MONDAY, Feb. 13, 2006 (HealthDay News) -- If you have asthma, odds are that you'll develop at least one other chronic health condition, such as heart disease, stroke, osteoporosis, arthritis or cancer.
New research from Australia suggests that, compared with non-asthmatics, people with asthma have a nearly twofold risk for developing any of these chronic conditions. The risk is even higher for heart disease and stroke, they add.
"Asthma commonly coexists with other major health problems, particularly in older age groups. This coexistence is associated with significant adverse effects on physical health," conclude the authors of the study, which appears in the February issue of Chest.
What's unclear from this study, however, is whether there's any cause-and-effect relationship between asthma and these other diseases, or merely an association. It's also unclear whether maintaining good control over asthma symptoms could lessen the risk for some of these secondary conditions.
About 15 million Americans have asthma, according to the U.S. National Heart, Lung, and Blood Institute. Symptoms of the chronic lung disease include wheezing, coughing, tightness in the chest and shortness of breath.
The current study included data from phone interviews with more than 7,600 randomly sampled people from three different Australian states. From this sample, 834 had physician-diagnosed asthma.
People with asthma were 90 percent more likely to report having another chronic health condition compared to people without asthma, the study authors found.
Overall, the risk of stroke was 2.5 times as high for people with asthma vs. people without the illness. For heart disease, asthmatics had 2.2 times the risk compared to those without asthma. People with asthma also had an 80 percent higher chance of having arthritis, and a 70 percent increased chance of developing osteoporosis. Cancer risk was 50 percent higher in people with asthma, according to the study. The risk of diabetes was 20 percent increased in asthmatics.
Age may play a role: When the researchers broke the data down by age, they found that people over 55 tended to have the most significant risk of having another chronic illness.
"As adults with asthma age, the likelihood of developing other chronic conditions becomes greater," study senior author Dr. Richard Ruffin said in a prepared statement.
The researchers pointed out that there were some limitations to the study. One is that people with asthma may simply be more likely to be diagnosed with other conditions because they regularly see their physicians for asthma treatment. Also, the researchers didn't collect data on asthma severity, so they don't know if more severe asthma results in more coexisting conditions.
Dr. Jonathan Field, director of the allergy and asthma clinic at New York University Medical Center/Bellevue in New York City, said he wasn't surprised to see a link between asthma and other chronic conditions, and explained that there could be a number of reasons for this association.
Some of those reasons are more obvious than others, he said. People whose asthma isn't managed well often have to take oral steroids to get the disease back under control. However, oral steroids can affect bone health, which may contribute to arthritis or osteoporosis. Also, these drugs can affect blood sugar levels, which might contribute to worsening diabetes.
Oral steroids and possibly some other asthma medications may also weaken the immune system, which could possibly contribute to an increased risk of cancer, Field added.
Asthma increases pressure on the lungs, which can in turn affect the artery supplying the heart with blood, upping risks for cardiovascular disease. Also, the authors of the study point out that uncontrolled asthma may cause people to be more sedentary -- a known risk factor for heart disease.
"People need to realize that having asthma puts you at risk for worsening states of other diseases," said Field.
Clearly, he said, what's important is how well asthmatics control their symptoms. People who manage their disease aggressively generally won't need oral steroids to control their symptoms, thus reducing the potential for side effects, Field said.
"You have to look at asthma treatment as part of your overall health treatment and understand that untreated asthma may cause other health problems to worsen," said Field.
While agreeing that while asthmatics are prone to poorer health in general, at least one expert isn't convinced that asthma is at the root of these coexisting conditions.
"From this study, I don't think you can conclude that asthma is a disease that leads to other medical problems," said Dr. Marc Siegel, a clinical associate professor at the New York University School of Medicine in New York City.
Siegel pointed out that the authors didn't control for current smoking or a prior history of smoking. In addition, asthma diagnosis was self-reported, not confirmed independently by a physician. These factors at mean what people are reporting as asthma could actually be emphysema, and there's clearly a link between smoking and heart disease, stroke and cancer, he said.
For much more on asthma, head to the U.S. National Heart, Lung, and Blood Institute.