Estrogen Use Linked to Asthma in Postmenopausal Women

      SAN FRANCISCO -- Researchers report that use of estrogen replacement therapy may double the risk of asthma in postmenopausal women.

      Using records from the massive Nurses Health Study that has followed more than 121,000 women since 1975, doctors investigated whether the use of the hormone replacement strategy to protect against other diseases following menopause was related to increases in asthma cases among women. At the time they began the study, the women were between 30 and 55 years old.

      Study leader Dr. Graham Barr did note his preliminary analysis does not indicate that the development of asthma in these women leads to increased healthcare needs-especially urgent physician visits or emergency room visits-among these women.

      Barr, a fellow in respiratory epidemiology at Channing Laboratory at Brigham and Women''s Hospital, Boston, said previous studies indicated an increase in asthma among women during puberty and among women on estrogen-containing contraceptive pills. He wanted to determine if estrogen replacement after menopause also correlated with increases in asthma.

      In a presentation at the annual meeting of the American College of Chest Physicians in San Francisco, Barr said he found an 80 percent increased risk in asthma among women taking the estrogen replacement and a doubling of the risk of developing asthma and chronic obstructive pulmonary disease, another lung disorder, abbreviated COPD.

      "This appears to be something that a physician should discuss with his patients as a question of informed consent," commented Dr. John Mitchell, chief of the pulmonary and chest center at Travis Air Force Base, California.

      Mitchell said that the concern over asthma should not outweigh the benefits of estrogen in reducing the risk of other conditions such as heart disease and osteoporosis in postmenopausal women.

      Barr reported that among postmenopausal women who had never used estrogen replacement therapy there were 255 new cases of asthma; among women who had used estrogen replacement in the past there were 174 asthma cases; there were 195 cases of asthma among women using conjugated estrogen formulations and 132 cases of women using combination of estrogen and progestin formulation. That amounted to an odds ration of 1.8 -- an increased risk of 80 percent for all estrogen users.

      Mitchell observed, however, that the studies do not explain if the women are predisposed to asthma or whether the inclusion of estrogen worsens symptoms already present.

      Barr explained that estrogen has pro-inflammatory effects which may be relevant to the inflammatory components of asthma and COPD.

      In the nurses study, all the participants are sent questionnaires about their health status every two years. In 1998 a supplemental questionnaire was sent to the women to confirm cases of asthma or COPD.

      Barr said his data show that the risk of developing asthma increased with the length of time on estrogen replacement therapy as well as with increased dosages of estrogen taken by the women.

      On the basis of the results, Barr said, "Further research is warranted to evaluate pulmonary responses to female reproductive hormones. We are currently doing more extensive analyses to determine if hormone replacement therapy worsens asthma severity."

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