A new study has found that people with asthma may have a higher risk of developing diabetes and heart disease. The study looked at the relationship between asthma and four other inflammatory conditions.
The study looked at medical record of almost 2,400 subjects with asthma and a control group of 4,784 people without asthma from 1967 to 1983, matching asthmatics with non-asthmatics for gender and age. The average age of onset for the condition was 15 years. A vast majority was white and 57 percent were male. The study found that among asthmatics, about 138 people per 100,000 had diabetes, compared to 104 for people without asthma; the rate for coronary heart disease was close to 189 per 100, 000, versus 134 among non-asthmatics.
The team led by Dr. Young J. Juhn, of the department of pediatric and adolescent medicine at the Mayo Clinic in Minnesota, also found that people with asthma were not at greater risk of developing inflammatory bowel disease or rheumatoid arthritis.
Asthma, a chronic lung disease that can range from mild to severe, affects close to 25 million Americans ranging from newborns to elderly adults, according to the study. Symptoms include severe breathlessness, tightness in the chest, coughing and wheezing. The underlying cause is unknown but the illness can be triggered by allergies, exercise or environmental contaminants such as chemical fumes or dust. About 70 percent of asthmatics have allergies. Asthma can prove deadly. According to the American Academy of Allergy, Asthma and Immunology, close to 3,400 deaths from asthma occurred in 2005.
This was a novel and surprising result since it is well established that asthmatics have a different immune system profile from cardiac and diabetes patients. “It was surprising because there are two broad categories (of immune profiles) that they're looking at here,” explained Dr. Jennifer Appleyard, chief of allergy and immunology at St. John Hospital and Medical Center in Detroit. She explained that one type of profile is more common to people with asthma, and the other more common to those with inflammatory diseases such as arthritis and coronary heart disease. And this means that in theory, a person prone to asthma should not be prone to diabetes.
She called for more research in this area to be sure of the association.“It’s important to look at how they (asthma, and diabetes or heart disease) interact or affect each other, both looking at possible causes and risk factors, and then specific treatment geared to that part of the immune system,” Appleyard said.
Lead author Juhn noted that although people with asthma have a more allergy-prone immune profile, it is balanced by a counter-regulatory one known as the Th1 immune profile, which underlies pro-inflammatory conditions such as coronary artery disease and diabetes. She speculated that there might be “an inverse relationship” between asthma and those types of pro-inflammatory conditions.
The findings were reported Sunday at the annual meeting of the American Academy of Allergy, Asthma & Immunology in San Francisco.
According to an asthma specialist it must be kept in mind that the data was from records and this may not always be accurate. “It would warrant a prospective study to find patients with asthma now and follow them to see what happens,” said Dr. Linda Dahl, an ear, nose and throat specialist and surgeon at Lenox Hill Hospital. “It would be important to assess both the disease and treatment, and how that affects what other illnesses develop.” Dahl added that therapy during that time relied more on heavy use of steroids. These steroids may have led to weight gain - a known risk factor for diabetes and heart disease. “Sometimes treatment can be part of the problem,” she said. With current improved therapies this association remains to be seen.
But Dahl also said she noticed that many of her asthma and allergy patients had other inflammatory diseases such as arthritis and irritable bowel syndrome. However, “it is hard to know if one is causing the other, or if they are just found together,” by coincidence, she said.