Can emphysema changes on chest X-ray (CXR) be related to asthma, or are they always associated with Chronic Obstructive Pulmonary Disease (COPD)?

From the Guidelines

Emphysema changes on chest X-ray (CXR) are typically associated with COPD rather than asthma, though there can be some overlap in long-standing cases, as noted in the 2015 study by 1. Asthma primarily causes reversible airway obstruction without permanent structural lung damage in most cases, which is why emphysematous changes (permanent destruction of alveolar walls and enlarged airspaces) are not characteristic of typical asthma. However, some patients with long-standing, severe, or poorly controlled asthma may develop a condition called "asthma-COPD overlap syndrome" (ACOS) where features of both diseases are present, as discussed in the 2015 study by 1. Additionally, some patients with asthma who smoke can develop COPD features including emphysema. When emphysema is seen on imaging, other causes should be considered including alpha-1 antitrypsin deficiency, especially in younger patients or those with minimal smoking history. The distinction matters clinically because treatment approaches differ - asthma management focuses on controlling inflammation and bronchospasm with inhaled corticosteroids and bronchodilators, while COPD treatment emphasizes bronchodilation first with medications like tiotropium and salmeterol, with less emphasis on steroids except in specific circumstances, as outlined in the guidelines by 1 and 1.

Some key points to consider in the diagnosis and management of emphysema and asthma include:

• The presence or absence of some clinical features may help in distinguishing between COPD and asthma, such as a history of heavy smoking, evidence of emphysema on imaging, decreased diffusing capacity, and chronic hypoxaemia, which favor the diagnosis of COPD, as noted in the 1995 study by 1.
• The use of spirometry to confirm the diagnosis of COPD or asthma, as recommended in the guidelines by 1 and 1.
• The importance of considering other causes of emphysema, such as alpha-1 antitrypsin deficiency, especially in younger patients or those with minimal smoking history, as discussed in the example answer.
• The need for a problem-based individualized approach to treatment, targeting each of the pathological processes identified, as suggested in the 2015 study by 1.

Overall, the diagnosis and management of emphysema and asthma require a comprehensive approach, taking into account the patient's clinical history, physical examination, radiology, and potentially screening questionnaires, as well as the use of spirometry to confirm the diagnosis, as outlined in the guidelines by 1, 1, and 1.

From the Research

Emphysema Changes on Chest X-ray (CXR) and Their Relation to Asthma and COPD

• Emphysema changes on CXR can be related to both asthma and Chronic Obstructive Pulmonary Disease (COPD) 2.
• A study classified obstructive airway diseases into five groups, including asthma, Asthma-COPD Overlap Syndrome (ACOS), chronic bronchitis, emphysema, and undifferentiated obstruction (UNDO), which includes emphysema with chronic bronchitis and emphysema with asthma 2.
• The study found that 14 patients (6%) had emphysema with chronic bronchitis and asthma, indicating that emphysema changes on CXR can be associated with both asthma and COPD 2.

Diagnosis of Emphysema Using Chest X-ray (CXR) and High-Resolution Computed Tomography (HRCT)

• A study compared the use of CXR and HRCT in diagnosing emphysema in patients with COPD and found that CXR scores of emphysema correlated linearly with HRCT visual scores and quantitative data 3.
• The study suggested that CXR can be a useful tool in diagnosing emphysema, especially in patients with no signs of emphysema on CXR, who had mean expiratory CT numbers within normal range and a fraction of lung area with CT numbers < -900 HU on expiratory scan not exceeding 15% of total cross-sectional area 3.

Emphysema Severity Index (ESI) and Its Relation to COPD

• A study introduced the Emphysema Severity Index (ESI), a simple parameter that reflects CT-assessed emphysema, and found that ESI values were greatly dispersed within each GOLD class, indicating that GOLD classification cannot discriminate emphysema and conductive airways changes in patients with similar airflow limitation 4.
• The study suggested that ESI computation from spirometric data can help define the prevailing pathogenetic mechanism underlying the measured airflow limitation and can be a reliable advancement to select large samples of patients in clinical or epidemiological trials 4.

Prevalence of Emphysema in Asymptomatic Participants with and without a Prior Diagnosis of COPD

• A study found that 23.8% of participants undergoing low-dose CT screening had CT evidence of emphysema, and 76.5% of these participants had no prior COPD diagnosis 5.
• The study suggested that low-dose CT screening can provide an opportunity to identify emphysema and recommend smoking cessation, especially in asymptomatic participants with no prior COPD diagnosis 5.