Asthma and Chronic Obstructive Pulmonary Disease (COPD) are two of the most common chronic respiratory conditions affecting millions of people worldwide. However, there’s a lesser-known yet increasingly recognized condition where both diseases coexist — Asthma-COPD Overlap Syndrome (ACOS).
ACOS presents a complex clinical challenge because it shares characteristics of both asthma and COPD, yet behaves differently from either condition alone. Understanding ACOS is essential for accurate diagnosis and effective management, as it requires a tailored approach combining treatments for both diseases.
This article explores the causes, symptoms, diagnostic criteria, and treatment options for ACOS, helping patients and caregivers better manage this overlapping respiratory disorder.
What Is Asthma-COPD Overlap Syndrome (ACOS)?
Asthma-COPD Overlap Syndrome (ACOS) refers to a condition in which a patient exhibits features of both asthma (a chronic inflammatory airway disease) and COPD (a progressive disease that obstructs airflow).
Although ACOS is not a distinct disease, it is recognized as a clinical phenotype that requires specialized attention. People with ACOS tend to experience frequent exacerbations, more severe symptoms, and reduced quality of life compared to those with asthma or COPD alone.
Key Characteristics of ACOS
Persistent airflow limitation (like COPD)
Airway hyperreactivity (like asthma)
Frequent respiratory symptoms such as wheezing, coughing, and shortness of breath
A history of asthma, smoking, or exposure to lung irritants
Asthma vs. COPD vs. ACOS: Understanding the Differences
| Feature | Asthma | COPD | ACOS |
|---|---|---|---|
| Onset | Early in life | Usually after age 40 | Often mid-life |
| Airflow limitation | Reversible | Irreversible or partially reversible | Partially reversible |
| Symptoms | Variable, triggered by allergens or exercise | Persistent and progressive | Persistent with variable intensity |
| Smoking history | May or may not be present | Common | Often present |
| Inflammation type | Eosinophilic | Neutrophilic | Mixed |
| Response to inhaled corticosteroids (ICS) | Excellent | Limited | Moderate to good |
Causes and Risk Factors of ACOS
The exact cause of ACOS is not completely understood, but it likely arises from shared risk factors and pathophysiological mechanisms of both asthma and COPD.
Common Causes and Triggers
Genetic susceptibility – Family history of asthma or COPD may increase risk.
Smoking – The leading modifiable risk factor for COPD and a major contributor to ACOS.
Environmental pollutants – Exposure to dust, fumes, or industrial chemicals.
Chronic airway inflammation – Long-term airway damage due to untreated asthma or irritant exposure.
Respiratory infections – Early-life or recurrent infections can alter airway structure.
Age – Middle-aged and older adults are more prone to overlap features.
Symptoms of Asthma-COPD Overlap Syndrome
ACOS symptoms combine features of both diseases, making diagnosis challenging. These symptoms can vary in frequency and intensity, often worsening with environmental exposure, infections, or poor air quality.
Common Signs and Symptoms
Chronic cough (with or without mucus)
Shortness of breath (dyspnea), especially during exertion
Chest tightness or pain
Fatigue and reduced exercise tolerance
Frequent respiratory infections
Exacerbations requiring medical intervention
When to Seek Medical Attention
If you have asthma or COPD and experience worsening symptoms, increased medication use, or reduced ability to perform daily activities, it’s essential to consult a pulmonologist. Early management prevents further lung damage and improves quality of life.
How Is ACOS Diagnosed?
Diagnosis of ACOS requires a comprehensive clinical assessment since there’s no single test to confirm it. Physicians typically use a combination of medical history, lung function tests, and imaging.
1. Medical History and Symptom Review
History of asthma or COPD
Smoking history
Frequency and severity of respiratory symptoms
Response to bronchodilators or inhalers
2. Physical Examination
Wheezing or decreased breath sounds
Signs of hyperinflation in the chest
Use of accessory muscles for breathing
3. Pulmonary Function Tests (PFTs)
Spirometry measures airflow limitation and reversibility.
FEV1/FVC ratio < 0.70 suggests obstruction.
Partial reversibility after bronchodilator use indicates ACOS.
4. Imaging Studies
Chest X-ray or CT scan can reveal emphysematous changes or airway wall thickening.
5. Biomarkers and Blood Tests
Eosinophil count: Elevated levels suggest an asthma component.
IgE levels: May indicate allergic asthma.
6. Diagnostic Criteria (Simplified)
Patients are suspected to have ACOS if they:
Are over 40 years old
Have a history of smoking
Show persistent airflow limitation
Exhibit features of both asthma (allergy, variability) and COPD (fixed obstruction)
Treatment of Asthma-COPD Overlap Syndrome
There is no cure for ACOS, but it can be effectively managed with a combination of lifestyle changes, inhaled medications, and regular follow-up. The treatment strategy aims to reduce symptoms, prevent exacerbations, and improve lung function.
