February 21, 1996
Media Contact: Michael Purdy
Phone (410) 955-8725
In carefully selected patients, allergy shots can safely and effectively ease the suffocating symptoms of ragweed asthma and, in some cases, may be even better than conventional asthma treatment, according to a new study by researchers at Johns Hopkins Medical Institutions and the Mayo Clinic.
Doctors have recognized the value of allergy shots for treating sneezing, runny noses, and the other symptoms caused by ragweed allergic rhinitis, or "hayfever". But they have long debated the potential benefits of allergy shots for patients whose allergies trigger asthma attacks.
"Immunotherapy involves more time and trouble than typical asthma treatments, and there is a risk in allergic asthma patients of a more serious reaction to the treatment, which can shut down a patient's ability to breathe,"says Peter Creticos, M.D., a Hopkins associate professor of medicine and lead author of the new study.
But in a three-year double-blind study funded by the National Institute of Allergy and Infectious Diseases, Creticos and colleagues learned that ragweed immunotherapy safely improved all of the many indicators that they studied--ranging from the patients' descriptions of their breathing difficulties to objective laboratory measurements of their responses to ragweed.
Results will be published in this week's issue of the New England Journal of Medicine.
For the study, researchers recruited 77 patients in whom ragweed allergy was the primary cause of asthma. The patients were divided into two groups; both groups were observed for a year, and then entered a two-year treatment phase. During this phase, one group received injections of ragweed allergen--the proteins that trigger allergic reactions. The other group received a placebo injection and standard asthma treatments--such as inhaled steroids to control inflammation and bronchodilator drugs to relieve acute symptoms.
Regular injections of allergen, given in increasing doses, stimulate changes in the immune system that decrease the chance of future allergic reactions, Creticos explains. Because the injections can also cause allergic reactions, Creticos and colleagues used ragweed allergen doses already found to be safest and most effective for treating hayfever.
"Both the group getting ragweed injections and the placebo group, who also saw doctors regularly and received standard asthma treatments, improved," says Creticos.
"But the group receiving the active ragweed shots used significantly less medication during the peaks of the ragweed season. They demonstrated improvements in their daily peak flow rates, meaning they could expel more air from their lungs more rapidly; they were also less sensitive to ragweed when exposed to it in the laboratory. That's consistent with what you'd expect if you were really turning off the underlying disease process."
Because of the regular, required visits to the doctor's office, allergy shots still might not be the best treatment for some patients, Creticos notes. Additional studies are also needed to learn if allergy shots are effective for patients with asthma caused by other allergens, or multiple allergens.
Other authors of the study were Charles Reed, M.D.; Philip Norman, M.D.; Jane Khoury, M.S.; Franklin Adkinson, Jr., M.D.; C. Ralph Buncher, Sc.D.; William W. Busse, M.D.; Robert K. Bush, M.D.; Jyothi Gadde, M.D.; James Li, M.D., Ph.D.; Hal Richerson, M.D.; Richard Rosenthal, M.D.; William Solomon, M.D.; Paul Steinberg, M.D.; and John W. Yunginger, M.D.
Additional funding for the research was provided by the American Academy of Allergy, Asthma and Immunology.