The Differences Between COPD and Asthma

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Asthma and chronic obstructive pulmonary disease (COPD) are both respiratory diseases involving chronic inflammation that leads to airflow obstruction with similar symptoms. The main difference between COPD and asthma lies in the physical processes triggering the symptoms of each condition. In some cases, the conditions themselves may overlap in what is termed asthma-COPD overlap syndrome, or ACOS.

Symptoms Shared by COPD and Asthma

Both diseases may present these symptoms:

However, while the symptoms may be similar, the frequency and predominating symptoms in asthma and COPD are different. With COPD, you are more likely to experience a morning cough, increased amounts of sputum, and persistent symptoms. If you have asthma, you are more likely to experience symptoms in episodes and/or at night.

Another difference between asthma and COPD is the intermittent symptoms seen with asthma versus the chronic, progressive symptoms seen in COPD. Asthma symptoms are likely to occur after exposure to specific triggers, whereas COPD symptoms occur more regularly.

While airflow in asthma is mostly reversible, airflow in COPD is only partially reversible or may not be reversible at all.

There are a number of other differences between COPD and asthma:

Asthma

  • Often diagnosed in childhood or adolescence

  • Commonly triggered by allergens, cold air, exercise

  • Comorbid conditions include eczema and allergic rhinitis

  • Asthma patients are more commonly nonsmokers

  • Treatment usually involves inhaled steroids

COPD

  • Often diagnosed in adulthood

  • Exacerbations commonly triggered by pneumonia and flu or pollutants

  • Comorbid conditions include coronary heart disease or osteoporosis

  • Most patients with COPD have smoked or had significant secondhand smoke exposure

  • Treatment usually involves surgery and pulmonary rehabilitation

Causes

Both asthma and COPD may be considered inflammatory diseases, but the inflammation comes from different types of white blood cells.

In the pathophysiology of asthma, inflammation results acutely from the production of eosinophils, a type of white blood cell that increases in the presence of an allergen. This response causes airways to become inflamed and irritable when triggered by an allergen. When this happens it becomes more difficult to move air in and out of your airways, which leads to asthma symptoms.

In COPD, your lungs become damaged following exposure to certain irritants, most commonly due to chronic cigarette smoking. This chronic exposure and damage lead to airway obstruction and hyperinflation. The pathophysiology of COPD primarily involves the production of neutrophils and macrophages over many years.

Diagnosis

Both conditions are diagnosed with a simple, noninvasive breathing test called spirometry, usually performed in a doctor's office.

In both asthma and COPD, your doctor will measure certain aspects of your lung function such as forced expiratory volume, or FEV1. With asthma, treatment returns your lung function to normal or near-normal and you should not have many asthma symptoms between asthma exacerbations.

On the other hand, a COPD patient's lung function will generally not return to normal and only partially improves even with smoking cessation and bronchodilator treatment. In fact, even with smoking cessation, COPD patients may still experience a decline in lung function. This decline usually leads to symptoms, such as shortness of breath, that are often the reason the COPD patient is seeking care. Once a COPD patient develops symptoms, symptoms are generally chronic. Over time, COPD patients tend to experience symptoms that are not typical for asthma- losing weight, decreasing strength, endurance, functional capacity and quality of life.

Treatment

Asthma and COPD are treated and respond to treatments differently because the source of inflammation is different. The goals of treatment in asthma and COPD are also different. In asthma, your doctor will attempt to lower or suppress inflammation, while the goal of COPD treatment is generally to reduce symptoms and prevent the progression of damage to the lung while decreasing exacerbations and improving the quality of life.

While your doctor may use some of the same medications for the treatment of asthma and COPD, the "when, why, and how" of these medications may actually be different.

Medications used in both asthma and COPD may include:

  • Inhaled steroids: Inhaled steroids, such as Flovent, are advantageous in both asthma and COPD because the medication acts directly in the lung—but inhaled steroids are used differently in asthma and COPD. In asthma, inhaled steroids are typically used first when a daily medication becomes necessary, usually after a patient progresses from intermittent to mild persistent asthma. In COPD, inhaled steroids are added after patients develop severe COPD and multiple exacerbations.
  • Anticholinergics: While short-acting anticholinergics, such as Atrovent, are used in the treatment of acute asthma exacerbations, long-acting anticholinergics like Spiriva are generally not used as a controller medication in asthma. Spiriva, however, is used relatively early in COPD because it has been associated with improvements in lung function, symptoms, and quality of life while decreasing COPD exacerbations and hospitalizations.
  • Short-acting bronchodilators (SABAs): In asthma, SABAs are used for the periodic relief of acute symptoms, but once you use a SABA enough to meet the criteria for mild persistent asthma, additional medication is required. On the other hand, scheduled SABAs are one of the first treatments for COPD.
  • Long-acting beta-agonists (LABAs): While long-acting beta-agonists like Serevent may be used as a convenient method of initial COPD treatment, LABAs are not indicated in asthma until you have moderate persistent asthma.
  • Surgery: This is only available for COPD. This treatment is generally reserved for patients that have failed medical therapy. There are now some less invasive treatments where patients can gain the benefits of lung reduction surgery through a much less invasive procedure.
  • Bronchial thermoplasty: In this asthma-only treatment, patients with severe persistent asthma that is not well-controlled with inhaled corticosteroids and long-acting beta-agonists, undergo a bronchoscopy that applies heat to your airways to decrease their ability constrict and narrow following exposure to triggers that can lead to an asthma attack.

Asthma and COPD Overlap

While asthma and COPD have long been thought of as two separate conditions, clinicians have begun to come across patients with features of both conditions, in what is now termed overlap syndrome, more specifically known as asthma-chronic obstructive pulmonary disease, or ACOS.

COPD patients are increasingly noted to have an asthma component in addition to their COPD. Studies have shown that anywhere from 10 to 20 percent of COPD patients also have asthma. Surprisingly, 1 in 4 asthma patients smokes and is at risk for COPD, like any other smoker.

Some COPD patients demonstrate asthma-like reversibility on pulmonary lung function testing referred to as an "asthma component." If reversibility is not present, no asthma component exists. The American Thoracic Society defines reversibility as a post-bronchodilator increase in FEV1 of at least 12% for both COPD and asthma. When reversibility is present, it is generally less in a COPD patient compared to a patient with only asthma.​​​

The primary complication with ACOS is that if a patient with COPD also has features of asthma, it usually means more frequent exacerbations, worse quality of life and more comorbidities (other diseases or conditions occurring at the same time). In general, the prognosis is worse, but it is not known if asthma symptoms cause COPD to progress faster.

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Article Sources

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