In the last 30 years, COPD has become more prevalent in American women, who now make up more than half of patients currently diagnosed—an estimated 7 million women, in all.
By Bill Pruitt, MBA, RRT, CPFT, AE-C, FAARC
COPD is a major burden on healthcare in America and across the world. It has been estimated that COPD is the third leading cause of death worldwide and is the third leading cause of morbidity and mortality in the United States. According to the Centers for Disease Control and Prevention, a total of 137,353 Americans died as a result of chronic lower respiratory diseases in 2009.
The disease has traditionally afflicted more men than women, but over the past 30 years the United States has seen a change in the characteristics of the population being diagnosed with COPD. Today, more women die of COPD than men in the United States, with women accounting for an estimated 72,000 COPD-related deaths in 2009 compared to an estimated 65,000 for men (53% vs 47%). Many believe the cause of this change is rooted in a shift in behavior that goes back to the early and mid-1900s—namely, cigarette smoking in women.
“You’ve Come a Long Way, Baby”
By 1920, more than half of young men were smokers. By the time we reached the 1950s, a little more than a third of young women were smokers. In the 1920s, as women pushed for more political and social freedoms, tobacco companies seized on this idea by positioning cigarettes as symbols of liberation, independence, self-confidence, beauty, and adventure. As a result, cigarette consumption in women increased. Advertisements for brands like Camel cigarettes prominently used women portrayed as physicians in magazine ads from the 1940s. One example displayed the slogan, “More doctors smoke Camels than any other cigarette,” while showing an attractive young woman in a white lab coat with a doctor’s headlamp.
In the early 1960s and into the 1970s, female-focused slogans were heavily used in magazine, television, and radio advertising. Phrases such as, “You’ve come a long way, baby,” and “It’s a woman thing,” were used. In addition, new brand names for cigarettes such as Virginia Slims, Eve, and Satin were designed in order to entice women and girls to smoke.
The rate of smoking in females reached a peak in the mid-1960s but still remains high today. According to a 2008 report by the CDC, 21.1 million American women smoke—not far off the total number of American men (24.8 million). When examining the smoking habits of similar age groups of people (cohorts of smokers) from a study published in early 1980, smoking cessation rates were higher for men than for women. These facts are important because, according to the Global Initiative on Chronic Obstructive Lung Disease (GOLD) 2014 update, cigarette smoking is the “most commonly encountered risk factor for COPD.”
GOLD Guidelines on COPD
The 2014 update of the GOLD guidelines provides a comprehensive look at how to diagnose, manage, and prevent COPD. The issues of gender-related risk and gender-related severity have been mentioned in the GOLD guidelines, but these topics are not thoroughly addressed. The GOLD document refers to a systematic review and meta-analysis of studies covering 1990 to 2004, which concludes that the prevalence of COPD is much higher in smokers and ex-smokers compared to nonsmokers, in those over 40 years of age compared to people less than 40, and in men compared to women.
However, the GOLD guidelines also mention that, although prevalence of COPD has been greater in men, it is now almost equal between genders, reflecting the changes in use of tobacco in women. GOLD also mentions that some studies suggest that “women are more susceptible to the effects of tobacco smoke than men.” According to the 2004 Report of the US Surgeon General, “female smokers are nearly 13 times more likely to die from COPD compared to women who had never smoked.”
Mounting Proof in Peer-reviewed Literature
Between the years 1980 and 2000, the number of hospitalizations for COPD in women increased 42% and female deaths caused by COPD increased around threefold. A morbid but significant milestone was reached in 2000 when, in the United States, the female deaths caused by COPD exceeded those in men.8
In a study published in 2000, researchers studied families with a member (the index case) suffering from severe, early-onset COPD. To be included in the study, the index case had to have an FEV1 less than 40% predicted, be less than 53 years of age, and be free from alpha1-antitrypsin deficiency. All first-degree relatives of the index cases were asked to participate. The pool of participants came from the lung transplant programs and lung volume reduction surgery (LVRS) programs in the northeast region of the United States, plus patients in the area who were being seen at pulmonary clinics. For any of the transplant or LVRS patients enrolled, only the presurgery spirometry data were used.
In total, 84 index case subjects were enrolled. A significant number of the subjects were female (71.4%, or 60 of the 84 cases), which was markedly different from the predicted equal sex distribution. Of the 84 early-onset COPD patients, 64 had CT scans. Three of these were excluded due to limited information about the lung parenchyma. Of the 61 remaining cases, the CT scan revealed emphysema in 60. From the 84 index cases, 348 first-degree relatives were included in the study; this included parents, siblings, and children.
Overall analysis of these 348 subjects showed similar spirometry results and similar pre-post bronchodilator responses. No significant differences were discovered between males and females of this group of relatives. However, when the analysis was limited to current or ex-smoking first-degree female relatives, the FEV1/FVC was significantly lower. The diagnosis of asthma appeared more frequently in the female first-degree relatives when compared to males, but the difference was not significant. However, when the analysis was limited to current or ex-smoking first-degree relatives (male and female), the asthma diagnosis was significantly higher in the females along with a significantly higher response to a bronchodilator.
A more recent study published in 2011 found that women had a higher incidence of severe COPD and that it developed earlier in life. Participants in the research were male and female, between age 45 and 80, and had a minimum of 10 pack-years smoking history. Using a threshold of FEV1/FVC <70% and an FEV1 <50% predicted and an age <55 to look for early-onset severe COPD, the researchers found that severe COPD was more prevalent in women. Of the total 2,500 subjects (mean age 51 years old), severe, early-onset COPD was discovered in 70 subjects (2.8%). But, of those 70 subjects with severe, early-onset COPD, 66% were female. In addition, this study found that severe early-onset COPD was significantly associated with maternal history of smoking and maternal respiratory disease.
