Could That Chronic Cough Be Asthma?

How a Dry, Chronic Cough May Actually Be a Type of Asthma

CAV
Cough Variant Asthma. BSIP/UIG/Universal Images Group/Getty Images

While a cough may accompany the usual symptoms associated with asthma, in cough variant asthma, coughing alone may be a precursor to or the sole symptom in an asthmatic. When there are no other "classic" asthma symptoms, such as wheezing or shortness of breath and a chronic cough is the only asthma symptom, this is known as cough variant asthma (CVA).

Parents also tend to describe cough in different ways:

  • Dryness and wetness
  • Depth
  • Repetitiveness and persistence
  • Ticklishness

When describing a cough they often focus on the sound, perceived discomfort, straining, or sensation when holding the child to make these distinctions. Asthma coughing is commonly described as "short, dry, shallow, tickly, and repetitive." Likewise, absence of fever or productive cough may trigger a parent to describe the cough as related to asthma.

What is Cough Variant Asthma?

The main symptom of CVA is a chronic, non-productive (dry) cough. These asthma patients have cough as the main or only symptom of their asthma. These patients are a small percentage of total asthma patients. CVA patients are, however, a distinct group rather than merely being thought of as 'coughing asthmatics.' Anywhere from one fourth to one third of patients presenting to a doctor for evaluation of chronic cough may have CVA.

CVA patients have some differences from patients with typical asthma.

For example, while normal asthmatics do not differ from healthy volunteers in their cough reflex, CVA patients have a more sensitive cough reflex. Interestingly, CVA patients have a smaller reaction to methacholine challenge testing compared to other asthmatics.

Since CVA coughing can last longer than six to eight weeks, sometimes the condition is called chronic cough and can occur day or night, which can interrupt sleep.

How Is Cough Variant Asthma Diagnosed?

Because cough is a common symptom for asthma, your provider may order a common test to see how well your lungs work using a test called spirometry. If spirometry demonstrates reversible obstruction, your provider may start a therapeutic trial for asthma. However, asthmatics may have a normal lung exam and spirometry creating a 'diagnostic dilemma,' where your doctor may suspect, but is unable to prove, you have asthma.

In this case, your provider may preform methacholine challenge testing in-order to demonstrate bronchial hyper-responsiveness and diagnose asthma. If a methacholine challenge test does not produce hyperresponsiveness, it is unlikely that asthma is the cause of a cough. A definitive diagnose can be made if the cough symptoms respond after asthma treatment. Your doctor may also look at your sputum to see if eosinophils are present indicating an allergic, inflammatory condition such as asthma. Exhaled nitric oxide levels, a marker of inflammation released from lung cells, may also be elevated in patients with CAV.

The test has a high negative predictive value (ie you do not have CAV if the test is negative) for CAV if you have not recently received steroids.

How Is Cough Variant Asthma Treated?

Treatment of CVA is virtually the same as for asthma. Partial improvement of Chronic cough may be seen as quickly as 1 week with bronchodilators like Albuterol, but may not completely resolve for up to 8 weeks after starting an inhaled steroid like Flovent.

If the cough only partially resolves, your provider may try a more potent steroid like oral prednisone. Alternatively, your provider may do special tests to identify eosinophils, a marker of inflammation, in your lung. If eosinophils are present in the lung, and anti-inflammatory called Zafirlukast has been shown to improve cough among patients with CVA and has been beneficial in CVA patients without a good response to inhaled steroids.

A small group of patients may experience worsening of the cough with inhaled steroids due to the aerosols used in the inhaler device. Alternatively, if the cough worsens, it is important that it is not another condition, like GERD, causing the symptoms.

What Happens in the Future

It is hard to say what your asthma future will be as CAV is not commonly studied and there are not any large scale trials, but one small series of 42 patients showed that 7 patients went into remission and 13 ended up developing classical asthma over a 4 year period.

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Source:

Dicpinigaitis, Peter V. Chronic Cough Due to Asthma: ACCP Evidence-Based Clinical Practice Guidelines. Accessed 26 March 2016.

Matsumoto H, Niimi A, Takemura M, Ueda T, Tabuena R, Yamaguchi M, et al. Prognosis of cough variant asthma: a retrospective analysis. Accessed 26 March 2016.

National Heart, Lung, and Blood Institute. Accessed: March 26, 2016. Expert Panel Report 3 (EPR3): Guidelines for the Diagnosis and Management of Asthma

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