WEDNESDAY, Aug. 1 (HealthDay News) -- The breathing disorder called chronic obstructive pulmonary disease (COPD) hits women harder than men and in a different way, a new study finds.

COPD actually consists of two different lung diseases -- chronic bronchitis, which damages the lining of the airways, and emphysema, which damages the alveoli, the tiny sacs through which oxygen enters the blood. A study of more than 1,000 COPD patients, 38.8 percent of them women, found that bronchitis is more common in women and emphysema more common in men.

"Men and women respond differently to cigarette smoke exposure," said Dr. Fernando J. Martinez, a professor of internal medicine at the University of Michigan and lead author of the report. Smoking is the major cause of COPD.

"So the treatments for men and women are going to be inherently different," he said.

In addition, women in the study reported more breathlessness, a higher incidence of depression and a lower quality of life than the men.

There have been hints of differences in COPD between men and women and "multiple attempts to document the differences," Martinez said. "We were able to make two major advances. First, we were able to get a large number of people with COPD, men and women, and get detailed images of their airways. Second, the patients in the study got objective assessments of the condition of their airways."

COPD studies have tended to concentrate on men, Martinez said. For future studies on the possible causes of the different effects in men and women, "you really do need to have an appropriate sample of women in the group," he said.

The findings are published in the Aug. 1 issue of the American Journal of Respiratory and Critical Care Medicine.

One reason why the study is important is that the number of American women diagnosed with COPD now exceeds the number of men, said Dr. Dawn L. DeMeo, assistant professor of medicine at Harvard Medical School and associate physician at Brigham and Women's Hospital, who wrote an accompanying editorial in the journal.

"This article highlights the need for more research on COPD and gender," DeMeo said.

There are several possible explanations for the differences found in the study, she said. "Are there sexual differences, based on hormonal influences?" DeMeo said. "Or are there different genetic interactions? Another question is whether there are differences in the way men interact with the environment, not only in cigarette smoking but in other ways?"

Whatever the reason, the finding shows that "physicians need to continue to raise the awareness of COPD in women," DeMeo said. "It is a diagnosis that has not reached prominence in women. We need to raise awareness not only among lung specialists but also among basic health-care providers."

COPD is the fourth leading cause of death in the United States, and the number of women dying of the condition has exceeded the toll among men for four consecutive years, according to the American Lung Association. In 2003, more than 63,000 women died of COPD, compared to 59,000 men.

"What we really need is a very large study using CAT scans and other methods to see what the difference in damage is among those who have COPD," DeMeo said. "Smoking is not going away, so these studies are important, because the issue continues to arise."

More information

For more on COPD, visit the American Lung Association.