Asthma-COPD overlap

Asthma-COPD Overlap (ACO) is a condition that combines features of both Asthma and Chronic Obstructive Pulmonary Disease (COPD), leading to a complex respiratory disorder. It is characterized by persistent airflow limitation with several features usually associated with asthma and several features usually associated with COPD. ACO is increasingly recognized in the clinical setting, underscoring the need for a tailored approach to diagnosis and management.

Definition

ACO is defined by the presence of increased variability of airflow in combination with an incompletely reversible airflow obstruction. This condition is identified in patients who exhibit characteristics of both asthma and COPD, a scenario that complicates management and treatment strategies. The Global Initiative for Chronic Obstructive Lung Disease (GOLD) and the Global Initiative for Asthma (GINA) have provided guidelines to help in the identification and management of ACO.

Epidemiology

The prevalence of ACO varies widely, depending on the diagnostic criteria used. It is estimated that about 15-25% of individuals with COPD or asthma may have features of the overlap syndrome. ACO is more common in individuals over the age of 40 years, who have a history of smoking or exposure to biomass fuel.

Pathophysiology

The pathophysiological mechanisms underlying ACO involve aspects of both airway inflammation and remodeling seen in asthma, and the chronic obstructive changes associated with COPD. This includes chronic inflammation from various cells like neutrophils, eosinophils, and lymphocytes, along with structural changes in the airway walls and lung parenchyma.

Clinical Features

Patients with ACO may present with symptoms common to both asthma and COPD, including chronic cough, sputum production, wheezing, and shortness of breath. These symptoms are often more severe than in individuals with asthma or COPD alone and can lead to a higher frequency of exacerbations and a more rapid decline in lung function.

Diagnosis

Diagnosis of ACO requires a careful clinical assessment, including a detailed patient history and physical examination, spirometry with bronchodilator testing, and possibly other tests such as chest X-ray, high-resolution CT scan, and measurement of blood eosinophils. Identifying features of both asthma and COPD is key to diagnosing ACO.

Management

Management of ACO involves a combination of pharmacological and non-pharmacological treatments aimed at controlling symptoms, improving quality of life, and preventing exacerbations. Treatment may include the use of inhaled corticosteroids, long-acting beta-agonists, long-acting muscarinic antagonists, and short-acting bronchodilators. Smoking cessation, vaccination, pulmonary rehabilitation, and management of comorbidities are also important aspects of care.

Prognosis

The prognosis of ACO is generally considered to be worse than that of asthma or COPD alone due to the increased risk of exacerbations, hospitalizations, and mortality. However, with appropriate management, individuals with ACO can achieve a good quality of life and a level of symptom control.

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