COPD

What is COPD?

Chronic obstructive pulmonary disease (COPD) is a common lung condition that is preventable and treatable.^1,2 It is characterized by poorly reversible and progressive airflow obstruction, resulting from chronic inflammation and structural changes in the lungs.^1,2 A major cause of morbidity and mortality, COPD is now the third leading cause of death worldwide.^2,3

The pathophysiology of COPD

COPD is a heterogenous syndrome that covers several distinct and overlapping disease processes, some or all of which may be present to varying degrees in individual patients.^1-5

The bronchioles (small airways) are held open by alveolar attachments in normal, healthy lungs.²

In COPD, the following pathological processes contribute to the narrowing of the bronchioles, resulting in poorly reversible airflow obstruction and reduced lung function:²

• Chronic bronchitis (mucus hypersecretion by the goblet cells, which obstructs the bronchioles)^2,6
• Emphysema (destruction of the alveolar walls and attachments, accompanied by an enlargement of the alveoli)²
• Bronchiolitis (mucosal inflammation and fibrosis contribute to the thickening of the bronchiole wall, causing the bronchioles to narrow)²

Facts about COPD

COPD has been under diagnosed in Taiwan.

• In Taiwan, estimated prevalence in general population was 6.1%
• Based on Taiwan National Health Insurance from 1996 to 2002, the average annual medical reimbursement claims of COPD was only around 2.5%

Symptoms

Patients with COPD may present with a range of symptoms, from characteristic breathlessness to the less common wheezing and chest tightness.^1,8,9 Symptoms and exacerbations can make it challenging for patients to perform their daily activities and impact their quality of life.⁹

COPD symptoms may show daily variability and can precede the development of airflow limitation by many years, so it’s important to examine patients with symptoms for underlying conditions (especially if they have COPD risk factors).¹

COPD should be considered in patients over 35 with a risk factor (e.g. a history of smoking) who present with the following symptoms:^1,8

1. Dyspnea (shortness of breath)
2. Chronic cough
3. Sputum production

Risk factors and causes

Exposure to particles

Tobacco smoke (including second-hand or passive exposure) is the primary risk factor for COPD, but other factors such as air pollution, exposure to biomass fuels and occupational dusts and chemicals can also contribute to its development.^1,8,10

Genetic factors

Some people have genetic risk factors that predispose them to develop COPD – the most well documented of these is severe hereditary alpha-1 anti-trypsin deficiency.¹ Genetic factors may also interact with environmental factors to increase susceptibility to COPD, as a significant familial risk of airflow limitation has been observed in individuals who smoke and have siblings with severe COPD.^1,2

Other risk factors may include:¹

• Lower socioeconomic status and poverty
• Airway hyper-responsiveness
• History of respiratory infections – especially tuberculosis

Incidence and prevalence

The Asia-Pacific region bears the highest burden of COPD in terms of deaths, years spent living with disability, and years of life lost; however, the prevalence varies between countries in this region. The average annual prevalence of COPD in Taiwan based on national health insurance medical reimbursement claims from 1996 to 2002 was around 2.5%.⁷

A random cross-sectional national survey of adults older than 40 years was conducted in Taiwan. Of the 6,600 participants who completed the survey, 404 (6.1%) fulfilled the epidemiological case definition of COPD: 137 with diagnosed COPD and 267 possible COPD. With estimated prevalence of 6.1% in the general population, COPD in Taiwan has been underdiagnosed.⁷