Increasing incidence among women
According to the Centers for Disease Control and Prevention, chronic lower respiratory diseases, primarily COPD, were the fourth-leading cause of death in women in the United States in 2018, following only heart disease, cancer, and accidents/injuries.
And as a CDC analysis of data from the 2013 Behavioral Risk Factor Surveillance System showed, women were more likely to report being told by a physician that they had COPD than did men (6.6%, compared with 5.4%).
Dr. Sodhi and colleagues noted that, at all time points examined from 2005 to 2014, women had a higher proportion than men of COPD hospitalizations and in-hospital deaths. They also noted that female sex is associated with a threefold risk for severe early-onset COPD, and that women with COPD have lower diffusion capacity of lungs for carbon monoxide, despite having higher predicted forced expiratory volume in 1 second, compared with men.
“Historically, COPD wasn’t a disease that was so prevalent in women. It’s been in the past 20 years that the trends have changed,” said Patricia Silveyra, MSc, PhD, ATSF, associate professor of environmental and occupational health at Indiana University, Bloomington.
The increasing prevalence of COPD among women cannot be explained by smoking alone, she said in an interview.
“It used to be thought that it was because more women smoked, but actually a lot of women who don’t smoke can develop COPD, so it appears to be probably something environmental, but because it used to be a disease of older men, in the clinic there was also a bias to diagnose men with COPD, and women with asthma, so a lot of women went underdiagnosed,” Dr. Silveyra said.
In their review, Dr. Sodhi and colleagues noted that women with COPD “may be underdiagnosed as a result of having different symptoms from those classically recognized. Reasons for underdiagnosis or a delay in diagnosis may also be due to lack of a formal evaluation with spirometry, women seeking care later in the course of disease, physician bias, or associated fatigue or depression misdirecting diagnostic strategies. Underdiagnosis may be associated with psychological distress and worse health-related quality of life.”
Although the evidence is mixed, women tend to present more frequently with the chronic bronchitis phenotype of COPD, compared with the emphysema phenotype, and women tend to have greater degrees of pulmonary function impairment when exposed to tobacco smoke, even after controlling for differences in height and weight.
“For the same amount of exposure to tobacco smoke, females are likely to develop more severe airflow limitation at an earlier age than males, and have more exacerbation,” Dr. Sodhi and colleagues wrote.
Both Dr. Silveyra and Dr. Sodhi said that reason why men and women differ in their physiological reactions to smoke are still unknown.
Sex differences in drug responses
There is only limited evidence to indicate that women and men respond differently to various therapeutic agents, but what is clear is that more research into this area is needed, Dr. Sodhi and Dr. Silveyra said.
For example, among the few studies that have documented sex differences, one showed no sex differences in the efficacy of salmeterol/fluticasone combination therapy for reducing exacerbations or improving quality of life, whereas another showed that women were more likely than men to experience COPD symptoms or exacerbations after stopping inhaled corticosteroids, Dr. Sodhi and colleagues noted.
Both Dr. Sodhi and Dr. Silveyra emphasized the need for clinical trials that study the effects of sex on treatment outcomes in COPD, which could lead to better, more personalized therapeutic regimens that take sex and gender into account.
Dr. Sodhi and colleagues offered the following advice to clinicians: “Interaction with female patients should take into account that their symptoms may not conform to traditionally accepted presentations. Challenges exist for female patients at all levels of health care interaction and as clinicians we need to acknowledge the bias and willfully work toward recognition and elimination of unconscious and conscious bias. Empowering our patients to have frank discussions with their health care team when they perceive bias is another step to help promote equity.”
The review by Dr. Sodhi and colleagues was supported by grants from the National Institutes of Health. Dr. Sodhi and Dr. Silveyra reported having no conflicts of interest to disclose.