Patients who have severe asthma that is refractory to treatment pose a problem in clinical practice. The standard agents for treating asthma (e.g., corticosteroids) often do not help these patients, making controlling their asthma difficult. According to FP Barbara Yawn, M.D., M.Sc., of Rochester, Minn., a former chair of the Academy's (then) Commission on Clinical Policies and Research, the situation may be complicated by the fact that family physicians often share the responsibilities for treating these patients with allergists or pulmonologists. In fact, she says she thinks the majority of these patients are not seen by FPs for their asthma.
Is Severe Asthma Actually Different Disease?
Study Results Call for More Research, Says FP
By Barbara Bittner
2/27/2008
A study from the Severe Asthma Research Program, or SARP, in the February 2008 Journal of Applied Physiology may help to shed light on why these patients are so hard to treat. According to the study abstract, researchers looked at 287 patients who had severe asthma, defined as asthma that is poorly controlled chronically and refractory to treatment, and 382 patients who had nonsevere asthma.
The study showed that patients with severe asthma are much more likely to show signs of "air trapping" in the lungs, a condition that prevents these patients from exhaling completely. The researchers also found that these patients were more likely to have airway obstruction even after maximal bronchodilation.
The researchers concluded that air trapping is characteristic of severe asthma, suggesting that there is a pathological process associated with the severe form of asthma that makes airways more vulnerable to this physiological response. In short, they suggest that those who suffer severe asthma may have a different form of the disease.
The study showed that patients with severe asthma are much more likely to show signs of "air trapping" in the lungs, a condition that prevents these patients from exhaling completely. The researchers also found that these patients were more likely to have airway obstruction even after maximal bronchodilation.
The researchers concluded that air trapping is characteristic of severe asthma, suggesting that there is a pathological process associated with the severe form of asthma that makes airways more vulnerable to this physiological response. In short, they suggest that those who suffer severe asthma may have a different form of the disease.
Study Fundamentals
The SARP researchers used lung function data collected at 10 different research centers. They studied aspects of lung function that included airflow limitation (i.e., the longer-than-normal period of time required to exhale a volume of air that is characteristic of any grade of asthma and is probably related to airway narrowing) and air trapping. Patients who do not have asthma normally can exhale about 70 percent of their lung volume. Patients who experience air trapping exhale significantly less than 70 percent of lung volume because of extreme narrowing or complete closure of airways.
The researchers found that air trapping was characteristic of the study participants who had severe asthma, but not of those who had nonsevere asthma. And as airflow limitation became more pronounced, more air trapping was seen in the patients who had severe asthma, but not among those who had nonsevere asthma.
In addition, the study found that patients who had severe asthma showed incomplete reversibility with bronchodilator treatment.
The researchers found that air trapping was characteristic of the study participants who had severe asthma, but not of those who had nonsevere asthma. And as airflow limitation became more pronounced, more air trapping was seen in the patients who had severe asthma, but not among those who had nonsevere asthma.
In addition, the study found that patients who had severe asthma showed incomplete reversibility with bronchodilator treatment.
"Stay Tuned"
Yawn says she thinks that, although the results of this study are not immediately applicable for most FPs' clinical practices, the results eventually may have an effect on how patients with severe asthma are treated. Because these patients are so often refractory to treatment, Yawn says that most FPs who encounter such patients either refer them to allergists or pulmonologists or treat them in coordination with these subspecialists. She estimates that patients with severe asthma make up only about 1 percent of all patients FPs see in their practices.
The study's results show that severe asthma "looks more like COPD (chronic obstructive pulmonary disease) than we ever thought," says Yawn. She adds that it raises questions about whether anti-inflammatory drugs, such as corticosteroids, really are the right way to treat these patients. These drugs may work for narrowing of the airways, but not necessarily for air trapping.
The great strength of the study, Yawn notes, is that it helps "separate the mechanics of COPD from those of asthma," which could lead to new treatments for both diseases. It also is "one of the first important steps in teasing asthma into the different conditions" that make up the disease, she says.
However, the study does not answer the question of how to deal with severe asthma when it is encountered in an FP's office -- a topic that needs and deserves further research, according to Yawn. She says she thinks most FPs do not have the time or equipment necessary to test patients with severe disease to determine their lung function, and she recommends that FPs send these patients to pulmonologists who are better equipped to test and treat them. She also recommends that FPs "stay tuned" and keep listening for more developments that should follow from this study.
The study's results show that severe asthma "looks more like COPD (chronic obstructive pulmonary disease) than we ever thought," says Yawn. She adds that it raises questions about whether anti-inflammatory drugs, such as corticosteroids, really are the right way to treat these patients. These drugs may work for narrowing of the airways, but not necessarily for air trapping.
The great strength of the study, Yawn notes, is that it helps "separate the mechanics of COPD from those of asthma," which could lead to new treatments for both diseases. It also is "one of the first important steps in teasing asthma into the different conditions" that make up the disease, she says.
However, the study does not answer the question of how to deal with severe asthma when it is encountered in an FP's office -- a topic that needs and deserves further research, according to Yawn. She says she thinks most FPs do not have the time or equipment necessary to test patients with severe disease to determine their lung function, and she recommends that FPs send these patients to pulmonologists who are better equipped to test and treat them. She also recommends that FPs "stay tuned" and keep listening for more developments that should follow from this study.
