Do hormonal contraceptives influence asthma severity?

Case reports suggest that exogenous sex hormones influence women's asthma symptoms. Hormone replacement therapy is associated with an increased risk of developing asthma (Troisi RJ et al, Am J Respir Crit Care Med 1995;152:1183-1188). This study aimed to explore the effect of hormonal contraceptives on asthma severity. A questionnaire was mailed to 891 asthmatic women aged 20 to 30 recruited from London general practices. It included questions about use of hormonal contraceptives, perceptions of their side effects, and the Asthma Quality of Life Questionnaire (AQLQ), a measure of seventy which gives a Normally distributed score after square root transformation; the higher the score, the more severe the symptoms and their effect on daily activities. Of the 461 respondents, 84% had ever taken hormonal contraceptives. 3.9% of these reported that hormonal contraceptives had made their asthma worse, and 2.1% that they had made their asthma better. There was no significant difference in asthma severity between current users and non-users of hormonal contraceptives. Mean AQLQ score in current users of hormonal contraceptives was 2.3 out of 10, and in non-users 2.5 out of 10 (mean square root AQLQ in current users 1.4, in non-users 1.5, 95% confidence intervals of the difference -0.2 to 0.03). Women who reported that hormonal contraceptives had made their asthma worse had more severe asthma than the remainder (mean square root AQLQ 1.7 vs. 1.5, 95% confidence intervals of difference 0.01 to 0.5). This represents only a very small difference in responses to the questionnaire so is likely to be clinically small. This study showed no important effect of hormonal contraceptives on asthma severity in women with mild asthma, but there may be a small effect in women with more severe asthma.