What is cough variant asthma?
Although CVA does not share other symptoms with regular asthma, it affects the body in several similar ways.
Indoor and outdoor allergens often trigger it, and it can increase the risk of developing other allergic conditions.
It also increases the sensitivity of the airways, and it narrows and swells the airways, which can disrupt air flow.
The lung changes that occur with CVA tends to be milder than those in classic asthma. However, studies suggest that 30 to 40 percent of adults with CVA will go on to develop classic asthma.
Being able to recognize the signs and symptoms of CVA and seeking appropriate treatment may prevent the onset of classic asthma.
Pollutants can trigger CVA, and it appears to be linked to allergies.
The causes of CVA are not entirely understood, but an asthma cough often occurs with the following triggers:
- exposure to allergens or irritants
- having a cold or upper respiratory infection, such as sinusitis
- using certain medications
- changes in the weather
There is a clear link between asthma and allergies. As many as 80 percent of all people with asthma also have nasal allergies.
Allergies happen when the immune system overreacts to a substance that should not normally cause a reaction.
This suggests that the immune system is linked to CVA. It could also explain why CVA responds well to the medications that are effective in treating classic asthma.
Certain people may have a higher risk for developing CVA and other allergic diseases.
Risk factors can include:
- having another allergic condition, such as eczema
- having classic asthma
- having a relative with asthma
- being overweight
- being a smoker or exposed to secondhand smoke
- being exposed to environmental or occupational irritants
Knowing the risk factors for CVA and recognizing if a person has them may help a doctor to make a diagnosis.
CVA involves a chronic cough that does not produce mucus. This is often the only symptom.
A chronic cough is any cough that lasts more than 8 weeks in adults and more than 4 weeks in children.
CVA may not significantly affect lung function, but the chronic cough can be disruptive.
A cough from CVA can cause:
- sleep disruption
- urinary leakage and incontinence
The complications of CVA can disrupt a person's quality of life, for example, through fatigue and absence from work.
Without treatment, CVA may progress to become classic asthma.
Classic asthma symptoms include the following, in addition to a cough:
- difficulty breathing
- chest tightness
- shortness of breath
- asthma attacks, in which air cannot reach the lungs due to airway narrowing
The long-term complications of poorly controlled asthma can include decreased lung function and chronic obstructive pulmonary disease (COPD).
Serious and potentially life-threatening complications can include:
- permanent narrowing of the bronchial tubes
- collapsed lung
- asthma attacks that don't respond to treatment
- lung failure
An x-ray is usually normal with CVA, but it can help rule out other conditions.
People should see a doctor if a cough lasts for more than 8 weeks with no known cause. Early treatment may prevent the development of complications or chronic asthma.
CVA can be difficult to diagnose since the only symptom is a chronic cough, and this can be a symptom of various health conditions.
However, a study of 131 cases of chronic cough found that 24 percent of these were due to CVA.
If any of the following symptoms develop, people should see a doctor sooner to rule out other conditions:
- a fever of over 100°F
- shortness of breath
- chest pain
- coughing up blood
- difficulty tolerating physical activity
Other conditions or factors that cause a chronic cough can include:
- upper respiratory infections, like sinus infections
- post nasal drip
- acid reflux and GERD
- blood pressure medications
- COPD and chronic bronchitis
A number of tests can help rule out other conditions when diagnosing CVA.
Since people with CVA often have normal results in a chest X-ray or spirometry test, a doctor may carry out a methacholine challenge.
When a person with asthma inhales methacholine, it triggers coughing and bronchial spasms. A person with asthma will be more sensitive to methacholine than most people causing lung function to drop during the test.
If a doctor strongly suspects CVA, they may skip the methacholine test and prescribe asthma treatments to see if improvement occurs.
If cough symptoms improve with use of the asthma medications, but no other signs or symptoms of classic asthma are present, the provider will likely diagnose CVA.
Treatment and prevention
CVA and asthma affect the airways. Medications can relieve breathing problems.
The goal of treatment is to prevent complications from developing.
The treatments for CVA are the same as the treatments for classic asthma. The right treatments vary from one individual to another.
They can include a combination of:
- inhaled corticosteroids or inhaled anti-inflammatory drugs that ease and prevent swelling in the airways
- rescue inhalers or inhalers that reduce inflammation quickly in the case of an asthma attack
- combination inhalers that combine both preventive medicines and fast-responding medicines
- leukotriene inhibitors, medications that block the activation of certain parts of the immune system
- anti-histamines or other allergy medications
- preventive oral medications that work to keep the airways open
Preventing the symptoms of CVA from flaring is the best treatment.
People who use medications to prevent asthma symptoms should follow their doctor's advice to prevent episodes and keep CVA from worsening.
Individuals can lower the risk of developing classic asthma if they:
- take all medications as directed
- maintain a healthy weight
- know their personal risk factors
- manage any allergic conditions properly
- avoid known allergens whenever possible
- quit or avoid smoking
- avoid secondhand smoke and other environmental and occupational irritants
CVA can progress to classic asthma in some cases, and uncontrolled asthma can be fatal.
For this reason, it is important to seek treatment for a chronic cough.
Most people who develop asthma can lead a normal, active live if they control their condition and follow their treatment plan.
If a person has severe asthma and does not manage it, they are more likely to have long-term consequences.