Study objectives: To characterize asthma symptoms and pulmonary function throughout two menstrual cycles, with and without exogenous estradiol administration, in women with premenstrual asthma, and to determine the effect of estradiol administration on asthma symptoms, pulmonary function, quality of life, and biomarkers of airway inflammation.
Design: Double-blind, randomized, placebo-controlled, crossover study.
Setting: Respiratory clinic and clinical research center.
Subjects: Twelve women with documented premenstrual asthma (> or = 20% premenstrual worsening of asthma symptoms and/or of peak expiratory flow [PEF] during a 1-month screening phase).
Intervention: Each woman received either estradiol 2 mg or placebo orally between cycle days 23 and 28 (i.e., premenstrually, or before the onset of menses) in the first cycle and then crossed over to the other arm in the second cycle. Throughout both cycles, the women recorded daily morning and evening PEF readings and asthma symptoms.
Measurements and main results: Spirometry testing and measurement of serum estradiol and biomarkers of airway inflammation were performed on days 8 (follicular phase), 22 (luteal phase), and 28 (premenstrually) of both the estradiol and placebo cycles. During the two premenstrual visits, the Asthma Quality of Life Questionnaire was administered. No notable differences were observed between the estradiol and placebo cycles in daily PEF recordings or composite asthma symptoms scores. The area under the curve (AUC) for the composite asthma symptoms versus time profile was numerically, but not statistically, lower (denoting less severe symptoms) during the estradiol cycle than during the placebo cycle. Likewise, no significant difference in AUC values for morning PEF or evening PEF was found between the estradiol cycle and the placebo cycle. Despite differences (p<0.05) in day-28 estradiol concentrations for estradiol and placebo cycles, no significant differences were found in forced expiratory volume in 1 second, serum endothelin-1, serum and urine eosinophil protein X, urine leukotriene E4, or quality-of-life scores.
Conclusion: Exogenously administered estradiol did not have a significant effect in women with premenstrual asthma whose asthma was classified predominantly as mild and under excellent control. As in the case of premenstrual syndrome, the placebo effect may be prominent in premenstrual asthma. Further trials, involving women with more severe asthma under poorer control, are warranted to discern underlying mechanisms for the worsening of asthma in relation to menstruation.