Risk Factors of COPD Among Women

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Historically, men have been perceived to have a higher prevalence of chronic obstructive pulmonary disease (COPD) as compared to women, however, studies now show that more women are diagnosed with COPD and their mortality rates are higher. There is evidence of susceptibility among women of the risk factors associated with COPD.

The World Health Organization (WHO) in conjunction with the Global Burden of Disease (GBD), reports a prevalence of 251 million cases of COPD as of 2016. In 2015, it was estimated that 3.17 million deaths, accounting for 5% of global deaths, were caused by COPD. This is something that WHO had not predicted to occur until the year 2030.

As we know, COPD is a progressive respiratory condition that causes various limitations for breathing.

  • Pathophysiological changes involve inflammation in the lungs, narrowing of the airways, and damage to the lung parenchyma
  • The most common risk factors associated with the development of COPD include smoking, exposure to secondhand smoke, air pollution as well as occupational dust and fumes that are inhaled
  • WHO estimates that 25% of deaths attributed to COPD involve low- and middle-income countries and correlate to the increased exposure of household air pollution
  • Women who are exposed to high levels of indoor smoke and are twice as likely to develop COPD as compared to women that use cleaner fuels and technologies

While the diagnosis and treatment of men or women with COPD are the same, the risk factors are not consistent among both sexes. The associated risk factors among women that will be discussed include smoking status, associated comorbidities, occupational exposure, as well as anatomical and biological differences.

Smoking Status

As we know, tobacco smoke is the main cause of COPD in the United States and smoking is the leading cause of preventable death. According to information available from the Centers for Disease Control (CDC) and the U.S. Department of Health and Human Services (HHS) cigarette smoke causes about one of every five deaths annually, or 1,300 deaths every day. Cigarette smoking is responsible for more than 480,000 deaths per year in the United States, of which 201,773 deaths are among women.

The use of tobacco among women has steadily increased over the years, with a dramatic increase in use since the 1950s. During this time, it was more socially acceptable for women to smoke, and the tobacco industry targeted women in their marketing campaigns by promoting sex appeal, independence, and style. Decades later, tobacco companies continued their strategies by marketing cigarettes with slogans that included phrases such as “It’s a woman thing” or “You’ve come a long way, baby.” Some companies even suggesting that reaching for a cigarette was better than reaching for food and over-indulging, aligning with their campaigns that smoking made you more appealing and stylish. The effects of advertising are attributed to the rise in smoking among women in that era and their shift in use explains why consumption levels remain higher in places such as France, as compared to other countries.

Associated Comorbidities

COPD is typically associated with accompanying comorbidities and includes more organ systems than just our lungs. A recent publication in the respiratory care journal shares data researchers gathered regarding comorbidities among COPD patients and their associated healthcare use. The study included a total of 70,274 COPD subjects, women made up 58.2% of the total COPD subjects. Fifteen comorbidities were identified and the most prevalent diagnosed were hypertension accounting for 47.6%, high cholesterol at 29%, and allergies accounting for 34.2%. Women were found to have at least one or more comorbidities, 51.2% of the subjects studied, and had three times as many diagnosed comorbidities than their male counterparts.

In a 2016 review, Barnes discusses sex differences in COPD and notes that women with severe COPD have a higher risk of hospitalization and death from respiratory failure and associated comorbidities. For those women that have developed COPD due to smoking, their risk of dying from coronary heart disease as compared to other middle-aged nonsmokers’ women is five times higher.

Often, comorbidities in COPD patients go undiagnosed and therefore lead to failure in treatment for their needs. More standardized protocols should be developed by organizations with a goal to provide useful management of patients with COPD and comorbidities so that those healthcare providers caring for these patients provide the right care.

Occupational Exposure

Occupational and biomass exposure is another common risk factor for COPD. Workplace exposures can include things such as dust, fumes, gases, and secondhand smoke. Presently, some three billion people use biomass or solid fuel as energy sources to heat and light their homes, and to cook. In developing countries, women often are exposed to these risks as they spend most of their time in the home and do most of the cooking leaving them disproportionately exposed to larger amounts of biomass irritants.

It has been studied that a lower a person’s socioeconomic status, the higher their risk of poor health. This statistic includes women and children who live in severely impoverished countries and have the greatest exposure to air pollutants. In a 2006 WHO review on energy and health, women who cook with solid fuels have an equivalence of smoking two packs of cigarettes a day. To put it in perspective, a 1-year old girl can accumulate a two-pack year smoking history without ever having been exposed to tobacco smoke.

