Chest
Volume 137, Issue 1, January 2010, Pages 31-36
Journal home page for Chest

Original Research
COPD
Increased Relative Mortality in Women With Severe Oxygen-Dependent COPD

https://doi.org/10.1378/chest.09-0636Get rights and content

Background

Although the incidence of COPD is rapidly increasing in women, knowledge is lacking concerning differences in relative mortality and causes of death in women compared with men. We aimed to analyze differences in relative mortality and cause-specific mortality between men and women on long-term oxygen therapy (LTOT) for COPD.

Methods

Patients starting LTOT for COPD in Sweden between January 1, 1987, and December 31, 2004, were prospectively followed until termination of LTOT or through December 31, 2004. Causes of death according to the Swedish National Causes of Death Register were compared between the study group and the general Swedish population matched for age and sex, with the relative mortality expressed as standardized mortality rates (SMRs).

Results

A total of 7,646 patients, 4,033 women and 3,613 men, were followed for a median of 1.7 years (range 0–18.0). No patient was lost to follow-up. A total of 5,448 patients, 2,745 women and 2,703 men, died. Women had a higher SMR than men: overall mortality, SMR 12.0 (95%, 11.6–12.5) vs 7.4 (95% CI, 7.1–7.6); for respiratory disease, SMR 127.9 (95% CI, 122.4–133.6) vs 66.0 (95% CI, 63.1–69.0); cancer, SMR 3.5 (95% CI, 3.0–3.9) vs 2.2 (95% CI, 1.9–2.5); and cardiovascular disease, SMR 3.7 (95% CI, 3.3–4.1) vs 2.5 (95% CI, 2.3–2.7), respectively.

Conclusions

In severe COPD treated with long-term oxygen, women have higher relative mortality than men both overall and for respiratory disease, as well as for cardiovascular disease and cancer.

Section snippets

Materials and Methods

Patients starting LTOT for chronic hypoxia due to COPD in Sweden between January 1, 1987, and December 31, 2004, were included in a National Oxygen Register administered by the Swedish Society of Respiratory Medicine.17, 18, 19 Every center prescribing LTOT in Sweden agreed on the national guidelines from the Swedish Society of Respiratory Medicine, as described elsewhere.9 Patients who started LTOT more than once were excluded. All other patients were followed prospectively, with cause of

Results

A total of 7,646 patients, 4,033 women and 3,613 men, were included in the study after exclusion of 71 patients who had started LTOT more than once. No patient was lost to follow-up. LTOT was withdrawn in 436 (5.7%) patients as a result of improvement in oxygenation (n = 195), poor compliance (n = 36), or for other reasons (n = 205).

Patient characteristics at baseline are shown in Table 1. Women had a slightly lower mean age at the start of LTOT and a slightly higher Paco2 both when breathing

Discussion

A new finding in the present study is that women have significantly higher relative mortality than men, not only concerning all-cause mortality and mortality from respiratory disease, but also from cardiovascular disease and cancer.

Studies of differences in observed survival rates between men and women after initiation of LTOT for COPD have shown contradictory results. Most studies showed higher survival rates for women,5, 6, 7, 9, 13 whereas the study by Machado et al8 found a survival

Acknowledgments

Author contributions: Dr Ekström: contributed to the design of the study and the analysis, interpretation, and presentation of data, drafted the submitted article, and provided final approval of the version to be published.

Dr Franklin: contributed to the analysis and interpretation of data, revised it critically for important scientific content, and provided final approval of the version to be published.

Dr Ström: was responsible for the Swedish Oxygen Register 1987–2007 during the collection of

References (0)

Cited by (21)

  • Risk of cancer after lung transplantation for COPD

    2017, International Journal of COPD
View all citing articles on Scopus

Funding/Support: The study was supported by grants from the Swedish Heart and Lung Foundation, the Swedish National Board of Health and Welfare, and the Research Council of Blekinge.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/site/misc/reprints.xhtml).

View full text