It is the first study to directly compare men and women with COPD (chronic obstructive pulmonary disease) characterized by emphysema. Researchers found that despite having less severe emphysema than men, women more often had greater shortness of breath. They also reported more depression and poorer overall quality of life.
The women in the study also smoked for fewer years than the men before developing COPD.
"Ours is not the first study to find that women are more susceptible to smoking, but this is still a controversial idea in some camps," University of Michigan Medical School professor of internal medicine Fernando J. Martinez, MD, tells WebMD. "This research adds a piece to the puzzle, but it doesn't answer the question."
Men, Women, and COPD
Women are increasingly being diagnosed with COPD, and more women in the U.S. now die of the disease than men.
As many as nine out of 10 COPD deaths are caused by smoking, according to the American Lung Association.
In an effort to better understand sex differences in COPD, Martinez and colleagues analyzed the cases of 1,053 patients with severe emphysema enrolled in a multicenter study of surgical treatment. Roughly 40% of the patients were women.
COPD severity among the men and women in the study was judged to be similar, but the two sexes had distinctly different disease presentations.
The women tended to be slightly younger than the men, and they had less severe emphysema.
But examination of lung tissue showed that women also had more airway problems indicative of chronic bronchitis.
This may explain why they experienced more breathlessness and decreased capacity to exercise compared to men, Martinez says.
This finding, and the fact that the female COPD patients reported more depression and poorer overall well-being than men, highlights the importance of considering gender in future studies of COPD, he says.
These differences could have major implications for new treatments, Martinez adds.
It is not clear if the observed differences among sexes are seen in COPD patients without severe emphysema because the study only included this subset of patients.
The study is published in the August issue of the American Journal of Respiratory and Critical Care Medicine.
"The next step is determining whether the findings apply to a broader group of COPD patients," Martinez says.
Studying Gender Differences in COPD
If so, these gender differences may prove to be an important part of the management of pulmonary disease, just as they have proven to be important in the management of heart disease.
COPD researcher Dawn L. DeMeo, MD, MPH, of Harvard Medical School and Brigham and Women's Hospital, points out that COPD is still considered a man's disease by many.
In an editorial accompanying the study, DeMeo writes that Martinez and colleagues make a convincing case that "sex and gender matter in the study of COPD."
"The hope is that studies like this one will raise awareness," she tells WebMD. "Heart disease was once considered a man's disease, but we now know that this is not the case. COPD has traditionally been thought of as a disease of men, and it is often missed in women."