COPD: An Overview

Chronic obstructive pulmonary disease (often called “COPD”) is one of the most important diseases of the 21st century, being a major cause of death and disability. COPD is a common, preventable, and treatable disease characterized by persistent respiratory symptoms and airflow limitation that is not fully reversible. The airflow limitation is usually both progressive and associated with an abnormal inflammatory response of the airways and/or alveolar abnormality caused due to significant exposure to noxious particles or gases.
Chronic airflow limitation leads to lung hyperinflation which is the main mechanism of the characteristic exertional dyspnea in COPD. Phenomenon of hyperinflation develops early in COPD, is increased with exercise, and is believed to lead eventually to pulmonary hypertension and right heart failure (CorPulmonale) as the disease progresses. Up to 25% of COPD patients may suffer from co-morbid conditions, such as cardiovascular disorders, including myocardial infarction and angina, weight loss, nutritional abnormalities, skeletal muscle dysfunction, osteoporosis, bone fractures, diabetes, sleep disorders, depression, anemia, and glaucoma. Some significant co-morbid conditions might contribute to the severity of COPD in some individuals. As a consequence of its high prevalence and chronicity, COPD causes high resource utilization with frequent clinician visits, frequent hospitalizations due to acute exacerbations, and the need for chronic therapy (for example, supplemental oxygen therapy and medication).
There is growing evidence that indoor biomass exposure to modern and traditional fuels used during cooking may predispose women to develop COPD in many developing countries. Most epidemiological studies have found that the prevalence of morbidity and mortality due to COPD have increased over time and are greater in men than in women. Poverty is consistently associated with airflow obstruction, and lower socioeconomic status is associated with an increased risk of developing COPD. There is evidence that HIV patients are at increased risk of COPD, compared to HIV-negative controls.
Worldwide, the most commonly encountered risk factor for COPD is tobacco smoking. Other types of tobacco (pipe, cigar, water pipe) and marijuana, outdoor and indoor pollution, including the burning of biomass fuels used for cooking, as well as environmental tobacco smoke are other major risk factors. Occupational exposures, including organic and inorganic dust and chemical agents and fumes, are under-appreciated risk factors for COPD. Household air pollution and outdoor air pollution also contribute to the lungs’ total burden. Genetic factors, such as severe hereditary deficiency of alpha-1-antitrypsin (AATD), lead to COPD. Aging increases COPD risk. Any factors that affect lung growth during gestation and childhood (low birth weight, respiratory infections, etc.) increase risk of COPD. Socioeconomic status, poor nutrition, crowding, and frequent infections increase the risk of developing COPD. Bronchial asthma and airway hyper-reactivity are also major risk factors. Chronic bronchitis increases the frequency of total and severe exacerbations.
COPD globally is significant, as it greatly impacts public health resources and impairs the patient’s quality of health. COPD is presently the fourth leading cause of death in the world and it is predicted to become the third leading cause by 2020. COPD should be considered in any patient who has these symptoms, and/or a history of exposure to COPD risk factors.
Common respiratory symptoms are shortness of breath, chronic cough, and sputum production. Spirometry, or pulmonary, function test is required to diagnose COPD. For physicians, common assessment to measure breathlessness or to grade the severity of COPD, GOLD A, B, C, D classes, or modified British Medical Research Questionnaire (mMRC), and COPD Assessment Test (CAT) are commonly used. Some use all these three criteria as combined COPD assessment tools.
For COPD prevention and maintenance strategy, “smoking cessation is key”. Pharmacotherapy and nicotine replacement reliably increase long-term smoking abstinence rates. The safety of e-cigarettes as a smoking cessation aid is uncertain at present. The mainstays of therapy for stable COPD are inhaled bronchodilators (beta agonists and muscarinic antagonists) given alone, in combination, or with the addition of inhaled glucocorticoids. Pharmacologic therapy can reduce COPD symptoms, reduce the frequency and severity of exacerbations, and improve the health status and exercise tolerance.
Each pharmacologic treatment regimen should be individualized and guided by the severity of symptoms, risk of exacerbations, side-effects, co-morbidities, drug availability and cost, and the patient’s response, preference, and ability to use various drug delivery devices.
No “one size fits all” for patients with COPD using bronchodilator treatment, different inhaler medications such as short-acting beta agonist (SABA), long-acting beta agonist (LABA), long-acting muscarinic antagonist (LAMA), and inhaled glucocorticoids (ICS), either alone or in combination is used. If the frequency of COPD exacerbations is noted, and blood eosinophils are high, Inhaled glucocorticoids (ICS) use is strongly recommended. Inhaled triple therapy of LABA+LAMA+ICS has been popular for the last two years in many developed countries. Nonpharmacologic therapies like smoking cessation, pulmonary rehabilitation, vaccination, and nutrition should be initiated along with pharmacotherapy.
Inhaler technique of COPD patients needs to be assessed regularly. Annual influenza vaccination decreases the incidence of lower respiratory tract infections, as does pneumococcal vaccination. Pulmonary rehabilitation improves symptoms, quality of life, and physical and emotional participation in everyday activities. Physical activity at optimal level should be encouraged. In patients with severe resting chronic hypoxemia, long-term oxygen therapy improves survival.
In patients with stable COPD and resting or exercise induced moderate desaturation, long-term oxygen treatment should not be prescribed routinely. However, individual patient factors must be considered when evaluating the patient’s need for supplemental oxygen. In patients with severe chronic hypercapnia and a history of hospitalization for acute respiratory failure, long-term non-invasive ventilation may decrease mortality and prevent re-hospitalization. In select patients with advanced emphysema refractory to optimized medical care, surgical or bronchoscopic interventional treatments may be beneficial. Surgical options include lung-volume–reduction surgery (LVRS) and lung transplantation. Bronchoscopic one-way valve insertion in the airway is also promising in selected patients.
Palliative approaches are effective in controlling symptoms in advanced COPD.