Screening for COPD: Targeting a Disease That Targets Women (Women's Health Matters article) (Web resource; WHM resource) Author: Patricia Nicholson Organization: Women's College Hospital, Women's Health Matters Screening programs for diseases such as breast cancer, osteoporosis and cervical cancer have been very successful in increasing early diagnosis of these conditions in women. But Dr. Anna Day, director of the Gender and Airways Program at Women’s College Hospital in Toronto, would like to see another test added to women’s regular screening checkups: spirometry. Spirometry measures lung function, and is an important tool in diagnosing chronic obstructive pulmonary disease (COPD), a condition that may be more of a health risk for women than for men. Screening for COPD in women who are at risk for it – smokers and former smokers over age 40 – might help identify more cases at an earlier stage. ‘Why a targeted screening program for women at risk? Because we believe they are underdiagnosed. We believe there is late diagnosis,’ Dr. Day said during a presentation on Gender and COPD at Women’s College Hospital on Oct. 21, 2009. She explained that COPD may have no symptoms for a long period during which lung function is declining, and that when women do develop symptoms, they are often not the textbook symptoms of cough and sputum. Instead, women may present with shortness of breath, which is often seen as a symptom of heart disease rather than COPD. Rising mortality rates in women To illustrate the dangers of COPD for women, Dr. Day presented some curious data: despite a steep decline in smoking rates in recent decades, there has not been much change in mortality rates from COPD and lung cancer. But a closer look at those mortality rates showed that when the data for men and women were separated, the mortality rate for men had dropped, even though the overall rate had stayed the same. ‘There has actually been a decrease in mortality rates from COPD for men. So as a corollary it must mean that someone’s rate is going up,’ Dr. Day said. ‘If we look at the COPD mortality rates for women by age group, between 1989 and 2004 you’ll see that in fact there has been an increase in mortality rate for women from COPD. So we have a bit of a paradox here.’ A look at smoking rates in men and women doesn’t explain this difference. ‘There are more men who smoke than women who smoke, but we’re seeing a decrease in mortality for them and an increase in mortality for women. Again, a bit of a paradox.’ Although smoking rates have declined over the past 30 years, illness and death from COPD is increasing in women. ‘Today there isn’t much controversy that smoking for some reason seems to impact lung function more adversely for women than for men,’ Dr. Day said, citing studies that indicate greater loss of lung function in female smokers than males, both in adolescence and as adults. ‘The good news is that when women stop smoking they actually recover more lung function than do male ex-smokers.’ Different risks In probing the potential reasons for the increase in illness and mortality in women, Dr. Day explored several possible contributing elements. Women may have different risk factors than men. They may be biologically more susceptible than men. Gender may play a role in diagnosis, and treatments may work differently in women than in men. In terms of risk factors, women’s smoking habits are different from men’s. Women tend to smoke ‘light’ cigarettes, which often contain less tar. While less tar might seem like a good thing, tar is required for nicotine to enter the brain rapidly, Dr. Day explained. ‘That’s why nicotine patches and oral nicotine don’t work very well: because you actually need tar to allow the rapid absorption and uptake of nicotine,’ she said. ‘When you have less tar you actually have to smoke more.’ The result is that by smoking lighter cigarettes, women are exposed to higher carbon monoxide levels in order to get the same level of nicotine. But even with similar smoking habits, women may be more susceptible to the damaging effects of tobacco. This could be because their airways are smaller than men’s, because more toxic substances may be deposited in the lungs, or because their lungs may be less able to clear toxins. Enzymes, hormones and oxidative stress There could also be an exaggerated biological response to these toxins. When people smoke, an enzyme called cytochrome p450 is responsible for processing – or metabolizing – the toxins from cigarettes, creating metabolites that then cause oxidization that damages the lungs. ‘The result is what we call oxidative stress and tissue damage, which leads to chronic obstructive pulmonary disease,’ Dr. Day explained. To help prevent this, the body also produces antioxidants that target these dangerous metabolites and clear them away. However, women may not produce enough of these antioxidants to avoid the oxidation and damage. One theory is that estrogen may affect the balance between the enzyme making the toxic metabolites, and the detoxifying antioxidants. ‘We know that estrogen actually increases the level of cytochrome p450, but does not increase the level of the antioxidants,’ Dr. Day said. ‘You can actually measure higher levels of oxidants in the blood of women in the studies that have been done. So it looks like there is actually a metabolic reason why the same amount of cigarette smoke may have a greater impact in terms of damage to the airways.’ Women may also be more susceptible to inflammation of their airways, and to the bronchial hyper-responsiveness that results in more severe asthma. ‘So there is a lot of information coming up in terms of biologic susceptibility,’ Dr. Day said. ‘It’s now accepted that these issues of inflammation and damage from oxidative stress are important components in causing COPD.’ Diagnostic gender gap But biological susceptibility may not be the only contributor to the increasing mortality rate in women from COPD. There may be a problem in recognizing and diagnosing COPD in women. Despite the greater prevalence of COPD in women than men in Canada, COPD may still be thought of as a condition that’s more common in males. In a study that asked doctors what percentage of their patients with COPD was female, three-quarters of doctors said they felt that their COPD patients were predominantly men. In another study, 200 family doctors were given two cases of smokers with the same symptoms. The only difference was that one was a man and one was a woman. After reviewing these two cases as part of a larger series of patient scenarios, significantly more doctors diagnosed the man with COPD than the woman. ‘So given the same scenario, physicians were less likely to consider COPD as a diagnosis for a woman,’ Dr. Day said. The differences might not end with diagnosis. A study of 3,500 cases in Europe and Canada found that men with COPD were more likely than women to have spirometry tests to confirm the diagnosis. One diagnostic hurdle is that women tend to present with shortness of breath, rather than cough and sputum. Understandably, they are sent for cardiac testing, which can hold up the diagnosis of COPD. Age and lung function Part of the danger of COPD is the long stretch of time during which people can be losing lung function and not know it because they have no symptoms. ‘The only way you can know if you’re losing lung function is if you do screening spirometry,’ Dr. Day said, noting that it’s impossible to predict the impact of smoking on lung function in an individual patient. ‘The clinical symptoms do not correlate well with lung function,’ she said. ‘There can be significant lung destruction before smokers become symptomatic.’ Some people may have symptoms such as a cough and sputum, and have normal spirometry. But other people can have no symptoms at all, and have abnormal spirometry. ‘So why should we screen for women? It’s a high risk population,’ Dr. Day said. ’Women who smoke have a higher risk of developing COPD. We have a bias in suspecting disease in the first place, and sometimes their symptoms, such as shortness of breath, are discounted. ‘So how can we know who the individuals are that are losing lung function quickly? And we’re very concerned that one of the reasons we’re having increased morbidity and mortality is that women are being diagnosed very late.’ Screening spirometry might help catch COPD earlier. Dr. Day supports ongoing screening spirometry in smokers over age 40, and also recommends giving ex-smokers a single test as well. Purpose:  Consumer information/support; Health information Information Source:  Hospital/Clinic Geographic Origin:  Canada Language of Resource:  English Groups:  Adult women; Middle-aged women; Older women Last Reviewed by Women's Health Matters:  November 11, 2009