By Dr. Irvin Mayers, MD
Asthma in general affects about 10% of Canadian adults. Approximately 10% of adults with asthma have severe asthma. Understanding how to treat severe asthma has improved greatly over the last five years. Our clinic has now joined a cross-Canadian effort at further improving the care of patients with severe asthma.
All patients with asthma need careful assessment to make a clear diagnosis. This should always include measuring breathing capacity (Pulmonary Function Testing) in addition to a thorough history and physical examination. Once a diagnosis of asthma is firmly made, treatment can be started. For most adults treatment of asthma will require the use of a class of drugs known as inhaled corticosteroids (ICS). These drugs have been available in Canada since the 1970’s and they revolutionized the treatment of asthma. If symptoms of asthma are not controlled on low doses of ICS, then usually additional drugs are added and the dose of ICS increased. Severe asthma is diagnosed for those people who are still having significant symptoms of asthma despite being on high dose ICS therapy. Patients with severe asthma in our clinic are then re-evaluated for possible causes.
- Cigarettes: Inhaling tobacco smoke inactivates ICS therapy. Treatment is focused on helping with quitting smoking and then asthma control is re-evaluated.
- Chronic sinus inflammation or infection: Treating sinus inflammation separately can help reduce the severity of asthma.
- Heartburn: Uncontrolled stomach acids flow back into the esophagus can worsen asthma control.
- Pets: If people are allergic to their pets, medication alone is often not enough. The most common problem pets are cats.
There are other specialized tests we can do to help better understand the causes of severe asthma to then help focus treatment better. We can look for ongoing evidence of airway inflammation using an Induced Sputum test. This test allows sampling of phlegm from deep in the airways to sort out the specific type of inflammation that is causing symptoms. A simpler test we can also perform is known as Exhaled Nitric Oxide and measures for inflammation in the exhaled air from a patient. There are additional ways of helping define the problem to find a solution.
There are new drugs used to treat severe asthma with many more under development. The newest drug is called omiluzimab (Xolair). This drugs blocks one of the antibodies responsible for developing some of the allergic symptoms in severe asthma. It is given as an injection every 2 to 4 weeks. Our clinic currently follows over 40 patients on this type of treatment.
There are many reasons why one person has mild asthma while another person has severe asthma. Understanding the underlying causes of the disease that are unique to each person helps to personalize treatment to get the best outcomes possible.