The effect of the menstrual cycle on asthma presentations in the emergency department.

Background: Seventy-five percent of all adult hospital admissions for asthma are women.

Objective: To determine whether a relationship exists between phases of the menstrual cycle and asthma exacerbations in adult females.

Methods: Data were analyzed from 182 nonpregnant, adult females with asthma aged 13 years to menopause. Date of presentation, patient age, duration of asthma attack, date of last menstrual period, regular interval between menses, presenting peak expiratory flow rate, and admission and discharge decision were recorded prospectively. Treatment interventions abstracted retrospectively from patient charts included use of oxygen, xanthines, beta-adrenergic agonists, corticosteroids, and magnesium sulfate. The menstrual cycle was divided into 4 phases based on fluctuations in serum estradiol levels. The 4 intervals were preovulatory (days 5-11), periovulatory (days 12-18), postovulatory (days 19-25), and perimenstrual (days 26-4).

Results: Data were analyzed with a goodness-of-fit chi 2. Between June 1991 and May 1992, 182 females (mean +/- SD age, 28.5 +/- 8.0 years) were surveyed. No significant differences were noted for use of oxygen, beta-adrenergic agonists, xanthines, or magnesium among members of the 4 menstrual groups. Intervention with corticosteroids was least in the postovulatory interval (y:n) 0.5:1 and greatest in the preovulatory interval 3.0:1 (alpha = .03) Presentations by menstrual interval were as follows: preovulatory, 36 (20%); periovulatory, 43 (24%); postovulatory, 18 (10%); and perimenstrual, 85 (46%) (alpha < .01).

Conclusions: Asthma presentations are least frequent when serum estradiol levels are at a sustained peak. We observed a 4-fold variation in asthma presentations during the perimenstrual interval, when serum estradiol levels decrease sharply after that prolonged peak. These findings suggest that monthly variations in serum estradiol levels may influence the severity of asthma in adult females.