Gender differences in medical care and mortality

Chronic obstructive pulmonary disease (COPD) is a growing global epidemic, as described by a great PLoS article. It is associated with smoking and is a major cause of disability. In 1990, it was the 6th leading cause of death worldwide. It is projected to climb to Bronze (in the Olympics of Morbidity and Mortality) by 2020. To put it in prospective, it is currently being beaten out by heart attacks, strokes, and AIDS. While we have been better able treat and prolong life with these other diseases, COPD is actually on the rise. It affects 10% of the global population--not a small chunk of people by any means. Of smokers 25% of them will develop COPD and despite the public and medical bias, the rates between men and women are equal according to a 25 year study published in 2006 in Thorax. Importantly, the rate is rising faster in women.

About COPD:
According to the Global Initiative for Chronic Obstructive Lung Disease COPD is “a preventable and treatable disease.‥characterized by airflow limitation that is not fully reversible. The airflow limitation is usually progressive and associated with an abnormal inflammatory response of the lung to noxious particles or gases”.

There are two variants of COPD. With the chronic bronchitis subtype, you slowly lose the ability to breathe because your windpipes fill with mucus and plug up. With emphysema, your smallest airsacs, where the essential transfer of oxygen to the blood occurs, begin to dissolve. We measure the decline by following the forced expiratory volume (FEV1), which is the amount of air you can force out in 1 second. People with COPD lose 50-100 mililiters of volume each year. 'Normal' people only decline by less than 30 mililiters per year.

According to another great article in PLoS, while life expectancy has been steadily on the rise (7 years for men, 6 years for women), this increase is not distributed equally across socio-economic groups. The figure below is from that article. The darker the green, the higher the life expectancy compared to the national average, where as the darker the red, the lower. As you can see by the map in the lower right, women are doing worse as a whole (i.e. the map is more red).


Women are also more likely to die from COPD. Why?

Women are less likely to be properly diagnosed as having COPD. Below is an excerpt from "Gender and Chronic Obstructive Pulmonary Disease":

A 2001 study [Chapman K, Tashkin D, Pye D. Chest] that sampled 200 primary care physicians in North America presented two hypothetical cases of cough and dyspnea in smokers, one male and the other female. Physicians were then asked for provisional diagnosis and initial diagnostic steps. COPD was given as the most probable diagnosis significantly more often for the male case scenario than for the female case scenario (64.6 vs. 49%).

Women are more likely thought to just have asthma. A similar study was conducted in Spain with similar results, so it's not just us in the US. If a doctor is less likely to think a [female] patient has COPD, that doctor is less likely to order the proper tests and make the right diagnosis.

Women are more susceptible to tobacco. It is not clear why, but the same amount of smoking is more damaging to female lungs. Women also tend to decline more quickly once they do develop COPD. As described by Gan et al., women have an accelerated rate of decline of FEV1 as compared to men.
Women are more symptomatic. Women are more likely to have severe shortness of breath (dyspnea) with less pack year (number of cigarette packs smoked per day x number of years). Additionally, FEV1 (the above mentioned marker of disease progression) correlates significantly better with male disease and death.

Women are differently biologically. Sex hormones may affect the way the body deals with smoking. Just as children are NOT little adults; women are NOT men. We need specifically tailored drug and clinical trials. Women have smaller lungs, increased airway responsiveness, and hormones which modulate the body's response to irritants like smoke. From Han et al. :

It is interesting to note that chronic bronchitis is more prevalent in women, whereas emphysema is more prevalent in men. Gender dimorphism in COPD was first suggested by Burrows and colleagues in 1987.

Women are socially disadvantaged. As women have a lower socio-economic station, they have less access to health care and early intervention. Globally, particularly in poor countries, women have increased exposure to indoor toxins from burning dung, charcoal, and wood indoors for fuel for cooking and heating. This has led to increased rates of COPD in even non-smoking females.

Women choose to smoke more dangerous cigarettes. Cigarettes marketed towards women as "light" or "low tar" are typically lower in nicotine. The other toxins, however, are still in the same concentration. The low nicotine content results in a deeper and longer inhalation and thus more contact between the toxins and the lung surfaces.

COPD is a real threat towards women and the inequalities which exist are unacceptable. We need better education of the public and medical communities. We need better recognition of the disease in women and ultimately better treatments.
This post was inspired by a great lecture by a female physician.