UK: The use of hormonal contraceptives by women of reproductive age reduces the risk of new-onset asthma, finds a recent study in the Journal of Allergy and Clinical Immunology.
Until puberty, asthma is more common in boys than in girls. After which, the risk of developing new-onset asthma and more severe disease increases in women. The reason behind is female sex hormones that largely explain these sex-related differences. Hormonal contraceptives suppress the production of endogenous hormones and thus may contribute to improving asthma outcomes. However, still there remains uncertainty on the role of sex steroids in the development of asthma in women. To clarify the same, Bright I. Nwaru, The University of Edinburgh, Edinburgh, United Kingdom, and colleagues sought to investigate whether hormonal contraceptive use, its subtypes, and duration of use were associated with new-onset asthma in reproductive-age women.
For the purpose, the researchers constructed an open cohort of 16- to 45-year-old women (N = 564,896) using the Optimum Patient Care Research Database, a UK national primary care database. They were then followed for up to 17 years (ie, January 1, 2000, to December 31, 2016). Multilevel Cox regression models was used to analyze the data.
At baseline, 26% of women were using any hormonal contraceptives.
Key findings of the study include:
During follow-up (3,597,146 person-years), 25,288 women developed asthma, an incidence rate of 7.0 per 1000 person-years.
Compared with nonuse, previous use of any hormonal contraceptives (hazard ratio [HR], 0.70), combined (HR, 0.70), and progestogen-only therapy (HR, 0.70) was associated with reduced risk of new-onset asthma.
For current use, the estimates were as follows: any (HR, 0.63), combined (HR, 0.65), and progestogen-only therapy (HR, 0.59).
Longer duration of use (1-2 years: HR, 0.83; 3-4 years: HR, 0.64; 5+ years: HR, 0.46) was associated with a lower risk of asthma onset than nonuse.
"Mechanistic investigations to uncover the biological processes for these observations are required. Clinical trials investigating the safety and effectiveness of hormonal contraceptives for primary prevention of asthma will be helpful to confirm these results," concluded the authors.
"Hormonal contraceptives and onset of asthma in reproductive-age women: Population-based cohort study," is published in the Journal of Allergy and Clinical Immunology.
DOI: https://www.jacionline.org/article/S0091-6749(20)30336-5/fulltext