Does asthma increase the risk of endometriosis?

A retrospective population-based study showed a linkage between asthma and endometriosis

Key Points

Highlights:

• Among the women of reproductive age, women with asthma are at a higher risk of endometriosis than women without asthma, although the mechanism behind this link is yet to be determined.

Importance:

• The relationship between asthma and endometriosis has been explored before; however, the evidence is limited and inconsistent. A nationwide large cohort study like this can provide some additional evidence for the association between these two diseases.

What’s done here?

• A nationwide population-based retrospective study of 7,337 women with asthma and 29,348 age-matched unaffected women to investigate whether women with asthma are at a higher risk of endometriosis compared to age-matched women without asthma.

Key results:

• Risk of endometriosis in women with asthma is 1.5 fold higher than the risk in the non-asthma group.
• Analysis by age group further revealed that the risk is higher in the age groups of 21-50 years.

Limitations of the study:

• Since this is a retrospective study, the information recorded in the database was limited. Detailed information on potential risk factors for endometriosis such as menstrual cycle length and intensity, lower body mass index, and age at menarche were not available for analysis.
• Also missing was the information on the severity and phenotype of both asthma and endometriosis for a deeper analysis of their correlation.

Lay Summary

Previous studies have shown an association between asthma and endometriosis but with inconsistency. It is still unclear whether women who have asthma are at a higher risk of endometriosis than women without asthma symptoms. Peng et al., conducted a large nationwide retrospective study, studied data from Taiwan National Health Insurance Database identified 7,337 women aged 12-50 years with newly diagnosed asthma or using asthma medications, and 29,348 age-matched women without asthma in an attempt to investigate the association between asthma and endometriosis. Results showed a 1.5 fold higher risk of endometriosis in women with asthma compared with those without asthma. More in-depth analysis by age groups revealed that patients with asthma were at a higher risk of endometriosis in age groups of 12-50 years.

The underlying mechanisms linking asthma and endometriosis, two virtually unrelated diseases, are yet to be determined. However, a significant amount of data suggests the involvement of immune system – in particular, overproduction of T helper cytokines – in both diseases. Inflammatory reactions and many inflammatory cytokines such as tumor necrosis factor alpha, interleukin 4 and 6, transforming growth factor beta, and vascular endothelial growth factor are all involved in the development of endometriosis and the inflammatory response and airway remodeling in asthmatic lungs. Another plausible connection between the two diseases is estrogen levels. Women with endometriosis tend to have higher levels of estrogen, which has also been associated with asthma onset. Despite these possible explanations suggested by multiple investigations, future studies are needed to explore the exact underlying mechanisms of the association between asthma and endometriosis.

Research Source: https://www.ncbi.nlm.nih.gov/pubmed/29229082