A new study shows that there is a high chance of chronic obstructive pulmonary disease (COPD) in women who have asthma, but also that this risk can be reduced by appropriate intervention.
The risk of developing COPD superimposed on pre-existing asthma, which is called asthma and COPD overlap syndrome, or ACOS, was 42 percent in women, according to these findings.
The risk factors for this progression to ACOS were found to be related to individual habits rather than exposure to fine particulate matter (particles which are so small that they lodge deep in the lung tissue). The study covered data taken from a 14-year follow up of women diagnosed with asthma, and was published in the Annals of the American Thoracic Society.
ACOS is important because it lowers quality of life and increases the frequency and severity of acute exacerbations of asthma, compared to women with either asthma or COPD alone. Its incidence is rising rapidly, and it also causes more deaths in women than in men. This was the motivation behind the attempt to find the risk factors for its development.
The most obvious risk factor was smoking, with women who had smoked over five pack-years (namely, they smoked more than the equivalent of one pack of cigarettes each day for five years) having a significantly higher risk of ACOS than non-smokers or more moderate smokers. However, ACOS did affect 38 percent of non-smoking women with asthma as well, so that smoking was not a specific risk factor in this study.
Other factors identified by the researchers that were associated with a higher risk of ACOS included obesity, rural location, lower educational strata and unemployment. The reasons for this linkage were not investigated due to lack of sufficient information.
However, they may include not getting medical help, lack of proper treatment for asthma, and failure to comply with medical advice, all of which in turn led to more frequent exacerbations of asthma.
Other potential risk factors such as exposure to second-hand smoke and air pollution were not studied as data was not available on these over the whole duration of the follow-up period.
The most important finding, for the scientists who reported this study, was the fact that most of the identified risk factors were modifiable, meaning that it is possible to reduce the risk of ACOS in women with asthma.
Since smoking and obesity, for instance, are already known to increase the risk of disease, their cumulative impact when coupled with asthma or COPD may further worsen the health of these women.
Identifying modifiable risk factors in the progression from asthma to COPD is an essential first step in developing prevention strategies that lead to a healthy, active lifestyle."
Dr. To, senior scientist, Child Health Evaluative Sciences, The Hospital for Sick Children, and also professor, Graduate School of Public Health at the University of Toronto in Canada.