Women now work in similar jobs as do men, taking on careers in factories and chemical plants, working as farmers, mechanic shops, and in the hospitality industry. All these job fields along with others risk their health through exposure to harmful toxins that can in time lead to the development of COPD.

Anatomical and Biological Differences

Recent studies have also discussed the anatomical differences among men and women and how that is factored into the development of COPD. Various authors have compared lung sizes via different radiological tests and proven that men’s lungs are bigger. According to Aryal et al.,  women are more susceptible to developing COPD due to the size difference of their airways. Their airways are relatively smaller than those of males in comparison to their respective lung volumes.  Therefore, the level of tobacco smoke may be increasingly concentrated per unit of small airway surface. However, no difference in size has been observed in the number of alveoli per unit area, the number of alveoli per unit area volume, individual lung units, and alveolar dimensions. Collectively, more studies should investigate the specific differences in lung size as it relates to tobacco particle disposition and inhaled irritants.

Tobacco smoke contains more than 4,000 chemicals, the smoke inhaled into the lungs is then absorbed and metabolized throughout the body. The process involves a multistep approach but what is important to note about it is that cytochromes p450 (CYP) are what differentiates COPD between men and women. CYP is important in the clearance and breakdown of various compounds, irritants from inhaled tobacco being one of them. In fact. According to a 2016 publication by Hardin, female smokers have increased lung expression of CYP enzymes compared with male smokers. This evidence explains why estrogen levels in women have also been linked to the development of COPD. Estrogen may regulate CYP expression, specifically the estrogen receptor Era, which is more prevalent in women. This information collectively suggests female hormones may hasten the metabolism of tobacco smoke, via the CYP pathways, and accelerate the metabolism of nicotine.

Closing Thoughts

While the number of COPD-related deaths has fallen over the years, the number of diagnosed cases is rising. In the UK, COPD cases continue to rise as the population ages. The long-term effects of smoking are also likely to increase the present burden of COPD on healthcare systems. This presents challenges for both patients and the healthcare systems, not just in the U.S. and UK, but worldwide. It is imperative that we understand the underlying differences between men and women as it relates to COPD.  We should continue to work towards improving the diagnosis, treatments, and monitoring of COPD in women. Reducing the stigma surrounding COPD, raising awareness about various risk factors, and tailoring smoking cessation programs to women can help flatten the curve of this incurable disease.

 

Resources:

Aryal, S., Diaz-Guzman, E., & Mannino, D. M. (2014). Influence of sex on chronic obstructive pulmonary disease risk and treatment outcomes. International journal of chronic obstructive pulmonary disease, 9, 1145–1154. https://doi.org/10.2147/COPD.S54476

CDC – Data and Statistics – Chronic Obstructive Pulmonary Disease (COPD). (2018, June 05). Retrieved September 22, 2020, from https://www.cdc.gov/copd/data.html

Barnes PJ. Sex Differences in Chronic Obstructive Pulmonary Disease Mechanisms. Am J Respir Crit Care Med. 2016 Apr 15;193(8):813-4. DOI: 10.1164/rccm.201512-2379ED. PMID: 27082528.

Han, MeiLan. (2020). Chronic Obstructive Pulmonary Disease in Women: A Biologically Focused Review with a Systematic Search Strategy. International Journal of Chronic Obstructive Pulmonary Disease. Volume 15. 711-721. 10.2147/COPD.S237228.

Hardin M, Foreman M, Dransfield MT, et al. Sex-specific features of emphysema among current and former smokers with COPD. Eur Respir J. 2016;47(1):104-112.

Quaderi, S. A., & Hurst, J. R. (2018). The unmet global burden of COPD. Global health, epidemiology, and genomics, 3, e4. https://doi.org/10.1017/gheg.2018.1

Soriano JB, Maier WC, Egger P, et al. Recent trends in physician-diagnosed COPD in women and men in the UKThorax 2000;55:789-794.

U.S. Department of Health and Human Services. The Health Consequences of Smoking—50 Years of Progress. A Report of the Surgeon General. Atlanta: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2014. Accessed September 22, 2020.

World Health Organization (WHO). Chronic obstructive pulmonary disease (COPD). http://www.who.int/respiratory/copd/en/. Accessed September 20, 2020