Women with asthma at higher risk of chronic lung disease

Smoking, obesity identified as risk factors too

More than 40% women with asthma may go on to develop chronic obstructive pulmonary disease (COPD), according to a new study in the Annals of the American Thoracic Society.

In “Asthma and COPD Overlap in Women: Incidence and Risk Factors,” Teresa To, PhD, and coauthors report that of the 4,051 women with asthma included in their study, 1,701, or 42 percent, developed COPD. On average, the women were followed for about 14 years after being diagnosed with asthma.

Women who had a more than five-pack-year smoking history, meaning they had smoked more than a pack of cigarettes a day for five years, were at higher risk

The researchers examined risk factors for developing asthma and COPD overlap syndrome, also known as ACOS. Those who develop ACOS suffer multiple attacks of breathing difficulty requiring repeated hospitalisations and have a lower quality of life, compared to those who have asthma or COPD alone.

“Previous studies have found an alarming rise in ACOS in women in recent years and that the mortality rate from ACOS was higher in women than men,” said Dr. To, a professor in the Graduate School of Public Health at the University of Toronto in Canada. “We urgently need to identify and quantify risk factors associated with ACOS in women to improve their health and save lives.”

The individual risk factors played a more significant role in the development of ACOS than exposure to air pollution.

Women who had a more than five-pack-year smoking history, meaning they had smoked more than the equivalent of a pack of cigarettes a day for five years, were much more likely to develop ACOS than those who smoked fewer cigarettes or never smoked.

However, ACOS did not affect only those who smoke: 38 percent of the women who developed ACOS in the study had never smoked.

The study identified obesity, rural residence, lower education levels and unemployment as significant risk factors for ACOS. These factors were responsible for under-treatment of asthma and poor compliance to medications, which in turn leads to more frequent asthma attacks. These attacks in turn may lead to airway remodeling that increases the chances of developing ACOS.

The authors wrote that they were encouraged by the fact that most of the risk factors identified in their study were modifiable.

Limitations of the study include not having information about exposure to second-hand smoke and exposure to air pollution over the entire time the women were followed.

“The adverse impact of smoking and obesity on health may be even worse in those who are already living with asthma or COPD,” added Dr. To.