Lifestyle Factors, Not Air Pollution, Exacerbate Asthma in Women

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More than 40% of women with asthma developed asthma and chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS) in a new study, published in the Annals of the American Thoracic Society. ACOS is associated with a high mortality rate, low quality of life, and high healthcare costs.

The results suggest that individual risk factors play a more significant role in the development of ACOS vs exposure to fine particulate matter, a major air pollutant.

“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. We urgently need to identify and quantify risk factors associated with ACOS in women to improve their health and save lives,” said lead author Teresa To, PhD, professor in the Graduate School of Public Health at the University of Toronto in Canada.

The researchers linked data for 4051 women with asthma who participated in the Canadian National Breast Screening Study from 1980 to 1985 to health administrative databases. The women were followed from 1992 to 2015. A competing risks survival model measured the associations between sociodemographic, lifestyle and environmental risk factors, and time to COPD incidence, accounting for death as a competing risk. The women had a mean age of 79 years at the study’s end.

The results showed high levels of cigarette smoking were associated with ACOS incidence. Women who had a >5 pack-years smoking history were much more likely to develop ACOS vs those who smoked fewer cigarettes or never smoked. However, 38% of the women who developed ACOS had never smoked.

In addition, the researchers identified a high body mass index, low education level, rural living, and unemployment as significant risk factors for ACOS. They speculate that obesity may be a marker of sedentary lifestyle associated with prevalent asthma and/or COPD. The other factors may indicate suboptimal access to care, under-treatment of asthma, and poor compliance with medications, all of which lead to more frequent asthma attacks. These attacks in turn may lead to airway remodeling that increases the chances of developing ACOS.

“Overall, findings of this study suggest that lifestyle risk factors, rather than air pollution, play a significant role in ACOS development in this population of women with asthma,” the researchers concluded.

They noted that most of the risk factors identified in their study were modifiable. “The adverse impact of smoking and obesity on health may be even worse in those who are already living with asthma or COPD. 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,” said To.

The researchers call for more proactive prevention strategies, especially those that address risk factors outside of cigarette smoking.

References:

To T, Zhu J, Gray N, et al. Asthma and COPD overlap in women: Incidence and risk factors. Ann Am Thorac Soc. 2018.