© 2008 American Thoracic Society
Gender and Prognosis of Chronic Obstructive Pulmonary DiseaseFrom the Authors:We thank Dr. Machado for her letter commenting on our article, which reviews the impact of gender on chronic obstructive pulmonary disease (COPD) (1). Dr. Machado states that we propose that women with COPD have a survival advantage, while other articles have reported worse survival for women with COPD. She makes the important point that the effect of gender on COPD prognosis, particularly survival, is "fraught with complexities." It appears that our points of view on this matter are closer than it seemed. We too agree that this is a complex matter. At the beginning of our article, we highlight that death rates due to COPD in women have tripled between 1980 and 2000, and that in terms of absolute numbers, more women have died of COPD than men in the United States since 2000 (2). Data from Canada also report increasing mortality for women with COPD (3). Certainly, these data could be biased by the differential presence of comorbidities, such as depression or body mass depletion, or by the fact that women, in general, live longer, but in our article we also state that if such data are real, then they raise a concern that the disease course for men and women may actually differ. The section of our article to which Dr. Machado refers discusses possible gender differences in response to therapeutics for COPD, particularly long-term home oxygen therapy (LTOT). We described two studies, one by Miyamoto and coworkers (4), which concludes that LTOT is associated with improved survival in women with COPD, and Machado and coworkers' article (5), which reports worse survival for women with COPD receiving LTOT, in addition to those with lower body mass index (BMI) and lower PaO2. These data do not necessarily reflect overall mortality in COPD patients, yet pertain to patients with very severe COPD requiring oxygen treatment. In our article, we also state that Dr. Machado's analysis does not stratify by gender. Indeed, while predictors of survival were not tested separately by gender for significance, she writes to point out that her survival analyses did test for interactions between gender and other predictors of survival, including PaO2 and BMI, and found these not to be significant. We thank Dr. Machado for drawing attention to the fact that more such analyses exploring how gender modifies predictors of COPD prognosis are needed.
University of Michigan Health System
University Medical Center Groningen
University of Michigan Health System FOOTNOTES Conflict of Interest Statement: M.K.H. has no financial relationship with a commercial entity that has an interest in the subject of this manuscript. D.P. has no financial relationship with a commercial entity that has an interest in the subject of this manuscript. F.J.M. is a consultant for Altana Pharma and has received compensation greater than $10,000; he has been a member of several advisory boards, CME committees, and the speaker's bureau for Boehringer Ingelheim, Pfizer, and GlaxoSmithKline; his total compensation per company is greater than $10,000; in addition, he is on the advisory board for Novartis and speaker's bureau for Sepracor and Astra, receiving less than $10,000 per company; he has been an investigator for industry-sponsored studies for GlaxoSmithKline, Boehringer Ingelheim, and Actelion. REFERENCES
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