Which of the following is NOT a subset of COPD?

• A. Chronic bronchitis
• B. Emphysema
• C. Chronic obstructive asthma
• D. Asthmatic bronchitis

Answer: (D)

Chronic obstructive pulmonary disease (COPD) encompasses a group of progressive lung diseases primarily characterized by ongoing respiratory symptoms and airflow limitation. The primary subsets of COPD recognized in clinical practice are chronic bronchitis and emphysema, both of which have distinct pathophysiological mechanisms leading to their respective symptoms.

Chronic bronchitis is defined by a persistent cough and mucus production due to inflammation of the airways, whereas emphysema involves the destruction of the alveoli, leading to decreased elastic recoil and impaired gas exchange. Both conditions are commonly found in smokers and are integral to the diagnosis of COPD.

Chronic obstructive asthma and asthmatic bronchitis are terms sometimes used in discussions related to airway obstruction and inflammation, but they are not officially classified within the COPD category. Asthma, while it can share certain characteristics with COPD, is generally considered a separate condition, particularly because it is often reversible and involves different inflammatory pathways compared to the chronic, irreversible airflow limitation observed in COPD.

Therefore, asthmatic bronchitis lacks the same status as chronic bronchitis and emphysema in the context of COPD classification, making it the correct answer to the question of which is NOT a subset of COPD.