Increased Relative Mortality in Women With Severe Oxygen-Dependent COPD

Abstract

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. 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). 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. 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.