risk for COPD. Both studies aim to evaluate the risk factors for COPD and identify biomarkers for COPD using high throughput genetics and genomics, radiographic methods, and new approaches to phenotyping.