Therapeutic Trial for Diagnosing Asthma

Doctor Auscultating a patient
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A therapeutic trial is when a physician makes a diagnosis and starts treatment based on symptoms alone, without significant additional testing. For example, a patient may be started on Albuterol if wheezing or Prilosec if one has gastroesophageal reflux (GERD) symptoms.

Why a Doctor Might Start a Therapeutic Trial

Generally, you present to your doctor with symptoms. In asthma, that might mean that you have classic symptoms of asthma such as chest tightness, chronic cough, shortness of breath, wheezing or even maybe some atypical symptom. Whatever the complaint you have, your doctor suspects asthma. They then decide they want to see if you benefit from some sort of asthma treatment. Most commonly this will be giving you a rescue inhaler and seeing if this relieves your symptoms, but there is no reason why a therapeutic trial could not be started with an inhaled steroid. The only downside of the therapeutic trial with an inhaled steroid is that it will take a longer period of time to see if it is working.

Do I Still Need Diagnostic Tests for Asthma?

This will depend on the decisions you and your doctor make. In general, I would say yes.

An asthma diagnosis requires the presence of two components: 1) Symptoms compatible with asthma; 2) Some sort of objective measure of decreased airflow (either partial or complete) that improves spontaneously or with treatment. Without demonstrating these criteria you may have a condition that mimics asthma that also may improve symptomatically, but you will not be treating the underlying condition.

Some of the testing your doctor may do could include:

  • Peak Expiratory Flow Rate (PEFR): Not generally used to diagnose asthma, but your doctor may have readily available in their office. PEFR is a measurement of how much airflow you can generate from your lungs. This simple hand held device measures the amount of air that you can forcefully exhale. Your physician may have you keep a measurement record at home as part of your asthma action plan and your self-treatment is based off your personal best PEFR that will tell you how well your asthma is controlled.
  • Spirometry: A test similar to the PEFR that requires more advanced equipment and can be done in many physician's offices. This test allows your doctor to better determine the severity and cause of your airflow obstruction. Your doctor will be able to determine FEV1 and other components of lung function with this test.
  • Bronchodilator Response: A key characteristic of asthma is the improvement of symptoms and lung function after treatment with a rescue inhaler or bronchodilator. If repeat spirometry 10-15 minutes after treating you with a bronchodilator demonstrates increases in the airflow of 10% or more, your doctor will likely consider this a positive test and assist in making a diagnosis of asthma.

    In order to make an asthma diagnosis, your doctor will consider your historical information about symptoms and family, your physical exam, and the result of your objective tests to decide what treatment and plan are most appropriate for you.

    Could a Therapeutic Trial Be Bad?

    I do not think so. The only scenario I can think of where one would be bad for you is a scenario where a rescue inhaler improves your symptoms and you decide to forgo further testing. In this case, you have never really been diagnosed and I worry that you may not be treating the underlying cause of your symptoms.

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