According to published reports, researchers say asthma may significantly increase the risk of hospitalization and death from heart disease in non-smokers, according to a study reported today at the American Heart Association’s 41st Annual Conference on Cardiovascular Disease Epidemiology and Prevention.
“Prior studies have indicated a higher cardiovascular death rate among people with asthma but none of them looked specifically at non-smokers. With this new study, we know now this is true even among non-smokers,” says principal investigator Carlos Iribarren, M.D., Ph.D., M.P.H., with Kaiser Permanente’s Division of Research in Oakland, Calif. The researchers studied non-smokers in order to rule out the strong influence of smoking on both asthma and heart disease.
Researchers found that self-reported asthma, regardless of whether the patient was treated for it or not, was associated with a 33 percent increased risk of developing heart disease. Further, the study shows that individuals who were getting treatment for asthma at the time of their enrollment were 82 percent more likely to develop heart disease.
“This new evidence has important public health implications because asthma affects about 6 percent of the general population, and heart disease continues to be the leading cause of death in the United States,” says Iribarren. He says the possibility that medications to treat asthma, including inhaled and oral steroids, may increase the risk of heart disease is a topic he plans to research in the future. Asthma is a chronic inflammatory disease known to cause lung and breathing problems and related death.
“Asthmatic patients and their doctors should be particularly mindful, not only about managing asthma, but also about managing cardiovascular risk factors such as cholesterol, blood pressure and blood glucose,” says Iribarren.
Asthma was still significantly associated with the risk of heart disease even after the researchers made adjustments for the influence of other risk factors such as age, gender, ethnicity, level of education, cholesterol, body mass index, high blood pressure and diabetes. Because inflammation is now believed to play an important role in the development of atherosclerosis – the underlying process that leads to narrowing and hardening of the arteries – the researchers hypothesized that asthma and its associated airway and systemic inflammatory state may also contribute to coronary disease risk.
“Studies to fully understand the imbalance of immune regulating factors in asthma and its effect on cardiovascular disease risk are clearly needed,” says Iribarren.
The population-based study collected data for up to 20 years among members of the Northern California Kaiser Permanente Medical Care Program, a large health maintenance organization (HMO) in the San Francisco Bay Area. The study was done in collaboration with the University of California San Francisco’s department of medicine.
A total of 22,036 patients (64 percent women and 56 percent white) between the ages of 35 and 89, with an average age of 50, were enrolled at the beginning of the study. Data on health conditions including asthma and cardiovascular risk factors were collected. All enrollees reported they had never smoked and were free of known coronary heart disease. Of these, 652 women and 410 men reported they had been diagnosed with asthma. Information on the subjects’ hospitalization and/or death due to heart disease was collected for an average of 13 years, through the end of 1998.
Self-reported asthma meant that a participant answered “yes” to the question, “Has a doctor or a nurse ever told you that you have asthma?” Those who responded in the affirmative were also asked, “Is your asthma currently under treatment?” Patients were defined as “never smoking” if they answered “no” to the question, “Have you ever used any tobacco product (cigarettes, cigars, pipe, chewing tobacco)?”
Co-authors include Mark D. Eisner, M.D.; Alan S. Go, M.D.; Stephen Sidney, M.D., M.P.H.; and Arthur L. Klatsky, M.D.
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