Dec. 14, 2007 -- The lung disease known as chronic obstructive pulmonary disease (COPD) has long been considered more a man's disease than a woman's disease. Nothing is farther from the truth, according to a new review.
"COPD is a huge problem in women," says MeiLan Han, MD, MS, an assistant professor of medicine at the University of Michigan Health System, Ann Arbor, and director of its Women's Respiratory Health Clinic. She is the lead author of a clinical commentary on the topic of gender and COPD published in the American Journal of Respiratory and Critical Care Medicine.
COPD in women has been on the rise in recent years. More women than men in the U.S. now die from it each year, she says. Even so, experts have much to learn about the gender bias surrounding COPD, she says. Doctors may not always think to give a woman with COPD symptoms the breathing function tests used to help diagnose it early.
What Is COPD?
COPD is the preferred name for what used to be looked on as two different diseases -- emphysema and chronic bronchitis. Smoking cigarettes is the main risk factor for getting the disease. In emphysema, the tiny air sacs in the lung (called alveoli) are irreversibly damaged. In chronic bronchitis, the bronchial tubes are inflamed and eventually scar. COPD is the fourth leading cause of death in the U.S.
According to the American Lung Association 61,000 women and 57,260 men died of the disease in 2004; about 12 million adults in the U.S. have COPD. Symptoms include a chronic cough, shortness of breath, frequent clearing of the throat, and increased production of mucus.
Medications can help relax and open air passages. Other treatment includes supplementary oxygen therapy.
COPD: Men vs. Women
Han and her colleagues reviewed numerous scientific published studies to write the commentary, trying to piece together the current understanding of how COPD affects men and women differently -- and what questions yet need to be addressed.
Sex differences in COPD have been suspected for about 20 years, she says, but experts haven't investigated the information very thoroughly until recently. Women's increased use of tobacco probably explains part of the rise in the disease, Han says, but not all.
Her team looked at, among other data sources, two large surveys, the National Health Interview Survey and the National Health and Nutrition Examination Survey (NHANES).
The researchers found:
- Death rates from COPD differ by sex. Beginning in 2000, annual deaths of women from COPD surpassed those of men in the U.S.
- Symptoms tend to differ by sex. Women were more likely to report severe shortness of breath than were the men, even with fewer years of smoking, but reported similar degrees of cough.
- Women may be more susceptible than men to tobacco smoke. Cigarette smoking is the primary risk factor for the disease, although air pollution, secondhand smoke and heredity can contribute. "Women may also have a harder time quitting," Han tells WebMD. Exactly why isn't certain, she adds. If the gender susceptibility holds true, she says, "Smoking cessation, while it may be harder for women, may be even more important [in preventing or minimizing the disease.]"
- Women are less likely to be diagnosed with COPD promptly or offered appropriate tests. In research that investigated whether doctors show bias against diagnosing the disease in women, COPD was given as the most probable diagnosis much more often for males than females (64% vs. 49%) Han found. In a survey of COPD patients, women were less likely than men to have been offered breathing function tests.
Another expert who has studied gender differences in COPD agrees with Han's contention that the stereotype of COPD is outdated. "It is no longer accurate to say this is [primarily] a disease of elderly men," says Susan Kennedy, PhD, MSc, professor of environmental health at the University of British Columbia, Vancouver, Canada.
"There are a lot of unanswered questions," she says. Among them: "Are women more susceptible to dirty air, primarily cigarette smoke?"
"There is some intriguing evidence that postmenopausal women may have a different way of metabolizing the contaminants in dirty air," she says.
Take-Home Message for Women
For women, Kennedy says, the message is clear: "If they have difficulty breathing, regardless of whether they are [or have been] a smoker or not, they should see their doctor and ask for breathing tests to be done. Doctors are less likely to diagnose COPD in women than in men and are less likely to order breathing tests."
Occupational and environmental exposures can contribute, too, Kennedy says. "We also tend to make the mistake that only men have this kind of exposures." But there is growing evidence that things such as cleaning products and other contaminants that are used predominantly in jobs done by women can play a role, too, she says.
Smoking cessation, of course, is crucial, says Han.
Several co-authors, but not Han, report receiving fees for research, speaking, and consulting from pharmaceutical companies.