Background: Female reproductive hormones appear to influence asthma, although data are conflicting, and may modulate development of chronic obstructive pulmonary disease (COPD). Therefore, in a prospective cohort study, we evaluated whether postmenopausal hormone use was associated with an increased rate of newly diagnosed asthma and, separately, newly diagnosed COPD.
Methods: Postmenopausal hormone use was assessed by questionnaire biennially from 1976 onward. New physician diagnoses of asthma or COPD were reported on questionnaires from 1988 to 1996 and confirmed in 1998 using supplementary questionnaires. Grades of diagnostic certainty were established from reports of medication use and pulmonary function using validated definitions.
Results: During 546259 person-years of follow-up, current use of estrogen alone was associated with an increased rate of asthma (multivariate rate ratio, 2.29; 95% confidence interval [CI], 1.59-3.29) compared with those who never used hormones. Current users of estrogen plus progestin had a similarly increased rate of newly diagnosed asthma. Rate ratios increased with certainty of diagnosis of asthma. In contrast, rates of newly diagnosed COPD were the same among hormone users and nonusers (multivariate rate ratio, 1.05; 95% CI, 0.80-1.37).
Conclusions: Postmenopausal hormone use was associated with an increased rate of newly diagnosed asthma but not newly diagnosed COPD. Female reproductive hormones may contribute to the onset of asthma among adult women, but do not appear to hasten the development of COPD.