Chronic obstructive pulmonary disease
Risk factors for the development of COPD include cigarette smoke exposure (primary or secondary) and occupational exposures (organic and inorganic dusts, chemical fumes, and smoke) as well as biomass fuel exposure (fuel developed from plant or animal materials, eg, wood, crops, animal waste, and some municipal solid waste) in the developed setting.
COPD due to cigarette smoke exposure leads to more severe emphysema and more rapid decline in lung function compared with COPD from biomass exposure. The latter presents with distinctive airway wall thickening and sees lung function improve from the use of bronchodilators. The number of symptoms, exacerbations, and hospitalizations is higher in patients with asthma leading to COPD compared with patients with smoking-associated COPD, although, paradoxically, the asthma-associated mortality rate is lower.
Eosinophilic COPD represents a distinct subgroup of COPD patients with increased corticosteroid response. It has been labeled as a part of the asthma-COPD overlap syndrome, although these patients are often notable for having serum eosinophilia > 3%. Of note, unlike other patients with asthma-COPD overlap syndrome, eosinophilic COPD patients tend to be older and have fewer environmental allergies and fewer overall exacerbations. It is not clear that these subcategories of COPD should impact the approach to management, however.
Most patients with COPD present with cough and dyspnea, symptoms that often have developed insidiously by the time the patient finally presents to care. Chronic daily cough is predictive of frequent exacerbations. Per the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines, a post-bronchodilator forced expiratory volume in 1 second (FEV-1) / forced vital capacity (FVC) ratio of less than 70% defines COPD. The FEV-1 (% predicted) determines severity.
Hypertension is the most common concurrent disease in patients with COPD. Other common coexisting conditions include ischemic heart disease, atrial fibrillation, heart failure, osteoporosis, lung cancer, gastroesophageal reflux, anxiety, and depression, all of which may occur at younger ages in COPD patients than in the general population.
J44.9 – Chronic obstructive pulmonary disease, unspecified
13645005 – Chronic obstructive lung disease
Differential Diagnosis & Pitfalls
- Asthma – Typically at least partially reversible airflow obstruction and more allergic overlay; can co-exist with COPD in the asthma-COPD overlap syndrome.
- Chronic bronchitis with normal spirometry
- Central airway obstruction – Symptoms generally do not improve with inhaled bronchodilators; flow volume loops can show changes demonstrating central airway obstruction.
- Congestive heart failure – Usually a restrictive pattern on pulmonary function tests.
- Constrictive bronchiolitis / bronchiolitis obliterans – Usually seen following organ or stem cell transplant, after inhalational injury, or in context of a rheumatologic disorder such as rheumatoid arthritis or inflammatory bowel disease.
- Diffuse panbronchiolitis – Generally nonsmokers; commonly have coexistent sinusitis.
- Lymphangioleiomyomatosis – Seen in women of childbearing age. Centrilobular thin-walled cysts can be mistaken for emphysematous blebs. Can lead to pneumothorax. Airflow obstruction is generally mild.