Can asthma cause emphysema (Chronic Obstructive Pulmonary Disease, COPD)?

Can Asthma Cause Emphysema?

Yes, asthma can be a risk factor for the development of emphysema and COPD, particularly in patients with chronic, severe, or poorly controlled asthma. According to the Global Initiative for Chronic Obstructive Lung Disease (GOLD), asthma is recognized as a risk factor for the development of chronic airflow limitation and COPD 1.

Relationship Between Asthma and Emphysema

Pathophysiological Connection

• Chronic inflammation in asthma can lead to airway remodeling over time
• Long-standing asthma, especially when poorly controlled, may contribute to permanent structural changes in the lungs
• Airway hyperresponsiveness, even without a clinical diagnosis of asthma, is an independent predictor of COPD and respiratory mortality 1

Evidence Supporting the Connection

• The Tucson longitudinal study found that subjects with active asthma had a 17-times higher risk of receiving a diagnosis of emphysema compared to non-asthmatics, even after adjusting for smoking history 2
• Patients with active asthma had a 12.5-times higher risk of fulfilling COPD criteria than non-asthmatics 2
• Some treated non-smokers with moderate to severe asthma develop persistent expiratory airflow limitation despite partial reversibility 3

Mechanisms of Emphysema Development in Asthma

Structural Changes

• Chronic inflammation in asthma can lead to loss of lung elastic recoil
• Recent pathophysiologic observations in never-smokers with asthma and persistent airflow obstruction revealed microscopic mild centrilobular emphysema in autopsy specimens 3
• These changes were not easily identified on lung CT scans, suggesting subtle structural damage 3

Inflammatory Processes

• Proinflammatory and proteolytic mechanisms in chronic asthma may contribute to lung tissue breakdown
• Persistent inflammation can lead to structural changes in both large and small airways

Asthma-COPD Overlap (ACO)

Clinical Features

• Patients with both asthma and COPD features represent a distinct clinical population
• These patients experience more frequent and severe respiratory exacerbations despite younger age and reduced lifetime smoking history 4
• ACO patients demonstrate worse disease-related quality of life compared to those with COPD alone 4

Diagnostic Considerations

• Smoking history (≥10 pack-years) is a useful marker for differentiating ACO from asthma with chronic airflow obstruction 5
• Presence of emphysema on imaging is a useful marker for classifying subtypes of ACO 5
• ACO patients with emphysema experience more frequent admissions due to COPD exacerbations, while those without emphysema have more frequent admissions due to asthma attacks 5

Prognostic Implications

Mortality and Lung Function Decline

• Emphysema-predominant COPD shows greater yearly decline in lung function and worse survival compared to airway obstruction-predominant COPD or asthma 6
• The presence of emphysema in patients with chronic airflow obstruction is associated with higher five-year mortality 6
• Oxygen desaturation during exercise (SpO₂ ≤ 80%) and higher emphysema scores are strong risk factors for mortality 6

Clinical Management Considerations

Monitoring and Prevention

• Regular spirometry monitoring is essential in patients with chronic asthma to detect early signs of fixed airflow obstruction
• Early and aggressive treatment of asthma may help prevent the development of irreversible airflow limitation
• Smoking cessation is crucial, as smoking significantly increases the risk of developing emphysema in asthmatic patients

Treatment Approach

• The British Thoracic Society notes that differentiating severe COPD from chronic severe asthma can be difficult since some degree of improvement in FEV₁ can often be produced by bronchodilator therapy 1
• Pathological changes of bronchial asthma in large airways can coexist with those of COPD which predominantly affects small airways 1
• Some patients with COPD have pathological evidence of non-asthmatic inflammation within their airways that may respond to anti-inflammatory treatment 1

Key Takeaways

• Asthma, particularly when chronic and poorly controlled, can lead to emphysema and COPD
• The differentiation between severe COPD and chronic severe asthma can be challenging
• Regular monitoring of lung function in asthmatic patients is essential for early detection of fixed airflow limitation
• Proper asthma management may help prevent the development of emphysema and COPD
• Patients with features of both asthma and COPD represent a distinct clinical population with unique management needs