Why Is There a Gender Difference for COPD?
Research is ongoing to examine why gender differences exist for COPD. Some experts argue that the changing demographics for COPD in women are due to the changes in behavior. Behavioral changes, mentioned above, include the adoption of smoking as a symbol of independence and freedom, and the erosion of the societal perception of smoking as a “macho” or manly behavior.
Another factor for the increase in COPD diagnoses in women may be linked to environmental exposure to occupational dust or chemicals. Beginning in the mid-20th century, women began moving into jobs that were historically held by men, and their on-the-job exposure to dust or chemicals may play a role in the change in gender-related diagnosis of COPD. Exposure to secondhand smoke, as well as occupational and everyday exposure to air pollution, also can play a role in gender differences for COPD. Worldwide efforts to reduce the prevalence of COPD have been directly linked to reducing exposure to smoke from biomass fuel—especially in the exposure to these indoor and outdoor pollutants among women and children. GOLD recommendations include providing efficient ventilation, use of flues, and use of non-polluting cooking stoves.
Other issues for consideration may be in cigarette brand preferences and in differing inhalation techniques between men and women. There may be a difference in the inhaled particles and chemicals between cigarette brands that influence the gender-related risk of developing COPD. Brands that are more popular among men may have a different “payload” of detrimental ingredients as opposed to the brands preferred by women.
In addition, there may be gender-related differences in the breathing patterns, depth of inhalation, breath-hold, and frequency of taking a “puff” from a cigarette that could influence the risk of COPD. (A brief search of peer-reviewed articles did not uncover any published investigations examining these particular aspects of smoking. For the purposes of this article, this is merely speculation but may suggest areas for future research.)
Studies have shown that women develop severe COPD at a younger age than men and that this is occurring despite less exposure to cigarette smoke (in terms of fewer pack-years history).[11,13] These studies support the idea that there may be a gender-specific genetic component that drives the earlier and more severe diagnosis of COPD. Physically, women have smaller airways than men, which would result in a proportionally higher exposure to smoke given similar pack-year histories between male and female populations.[11,13] Female sex hormones also may play a role in COPD development—this possibility is already mentioned in the literature due to the gender differences seen in airway function and asthma.
Another idea considered in the literature is that what may be initially thought of as COPD may actually be asthma with fixed airflow obstruction. The terms COPD and asthma are sometimes used interchangeably in the general population, which could confuse the issue when using a survey that asks, “Have you ever been diagnosed with a lung disease such as asthma or COPD?”
Females have different patterns for lung growth and development than males. Airway growth and parenchymal development are proportional in females, while males have more rapid parenchymal growth in relationship to their airways. Females have a peak in FEV1 at about 13 years of age and reach a plateau at around 16; by contrast, males have a peak in FEV1 at age 14 and plateau at around 18 to 19 years old.
There also appears to be a difference in the expression of COPD related to gender. Data from the National Health Interview Survey suggest that chronic bronchitis is more common in females while emphysema is more common in men. This phenotypic difference has been supported by CT scan evidence that women have less evidence of emphysema and have significantly thicker airway walls and smaller airway lumen.
The development of COPD in women (or men, for that matter) is not entirely due to smoking habits. Some 15% of all people diagnosed with COPD have never smoked, but within this group, almost 80% are women. This also lends credence to the idea that genetic factors may play a significant role in the development of COPD.
Maternal smoking, smoking during pregnancy, and maternal COPD also appear to be other factors influencing the smoking habits and the diagnosis of COPD in female offspring.[11,16]
Another aspect of gender differences in COPD is that of quality of life. Those diagnosed with COPD often suffer from many comorbidities that complicate care and increase their burden financially, physically, and psychologically. When examining men and women with moderate COPD, women were younger, smoked less than men, and had fewer comorbidities, but had worse walking test scores.[17-18] What’s more, in comparison to men with similar levels of FEV1, females had higher dyspnea scores. Women also had almost twice the incidence of depression and anxiety as compared to men.[17-18]
Research exploring disease differences between men and women has been increasing over the last several decades but more needs to be done. In October, COPD will join three other diseases (congestive heart failure, pneumonia, and acute myocardial infarction) as a targeted disease in the Hospital Readmission Reduction Program (HRRP), which was established by the Patient Protection and Affordable Care Act in 2010. The HRRP is being administered by the Centers for Medicare and Medicaid Services and will carry a reimbursement penalty for hospitals that have any of these patients readmitted for all causes within 30 days of discharge. The thought is that this program will help reduce readmissions and help stem the rising tide of Medicare dollars. As evidence reveals the growing prevalence of COPD in women, it stands to reason that a great deal of the success of the HRRP will rely on reducing and preventing readmissions in these patients. According to information cited in a 2013 report on women and COPD by the American Lung Association, since 1993, women have surpassed men in number of COPD hospitalizations, with 57.2% of the 715,000 hospital discharges in 2010 being women.
COPD has been shown to develop differently between the sexes and the details are becoming clearer as more scientists study this issue. With continuing research and advancement in medications, there may come a time in the future where pharmacological and nonpharmacological treatment approaches for COPD take gender differences into consideration. As smoking habits change and changing levels of air pollution alter the environment, this issue will continue to evolve. Armed with this knowledge, RTs can be better prepared to care for women and to help decrease both their risk and their burden of COPD.
Bill Pruitt, MBA, RRT, CPFT, AE-C, FAARC, is a senior instructor and director of clinical education in the department of Cardiorespiratory Sciences, College of Allied Health Sciences, at the University of South Alabama in Mobile. He also works as a PRN therapist at Springhill Medical Center. For further information, contact [email protected].
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