1. Pharmacological Management
a. Inhaled Corticosteroids (ICS)
Reduce airway inflammation and prevent asthma-related symptoms.
Commonly used in combination with long-acting bronchodilators.
b. Long-Acting Beta-Agonists (LABA)
Relax airway muscles and improve airflow.
Always used alongside ICS in ACOS patients.
c. Long-Acting Muscarinic Antagonists (LAMA)
Reduce bronchoconstriction and mucus production.
Especially beneficial for COPD-related symptoms.
d. Combination Inhalers
ICS + LABA or ICS + LABA + LAMA (triple therapy) is often prescribed for ACOS management.
e. Oral Medications
Leukotriene modifiers, theophylline, or short-course oral corticosteroids during exacerbations.
f. Vaccinations
Influenza and pneumococcal vaccines to prevent infections that worsen symptoms.
2. Non-Pharmacological Management
a. Smoking Cessation
The single most effective step to slow disease progression and improve lung function.
b. Pulmonary Rehabilitation
Structured exercise and breathing programs that enhance endurance, reduce dyspnea, and improve quality of life.
c. Oxygen Therapy
Prescribed for patients with low blood oxygen levels.
d. Nutrition and Weight Management
Maintaining a healthy body weight supports respiratory function and energy levels.
e. Environmental Control
Avoid exposure to smoke, pollution, strong fragrances, and dust.
f. Patient Education
Understanding how and when to use inhalers, recognizing early signs of exacerbation, and adhering to treatment plans are vital for long-term success.
Living with Asthma-COPD Overlap Syndrome
Living with ACOS can be challenging, but adopting certain lifestyle habits can help patients manage their condition effectively:
Follow medication schedules diligently.
Monitor symptoms using a daily peak flow meter.
Engage in mild to moderate exercise like walking or yoga.
Avoid known triggers such as allergens, cold air, or chemical fumes.
Get regular check-ups and spirometry tests to track lung function.
Stay hydrated to thin mucus and make breathing easier.
Complications of ACOS
Without proper management, ACOS can lead to severe health issues such as:
Frequent and severe exacerbations
Hospitalization for respiratory failure
Accelerated decline in lung function
Reduced oxygen levels and organ damage
Decreased quality of life
Early diagnosis and adherence to treatment are crucial to preventing these complications.
Prevention Tips
While not all causes of ACOS are preventable, certain actions can significantly reduce the risk:
Quit smoking and avoid secondhand smoke.
Wear masks in polluted environments.
Treat asthma early and maintain long-term control.
Get vaccinated against flu and pneumonia.
Maintain indoor air quality using purifiers and avoiding dust.
Stay active to strengthen lungs and immunity.
Prognosis
The prognosis for ACOS varies depending on disease severity, treatment adherence, and lifestyle habits. With proper management, many patients can lead active, symptom-controlled lives. However, those who continue to smoke or delay treatment may experience faster lung function decline and poorer outcomes.
Frequently Asked Questions (FAQ)
1. What is the main difference between ACOS and COPD?
While COPD involves irreversible airflow limitation due to long-term exposure to irritants, ACOS features partially reversible obstruction along with asthma-like airway inflammation.
2. Can a person have both asthma and COPD?
Yes. Many patients with long-standing asthma who smoke or are exposed to irritants develop COPD-like symptoms, resulting in ACOS.
3. Is ACOS curable?
No, ACOS cannot be cured, but it can be effectively managed with medication, pulmonary rehabilitation, and lifestyle modifications.
4. What type of doctor treats ACOS?
A pulmonologist (chest specialist) is the best professional to diagnose and manage ACOS.
5. Can ACOS worsen over time?
Yes. Without appropriate treatment or if smoking continues, ACOS can progress and lead to severe respiratory disability.
6. Are inhalers safe for long-term use?
Yes. When used as prescribed, inhalers are safe and essential for controlling airway inflammation and maintaining normal breathing.
7. Does ACOS increase the risk of infections?
Yes, because chronic airway inflammation and mucus buildup can make patients more prone to respiratory infections.
Asthma-COPD Overlap Syndrome (ACOS) represents a unique respiratory condition that combines features of both asthma and COPD. While it poses diagnostic and therapeutic challenges, timely intervention, personalized treatment, and lifestyle modifications can dramatically improve outcomes.
If you experience persistent coughing, wheezing, or shortness of breath, don’t ignore the symptoms — seek medical evaluation to identify whether you might have ACOS.
At Sparsh Diagnostic Centre, Kolkata, we provide advanced diagnostic tests and expert respiratory care to help manage chronic lung conditions effectively.
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