Sex differences in survival of oxygen-dependent patients with chronic obstructive pulmonary disease.
BACKGROUND
Chronic obstructive pulmonary disease (COPD) is a leading cause of death worldwide. The prevalence of COPD is rising among women and is approaching that of men, but it is not known if sex affects survival.


OBJECTIVE
To measure the survival differences between men and women with oxygen-dependent COPD.


METHODS
We conducted a 7-yr prospective cohort study of 435 outpatients with COPD (184 women, 251 men) referred for long-term oxygen therapy (LTOT) at two respiratory clinics in Sao Paulo, Brazil. Baseline data were collected on enrollment into oxygen therapy, when patients were clinically stable.


METHODS
We examined the effect of sex on survival using Kaplan-Meier survival curves, and then used Cox proportional hazards models to control for potential confounders.


RESULTS
In unadjusted analyses, we observed a nonsignificant trend toward increased mortality for women (hazard ratio, 1.28; 95% confidence interval, 0.98-1.68; p = 0.07). After accounting for potential confounders (age, pack-years smoked, Pa(O(2)), FEV(1), body mass index), females were at a significantly higher risk of death (hazard ratio, 1.54; 95% confidence interval, 1.15-2.07; p = 0.004). Other independent predictors of death were lower Pa(O(2)) (p < 0.001) and lower body mass index (p < 0.05).


CONCLUSIONS
Among patients with COPD on LTOT, women were more likely to die than men.
Machado
Maria-Christina L
MC
State Public Hospital of São Paulo, São Paulo, Brazil. mchrismachado@pneumo.epm.br
Krishnan
Jerry A
JA
Buist
Sonia A
SA
Bilderback
Andrew L
AL
Fazolo
Guilherme P
GP
Santarosa
Michelle G
MG
Queiroga
Fernando
F
Vollmer
William M
WM
D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D010102:Oxygen Inhalation Therapy; D016016:Proportional Hazards Models; D029424:Pulmonary Disease, Chronic Obstructive / Q000401:mortality* / Q000503:physiopathology / Q000628:therapy*; D012737:Sex Factors; D016019:Survival Analysis; D015996:Survival Rate